prosthodontic treatment for edentulous patients: complete dentures and implant-supported prostheses

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PROSTHODONTIC TREATMENT FOR EDENTULOUS PATIENTS: ISBN 0-323-02296-0 COMPLETE DENTURES AND IMPLANT-SUPPORTED PROSTHESES Copyright © 2004, Mosby, Inc. All rights reserved.

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The Publisher


This text is dedicated to the memory of Carl O.Boucher and to Judson Hickey. It is also dedi-

cated to Gunnar E. Carlsson, who continues to beour discipline’s best global ambassador. We

remain grateful to these extradordinary friendsfor their legacy of clinical scholarship in all its

aspects—education, research, and service.

George A. ZarbCharles L. Bolender

Steven E. EckertRhonda F. JacobAaron H. Fenton

Regina Mericske-Stern


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Tomas Albrektsson, MD, PhDProfessor and HeadDepartment of Biomaterials/Handicap ResearchInstitute of Surgical SciencesGöteborg UniversityGöteborg, Sweden

James D. Anderson, BSc, DDS, MScDProfessor of ProsthodonticsDepartment of Clinical SciencesFaculty of DentistryUniversity of TorontoToronto, Ontario, CanadaDirector, Craniofacial Prosthetic UnitToronto Sunnybrook Regional Cancer CentreToronto, Ontario, Canada

Nancy S. Arbree, DDS, MSAssociate Dean of Academic Affairs and ProfessorDepartment of AdministrationDepartment of Restorative DentistryTufts University School of Dental MedicineBoston, Massachusetts

Nikolai Attard, BChD, MScResearch Associate in ProsthodonticsFaculty of DentistryUniversity of TorontoToronto, Ontario, Canada

S. Ross Bryant, BSc, DDS, MSc, PhD, FRCD(C)Assistant ProfessorDepartment of Oral Health SciencesFaculty of DentistryUniversity of British ColumbiaVancouver, British Columbia, Canada

Ejvind Budtz-Jørgensen, DDS, DrOdontProfessorDepartment of Gerodontology and Removable

ProsthodonticsSection of Dental MedicineUniversity of GenevaGeneva, Switzerland

Alan B. Carr, DMD, MSProfessor of DentistryDepartment of Dental SpecialtiesMayo ClinicRochester, Minnesota

Douglas V. Chaytor, DDS, MS, MEdProfessor of Prosthodontics and Director of

Implant DentistryDepartment of Dental Clinical SciencesFaculty of DentistryDalhousie UniversityHalifax, Nova Scotia, Canada

Thuan Dao, DMD, MSc, Dip Prostho, PhDAssociate Professor of ProsthodonticsDepartment of Clinical SciencesFaculty of DentistryUniversity of TorontoToronto, Ontario, Canada

David M. Davis, PhD, FDSRCS (Eng), BDSSenior Lecturer and Honorary ConsultantDepartment of Prosthetic DentistryGuy’s, Kings, St. Thomas’ Dental InstituteLondon, England

Randa R. Diwan, BDS, PhDAssistant Professor of ProsthodonticsDepartment of Clinical SciencesFaculty of DentistryUniversity of TorontoToronto, Ontario, Canada

Contributors

vii

Emad S. Elsubeihi, BDS, MSc, Dip Prosth, PhDAssistant Professor of ProsthodonticsDepartment of Clinical SciencesFaculty of DentistryUniversity of TorontoToronto, Ontario, Canada

Mary P. Faine, MS, RDAssociate Professor EmeritusDepartment of ProsthodonticsSchool of DentistryUniversity of WashingtonSeattle, Washington

Yoav Finer, BSc, MSc, DMD, PhDResearch Associate in ProsthodonticsFaculty of DentistryUniversity of TorontoToronto, Ontario, Canada

Stig L. Karlsson, DDS, Odont DrProfessor and HeadDepartment of Prosthetic Dentistry and Dental

Materials ScienceFaculty of OdontologyGöteborg UniversityGöteborg, Sweden

Howard M. Landesman, DDS, MEdDean and ProfessorDepartment of Restorative DentistrySchool of DentistryUniversity of Colorado Health Sciences CenterDenver, Colorado

Michael I. MacEntee, LDS(I), Dip Prosth, FRCD(C)ProfessorDepartment of Oral Health SciencesUniversity of British ColumbiaVancouver, British Columbia, Canada

Kenneth Shay, DDS, MSAdjunct Associate Professor Department of Periodontics,

Prevention, and Geriatric DentistrySchool of Dentistry University of Michigan Ann Arbor, MichiganDirector of Geriatrics and Extended Care Service

LineVeterans Integrated Service Network #11U.S. Department of Veterans AffairsAnn Arbor, MichiganChief of the Section of Dental Geriatrics and

Affiliated Investigator of the Geriatrics Research, Education, and Clinical Center

Ann Arbor VA Healthcare SystemAnn Arbor, Michigan

Ann Wennerberg, LDS, PhDProfessorDepartment of Biomaterials/Handicap ResearchInstitute of Surgical SciencesGöteborg UniversityGöteborg, Sweden

John P. Zarb, DDS, MScClinical Assistant ProfessorDepartment of Restorative DentistrySchool of DentistryUniversity of Illinois at ChicagoChicago, Illinois

viii Contributors

We readily acknowledge our indebtedness to themany teachers and colleagues whose influence overthe years enabled us to both enjoy and grow in ourdiscipline. They, together with our secretaries, den-tal technicians, assistants, and photography person-nel, are the ones who really made this text possible.While they are too numerous to mention, they con-tinue to occupy a very special place in our hearts.

We are also grateful to past contibutors of thistext—notably, Gunnar Carlsson, Warner Kalk,Brien Lang, and Adrianne Schmitt.

Janet deWinter’s indispensable organizationalrole throughout the preparation of this text demandsa very special mention. Her diligence, tenacity,and, above all, her sense of humor continue to beappreciated.

Acknowledgments

xi


This twelfth edition of Prosthodontic Treatment forEdentulous Patients: Complete Dentures andImplant-Supported Prostheses seeks to assist den-tal students, dentists, and prosthodontists to makeinformed clinical decisions on the optimal manage-ment of edentulous patients. In correlating basicand behavioral sciences with technical skills, oursis an effort to balance the art of patient treatmentwith the physical and biological sciences involvedin prostheses fabrication. As active academic clini-cians, we continue to seek educational formats thatreconcile clinical research development with aprovocative pedagogic approach, one which neverloses sight of those who should benefit most fromour service—our patients or clients. Eachpatient/client in today’s practice is increasinglyaware of his or her right to efficacious and effectivedental therapy—hence this text, which provides abasis for a participatory partnership betweenpatient and dentist.

Impact of Clinical Research on Text’s Contentand Organization

The prosthodontic educational and research focushas evolved dramatically in recent years. Thisprogress resulted from three major initiatives. First,materials research has simplified impression-mak-ing protocols and denture relining techniques.Second, understanding of the role and particularlythe limitations of mechanical analogues for themasticatory system (i.e., articulators) has improved.Both of these lateral shifts in traditional prostho-dontic thinking have reduced the self-imposedtechnique burden that characterized denture fabri-cation in so many teaching institutions. The thirdinitiative, arguably the most compelling advance inthe management of edentulism, is implant prostho-dontics. Osseointegration has had a profound

impact on research and education in virtually all ofour clinical endeavors. As a result, the conse-quences of an aging edentulous environment or aterminal dentition have been more successfullyaddressed than ever before and many clinicianseven began to forecast the demise of the completedenture technique.

Optimal management of the edentulous predica-ment in virtually all its forms is now seen in abroader and more rational context, and there isclearly still a major ongoing role for complete den-ture therapy. In fact, the cost effectiveness, simplic-ity, efficacy, and effectiveness of this treatmenttechnique is virtually universal. However, long-term adverse sequelae of denture wearing or behav-ioral problems associated with the experience nolonger militate against our traditional efforts tocope with chronic and unsolvable clinical prob-lems. Implant support, be it of the fixed or over-denture variety, has enlarged and enriched thetherapeutic scope of a previously limited prostho-dontic paradigm. Furthermore, the conviction hasreemerged that basic principles of managing eden-tulism with complete denture fabrication are morenecessary than ever, since implant-supported treat-ment remains an outgrowth of traditional prostho-dontic protocols.

We have chosen an eclectic approach to thetopic and invited leading international educators tojoin us in articulating a strong case for understand-ing the edentulous predicament and its manage-ment. Our contributors remain committed tooptimal patient therapy but never lose sight of thetotal picture of the biological underpinnings ofthe edentulous milieu. This is where the twelfthedition’s thrust and novelty lies—an enriched andintegrated interpretation of what it means to beedentulous plus ways and means of addressing itsconsequences.

Preface

ix

C H A P T E R 1The Edentulous PredicamentGeorge A. Zarb

3

Loss of teeth causes adverse esthetic and biome-chanical sequelae, a predicament that is worsewhen the patient is completely edentulous and theentire periodontal ligament is lost. This leads todrastic changes in the potential support for anyplanned prosthesis because the residual ridges are apoor substitute for the missing periodontal liga-ment support. Until recently, prosthodontic therapyfocused mainly on the technical skills and clinicaljudgment expertise required to fabricate completedentures. Such knowledge helped nurture thedevelopment of new materials and knowledgeabout the relationships among esthetics, occlusion,and patients’ expectations. This, in turn, led tostrong convictions about the inherent merits ofcomplete denture treatment as dentists all over theworld presumed that their prosthodontic endeavorscould meet the gold standard of healthy intact den-titions. Most denture-wearing patients appear tohave benefited from this professional attitude, andcompromised oral health and esthetic appearancewere treated with extractions and complete denturereplacements. Regrettably, partial and entire denti-tions were sometimes needlessly sacrificedbecause the complete denture prescription oftenwas regarded as an alternative to, or a solution for,expensive periodontal and restorative therapy or anunesthetic dentition.

History supports the conviction that the skillsand ingenuity of complete denture fabrication havecontributed to a better quality of life for edentulouspatients. The passage of time allowed dentists torefine requisite technical skills and to develop sci-entifically based rationales for their use. As aresult, the complete denture treatment method

became, and indeed remains, an integral andimportant part of dental education and practice. Asa clinical teaching and professional activity, itdemands knowledge of applied basic sciences, bio-materials, occlusion, and esthetics. In fact, thebasis for most of the esthetic clues or decisions cur-rently used to improve the appearance of the natu-ral smile is an extension of complete dentureesthetic principles described in Part 3 of this text. Itprovides, above all else, the challenge and satisfac-tion of managing patients’ behavioral and age-related concerns and infirmities. In a public-healthcontext, complete denture prosthodontics remainsa relatively simple and inexpensive treatmentmethod, one that offers scope for virtual universalapplication. Nevertheless, it is not a panacea for theedentulous predicament (Plate 1-1).

Many health care professionals may forget thatalthough much research and attention have beendevoted to various forms of organ loss, such asmastectomies and hysterectomies, the edentulousstate has received relatively little psychologicalattention. Only a few authors have acknowledgedthe fact that it is a serious emotional life issue,albeit not a life-threatening one. Furthermore, out-come measures of health care treatment are onlypartially defined by technical excellence and arenot exclusively dentist determined. Patient percep-tions and responses to health care measures arenow regarded as an integral part of the clinicaldecision-making paradigm. It is therefore not sur-prising to note that many edentulous patients maybe described as unable to adapt to complete den-tures and are described as prosthetically “maladap-tive.” The term is used in this very specific context

in this text. We recognize the fact that such patientsperceive their denture-wearing experience as onethey cannot adapt to and that this can occur despitethe dentist’s skills and humanitarian concerns.Most dentists have been inclined to regard mal-adaptive denture wearing as a result of anatomicalor physiological causes. They have treated suchpatients with technique (and hopefully improved)modifications and with occasional surgicalattempts to enlarge the denture-bearing areas, evenif the latter measures proved to be palliative at best.These patients have also received a diagnosis andbeen dismissed as long-term complainers, and evenregarded as needing psychiatric help to cope withtheir maladaptation. Regrettably, the poignant con-sequences of such patients’ edentulous predica-ment were overlooked.

Clinical experience also has demonstrated thatpatients who are initially adaptive may indeedbecome maladaptive in the end. The reason is thatregressive, or degenerative, changes in the support-ing tissues and neuromuscular control militateagainst a continuum of an adaptive functional andesthetic experience. In fact, it must be admitted thatthe field of complete denture prosthodonticresearch has been characterized by a lack ofmethodological rigor in developing treatment out-come measures. As a result, practical, useful resultsfrom studies involving presumed determinants ofprosthetic success underscore the unpredictabilityof the complete denture service. Furthermore,quantifiable measurements of patients’ quality oflife after undergoing prosthodontic treatment arestill evolving.

IMPLANT PROSTHODONTICSThe objective of stabilizing replacement or pros-thetic dentitions with endosseous anchorage wentthrough numerous pioneering efforts. However,predictable time-dependent and morbidity-freedocumented outcomes proved to be elusive untilthe publication of Per Ingvar Brannemark’s seminalresearch on the technique of osseointegration. In1982 the Toronto Conference on Tissue IntegratedProstheses introduced the concept of inducing acontrolled interfacial osteogenesis between dentalimplant and host bone to the dental academic com-munity. The ability to safely locate alloplastic tooth

roots in the jawbones had finally become a reality.This was soon followed by an internationalresearch endorsement of the merits of the tech-nique for maladaptive edentulous patients whocould be treated with both implant-retained fixedor removable overdenture prostheses.

In subsequent publications implant prosthodon-tics was demonstrated as a valid treatment optionfor any adaptive denture-wearing patient as well.The proviso would, of course, be that the patientshould be willing to undergo the required prepros-thetic surgical procedures and incur the necessaryadditional expenses (Plate 1-2).

In preparing the twelfth edition of this text, wecontinue a half-century-old tradition of describingthe objectives and methods of making completedentures. We also have acknowledged the impact ofimplant-supported prostheses on clinical decisionmaking for managing the edentulous patient. Since1985 we have recognized the merits of an appliedscientific concept that can place the required num-ber of implants in all edentulous jaws to “cure” theedentulous predicament. Nevertheless, we assertthat this approach is clearly neither realistic nordesirable for all patients because traditional com-plete denture therapy has compellingly alreadyproven its merits. We also remain convinced thatthe clinical skills and judgment required to makecomplete dentures are essential to the osseointegra-tion technique. They are the two sides of the samecoin—the treatment currency that ensures optimalprosthodontics therapy for edentulous patients.

Because of these requirements, there is a needfor this text and its increasingly dual purpose.Today’s dentist can offer all edentulous patients twotreatment options: complete dentures or implant-retained or implant-supported prostheses (Table 1-1). Choosing the best form of therapy is not alwaysa clear-cut selection. The clinical decision shouldideally reflect the dentist’s knowledge of theselected treatment efficacy and effectiveness, aswell as a patient’s understanding of treatment risksand cost-effectiveness. Biological, functional, per-sonality, and fiscal considerations may precludeone option or the other. Admittedly, the completedenture option lends itself to more frequent appli-cation than a fixed implant-supported prostheticone, with costs being a major determinant of patientchoice. On the other hand, an implant-supported

4 Part One On Being Edentulous

overdenture appears to combine the best of bothoptions without either method’s restrictions.Functional and esthetic requirements are betterachieved and maintained, with the risk of time-dependent supporting tissue morbidity com-pellingly reduced. We therefore endorse theemerging clinical educational conviction that thecurrent standard of complete denture service forprosthodontically maladaptive patients should be

an implant-supported overdenture, particularly inthe mandible (Plate 1-3).

Osseointegration has ushered in a new scien-tific era for the management of edentulous patients.Reconciliation of the technique’s potential with theproven merits and ingenuity of complete denturefabrication can only improve dentists’ ability toresolve the edentulous predicament.

Chapter 1 The Edentulous Predicament 5

Table 1-1Treatment Options for Edentulous Patients

Diagnosis Evidence-Based Treatment Choices Burden of Illness

Edentulous in one or both arches A. Complete dentures or Functional esthetic and B. Implant-supported overdentures or perceptual consequences C. Implant-supported fixed prosthesis that are encountered on a

time-dependent and escalating basis

I. Without prior denture experience A, B, or CII. With an adaptive complete A, B, or C

denture experienceIII. With a current history of B or C

maladaptive denture-wearing experience

Treatment choice is influenced by both patient and dentist-mediated concerns. However, the impact of time-dependent regressive changes in theprosthodontic adaptive experience can be significantly reduced through an implant-supported/retained prosthesis.

C H A P T E R 2Biomechanics of the Edentulous StateGeorge A. Zarb

6

It would be inaccurate to state that disease factorssuch as caries or periodontal disease are the solecauses of patients’ edentulism. Some authors actu-ally argue that tooth loss does not bear even a closerelationship to the prevalence of dental disease.Although the latter viewpoint is probably equallyinaccurate, research has demonstrated that severalnondisease factors such as attitude, behavior, den-tal attendance, and characteristics of the health caresystem play an important role in the decision tobecome edentulous. In addition, a significant rela-tionship exists between the edentulous state andfiscal concerns usually associated with low occu-pational levels. It is therefore reasonable to con-clude that edentulism is due to variouscombinations of cultural, financial, and dental dis-ease attitudinal determinants, as well as to treat-ment received in the past.

The heterogeneous etiology of edentulism hasbeen tackled on several worldwide fronts by thedental profession, resulting in a reported decreasein the numbers of edentulous persons. More recentreviews of tooth loss and edentulism in variousparts of North American and European countriespredict that treatment of patients with completedentures will continue to decline in the future whilethe needs for partial tooth replacement will likelyincrease in the short term (see Chapter 3).Although these observations may suggest the needfor a reduced dental educational commitment totreatment of edentulous patients, some very com-pelling points must be underscored:

1. Documented evidence reveals that despite pro-jections of declining edentulism, the unmet

need for complete denture treatment will remainhigh.

2. Predictions from several surveys regarding ahealthy elderly population indicate that a highpercentage of older people will be edentulous.Therefore the effective demand for prostheticcare for this population is likely to increase.

3. The impact of longevity on edentulism has notbeen fully ascertained. Clinical experience sug-gests that the cumulative consequences of bio-logical and chronological aging will likelyconfront dentists with a significant increase inthe number of difficult edentulous mouths thatrequire treatment.

Irrespective of precise future population needs,the psychological and biomechanical conse-quences of tooth loss must never be overlooked.Most patients regard tooth loss as mutilation andas a strong incentive to seek dental care for thepreservation of a healthy dentition and sociallyacceptable appearance. Dentists, on the otherhand, also regard tooth loss as posing the addi-tional hazard of an even greater mutilation: thedestruction of part of the facial skeleton with theaccompanying distortion of soft tissue shape,together with varying degrees of functional dis-comfort (Figure 2-1).

The edentulous state represents a compromisein the integrity of the masticatory system. It isfrequently accompanied by adverse functionaland esthetic sequelae, which are varyingly per-ceived by the affected patient. Perceptions of theedentulous state may range from feelings ofinconvenience to feelings of severe handicap


Chapter 2 Biomechanics of the Edentulous State 7

A B

C DFigure 2-1 Three female patients—young in A and B, middle-aged in C and D, elderly inE and F—whose edentulous state is reflected in a range of circumoral changes that are moreovert as a result of both chronological and biological aging determinants. Note the effect ofwell-designed dentures on varying degrees of recovery of soft tissue support with pleasingesthetic treatment outcomes.

Continued


E FFigure 2-1 cont’d

because many regard total loss of teeth as equiv-alent to the loss of a body part. Consequently, therequired treatment addresses a range of biome-chanical problems that involve a wide range ofindividual tolerances and perceptions.

This text seeks to provide an understanding ofthe effects of the edentulous condition and todescribe its clinical management.

SUPPORT MECHANISM FOR THE NATURAL DENTITIONThe natural or prosthetic dentition and its support-ing mechanism are the most visible and frequentlymanaged parts of the masticatory system. The mas-ticatory system is made up of closely related mor-phological, functional, and behavioral components.Their interactions are affected by changes in themechanism of support for a dentition when naturalteeth are replaced by artificial or prosthetic ones.An understanding of the many subtleties associated

with the transition from a dentulous to an edentu-lous state demands a comparison of the mecha-nisms of both natural teeth and complete denturesupport (Figure 2-2).

The masticatory apparatus is involved in thetrituration of food. Direct responsibility for thistask falls on the teeth and their supporting tissues.The attachment of teeth in sockets is but one ofmany important modifications that took place dur-ing the period when the earliest mammals wereevolving from their reptilian predecessors. The suc-cess of this modification is indicated by the factthat it appears to have been rapidly adoptedthroughout the many different groups of emergingMammalia. Teeth function properly only if ade-quately supported, and this support is provided bythe periodontium, an organ composed of soft andhard connective tissues.

The periodontium attaches the teeth to thebone of the jaws, providing a resilient suspensoryapparatus resistant to functional forces. It allows

the teeth to adjust their position when under stress.The periodontium comprises hard connective tis-sues (cementum and bone) and soft connectivetissues (the periodontal ligament and the laminapropria of the gingiva), which are covered byepithelium. The periodontium is regarded as afunctional unit and is attached to the dentin bycementum and to the jawbone by the alveolarprocess. The periodontal ligament and the laminapropria maintain continuity between these two hardtissue components.

The periodontal ligament provides the meansby which force exerted on the tooth is transmittedto the bone that supports it. The two principal func-tions of the periodontium are support and posi-tional adjustment of the tooth, together with thesecondary and dependent function of sensory per-ception. The patient who needs complete denturetherapy is deprived of periodontal support, and theentire mechanism of functional load transmissionto the supporting tissues is altered.

The occlusal forces exerted on the teeth arecontrolled by the neuromuscular mechanisms ofthe masticatory system. Reflex mechanisms withreceptors in the muscles, tendons, joints, and peri-odontal structures regulate mandibular movements.Through normal function, the periodontal struc-tures in a healthy dentition undergo characteristicmechanical stress. The most prominent feature of

physiological occlusal forces is their intermittent,rhythmic, and dynamic nature.

The greatest forces acting on the teeth are nor-mally produced during mastication and deglutition,and they are essentially vertical in direction. Eachthrust is of short duration, and for most people,chewing is restricted to short periods during theday. Deglutition, on the other hand, occurs about500 times a day, and tooth contacts during swal-lowing are usually of longer duration than thoseoccurring during chewing. Loads of a lower orderbut longer duration are produced throughout theday by the tongue and circumoral musculature.These forces are predominantly in the horizontaldirection. Estimates of peak forces from thetongue, cheeks, and lips have been made, and lin-gual force appears to exceed buccolabial force dur-ing activity. During rest or inactive periods, thetotal forces may be of similar magnitude.

During mastication, biting forces are transmit-ted through the bolus to the opposing teeth whetheror not the teeth make contact. These forces increasesteadily (depending on the nature of the food frag-ment), reach a peak, and abruptly return to zero.The magnitude, rise time, and interval betweenthrusts differ among persons and depend on theconsistency of the food, the point in the chewingsequence, and the dental status. The direction of theforces is principally perpendicular to the occlusalplane in normal function, but the forward angula-tion of most natural teeth leads to the introductionof a horizontal component that tends to tilt the teethmedially as well as buccally or lingually. Upperincisors may be displaced labially with each bitingthrust, and these tooth movements probably causeproximal wear facets to develop.

In healthy dentitions, teeth are in occlusiononly during the functional movements of chewingand deglutition and during the movements associ-ated with parafunction (i.e., clenching and grind-ing). It has been calculated that the total time duringwhich the teeth are subjected to functional forces ofmastication and deglutition during an entire dayamounts to approximately 17.5 minutes (Box 2-1).More than half of this time is attributable to jaw-closing forces applied during deglutition.Therefore the total time and the range of forcesseem to be well within the tolerance level ofhealthy periodontal tissues. It must be emphasized


Functions and parafunctions

Dentulous state with aperiodontal ligament

mechanism of support

Edentulous state withouta periodontal ligamentmechanism of support

Behavioral/adaptiveresponses

Morphologic face heighttemporomandibular joints

Figure 2-2 Possible interactions among the variouscomponents of the masticatory system in the context ofa change in the mechanism of occlusal support.

that the collective forces acting on a prostheticocclusion are not likely to be controlled or attenu-ated as effectively as they appear to be by the natu-ral dentition. Consequently, the time-dependentresponse of complete denture tissue support willmanifest itself differently from those changesobserved in the natural dentition.

SUPPORT MECHANISM FOR COMPLETEDENTURESThe basic challenge in the treatment of edentulouspatients lies in the nature of the difference betweenthe ways natural teeth and their artificial replace-ments are supported. The previous section empha-

sized the superbly evolved quantitative and qualita-tive aspects of periodontal ligament support for afunctioning dentition. The approximate area of 45cm2 in each arch combines with viscoelasticity,sophisticated sensory mechanisms, and osteogene-sis regulation potential to cope with the diversedirections, magnitudes, and frequencies of differ-ent forms of occlusal loading. On the other hand,the unsuitability of the tissues supporting completedentures for load-bearing function must be imme-diately recognized because the mucous membraneis forced to serve an identical purpose as the peri-odontal ligaments.

Mucosal Support and Masticatory Loads

The area of mucosa available to receive the loadfrom complete dentures is limited when comparedwith the corresponding areas of support availablefor natural dentitions. Researchers have computedthe mean denture-bearing area to be 22.96 cm2 inthe edentulous maxillae and approximately 12.25cm2 in an edentulous mandible. These figures, par-ticularly the mandibular ones, are in dramatic con-trast with the 45-cm2 area of periodontal ligamentavailable in each dental arch (Figure 2-3). It alsomust be remembered that the denture-bearing area(basal seat) becomes progressively smaller asresidual ridges resorb. Furthermore, the mucosademonstrates little tolerance or adaptability to den-ture wearing. This minimal tolerance can bereduced still further by the presence of systemicdiseases such as anemia, hypertension, or diabetes,as well as nutritional deficiencies. In fact, any dis-turbance of the normal metabolic processes maylower the upper limit of mucosal tolerance and ini-tiate inflammation.

Masticatory loads are much smaller than thosethat can be produced by conscious effort and are inthe region of 44 lb (20 kg) for the natural teeth.Maximum forces of 13 to 16 lb (6 to 8 kg) duringchewing have been recorded with complete den-tures, but the average loads are probably much lessthan these. In fact, maximal bite forces appearto be five to six times less for complete denturewearers than for persons with natural teeth.Moreover, the forces required for chewing varywith the type of food being chewed. Patientswith prostheses frequently limit the loading of


Calculation of Total Time during24 Hours When Direct FunctionalOcclusal Force Is Applied to the

Periodontal Tissues

ChewingActual chewing time 450 sec

per mealFour meals per day 1800 secOne chewing stroke 1800 strokes

per secDuration of each stroke 0.3 secTotal chewing forces 540 sec (9 min)

per day

SwallowingMealsDuration of one 1 sec

deglutitionDuring chewing, 30 sec (0.5 min)

three deglutitions per min, one third with occlusal force

Between mealsDaytime: 25/hr (16 hr) 400 sec (6.6 min)Nighttime: 10/hr (8 hr) 80 sec (1.3 min)

Total 1050 sec = 17.5 min

From Graf H: Dent Clin North Am 13:659-665, 1969.

Box 2-1

supporting tissues by selecting food that does notrequire masticatory effort exceeding their tissuetolerance.

Residual Ridge

The residual ridge consists of denture-bearingmucosa, the submucosa and periosteum, and theunderlying residual alveolar bone. Residual bone isthat bone of the alveolar process that remains afterteeth are lost. When the alveolar process is madeedentulous by loss of teeth, the alveoli that con-tained the roots of the teeth fill in with new bone.

This alveolar process becomes the residual ridge,which is the foundation for dentures. A variety ofchanges occur in the residual bone after toothextraction and use of complete dentures. Alveolarbone supporting natural teeth receives tensile loadsthrough a large area of periodontal ligament,whereas the edentulous residual ridge receives ver-tical, diagonal, and horizontal loads applied by adenture with a surface area much smaller than thetotal area of the periodontal ligaments of all thenatural teeth that had been present. Clinical experi-ence underscores the frequently remarkable adap-tive range of the masticatory system. On the other


Figure 2-3 The area of periodontal ligament supporting an intact natural dentition hasbeen computed to be approximately 45 cm2 in each arch (A). When teeth are lost, and apatient becomes edentulous (B), aspects of support for an occlusion are severely compro-mised both qualitatively and quantitatively.

A

B

hand, edentulous patients demonstrate very littleadaptation of the supporting tissues to functionalrequirement.

One of the few firm facts relating to edentulouspatients is that wearing dentures is almost invariablyaccompanied by an undesirable and irreversible boneloss. The magnitude of this loss is extremely variable,and little is known about which factors are mostimportant for the observed variations (Figure 2-4).Two concepts have been advanced concerning theinevitable loss of residual bone: One contends that asa direct consequence of loss of the periodontal struc-tures, variable progressive bone reduction occurs.The other maintains that residual bone loss is not anecessary consequence of tooth removal but dependson a series of poorly understood factors.

Clinical experience strongly suggests a definiterelationship between healthy periodontal ligamentsand maintained integrity of alveolar bone, thus thedentist’s commitment to the preservation and protec-tion of any remaining teeth to minimize or avoidadvanced residual ridge reduction. The tissue supportfor complete dentures is conspicuously limited inboth its adaptive ability and inherent capability of

simulating the role of the periodontium. This com-promised support is further complicated becausecomplete dentures move in relation to the underlyingbone during function. This movement is related to theresiliency of the supporting mucosa and the inherentinstability of the dentures during functional and para-functional movements. Almost all “principles” ofcomplete denture construction have been formulatedto minimize the forces transmitted to the supportingstructures or to decrease the movement of the pros-theses in relation to them. Because movement of den-ture bases on their basal seats can cause tissuedamage, it is tempting to conclude that the particu-larly recurrent movements of removable prosthesesduring parafunctional movements may be a majorfactor contributing to residual ridge reduction.

There are two physical factors involved in den-ture retention that are under the control of the den-tist and are technique driven. One is the maximalextension of the denture base; the other is the max-imal intimate contact of the denture base and itsbasal seat.

Muscular factors can be used to increase reten-tion (and stability) of dentures. In fact, the buccina-


Figure 2-4 A, Panoramic radiographs showing the jaws of four edentulous patients.Residual ridge reduction has occurred to variable extents.

A

Continued

tor, the orbicularis oris, and the intrinsic and extrin-sic muscles of the tongue are key muscles that thedentist harnesses to achieve this objective by meansof impression techniques. Furthermore, the designof the labial, buccal, and lingual polished surfacesof the denture and the form of the dental arch are

considered in balancing the forces generated by thetongue and perioral musculature.

As the form and size of the denture-supportingtissues (the basal seat) change, harnessing muscu-lar forces in complete denture design becomes par-ticularly important for denture retention.


Figure 2-4 cont’d B, The rate of ridge reduction is quantified between two stages ofobservation (a and b). The difference between a and b represents the reduction in height of thealveolar ridges between stages of observation. The shaded area denotes resorption. C is areproduction of progressive residual ridge reduction as reflected in a composite of five differentlateral cephalograms. (B, Modified from Tallgren A: J Prosthet Dent 27:120-132, 1972.)

B

C

Psychological Effect on Retention

The dentures may have an adverse psychologicaleffect on some patients, and the nervous influencesthat result may affect salivary secretions that affectretention. Eventually, most patients seem to acquirean ability to retain their dentures by means of theiroral muscle control. This muscular stabilization ofdentures is probably also accompanied by a reduc-tion in the actual physical forces used in retainingtheir dentures. Clearly, the physical forces of reten-tion can be improved and reestablished, up to apoint, by careful and frequent attention to the den-ture status. Periodic inspection, including reliningprocedures, will help prolong the usefulness of theprosthesis.

OCCLUSION: FUNCTIONAL ANDPARAFUNCTIONAL CONSIDERATIONS

The masticatory system appears to operate best inan environment of continuing functional equilib-

rium. This equilibrium depends on the interactionsof the many components represented in Figure 2-2.The substitution of a complete denture for theteeth/periodontium mechanism alters this equilib-rium. An analysis of this alteration is the basis forunderstanding the significance of the edentulousstate.

The primary components of human dentalocclusion are (1) the dentition, (2) the neuromus-cular system, and (3) the craniofacial structures.The development and maturation of these compo-nents are interrelated so that growth, adaptation,and change actively participate in the develop-ment of an adult occlusion. Dentition develop-ment is characterized by a period of dentalalveolar and craniofacial adaptability (Figure 2-5),which is also a time when motor skills and neuro-muscular learning are developing. Clinical treat-ment at this time may take advantage of suchresponsive adaptive mechanisms; for example,teeth can be guided into their correct alignment byorthodontic treatment.


Developing dentition

Healthy adult dentition

Deteriorating adult dentition

The edentolus state

1. Extensive sensory input2. Development of motor skills and neuromuscular learning3. Dental, alveolar, craniofacial adaptability

1. Dental adaptation (wearing, drifting, extrusion)2. Bone adaptation is reparative3. Learned protective reflexes and functional adaptation

1. Partial edentulism2. Periodontal disease3. Diminished dental reflex adaptation4. Risk of maladaptive prosthesis- wearing experience

1. Residual ridge reduction2. Compromised reflex adaptability3. Possible increase in parafunctional movements4. Increased risk of maladaptive denture-wearing experience

Figure 2-5 Development and adaptation of the occlusion.

In a healthy adult dentition, dental adaptivemechanisms are restricted to wear, extrusion, anddrifting of teeth. Bony adaptations are essentially ofa reparative nature and are slow in their operation.Protective reflexes are learned so one can avoid painand inefficiency of the masticatory system. If andwhen an adult dentition begins to deteriorate, thedentist resorts to fixed or removable prosthodontictherapy in attempts to maintain a functional occlusalequilibrium. This period is characterized by greatlydiminished dental and reflex adaptation and by boneresorption. Obviously, the presence of tooth loss anddisease and the depletion of reparative processespose a major prosthodontic problem. Finally, in theedentulous state, there are few natural adaptivemechanisms left. The prosthesis rests on tissues thatwill change progressively and irreversibly, and theartificial occlusion serves in an environment charac-terized by constant change that is mainly regressive.

Design and fabrication of prosthetic occlusionshave led to fascinating controversies. Dental occlu-sion was studied first in the field of complete den-tures and then in other disciplines. Early workersencountered enormous mechanical difficulties inconstructing reasonably well-fitting dentures thatwould be both durable and esthetic. Inevitably,these dentists had to be mechanically minded.Because anatomy was the first of the biologicalbasic sciences to be related to prosthodonticservices, its application dominated prosthodonticprotocol. Later, histology, physiology, and bio-engineering were recognized as having essentialroles in the treatment of edentulous patients. Theemphasis on and application of these basic scienceslifted prosthodontics from the early mechanical artto the applied clinical science it is today.

The modern complete denture service is char-acterized by an integration of biological informa-tion with instrumentation materials and clinicaltechniques. Complete dentures are designed sothat their occlusal surfaces permit multidirec-tional contact movements of the mandible.Orofacial and tongue muscles play an importantrole in retaining and stabilizing complete den-tures. This is accomplished by arrangement of theartificial teeth to occupy a “neutral zone” in theedentulous mouth so the teeth will occupy aspace determined by the functional balance of theorofacial and tongue musculature.

Function: Mastication and Other Mandibular Movements

Mastication consists of a rhythmic separation andapposition of the jaws and involves biophysical andbiochemical processes, including the use of thelips, teeth, cheeks, tongue, palate, and all the oralstructures to prepare food for swallowing. Duringmasticatory movements, the tongue and cheekmuscles play an essential role in keeping the foodbolus between the occlusal surfaces of the teeth.The control of mastication within the narrow limitsof tolerance of the mouth requires considerablesensory information because deviations from thenormal path of mandibular movement can injurethe tongue, buccal mucosa, and even the teeth andtheir supporting tissues. Here again, the reader’sattention must be drawn to the importance of theplacement of the arch of artificial teeth in the mak-ing of complete dentures. The teeth must be placedwithin the confines of a functional balance of themusculature involved in controlling the food bolusbetween the occlusal surfaces of the teeth.

The comminution of much twentieth-centuryfood does not demand a vigorous masticatory per-formance. Mastication has other functions, how-ever. It is necessary for a full appreciation of theflavor of foods and is therefore indirectly involvedin the excitation of salivary and gastric secretions.Because mastication results in the mixing of foodwith saliva, it facilitates not only the swallowingbut the digestion of carbohydrates by amylase aswell. Amylase activity, of minor importance whilefood is in the mouth, is responsible for the contin-uation of carbohydrate digestion in the stomach,and this phase can account for as much as 60% ofthe total carbohydrate digestion. Although noreports of quantitative tests on the importance ofchewing on the various stages of digestion haveappeared, it has been concluded that masticatoryefficiency as low as 25% is adequate for completedigestion of foods. Other investigators have notedthat loss of teeth can lead to a diminished mastica-tory efficiency. Patients do not compensate for thesmaller number of teeth by more prolonged or alarger number of chewing strokes—they merelyswallow larger food particles. Although it appearsthat the importance of a good dentition or denturein promoting digestion and use of food has not


been adequately demonstrated, clinical experiencesuggests that the quality of the prosthetic servicemay have a direct bearing on the denture wearer’smasticatory performance.

As mentioned previously, the maximal biteforce in denture wearers is five to six times lessthan in edentulous subjects. Edentulous patientsare clearly handicapped in masticatory function,and even clinically satisfactory complete denturesare a poor substitute for natural teeth.

The results of studies of mandibular movementpatterns of complete denture patients indicate thatthese movements are similar in denture-wearingpatients and persons with natural teeth. Thereforetreatment of partially edentulous and edentulouspatients might improve their chewing efficiencyand masticatory muscle activity, which would beaccompanied by a decreased duration of the occlu-sion phase and contribute to a lessening of elevatormuscle activity.

Chewing occurs chiefly in the premolar andmolar regions, and both right and left sides are usedto about the same extent. The position of the foodbolus during mastication is dependent on the consis-tency of the food, and the tougher the consistencythe greater is the person’s preference for using thepremolar region. The latter observation is apparenteven in patients who have worn bilateral, soft-tis-sue–supported, mandibular partial dentures oppos-ing complete upper dentures. There is an obviousadvantage that the patient accrues with the replace-ment of missing premolar and molar segments, andthese patients do not chew predominantly in the seg-ments where natural teeth are present.

The pronounced differences between personswith natural teeth and patients with complete den-tures are conspicuous in this functional context:(1) the mucosal mechanism of support as opposedto support by the periodontium; (2) the movementsof the dentures during mastication; (3) the progres-sive changes in maxillomandibular relations andthe eventual migration of dentures; and (4) the dif-ferent physical stimuli to the sensor motor systems.

The denture-bearing tissues are constantlyexposed to the frictional contact of the overlyingdenture bases. Dentures move during masticationbecause of the dislodging forces of the surroundingmusculature. These movements manifest them-selves as displacing, lifting, sliding, tilting, or

rotating of the dentures. Furthermore, opposingtooth contacts occur with both natural and artificialteeth during function and parafunction when thepatient is both awake and asleep.

Apparently, tissue displacement beneath thedenture base results in tilting of the dentures andtooth contacts on the nonchewing side. In addition,occlusal pressure on the dentures displaces soft tis-sues of the basal seat and allows the dentures tomove closer to the supporting bone. This change ofposition under pressure induces a change in therelationship of the teeth to each other.

Parafunctional Considerations

Nonfunctional or parafunctional habits involvingrepeated or sustained occlusion of the teeth can beharmful to the teeth or other components of the mas-ticatory system. There are no compelling epidemio-logical studies about the incidence of parafunctionalocclusal stress in populations with natural dentitionor with dentures. Nevertheless, clinical experienceindicates that teeth clenching is common and is a fre-quent cause of the complaint of soreness of the den-ture-bearing mucosa. In the denture wearer,parafunctional habits can cause additional loading onthe denture-bearing tissues (Table 2-1). The unsuit-ability of the mechanism of denture support hasalready been recognized and described.

The neurophysiological basis underlyingbruxism has been studied experimentally both inanimals and in human beings, and part of itsmechanism can be explained by an increase in thetonic activity in the jaw muscles. It is a very com-plex area of research and has been shown toresult from psychosocial factors (such as stress oranxiety) or to be a reaction to strong emotions(e.g., anger, frustration). It may be associatedwith specific medical conditions (oral tardivedyskinesia, Parkinson’s disease) or with sleepparasomnia (e.g., bruxism [tooth grinding], rapideye movement [REM] behavior disorders, oro-mandibular myoclonus) or sleep disorders(apnea). It may also be found concomitantly withcertain intraoral conditions such as pain, orallesions, xerostomia, and discomfort with prosthe-ses or occlusion.

The initial discomfort associated with wearingnew dentures is known to evoke unusual patterns of


behavior in the surrounding musculature.Frequently, the complaint of a sore tongue isrelated to a habit of thrusting the tongue against thedenture. The patient usually is unaware of thecausal relationship between the painful tongue andits contact with the teeth. Similarly, patients tend toocclude the teeth of new dentures frequently atfirst—perhaps to strengthen confidence in reten-tion until the surrounding muscles become accus-tomed or to provide some accommodation in thechewing pattern—and experimental closure of theteeth is part of the process of adaptation. A strongresponse of the lower lip and mentalis muscle hasbeen observed electromyographically in long-termcomplete denture wearers with impaired retentionand stability of the lower denture. It is feasible andprobable that the tentative occlusal contacts result-ing may trigger the development of habitual non-functional occlusion.

The mechanism whereby pressure causes sore-ness of the mucous membrane is probably relatedto an interruption or a diminution of the blood flowin the small blood vessels in the tissues. These vas-cular changes could very well upset the metabolismof the involved tissues. The relationship betweenparafunction and residual ridge reduction has notbeen investigated. Nevertheless, it is tempting toinclude parafunction as a possible significant pros-thetic variable that contributes to the magnitude ofridge reduction.

CHANGES IN MORPHOLOGICALFACE HEIGHT AND THETEMPOROMANDIBULAR JOINTSThe terminal stage of skeletal growth is usuallyaccepted as being at 20 to 25 years of age. It is also

recognized that growth and remodeling of the bonyskeleton continue well into adult life and that suchgrowth accounts for dimensional changes in theadult facial skeleton. It has been reported that mor-phological face height increases with age in per-sons possessing an intact or relatively intactdentition. Nevertheless, a premature reduction inmorphological face height occurs with attrition orabrasion of teeth. This reduction is even moreconspicuous in edentulous and complete denture-wearing patients. Figure 2-5 presents a flow chartof the presumed range of changes that take placeduring the development and adaptation of theocclusion. It also serves to underscore theresiliency of the masticatory system as it adapts tochanges associated with disease and attendantteeth loss.

Maxillomandibular morphological changestake place slowly over a period of years and dependon the balance of osteoblastic and osteoclasticactivity. The articular surfaces of the temporo-mandibular joints (TMJs) are also involved, and atthese sites, growth and remodeling are mediatedthrough the proliferative activity of the articularcartilages. In the facial skeleton, any dimensionalchanges in morphological face height or the jaw-bones because of the loss of teeth are inevitablytransmitted to the TMJs. It is not surprising, then,that these articular surfaces undergo a slow butcontinuous remodeling throughout life. Suchremodeling is probably the means whereby the con-gruity of the opposing articular surfaces is main-tained, even in the presence of dimensional orfunctional changes in other parts of the facialskeleton.

The reduction of the residual ridges under com-plete dentures and the accompanying reduction in


Table 2-1Direction, Duration, and Magnitude of the Forces Generated during Function and Parafunction

Force Generated

Direction Duration and Magnitude

Mastication Mainly vertical Intermittent and lightDiurnal only

Parafunction Frequently horizontal as well as vertical Prolonged, possibly excessiveBoth diurnal and nocturnal

vertical dimension of occlusion tend to causereduction in total face height and a resultantmandibular prognathism. In fact, in complete den-ture wearers, the mean reduction in height of themandibular process measured in the anterior regionmay be approximately four times greater than themean reduction occurring in the maxillary process(Figure 2-6). Furthermore, longitudinal studiessupport the hypothesis that the vertical dimensionof rest position of the jaws (which is allegedly notteeth related) does not remain stable and canchange over time. This clinical fact contradicts thepreviously popular and convenient concept of astable vertical dimension of rest position through-out the patient’s lifetime.

Obviously, complete dentures constructed toconform to clinical decisions regarding jaw-relation records are placed in an environment thatretains considerable potential for change. Therefore

concepts of reproducible and relatively unchange-able mandibular border movements may not applyas closely to edentulous patients as they do to per-sons with a healthy dentition. Practical methodsthat recognize these facts are described in subse-quent chapters. Nevertheless, it must be reempha-sized that the recognition that jaw relations are notimmutable does not invalidate the clinical require-ment of using a centric relation record as a startingpoint for developing a prosthetic occlusion.

Centric Relation

Concepts of centric relation of the upper and lowerjaws have been a dominant factor in prosthodonticthinking on occlusion. Centric relation is definedas the most posterior position of the mandible rela-tive to the maxillae at the established verticaldimension. Centric relation coincides with a repro-


Figure 2-6 A, A 67-year-old man who has worn unserviced dentures for almost 20 years.Notice the reduction in total face height and the increased mandibular prognathism. B, Contrast his appearance with that of a 24-year-old woman who recently acquired complete dentures but posed for this picture with her dentures out of her mouth.

A B

ducible posterior hinge position of the mandible,and it may be recorded with a high degree of accu-racy. It is regarded as a very useful reference orstarting point for establishing jaw relationships inany prosthodontics treatment, particularly in com-plete denture fabrication.

The use of centric relation has its physiologicaljustification as well. In the vast majority ofpatients, unconscious swallowing is carried outwith the mandible at or near the centric relationposition. The unconscious or reflex swallow isimportant in the developing dentition. The act andfrequency of swallowing are important influencesin the movement of teeth within the muscle matrix,and this movement determines the tooth positionand occlusal relations. The erupting teeth areguided into occlusion by the surrounding muscula-ture (the muscle matrix), whereas the position ofthe mandible is determined by its location in spaceduring the act of unconscious swallowing. The con-tacts of inclined planes of the teeth aid in the align-ment of the erupting dentition. During thisdevelopmental period most of the mandibularactivities have not yet been learned, at least not intheir adult form.

The occlusion of complete dentures is designedto harmonize with the primitive and uncondi-tioned reflex of the patient’s unconscious swallow.Tooth contacts and mandibular bracing against themaxillae occur during swallowing by completedenture patients. This suggests that complete den-ture occlusions must be compatible with the forcesdeveloped during deglutition to prevent disharmo-nious occlusal contacts that could cause traumato the basal seat of dentures. During swallowing,the mandible is close to, in centric relation, or theposition of maximum mandibular retrusion rela-tive to the maxillae at the established verticaldimension of occlusion. It is conceded, neverthe-less, that most functional natural tooth contactsoccur in a mandibular position anterior to centricrelation, a position referred to as centricocclusion.

However, in complete denture prosthodontics,the position of planned maximum intercuspationof teeth is established to coincide with thepatient’s centric relation. The coincidence of cen-tric relation and centric occlusion is consequentlyreferred to as centric relation occlusion (CRO).

The centric occlusion position occupied by themandible in the dentate patient cannot be regis-tered with sufficient accuracy when the patientbecomes edentulous. Consequently, clinical expe-rience suggests that the recording of centric rela-tion is the starting point in the design of anartificial occlusion.

Nevertheless, one must realize that an integralpart of the definition of centric relation—at theestablished vertical dimension—has potential forchange. This change is brought about by alterationsin denture-supporting tissues and facial height, aswell as by morphological changes in the TMJs. Anappreciation for the dynamic nature of centric rela-tion in denture-wearing patients, particularly in anaging context, recognizes the changing functionalrequirements of the masticatory system. It alsoaccounts for different concepts and techniques ofdesign of occlusions.

Temporomandibular Joint Changes

Numerous descriptions of TMJ function haveevolved because of several research methods. Thebasic physiological relationship among thecondyles, the disks, and their glenoid fossaeappears to be maintained during maximal occlusalcontacts and during all movements guided byocclusal elements. It seems logical that in the treat-ment with complete dentures, the dentist shouldseek to maintain or restore this basic physiologicalrelation. The border movements of the mandibleare reproducible, and all other movements takeplace within the confines of the classic “envelopesof motion.” Researchers have concluded that thepassive hinge movement tends to have a constantand definite rotational and reproducible character.The reproducibility of the posterior border path isof tremendous practical significance in the treat-ment of patients undergoing prosthodontics, butthis reproducibility has been established in healthyyoung persons only. It must be recalled that mostedentulous patients have experienced a spectrum ofvariations on the theme of a mutilated dentition.In the course of such periods, pathological or adap-tive structural alterations or changes of the TMJsmay have occurred. These investigations are mainlybased on autopsy studies; thus the results are onlyspeculative.


It has also been reported that impaired dentalefficiency resulting from partial tooth loss andabsence of or incorrect prosthodontic treatment caninfluence the outcome of temporomandibular dis-orders (TMDs). This is thought to be particularlythe case when arthritic or degenerative changeshave occurred. The hypothesis has been advancedthat degenerative joint disease is a process ratherthan a disease entity. The process involves jointchanges that cause an imbalance in adaptation anda degeneration that results from alterations in func-tional demands on or the functional capacity of thejoints. However, because the onset of degenerativeconditions is frequently encountered in the adultyears, and because the greater number of denturewearers are older patients who are edentulous, thetreatment of such conditions is very much the con-cern of the dentist. Clinical experience and long-term studies indicate that a combination ofadjunctive prosthodontic protocols, and appropri-ate pharmacological and supportive therapy, areusually adequate to provide these patients withcomfort.

One of the difficulties in managing degenera-tive joint involvement is achieving joint rest.Because of the necessity for mastication and for theavoidance of parafunctional habits, voluntary oreven enforced rest may be difficult to achieve.

ESTHETIC, BEHAVIORAL, AND ADAPTIVE RESPONSESEsthetic Changes

There is little doubt that tooth loss can adverselyaffect a person’s appearance. Patients seek dentaltreatment for both functional and esthetic or cos-metic reasons, and dentists have been successful inrestoring or improving many a patient’s appearance.

Box 2-2 lists some of the conspicuous and clin-ically challenging features that frequently accom-pany the edentulous state. It must be emphasizedthat one or more of these items are also frequentlyencountered in persons with intact dentitionsbecause the compromised facial support of the eden-tulous state is not the exclusive cause of the mor-phological changes. In clinical practice, wefrequently encounter situations in which factorssuch as a patient’s weight loss, age, and heavy tooth

attrition manifest orofacial changes suggestive ofcompromised, or absent, dental support for theoverlying tissues. Some patients fail to appreciatethe fact that aspects of their facial appearance forwhich they are seeking a solution are merely mag-nified perceptions or are unrelated to their edentu-lous predicament. In recent years, numerous plasticsurgical interventions, which address facial cos-metic issues, have been popularized. One or moreof the available techniques may provide the sort ofsolution desired by the patient, and which is not thedentist’s remit. In such a context, the dentist mustbe prepared to guide the patient with a referral toan experienced specialist in the field of cosmeticsurgery.

These patients can cause the dentist considerablefrustration. Experience suggests that early communi-cation about a patient’s cosmetic expectations shouldbe established to avoid later misunderstanding.Patients should be asked to provide photographs oftheir preedentulous appearance, and relevant detailsfrom these photographs should be carefully analyzedand discussed with the patient. If this is not possible,photographs of siblings or of children who resemblethe patient may be helpful.

Careful explanation of prosthodontic objectivesand methods is the basis for good communicationwith all patients. This is the case when the patient’scosmetic desires exceed morphological or func-tional realities.

Behavioral and Adaptive Responses

The process whereby an edentulous patient canaccept and use complete dentures is complex. It


Morphological ChangesAssociated with the

Edentulous State

1. Deepening of nasolabial groove2. Loss of labiodental angle3. Decrease in horizontal labial angle4. Narrowing of lips5. Increase in columella-philtral angle6. Prognathic appearance

Box 2-2

requires adaptation of learning, muscular skill, andmotivation and is related to the patient’s expecta-tions. The patient’s ability and willingness to acceptand learn to use the dentures ultimately determinethe degree of success of clinical treatment. Helpinga patient adapt to complete dentures can be one ofthe most difficult but also one of the most reward-ing aspects of clinical dentistry. The presence ofinanimate foreign objects (dentures) in an edentu-lous mouth is bound to elicit different stimuli to thesensorimotor system, which in turn influences thecyclic masticatory stroke pattern. Both exterocep-tors and proprioceptors are probably affected by thesize, shape, position, pressure from, and mobilityof the prostheses. The exact role and relativeimportance of mucosal stimuli in the control of jawmovements need clarification, but it has beenclearly demonstrated that control of dentures bymuscle activity is reduced if surface anesthetic isapplied to the oral mucous membrane. Although itis tempting to assume that there is a correlationbetween oral stereognosis and purposeful oralmotor activity, the results of most investigations upto now indicate that successful denture wearingpossibly involves factors other than oral perceptionand oral performance. It therefore remains verydifficult to apply learning theory concepts to thepresumed process, which a patient undergoes whilelearning to wear complete dentures.

Learning means the acquisition of a new activ-ity or change of an existing one. Muscular skillrefers to the capacity to coordinate muscular activ-ity to execute movement. The acceptance of com-plete dentures is accompanied by a process ofhabituation, which is defined as a “gradual diminu-tion of responses to continued or repeated stimuli.”The tactile stimuli that arise from the contact of theprosthesis with the richly innervated oral cavity areprobably ignored after a short time. Because eachstage of the decrease in response is related to thememory trace of the previous application of thestimulus, storage of information from the immedi-ate past is an integral part of habituation. Difficultyin the storage of information of this type accompa-nies older age, and this is the reason why olderpatients have difficulties becoming comfortablewith dentures. Furthermore, stimuli must be spe-cific and identical to achieve habituation. This iswhat probably prevents the transfer of habituation

evoked by an old familiar denture to a new denture,which inevitably gives rise to a new range of stim-uli, and several clinical applications of adaptationproblems may be encountered. The patient who hasworn a complete upper denture opposing a few nat-ural anterior mandibular teeth usually will find acomplete lower denture difficult to adapt to. Such apatient has to contend with altered size and orien-tation of the tongue. The tongue frequentlyresponds to the loss of posterior teeth and alveolarbone by changing size to bring its lateral bordersinto contact with the buccal mucosa. The insertionof a new denture introduces a new environment forthe tongue, and the intrinsic tongue musculaturereorganizes the shape of the tongue to conform tothe altered space available. A degree of retrainingtongue activity also takes place. Furthermore, theposterior residual ridges are exposed to new sensa-tions from the overlying prosthesis. Pressurestransferred through the denture base replace tactilestimuli from the tongue and frictional contact withfood. In addition, control of the upper denture fre-quently must be unlearned because the posteriorpart of the tongue is no longer required to counterthe dislodging effect on the denture produced bythe remaining mandibular dentition.

Edentulous patients expect, and are expected, toadapt to the dentures more or less instantaneously.That adaptation must take place in the context ofthe patient’s oral, systemic, emotional, and psycho-logical states.

The facility for learning and coordinationappears to diminish with age. Advancing agetends to be accompanied by progressive atrophyof elements in the cerebral cortex, and a conse-quent loss in the facility of coordination occurs.Certainly, patient motivation dictates the speedwith which adaptation to dentures takes place. Itis imperative that the dentist determine thepatient’s motivation in seeking treatment, culti-vate this motivation, and seek to foster it if it islacking or absent.

A distinct need exists for dentists to be able tounderstand a patient’s motivation in seekingprosthodontic care and to identify problems beforestarting treatment. Emotional factors are known toplay a significant role in the etiology of dentalproblems. The interview and clinical examinationare obvious ways to observe the patient and form


the best treatment relationship. Successful manage-ment begins with identification of anticipated diffi-culties before treatment starts and with carefulplanning to meet specific needs and problems.Dentists must train themselves to reassure thepatient, to perceive the patient’s wishes, and toknow how and when to limit the patient’s expecta-tions. An essential accompaniment of a denturedesign that is physically compatible with the oralcomplex is a good interpersonal relationshipbetween dentist and patient. It is up to the dentist toexplore the patient’s symptoms and tensions. Theway the patient handles other illnesses and dentalsituations will aid in the prediction of future prob-lems. It has been observed that the secure patientwill adjust readily, cope with discomfort, and becooperative.

It has also has been reported that when a com-plete denture population was examined for depres-sion most of the depressive symptoms were foundto coincide with age groups that included the great-est proportion of denture wearers. Awareness bythe dentist of high-risk groups for depressionwithin the patient pool may help explain difficul-ties in achieving patient satisfaction with dentures,facilitate recognition of a problem, and make pos-sible appropriate referral for diagnosis and treat-ment of the patient’s depression.

The whole area of prosthodontist/patient inter-personal relationships has not been adequatelystudied or emphasized by the dental profession.Recently, educational programs to modify theoften-unrealistic expectations of patients who weardentures have shown favorable results. Similarly,programs to modify the knowledge, skills, andhabits of patients who wear dentures may assistthem to adapt more successfully to denture wear-ing. Although the taking of a health history can beeffective, a great deal of experience and trainingare necessary to conduct a patient interview effec-tively and profitably. Unfortunately, the rigors ofdental practice prevent most dentists from takingthe time to carry out a thorough patient interview.Because a connection between emotional problemsand denture problems may exist, a health question-naire should be used as a guide for a structured per-sonal interview with the patient. It is a usefuladjunct to establishing a prognosis for the proposedtreatment.

Finally, the absence of a yardstick to gauge apatient’s adaptive potential to wearing a prosthesisis one of the most challenging facets of treatingedentulism. The success of prosthetic treatment ispredicated not only on the dentist’s manual dexter-ity but also on the ability to relate to patients and tounderstand their needs. The importance of empathyand correct clinical judgment on the part of thedentist can hardly be overemphasized. The dentist’sability to understand and recognize the problems ofedentulous patients, to select the proper course ofrequired treatment, and to reassure them has provento be of greatest clinical value.

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C H A P T E R 3The Effects of Aging on the Edentulous StateMichael I. MacEntee

24

THE AGING POPULATIONThe global population is aging at an unprecedentedrate (Table 3-1). This change is noticeable, particu-larly in Japan and in some European countries wherealmost 2 in 10 residents are older than 65 years ofage (Anderson & Hussey, 2000). The demographicscenario is similar in most industrialized countries,and is remarkable particularly among the “middle-old” (age 75 to 84) and “old-old” (age 85+) popula-tions. In Canada, for example, about half (45.2%) ofthe elderly population is older than 75 years of age(Statistics Canada, 2001), and in Japan the number ofpersons older than 80 years will more than double(from 3.7% to 7.5%) between 2000 and 2020(Anderson & Hussey, 2000). The expansion of thegeriatric population has been growing rapidly overthe last quarter of a century and will increase furtherprobably by at least one third within the next 20 yearsor so. The result has already produced a major shiftin health care away from the cure of acute diseasesand disorders to the management of chronic illness(Bury, 2001). The impact of this demographic changecauses great concern generally because of the poten-tial increase in health care costs, although the corre-lation currently between health care spending and anaging population is weak (Anderson & Hussey,2000).

Cardiovascular disease, cancer, and cirrhosis ofthe liver were particularly hazardous to men duringthe early part of the twentieth century, in large partbecause of industrial pollutants, smoking, and alco-hol abuse. Women seem to have benefited morefrom improved health care, especially in obstetrics.

Consequently, there are nearly twice as many olderwomen than older men simply because women livelonger, with an average life expectancy of 80 yearsversus 73 years for men. The reason for the pro-longed life expectancy of women is not fully under-stood, and it is not at all certain that women willcontinue to outlive men in the future.

A small but internationally consistent propor-tion (~6%) of persons 65 years of age and olderlive in long-term care facilities, but of course theproportion of older persons who are institutional-ized increases dramatically with advancing age.By age 75 nearly everyone is burdened by at leastone chronic disorder that limits access to dentalcare and influences dental treatment.Furthermore, most older persons believe that theyhave very little flexibility with their income, and alarge proportion of them, in North America atleast, receive an income that is below the povertyline. In 1995 nearly one fifth (17%) of the totalCanadian population and more than one third(36%) of unattached Canadian residents wereattempting to live on incomes below the povertyline (National Council of Welfare, 1999). Anotherperspective on poverty defines it as a lack ofresources “for achieving self-respect, taking partin the life of the community, (and) appearing inpublic without shame,” all influenced directly byoral health and a comfortable dentition (Sen,1999). Consequently, there are many older peoplewho are likely to be very concerned by unex-pected dental costs, unless the need for treatmentis explicit and reasonable to them.

DISTRIBUTION AND IMPACT OFEDENTULISM IN OLD AGEDistribution

The prevalence of edentulism is declining. Today,about one third to one half of the population65 years of age and older in most industrializedcountries are edentate, but there are large regionaland age-related variations (Table 3-2). More oldermen than women are likely to have teeth, probablybecause many women have had unsightly teethremoved earlier in life. The loss of natural teeth isalso associated with less affluent people. For exam-ple, in the United States within the last two decadesabout half (51%) of the less educated populationwere edentate, compared with about one quarter(29%) of the more highly educated population(Burt, 1992), which most likely reflects the scopeof health services accessible to individuals. Quitesimply, those who have less education and lessmoney are less exposed to preventive dental infor-mation and are unable to afford restorative treat-ment when needed (Dharamsi & MacEntee, 2002).

Despite the benefits of water fluoridation anddentistry, about three of four older persons withinthe last decade were using complete dentures in atleast one jaw (Mojon and MacEntee 1992;MacEntee, Stolar, and Glick, 1993), but even this issubstantially lower than the prevalence of completeedentulism reported only a few decades ago from

many countries (MacEntee, 1985). The decrease intotal tooth loss in the United States, for example,has dropped by about 10% each decade for the last30 years, although there will be a net increase inthe number of edentulous people for the foresee-able future with the growing numbers of older peo-ple overall (Douglass, Shih, and Ostry, 2002).

Impact

Residual alveolar ridges continue to resorb for sev-eral decades after extraction of teeth, yet older per-sons rarely seek treatment for problems withdentures, possibly because many of them have beendissatisfied with previous treatment (MacEntee et al.,1991). Moreover, older people usually adapt poorlyto new dentures, which probably explains why theyseldom return to have old but familiar denturesreplaced. When they do complain, it is usually aboutthe pain of chewing hard foods with uncomfortablyloose dentures on flat residual ridges.

THE IMPACT OF AGE ON THEEDENTULOUS MOUTHMucosa

Stomatitis and other mild inflammations are themucosal lesions encountered most frequently inolder edentulous mouths, especially of older men

Chapter 3 The Effects of Aging on the Edentulous State 25

Table 3-1Current (2002) and Expected (2020) Distribution of the Population 65 Years of Age and Older in Eight Countries (2000)

Percentage

Age 65 + yr Age 80 + yr

Country 2000 2020 Increase 2000 2020 Increase

Australia 12.1 16.8 39 2.8 3.7 30Canada 12.8 18.2 43 3.1 4.4 42France 15.9 20.1 26 3.8 5.5 45Germany 16.4 21.6 32 3.6 6.3 76Japan 17.1 26.2 54 3.7 7.5 107New Zealand 11.6 15.6 34 2.8 3.5 24United Kingdom 16.0 19.8 24 4.2 5.1 22United States 12.5 16.6 33 3.3 3.7 14

From Anderson GF, Hussey PS: Population aging: a comparison among industrialized countries, Health Affairs 19:191-203, 2000.

who wear dentures, smoke tobacco, and drink alco-hol excessively (MacEntee, Glick, and Stolar,1998). Oral cancer or precancerous lesions areunusual in Western countries, although they are themost common forms of cancer on the Indian sub-continent and in other parts of Asia. It is reasonablyclear that the incidence of oral cancer is higheramong African Americans than among the rest ofthe U.S. and Canadian populations of other racesand that the prognosis is also poorer among AfricanAmericans, which probably reflects the influenceof low socioeconomic status more than genes orculture (Arbes et al., 1999; Skarsgard et al., 2000).External carcinogens, such as nicotine and alcohol,should be more damaging to the oral mucosa in oldage because of atrophy, increased mitosis with slowturnover of cells, and increased number of elasticfibers. Therefore it is likely that the risk of oral

cancer is increased among edentulous denturewearers, especially among those who drink alcoholto excess and smoke tobacco, simply because manyof them are poor and they make little use of screen-ing services for early detection.

Bone

Bone mass is at its maximum in midlife, with sub-stantially more in men than in women, and in someracial groups more than others. However, evenwithin individuals, the quality of bone in all partsof the skeleton, including the jaws, varies greatlyand decreases with age (Esteves, 1994). Thedecrease occurs because osteoblasts are less effi-cient, estrogen production declines, and there is anoverall reduction of calcium absorption from theintestine in old age.


Table 3-2The Distribution of Edentulism in Old Age

Country Year Reference Age Group (yr) Percent Edentate

Australia 1987/1988 DHHLGCS (1993) >65 50>75 62

1999 DSRU (2001) >65 33United Kingdom 1988 Todd & Lader (1991) >65 69

1998 Walls & Steele (2001) 65-74 3975+ 60

Canada 1990 Charette (1993) >65 501992 Hawkins, Main and Locker (1998) 85+ 66

Denmark 1982 Ainamo & Österberg (1992) 65-81 60Finland 1990 Ainamo & Österberg (1992) >65 46Germany 1997 Nitschke (2001) 65-74 25Ireland 1990 O’Mullane and Whelton (1990) >65 48Japan 1993 Ministry Hlth and Welfare (1993) >65 30Norway 1989 Ainamo & Österberg (1992) >65 29Spain 1989 Bourgeois, Nihtila, and Mersel (1998) 65-74 40

1999 The Spanish Geriatric Oral Health Research Group (2001) >65 31

Sweden 1988/1989 Ainamo & Österberg (1992) 65-74 2975-84 50

United States 1985 Miller et al. (1987) >65 411988-91 Marcus et al. (1996) 65-74 29

75+ 431990 Douglass et al. (1993) >70 381999 MMWR (1999) >65 29

The turnover and metabolism of bone are influ-enced by many factors, including exercise, genes,hormones and nutrition, but usually resorption sur-passes formation somewhere around midlife inboth men and women. The jaws of both sexes alsobecome more porous with time probably becauseof metabolic rather than functional changes in thebone.

Osteoporosis is a disorder caused by an accel-erated loss of trabecular bone. It happens usually,but not exclusively, in women after menopause, andis discovered frequently when an older personbreaks a vertebra, hip, or forearm. It has primaryand secondary forms that are difficult to diagnose.The more prevalent Type I (postmenopausal) formaffects women for a decade or so after menopause,whereas the Type II (senile or idiopathic) form canattack men and women alike at any age for noobvious reason. Actually, the Type II form candevelop as a consequence of any disease, such ashyperparathyroidism, and induce bone loss.Residual ridge resorption may be a manifestationof primary Type I osteoporosis, but there is very lit-tle evidence to show that the two conditions areassociated (Esteves, 1994). Estrogen replacementtherapy, bisphosphonates, or other systemic treat-ments for osteoporosis do affect the density andcontent of jawbones as in other skeletal bone, butthe extent of the effect varies considerably at dif-ferent sites, and the preventive attributes of thetreatments are unknown (von Wowern, 2001).

Saliva

The role of saliva as a lubricant and as a chemicalbuffer is central to the comfort and function of themouth. The electrolytes, glycoproteins, andenzymes of mucous saliva lubricate, cleanse, andprotect the mucosa, and they ease the passage offood around the mouth while contributing to thesense of taste. Inadequate quality or quantity ofsaliva is particularly difficult for complete denturewearers because mucous saliva produced by theminor glands of the palatal helps to retain andlubricate the dentures. We do not know whether thequantity or quality of saliva in healthy individualsis disturbed by age, but we do know that older per-sons take a vast array of potentially xerostomicmedications for depression, sleeping disorders,

hypertension, allergies, heart problems and manyother geriatric problems. Indeed, stress, depres-sion, tobacco use, and abuse of alcohol alone candisturb salivary flow, whereas hyposalivation ofthe minor salivary glands of the palate, which dis-turbs denture retention, is a common side effect ofdigitalis preparations, tranquillizers, and poly-cyclic antidepressants (Niedermeier et al., 2000).Pharmacological side effects, especially on sub-mandibular glands, are complicated further by thebiochemical interactions of multiple medications(Wu et al., 1993). Sjögren’s syndrome and radia-tion treatment also cause dry mouth. Food mayhave a metallic or salty taste, and an unpleasantsensitivity to bitter and sour foods increases whensalivary flow is poor, whereas reduced sensitivityto sweet tastes can generate an unhealthy cravingfor sugar. A change in the quality of saliva mightnot be obvious clinically, but it should be suspectedas a cause of denture intolerance when a patient istaking multiple medications. Management ofhyposalivation is difficult, but recent evidence indi-cates that secretion of mucous saliva from thepalate improves measurably after drinking 2 L ofwater, when chewing or exercising vigorously, orwhen taking estrogen or pilocarpine (Niedermeieret al., 2000).

JAW MOVEMENTS IN OLD AGEPeople chew more slowly as they get older.Although the duration of the total chewing cycledoes not appear to change, it does seem that thevertical displacement of the mandible is shortened(Karlsson and Carlsson, 1990). Movements of themandible are governed by a generator in the brainstem influenced by proprioceptors in muscles,joints, and mucosa. Advancing age may delay thecentral processing of nerve impulses, impede theactivity of striated muscle fibers, and inhibitdecisions. It can also reduce the number of func-tional motor units and fast muscle fibers, anddecrease the cross-sectional area of the masseterand medial pterygoid muscles (Newton et al.,1987). Consequently, older people tend to have poormotor coordination and weak muscles. Muscle tonecan decrease by as much as 20% to 25% in old age,which probably explains the shorter chewingstrokes and prolonged chewing time (Sonies,


1992). Older persons also have a less coordinatedchewing stroke close to maximum intercuspation,probably because of a general deficit in the centralnervous system, and some individuals who assumethe characteristic stoop of old age experience painon swallowing because of osteophytes and spursgrowing on the upper spine adjacent to the phar-ynx. A noticeable change in swallowing stronglysuggests that there might be an underlying patho-sis, such as Parkinson’s disease or palsy that is nota part of normal aging (Sonies, 1992).

TASTE AND SMELLTaste and smell are frequently confused becausethe sensory mechanisms are closely related anddependent. The sensation of “tasting” rarely occursin isolation, but results from the interaction of pro-prioception, taste, and smell. Texture is felt, chem-ical constituents stimulate taste, and aromatic gasessmell. Bitter, sweet, sour, and salty tastes stimulatereceptors independently, so one may be damagedwithout disturbing the others. Olfactory cells sendprojections directly to the brain so they can be trau-matized anywhere along the way.

Sensitivity to taste declines with age, and espe-cially in older persons with Alzheimer’s disease(Murphy, 1993). Also, the preference for specificflavors changes over time to favor higher concen-trations of sugar and salt. Complaints of an impair-ment affecting the sense of taste at any age shouldbe investigated thoroughly because they forebodean upper respiratory infection or a serious neuro-logical disorder. The three cranial nerves (VI, IX,and X) carrying sensations of taste can be dis-turbed and damaged by tumors, viruses (e.g., Bell’spalsy and herpes zoster), and trauma (e.g., headinjury and ear washing), but, fortunately, damagein one part of the system can be compensated read-ily by increased sensitivity elsewhere.

NUTRITIONThere is some evidence, largely from animal stud-ies, that diet influences longevity and aging, withthe weight of evidence favoring restrictions on fatand protein. The relationship between diet and pro-longed life in human beings is complex and, as yet,inadequately explained. Currently, the recom-

mended daily allowances for the various vitamins,minerals, fats, carbohydrates, and proteins areprobably inaccurate because most of the data onintake of specific nutrients have been estimated foryoung adults. Nevertheless, the elderly populationis at particular risk for malnutrition because of avariety of factors that range from socioeconomicstress to an overconsumption of drugs, and includ-ing, to some extent, the state of the dentition.A national survey in the United States around 1970(Rhodus and Brown, 1990) revealed that older peo-ple frequently had inadequate calories or calciumin their diet and that many of them absorbed vita-mins (notably A, B, and C) and minerals poorly(Figure 3-1).

The role of the dentition in mastication andfood selection is complex. Some edentulous per-sons with faulty dentures restrict themselves to asoft diet high in fermentable carbohydrates,whereas others, even with uncomfortable and well-worn dentures, can eat nearly all of the food avail-able to them (Millwood and Heath, 2000). A recentpopulation-based study in the United Kingdomfound that edentulous older persons, comparedwith older persons with natural teeth, had signifi-cantly lower levels of plasma ascorbate and plasmaretinol, which could disturb their skin and eyesight(Sheiham and Steele, 2001).

AGING SKIN AND TEETHSkin

The scars of a lifetime are revealed dramatically onthe skin as wrinkles, puffiness, and pigmentations,but the changes are not all manifestations of degen-eration. For example, fewer Langerhans’ cells inolder skin can prevent undesirable immunologicalresponses, whereas mottling of the skin protectsagainst the sun. The leathery look characteristic ofthe older sun worshipper is caused by epidermalgrowths with large melanocytes—solar lentigines—that thicken in the epidermis. Gradually the dermisthins, enzymes dissolve collagen and elastin, andwrinkles appear when layers of fat are lost.

Age reduces the concavity and “pout” of theupper lip, and it flattens the philtrum. Thenasolabial grooves deepen, which produces a sag-ging look to the middle third of the face, whereas



Figure 3-1 Angular cheilitis (A and B) and stomatitis (C) in an elderly man caused bymalnutrition and/or liver dysfunction (white blood cell count, 3.19; hemoglobin, 12.4;hematocrit, 36.3; vitamin B12, 203).

A

B

C

atrophy of the subcutaneous and buccal pads of fathallows the cheeks. Subsequently, as the loss of fatcontinues, support for the presymphyseal pad offat disappears, and the upper lip droops (cheilopto-sis) over the maxillary teeth (Figure 3-2). Of course,these changes are accentuated even more dramati-cally when teeth are missing or when there is a lossof occlusal vertical dimension (Figure 3-3).

Teeth

The color of healthy, natural teeth ranges in huefrom yellow to orange, with large variation inchroma and value (MacEntee and Lakowski,1981). The chroma, and occasionally the hue, willchange as the enamel is abraded, exposing theunderlying dentine to extrinsic stains. The chromamay also deepen by a systemic distribution of var-ious medications, particularly those containingheavy metals. Ultimately, natural teeth take on thejagged brownish appearance of an aging dentitionwhen the incisal edges break and the exposed den-tine gathers extrinsic stains. It is not always easy toreproduce this rugged appearance in artificialteeth. In fact, some patients in conflict with theesthetic sense of their dentist prefer to have com-plete dentures with teeth that are smaller, straighter,and whiter than natural teeth.

CONCERNS FOR PERSONALAPPEARANCE IN OLD AGEOlder persons worry about their self-image asmuch, if not more, than at any other stage of life.They may be ambivalent about growing old, buttypically they attempt to strike a psychosocial bal-ance between the good and the bad effects.Unfortunately, the respect afforded occasionally toolder people can be diminished by feelings ofsocial rejection and physical collapse compoundedby the stigma of inadequate dentures (Goffman,1963).

The profits of the cosmetic industry, includingplastic surgery and esthetic dentistry, and the pop-ularity of the keep-fit industry, attest to a wide-spread concern that wrinkles, shifting body fat, andother “disfigurements” may inhibit or damage per-sonal relationships. Concealment of age hasbecome a preoccupation of the Western world, afixation that seems to disturb women more directlythan men. The aging woman is considered unat-tractive and judged, even by other women, moreharshly than the aging man, whereas women ingeneral seem less repelled by the graying or“mature look” of the older man.

Society frowns on anyone, young or old, (butespecially on elderly men) who use cosmetics or


Figure 3-2 Appearance of the lower two thirds of an elderly person’s face demonstratingthe typical droop of the upper lip that accentuates the mandibular incisors.


Figure 3-3 A and B, The influence of the vertical dimension of occlusion on the “youthful” appearance of the face.

A B

other concealments of age. Apparently, we admirethose who do not have to cover up their defects.Consequently, men are more furtive than womenabout seeking improvements to their appearance.Furthermore, age concealment is acceptable foroneself but not for others, a clear indication thatthere are double standards operating on the publicimage.

An attractive appearance is considered impor-tant to self-satisfaction. Healthy older persons fre-quently admit that they try hard to feel and lookyoung. A healthy person will accept the naturalconsequences of aging without undue disturbance,although psychosocial pressures can cause anunhealthy obsession with appearance, even to thepoint of anorexia surfacing for the first time in oldage (Nicholson and Ballance, 1998). Unusualrequests for alterations to appearance should bemanaged with caution and related directly to thepsychosocial status of the patient. Indeed, expecta-tions that seem to be in any way unrealistic, partic-ularly if the patient is depressed or deluded, shouldbe offered a very guarded prognosis. Actually, amarked discrepancy between the assessment of theclinician and the patient offers a valuable diagnos-tic clue to a problem, assuming of course that the

clinician has a rational rather than a distorted viewof aging.

SUMMARYThe need for complete dentures in the Westernworld will increase over the next quarter of a cen-tury despite the current successes of preventivedentistry and the apparent affluence of contempo-rary society. Management of edentulous elderlypatients involves a constant sensitivity to the poten-tial impact of a multitude of medical disorders.There are few disorders that are exclusive to olderindividuals; nevertheless, the mouth is a fine sen-sor of systemic stability, and occasionally it offersthe first physical manifestation of a disease. Forexample, the edentulous mouth can suffer from avery painful attack of shingles involving sensorynerves of the face, neck, and trunk, or display angu-lar cheilitis with a denture-induced stomatitis usu-ally without symptoms. Wounds heal more slowlyand possibly less effectively in old age because ofdecreased turnover of cells or poor blood circula-tion. Consequently, the mucosa and underlyingbone supporting complete dentures heal moreslowly from the trauma of ill-fitting dentures.

Prosthodontic treatment for older peoplerequires accurate diagnoses of systemic and localproblems before attending to the design of den-tures. Systemic problems, including psychologicaldistress and physiological disturbances, are fre-quently complicated by inappropriate use of pre-scribed medications. Local inflammation of thealveolar mucosa is caused usually by unhygienicand structurally defective dentures and can be cor-rected relatively easily by relining and repairing thedentures. Subsequently, mucosal inflammationshould resolve after improved hygiene.

New dentures are not accepted easily by olderpatients, so, whenever possible, modify denturesthat are familiar to the patient rather than make newdentures. However, if the denture must be replaced,it is preferable when possible to duplicate the gen-eral shape and tooth arrangement of the old den-ture. Lastly, every denture should have the patient’sidentity embedded visibly but inconspicuously inthe acrylic resin.

Overall, the management of problems encoun-tered in an aging population can seem like a series ofobjectionable compromises, but adaptation is thehallmark of successful aging, and coping with diffi-culties is an acceptable part of everyday life. Life atany age does have pleasant surprises and rewards.

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Skarsgard DP, Groome PA, Mackillop WJ, Zhou S, Rothwell D,Dixon PF, O’Sullivan B, Hall SF, Holowaty EJ: Cancers ofthe upper aerodigestive tract in Ontario, Canada, and theUnited States, Cancer 88:1728-1738, 2000.

Sonies BC: Oropharyngeal dysphagia in the elderly, ClinicsGeriatric Med 8: 569-576, 1992.

Statistics Canada: Canadian Statistics: The People: Population,2001.http://www.statcan.ca/english/Pgdb/People/popula.htm

The Spanish Geriatric Oral Health Research Group: Oral healthissues of Spanish adults aged 65 and over, Int Dent J 51:228-234, 2001.

Todd JE, Lader D: Adult dental health 1988 United Kingdom,London, 1991, HMSO.

Total tooth loss among persons aged ≥65 years—selected states,1995-1997, US Dept. of Health & Human Services, MMWR(1999) Morb Mortal Wkly Rep 48:206-210, 1999.

von Wowern N: General and oral aspects of osteoporosis:a review, Clinic Oral Investigat 5:71-82, 2001.

Walls AWG, Steele JG: Geriatric oral health issues in the UnitedKingdom, Int Dent J 51:183-187, 2001.

Wu AJ, Atkinson JC, Fox PC, Baum BJ, Ship JA: Cross-sectional and longitudinal analyses of stimulated parotidsalivary constituents in healthy, different-aged subjects,Journals of Gerontol 48: M219-224, 1993.


C H A P T E R 4Sequelae Caused by Wearing CompleteDenturesEjvind Budtz-Jørgensen

34

THE DENTURE IN THE ORALENVIRONMENTPlacement of a removable prosthesis in the oralcavity produces profound changes of the oral envi-ronment that may have an adverse effect on theintegrity of the oral tissues (Box 4-1). Mucosalreactions could result from a mechanical irritationby the dentures, an accumulation of microbialplaque on the dentures, or, occasionally, a toxic orallergic reaction to constituents of the denturematerial. The continuous wearing of dentures mayhave a negative effect on residual ridge formbecause of bone resorption. Furthermore, wearingcomplete dentures that function poorly and thatimpair masticatory function could be a negativefactor with regard to maintenance of adequate mus-cle function and nutritional status, particularly inolder persons.

There are several aspects of the interactionbetween the prosthesis and the oral environment.

Surface properties of the prosthetic materialmay affect plaque formation on the prosthesis;however, the original surface chemistry of theprosthetic material is modified by the acquiredpellicle and thus is of minor importance for theestablishment of plaque (Box 4-2). On the con-trary, surface irregularities or microporositiesgreatly promote plaque accumulation by enhanc-ing the surface area exposed to microbial colo-nization and by enhancing the attachment ofplaque. Furthermore, plaque formation is greatlyinfluenced by environmental conditions such asthe design of the prosthesis, health of adjacent

mucosa, composition of saliva, salivary secretionrate, oral hygiene, and denture-wearing habits ofthe patient.

The presence of different types of dentalmaterials in the oral cavity may give rise to elec-trochemical corrosion, but changes in the oralenvironment due to bacterial plaque may consti-tute an important cofactor in this process.Corrosive galvanic currents have been implicatedin the burning mouth syndrome (BMS), orallichen planus, and altered taste perception. Mostoften it is difficult to establish a definite causalrelationship because mechanical irritation orinfection may also be involved. For instance, localirritation of the mucosa by the dentures mayincrease mucosal permeability to allergens ormicrobial antigens. This makes it difficult to dis-tinguish between a simple irritation and an aller-gic reaction against the prosthetic material,microbial antigens, or agents absorbed to theprosthesis capable of eliciting an allergicresponse. The matter is further complicated by thefact that certain microorganisms (e.g., yeasts) areable to use methylmethacrylate as a carbonsource, thereby causing a chemical degradation ofthe denture resin.

In the interface between a prosthesis and theoral mucosa, microbial plaque may have importantnegative or harmful effects (Figure 4-1). Thus aprosthesis may promote infection of the underlyingmucosa, caries, and periodontal disease adjacent tooverdenture abutments, periimplant gingivitis, andchemical degradation or corrosion of prostheticmaterials.

DIRECT SEQUELAE CAUSED BYWEARING DENTURESDenture Stomatitis

The pathological reactions of the denture-bearingpalatal mucosa appear under several titles and termssuch as denture-induced stomatitis, denture soremouth, denture stomatitis, inflammatory papillaryhyperplasia, and chronic atrophic candidosis. In thefollowing sections, the term denture stomatitis willbe used with the prefix Candida-associated if theyeast Candida is involved. In the randomized popu-lations, the prevalence of denture stomatitis is about50% among complete denture wearers.

Classification According to Newton’s classifica-tion, three types of denture stomatitis can be distin-guished.

Type I A localized simple inflammation orpinpoint hyperemia (Figure 4-2).

Chapter 4 Sequelae Caused by Wearing Complete Dentures 35

Direct Sequelae Caused byWearing Removable Prostheses:

Complete or Partial Dentures

Mucosal reactionsOral galvanic currentsAltered taste perceptionBurning mouth syndromeGaggingResidual ridge reductionPeriodontal disease (abutments)Caries (abutments)

Box 4-1

Interaction of ProstheticMaterials and the Oral

Environment

Surface Properties: Plaque AccumulationChemical stabilityAdhesivenessTextureMicroporositiesHardness

Chemical PropertiesCorrosionToxic reactionsAllergic reactions

Physical PropertiesMechanical irritationPlaque accumulation

Changes of Environmental ConditionsPlaque microbiology

Box 4-2

Figure 4-1 A, Microbial plaque on the fitting denturesurface visualized with the stain erythrosin. B, Sectionof a denture showing microbial deposits penetratinginto irregularities of the fitting denture surface.

B

A

Type II An erythematous or generalized simpletype seen as more diffuse erythema involving a partor the entire denture-covered mucosa (Figure 4-3).

Type III A granular type (inflammatorypapillary hyperplasia) commonly involving thecentral part of the hard palate and the alveolarridges. Type III often is seen in association withtype I or type II (Figure 4-4).

Strains of the genus Candida, in particularCandida albicans, may cause denture stomatitis.Still, this condition is not a specific disease entitybecause other causal factors exist such as bacterialinfection, mechanical irritation, or allergy. Type Imost often is trauma induced, whereas types II and

III most often are caused by the presence of micro-bial plaque accumulation (bacteria or yeasts) on thefitting denture surface and the underlying mucosa.The often relative association of Candida-associateddenture stomatitis with angular cheilitis or glossitisindicates a spread of the infection from the denture-covered mucosa to the angles of the mouth or thetongue, respectively (Figure 4-5).

Diagnosis The diagnosis of Candida-associateddenture stomatitis is confirmed by the finding ofmycelia or pseudohyphae in a direct smear or theisolation of Candida species in high numbers fromthe lesions (≥50 colonies) (Figure 4-6). Usually,yeasts are recovered in higher numbers from thefitting surface of the dentures than from corre-sponding areas of the palatal mucosa. This indi-cates that Candida residing on the fitting surface ofthe denture is the primary source of the infection.

Etiology and Predisposing Factors The directpredisposing factor for Candida-associated denturestomatitis is the presence of the dentures in the oralcavity (Box 4-3). Thus the infection prevails inpatients who are wearing their dentures both day andnight; the infection will disappear if the dentures arenot worn. It is likely that bacteria, which constitutethe major part of the microorganisms of the dentureplaque, are also involved in the infection. In addi-tion, trauma could stimulate the turnover of thepalatal epithelial cells, thereby reducing the degreeof keratinization and the barrier function of theepithelium; thus the penetration of fungal and bacte-rial antigens can take place more easily.

The colonization of the fitting denture surfaceby Candida species depends on several factors,including adherence of yeast cells, interaction withoral commensal bacteria, redox potential of thesite, and surface properties of the acrylic resin. Thepathogenicity of denture plaque can be enhancedby factors stimulating yeast propagation, such aspoor oral hygiene, high carbohydrate intake,reduced salivary flow, and continuous denturewearing. The more important factors that can mod-ulate the host-parasite relationship and increase thesusceptibility to Candida-associated denture stom-atitis may be aging, malnutrition, immunosuppres-sion, radiation therapy, diabetes mellitus, andpossibly treatment with antibacterial antibiotics.


Figure 4-2 Pinpoint hyperemia, a characteristicfeature of type I denture stomatitis.

Figure 4-3 Type II denture stomatitis showing ery-thema of the entire mucosa in contact with the fittingdenture surface.


Figure 4-4 A, Type III denture stomatitis, papillary hyperplasia, the nodular type. B, Type III denture stomatitis, papillary hyperplasia, the mossy type.

Figure 4-5 Lesions of the oral mucosa in patients with Candida-associated denture stomatitis. A, Diffuse atrophic glossitis. B, Median rhomboid glossitis. C, Angular cheilitis. D, Erythema of the soft palate.

A

C

B

D

A B

Evidence supports that unclean dentures andpoor hygiene care are major predisposing factorsbecause healing of the lesions is often seen aftermeticulous oral and denture hygiene is instituted.However, the tissue surface of the dentures usually

shows micropits and microporosities that harbormicroorganisms that are difficult to remove mechan-ically or by chemical cleansing. According toseveral in vitro studies, the microbial contamina-tion of denture acrylic resin occurs very quickly,and yeasts seem to adhere well to denture basematerials.

Angular cheilitis is often correlated to the pres-ence of Candida-associated stomatitis, and it isthought that the infection may start beneath the max-illary denture and from that area spread to the anglesof the mouth (see Figure 4-5). It seems, however,that this infection results from local or systemic pre-disposing conditions such as overclosure of the jaws,nutritional deficiencies, or iron deficiency anemia.Frequently, a secondary infection caused byStaphylococcus aureus could be present. It must berecognized that visible infection by Candida speciescan be an early indicator of immune dysfunction andthe discovery of such should prompt a review of thepatient’s clinical background.

Although denture stomatitis and angular cheili-tis usually do not reflect a serious predisposing dis-ease or abnormality, with denture wearing as thedirect cause of the lesions, it should be realized thatsevere infections by Candida species may occur inthe immunocompromised host (Figure 4-7).

Management and Preventive Measures Becauseof the diverse possible origins of denture stomati-


Figure 4-6 A, Culture on Oriculty: left, positive culture in a noninfected carrier ofCandida; right, high number of yeast colonies from a patient with denture stomatitis indi-cates a Candida infection. B, Smear from the fitting denture surface yieldedpseudomycelium.

Factors Predisposing to Candida-Associated Denture

Stomatitis

Systemic FactorsOld ageDiabetes mellitusNutritional deficiencies (iron, folate, or vitamin

B12)Malignancies (acute leukemia, agranulocytosis)Immune defectsCorticosteroids, immunosuppressive drugs

Local FactorsDentures (changes in environmental condi-

tions, trauma, denture usage, denture clean-liness)

Xerostomia (Sjögren’s syndrome, irradiation,drug therapy)

High-carbohydrate dietBroad-spectrum antibioticsSmoking tobacco

Box 4-3

A B

tis, several treatment procedures could be used,including antifungal therapy, correction of ill-fittingdentures, and efficient plaque control.

The most important therapeutic and preventivemeasures are the institution of efficient oral and den-ture hygiene and correction of the denture-wearinghabits because the major etiological factor is the pres-ence of the denture. The patient should be instructedto remove the dentures after the meal and scrub themvigorously with soap before reinserting them. Themucosa in contact with the denture should be keptclean and massaged with a soft toothbrush. Patientswith recurrent infections should be persuaded not touse their dentures at night but rather leave themexposed to air, which seems to be a safe and efficientmeans of preventing microbial colonization. Thedentures often may cause trauma because they areold and ill fitting or because there are faults in thedesign. Rough areas on the fitting surface should besmoothed or relined with a soft tissue conditioner.About 1 mm of the internal surface being penetratedby microorganisms should be removed and relinedfrequently. A new denture should be provided onlywhen the mucosa has healed and the patient is able toachieve good denture hygiene.

There is no substantial evidence that harmlesscommercial denture cleansers are efficient in pre-venting colonization of the dentures by microor-ganisms. Polishing or glazing of the tissue surfaceof removable dentures should be considered a rou-

tine step in prosthodontic treatment to facilitatedenture cleansing by brushing.

Antifungal drugs could be used to removeCandida albicans residing on oral mucosa and thefitting denture surface, but recurrence of the infec-tion is often observed if the hygiene is notimproved. Treatment with antifungal agents shouldbe used mainly in the following patients:

1. In patients after the clinical diagnosis has beenconfirmed by a mycological examination.

2. In patients with associated burning sensationsfrom the oral mucosa.

3. In patients in whom the infection has spread toother sites of the oral cavity or the pharynx.

4. In patients with an increased risk of systemicmycotic infections due to debilitating diseases,drugs, or radiation therapy.

Local therapy with nystatin, amphotericin B, micona-zole, or clotrimazole should be preferred to systemictherapy with ketoconazole or fluconazole becauseresistance of Candida species to the latter drugsoccurs regularly. For a reduction in the risk of relapse,the following precautions should be taken:

1. Treatment with antifungals should continue for4 weeks (Figure 4-8).

2. When lozenges are prescribed, the patientshould be instructed to take out the denturesduring sucking.

3. The patient should be instructed in meticulousoral and denture hygiene; the patient should betold to wear the dentures as seldom as possibleand to keep them dry or in a disinfectant solutionof 0.2% to 2.0% chlorhexidine during nights.

Surgical elimination of deep crypt formations intype III denture stomatitis usually is a prerequisitefor effective mucosal hygiene. This could prefer-ably be achieved with cryosurgery.

It must be emphasized that the interrelationshipbetween host status and the clinical presentationsof oral candidiasis means that the dentist can gainuseful insight into the patient’s overall health. Inaddition to suggesting appropriate antifungal treat-ment, such insights may also help in the early diag-nosis and treatment of more serious and underlyingdisease.


Figure 4-7 Candida-associated denture stomatitisin an immunocompromised patient. There is evidenceof thrush on the hard palate.


Figure 4-8 A, Type III denture stomatitis showing modular hyperplasia with severeinflammation. B, After only a 2-week treatment with amphotericin B lozenges, which areusually prescribed for 4 weeks, the erythema has declined, but the hyperplasia has persisted.

A B

Flabby Ridge

Flabby ridge (i.e., mobile or extremely resilientalveolar ridge) is due to replacement of bone byfibrous tissue. It is seen most commonly in theanterior part of the maxilla, particularly when thereare remaining anterior teeth in the mandible, and isprobably a sequela of excessive load of the residualridge and unstable occlusal conditions (Figure 4-9).Results of histological and histochemical studieshave shown marked fibrosis, inflammation, andresorption of the underlying bone. Flabby ridgesprovide poor support for the denture, and it couldbe argued that the tissue should be removed surgi-cally to improve the stability of the denture and tominimize alveolar ridge resorption. However, in asituation with extreme atrophy of the maxillaryalveolar ridge, flabby ridges should not be totallyremoved because the vestibular area would beeliminated. Indeed the resilient ridge may providesome retention for the denture.

Denture Irritation Hyperplasia

A common sequela of wearing ill-fitting denturesis the occurrence of tissue hyperplasia of themucosa in contact with the denture border(Figure 4-10). The lesions are the result ofchronic injury by unstable dentures or by thin,overextended denture flanges. The proliferationof tissue may take place relatively quickly after

placement of new dentures and is normally notassociated with marked symptoms. The lesionsmay be single or quite numerous and are com-posed of flaps of hyperplastic connective tissue.Inflammation is variable; however, in thebottom of deep fissures, severe inflammation andulceration may occur.

After replacement or adjustment of the dentures,the inflammation and edema may subside and pro-duce some clinical improvement of the condition.After surgical excision of the tissue and replacementof the denture, the lesions are unlikely to recur.

When pressure ulcerations develop and irrita-tion from microbial products is severe, the patientmay experience marked discomfort. If lym-phadenopathy is present, the denture irritationhyperplasia may simulate a neoplastic process.

Traumatic Ulcers

Traumatic ulcers or sore spots most commonlydevelop within 1 to 2 days after placement of newdentures. The ulcers are small and painful lesions,covered by a gray necrotic membrane and sur-rounded by an inflammatory halo with firm, elevatedborders (Figure 4-11). The direct cause is usuallyoverextended denture flanges or unbalanced occlu-sion. Conditions that suppress resistance of themucosa to mechanical irritation are predisposing(e.g., diabetes mellitus, nutritional deficiencies, radi-

ation therapy, or xerostomia). In the systemicallynoncompromised host, sore spots will heal a fewdays after correction of the dentures. When no treat-ment is instituted, the patient will often adapt to thepainful situation, which subsequently may developinto a denture irritation hyperplasia.

Oral Cancer in Denture Wearers

An association between oral carcinoma and chronicirritation of the mucosa by the dentures has oftenbeen claimed, but no definite proof seems to exist(Figure 4-12). Case reports have detailed the devel-opment of oral carcinomas in patients who wear ill-fitting dentures. However, most oral cancers dodevelop in partially or totally edentulous patients.The reasons appear to include an association with


Figure 4-9 Flabby ridge (or hyperplastic replace-ment) of the anterior part of the maxilla.

Figure 4-10 A, Soft tissue hyperplasia of the maxillary sulcus. B, The tissue reaction is causedby chronic irritation by the denture flange. C, Fibroma produced by the lingual denture flange.

A

C

B


Figure 4-11 A, Acute ulcer produced by the maxillary denture in the hamular notch regiondistal to the tuberosity (arrows). B, Chronic ulcer produced by the lingual denture flange.

Figure 4-12 A, Basocellular carcinoma of the floor of the mouth, early stage. B, Carcinoma involving the alveolar ridge and the vestibule.

A B

more heavy alcohol and tobacco use, less education,and lower socioeconomic status, which predisposeto oral cancer as well as to poor dental health,including tooth extraction and denture wearing. Thisunderlines the necessity of strict and regular recallvisits at 6-month to 1-year intervals for comprehen-sive oral examinations. The opinion is still valid thatif a sore spot does not heal after correction of thedenture, malignancy should be suspected. Patientswith such cases and clinically aberrant manifesta-tions of denture irritation hyperplasia should bereferred immediately to a pathologist. It should berecognized that the prognosis is poor for oral carci-nomas, especially for those in the floor of the mouth.

BURNING MOUTH SYNDROMEBMS could be a sequela of denture wearing and ischaracterized by a burning sensation in one orseveral oral structures in contact with the den-tures. It is relevant to differentiate between burn-ing mouth sensations and BMS. In the formergroup, the patient’s oral mucosae are ofteninflamed because of mechanical irritation, infec-tion, or an allergic reaction. In patients with BMS,the oral mucosa usually appears clinically healthy.The vast majority of those patients affected byBMS is older than 50 years of age, is female, andwears complete dentures. In the edentulous

A B

patient wearing complete dentures, burning sensa-tions from the supporting tissues or the tongue arecommon complaints, particularly in post-menopausal women. Usually, there are no overtclinical signs, but the symptoms often appear forthe first time in association with the placement ofnew dentures.

Characteristically, the symptoms have a gradualonset, and the pain is often present in the morningand tends to become aggravated during the day. Thequality of pain is a burning sensation associatedwith a feeling of dry mouth and persistent alteredtaste sensation. Other associated symptoms mayinclude headache, insomnia, decreased libido, irri-tability, or depression. Aggravating factors includetension, fatigue, and hot or spicy foods, whereassleeping, eating, and distraction reduce pain inten-sity.

Etiological Factors

A multitude of causative factors have beendescribed for BMS, which can be classified inthree main categories: local, systemic, or psy-chogenic (Box 4-4).

Local In denture wearers, a coincidence has beenobserved between the wearing of faulty denturesand burning symptoms from the underlyingmucosa and the tongue. The causative factors couldbe instability of the dentures, prolonged period ofmasticatory muscle activity, parafunctional activityof the tongue, and undue friction on the mucosa.Candidal infections or allergic reactions may pro-duce the symptoms related to burning mouth sen-sations but seldom to BMS.

Systemic The relatively high prevalence of BMSin menopausal women is difficult to explainbecause there is no evidence of a direct hormonaleffect on the oral mucosa. Thus the oral discomfortis independent of the hormonal level measured, andresults of well-controlled clinical trials have shownno clinical effects of systemic or local treatmentwith estrogen. Vitamin (B12, folic acid) or ironhematological deficiencies are thought to be etio-logical factors in a varying number of patients withBMS. Furthermore, replacement therapy usually issuccessful in patients with vitamin deficiency but not

in patients without vitamin deficiency who haveBMS. Xerostomic conditions induced by radiationtherapy, systemic disease, or drugs are often associ-ated with a burning sensation of the oral tissues, butthere is no direct evidence that these conditions areetiologically important for BMS.

Psychogenic With the use of objective psycho-metric methods to assess the psychological statusof patients with BMS, anxiety and depression werethe most frequent diagnoses. Generally, patientswith BMS were more concerned with bodilyfunctions and more depressed, emotionallyrepressed, distrustful, anxious, and socially iso-lated. It is not quite clear, however, whether thesepsychopathological factors are causative of the oralcomplaints or merely the result of chronic pain.

Management A priori, none of the proposed eti-ological factors can be ruled out. As a conse-quence, a systematic approach is necessary toidentify the possible causes. In denture wearers in


Documented Possible Causes ofBurning Mouth Syndrome

Local FactorsMechanical irritationAllergyInfectionOral habits and parafunctionsMyofascial pain

Systemic FactorsVitamin deficiencyIron deficiency anemiaXerostomiaMenopauseDiabetesParkinson’s diseaseMedication

Psychogenic FactorsDepressionAnxietyPsychosocial stressors

Box 4-4

whom no organic basis for the complaints is iden-tified, the approach of the prosthodontist should bevery careful. The situation may be further compli-cated by the fact that the patients often claim thattheir psychiatric disorders are due to the poor den-tures and the inadequate prosthetic treatment theyhave received. It is important, with appropriatecounseling of the patient, to help the patient under-stand the benign nature of the problem, with subse-quent elimination of the fears. The patient’ssymptoms should always be taken seriously, butany comprehensive prosthetic treatment, includingtreatment with implant-supported overdentures,should be carried out only as a collaborative effortof psychiatrist and prosthodontist.

Gagging

The gag reflex is a normal, healthy defense mech-anism. Its function is to prevent foreign bodiesfrom entering the trachea. Gagging can be trig-gered by tactile stimulation of the soft palate, theposterior part of the tongue, and the fauces.However, other stimuli such as sight, taste, noise,as well as psychological factors, or a combinationof these, may trigger gagging. In sensitive patients,the gag reflex is easily released after placement ofnew dentures, but it usually disappears in a fewdays as the patient adapts to the dentures. Persistentcomplaints of gagging may be due to overextendedborders (especially the posterior part of the maxil-lary denture and the distolingual part of the

mandibular denture) or poor retention of the max-illary denture. However, the condition is often dueto unstable occlusal conditions or increased verti-cal dimension of occlusion because the unbalancedor frequent occlusal contacts may prevent adapta-tion and trigger gagging reflexes. In wearers of olddentures, gagging may be a symptom of diseases ordisorders of the gastrointestinal tract, adenoids orcatarrh in the upper respiratory passages, alco-holism, or severe smoking.

Residual Ridge Reduction

Longitudinal studies of the form and weight of theedentulous residual ridge in wearers of completedentures have demonstrated a continuous loss ofbone tissue after tooth extraction and placementof complete dentures. The reduction is a sequel ofalveolar remodeling due to altered functional stim-ulus of the bone tissue. It follows a chronic pro-gressive and irreversible course that often results insevere impairment of prosthetic restoration and oralfunction (Figure 4-13). The process of remodeling isparticularly important in areas with thin corticalbone (e.g., the buccal and labial parts of the maxillaand the lingual parts of the mandible). During thefirst year after tooth extraction, the reduction of theresidual ridge height in the midsagittal plane is about2 to 3 mm for the maxilla and 4 to 5 mm for themandible. After healing of the residual ridge, theremodeling process will continue but with decreasedintensity. In the mandible, the annual rate of reduc-


Figure 4-13 A, Severe residual ridge reduction—a sequela of wearing completedentures over several years. B, Note the location of the mental foramina near the top of theresidual ridge.

A B

tion in height is about 0.1 to 0.2 mm and in generalfour times less in the edentulous maxilla. However,the intraindividual variations are very important.

The pathogenesis of residual ridge reductionis not well understood (Box 4-5). It is assumedthat the degree of residual ridge reduction resultsfrom a combination of anatomical, metabolic,and mechanical determinants. For example,severe residual ridge reduction of the mandiblehas been related to a small gonial angle (i.e.,a marked mandibular base bend and a posteriorposition of the lower incisal edges in relation tothe mandibular body). Women are particularlyaffected by the frequency and extent of residualridge reduction, and it has been suggested thatprogressive loss of bone under dentures is a man-ifestation of osteoporosis. In fact, there is astrong association between the skeletal bone den-sity and bone density of the mandible, and themandible is also affected by osteoporosis.Recently, it has been shown that low bone min-eral content and osteoporotic changes predisposeto a more rapid residual ridge reduction, particu-larly in the maxilla.

The mechanical factors (i.e., masticatory or para-functional forces) transmitted by the denture or thetongue to the residual ridge are assumed to be impor-tant factors in the remodeling process. Thus a corre-lation exists between the years of denture wearingand the severity of atrophy, and the atrophy also ismore important in day-and-night wearers of denturesthan in day wearers. Apart from these observations,there is no direct evidence that the design of the den-tures or that functional or parafunctional forces arerelated to the degree of residual ridge reduction.

The consequences of residual ridge reductionare apparent loss of sulcus width and depth, withdisplacement of the muscle attachment closer tothe crest of the residual ridge; loss of the verticaldimension of occlusion, reduction of the lower faceheight, an anterior rotation of the mandible, andincrease in relative prognathia; changes in inter-alveolar ridge relationship after progression of theresidual ridge reduction, which is essentially cen-tripetal in the maxilla and centrifugal in themandible; and morphological changes of the alve-olar bone such as sharp, spiny, uneven residualridges and location of the mental foramina close tothe top of the residual ridge.

A close correlation between a patient’s satisfac-tion with dentures and the anatomical conditions ofthe residual ridges is not always present. However,in long-term complete denture wearers, the mor-phological changes and the reduction of the resid-ual ridges present serious problems to the clinicianon how to provide adequate support, stability, andretention of new dentures. Traditionally, theseproblems were approached by prescribing prepros-thetic surgical initiatives such as vestibuloplastieswith skin or mucosal grafts or, in severe situations,by performing ridge augmentation procedures.These techniques have been virtually eclipsed bythe introduction of the osseointegration technique,which is discussed in Part 4.

Overdenture Abutments: Caries andPeriodontal Disease

The retention of selected teeth to serve as abut-ments under complete dentures is an excellentprosthodontic technique (see Chapter 10) (Figure4-14). In this simple method, a few teeth in a strate-gically good position are preserved and are treated


Some Proposed EtiologicalFactors of Reduction of

Residual Ridges

Anatomical FactorsMore important in the mandible versus the

maxillaShort and square face associated with elevated

masticatory forcesAlveoloplasty

Prosthodontic FactorsIntensive denture wearingUnstable occlusal conditionsImmediate denture treatment

Metabolic and Systemic FactorsOsteoporosisCalcium and vitamin D supplements for possi-

ble bone preservation

Box 4-5

Figure 4-14 A, Complete overdentures in a patient with multiple aplasia. B and C, Thedentures have been in place for 25 years, and the remaining teeth/roots have preventedresidual ridge reduction.

A

C

B

endodontically before the crown is modified. Theexposed root surface and canal are filled withamalgam or a composite restoration. In this way,even periodontally affected teeth can be maintainedfor several years in a relatively simple way.

Overdenture treatment does not necessarilyincrease the risk of technical failures such as den-ture fractures or loss of denture teeth. However, thewearing of overdentures is often associated with ahigh risk of caries and progression of periodontaldisease of the abutment teeth. One of the reasonsfor this is that the bacterial colonization beneath aclose-fitting denture is enhanced, and good plaquecontrol of the fitting denture surface is generallydifficult to obtain. One reason is that the species ofStreptococcus and Actinomyces predominating indenture plaque are well known for their major con-tributions to dental plaque on smooth enamel sur-

faces, as well as on root cementum. The inflamma-tory potential of these species is illustrated by thefinding that early dentogingival plaque (in whichthey also predominate) initiates gingivitis after 1 to3 days of plaque accumulation when oral hygiene isdiscontinued. This could explain why it is difficultto maintain healthy periodontal conditions adjacentto overdenture abutments. Another outstanding fea-ture of denture plaque flora is its high proportionsof lactobacilli and Streptococcus mutans, whichcould explain why caries is difficult to controlbecause caries rates of up to 30% after 1 year havebeen observed in patients wearing overdentures.

For the success of overdentures to be improved,effective prevention of caries and periodontal dis-eases is necessary. The principal aim of the preven-tive measures should be to control accumulation ofplaque on the exposed dentin of the abutment teeth


as well as the root surface. The preventive measuresinclude mechanical and chemical plaque controland introduction of adequate denture-wearinghabits.

Longitudinal studies indicate that it is generallypossible to obtain reasonable oral and denturehygiene in overdenture wearers. However, it is neces-sary to motivate the patient and to introduce regularfollow-up examinations at intervals of 3 to 6 months.Despite these efforts, caries-susceptible patientswill have root or dentin caries, and progression ofperiodontal disease is also likely to take place.

The effect of daily application of gels containingfluoride or fluoride plus chlorhexidine has beenassessed in comparative studies. Patients wereinstructed to put a drop of the gel in the prosthesis atthe abutment site and to insert the prosthesis for atleast 30 minutes once a day. With the fluoride gel,there was no marked caries reduction when com-pared with the placebo gel and no effect on peri-odontal health. On the other hand, use of thefluoride-chlorhexidine gel controlled caries develop-ment and maintained healthy periodontal conditions.

The introduction of adequate denture-wearinghabits (e.g., to abstain from wearing the dentureduring the night) is another efficient way to controlcaries and development of periodontal disease inoverdenture wearers. In this way, the microbialplaque is less readily established, and saliva with itsbuffering capacity, antibacterial systems, and anti-bodies has free access to the abutments.

Treatment of superficial caries of the overden-ture abutments includes application of fluoride-chlorhexidine gel and polishing, and not exclusiveplacement of fillings, which could result in recur-rent caries. The placement of copings that cover theexposed dentin and root surface is indicated onlywhere caries is more deeply penetrating. This isalso a way to minimize the risk of new or recurrentcaries. Periodontal pockets greater than 4 to 5 mmshould be eliminated surgically because they pres-ent a high risk of acute periodontal complications.

INDIRECT SEQUELAEAtrophy of Masticatory Muscles

It is essential that the oral function in completedenture wearers is maintained throughout life. The

masticatory function depends on the skeletal mus-cular force and the facility with which the patient isable to coordinate oral functional movements dur-ing mastication. Maximal bite forces tend todecrease in older patients. Furthermore, computedtomography studies of the masseter and the medialpterygoid muscles have demonstrated a greateratrophy in complete-denture wearers, particularlyin women. This indicates that reduced bite forceand chewing efficiency are sequelae caused bywearing complete dentures, resulting in impairedmasticatory function. There is little evidence thatthe placement of a new denture significantlyimproves masticatory efficiency. Indeed, elderlydenture wearers often find that their chewing abil-ity is insufficient and that they are obliged to eatsoft foods.

Diagnosis Direct measurement of the capacity toreduce test food to small particles has verified thatchewing efficiency decreases as the number of nat-ural teeth is reduced and is worse for subjects wear-ing complete dentures. One of the consequences isthat wearers of conventional complete dentures needapproximately seven times more chewing strokesthan subjects with a natural dentition to achieve anequivalent reduction in particle size. As a conse-quence, complete-denture wearers prefer food that iseasy to chew, or they swallow large food particles.

Preventive Measures and Management Tosome extent, the retention of a small number ofteeth used as overdenture abutments seems to playan important role in the maintenance of oral func-tion in elderly denture wearers. Therefore treatmentwith overdentures has particular relevance in viewof the increasing numbers of older people who areretaining a part of their natural dentition later in life.

In the completely edentulous patients, place-ment of implants is usually followed by animprovement of the masticatory function and anincrease of maximal occlusal forces. This improve-ment may persist in a long-term perspective, andmaximal occlusal forces may even increase withthe years of denture wearing.

There is no evidence of a similar benefit aftera preprosthetic surgical intervention to improvethe anatomical conditions for wearing completedentures.


Nutritional Deficiencies

Epidemiology (see Chapter 6) Aging is oftenassociated with a significant decrease in energyneeds as a consequence of a decline in muscle massand decreased physical activity. Thus a 30% reduc-tion in energy needs should be and usually isaccompanied by a 30% reduction of food intake.However, with the exception of carbohydrates, therequirement for virtually all other nutrients doesnot decline significantly with age. As a conse-quence, the dietary intake by elderly individualsfrequently reveals evidence of deficiencies, whichis clearly related to the dental or prosthetic status.Severe nutritional deficiencies are rare amonghealthy individuals, even with poor masticatoryfunction. However, in chronically ill or hospitalizedpatients nutritional deficiencies are frequent. Inthese patients, factors such as ill-fitting dentures,salivary gland hypofunction, or altered taste per-ception may have a negative effect on the dietaryhabits and the nutritional status.

Masticatory Ability and Performance One ofthe strong indications for prosthodontic treatmentis to improve masticatory function. In this context,the term masticatory ability is used for an individ-ual’s own assessment of his or her masticatoryfunction, whereas efficiency is to be understood asthe capacity to reduce food during mastication. Aspreviously mentioned, the wearing of completedentures greatly compromises both masticatoryability and performance as compared with a situa-tion with natural teeth present. There is no strikingevidence that malnutrition could be a direct sequelaof wearing dentures. However, edentulous womenhave a higher intake of fat and a higher consump-tion of coffee and a lower intake of ascorbic acidcompared with dentate subjects within the sameage group.

Nutritional Status and Masticatory FunctionFour factors are related to dietary selection and thenutritional status of wearers of complete dentures:masticatory function and oral health, generalhealth, socioeconomic status, and dietary habits. Inhealthy individuals there is no evidence that thenutritional intake is impaired in wearers of com-plete dentures or that replacement of ill-fitting den-tures with well-fitting new dentures will cause

a major improvement of nutrition. In institutional-ized patients, some amelioration of the nutritionalintake could take place after prosthetic treatmentbecause some patients are likely to start eating hardbread and to choose new food items such as veg-etables and fruits.

The principal causes of protein energy malnutri-tion among elderly denture wearers are associatedprimarily with poor general health: poor absorption;intestinal, metabolic, and catabolic disturbances; oranorexia. Also, reduced salivary secretion rate dur-ing mastication has a negative effect on masticatoryability and efficiency (Box 4-6).

For the improvement and maintenance of thenutritional status it is often necessary to modifydietary habits. This reeducation of elderly denturewearers may be very difficult because their dietaryhabits are often firmly fixed and because they havea decreased appetite. In addition, poorly adapteddentures prevent patients from achieving improveddietary habits. Mechanical preparation of foodbefore eating will help mastication and reduce itsinfluence on food selection. However, it will notstimulate appetite and increase life quality. Themaintenance or reestablishment of oral health andmasticatory function remains an integral part of


Associations amongXerostomia, Denture Wearing,

Impaired Masticatory Function,and Undernutrition in Frail and

Dependent Older Persons

Reduced Stimulated Salivary Flow RateAssociated with:Complaints of xerostomiaChewing difficultiesComplaints related to wearing complete den-

turesIncreased number of chewing cycles before

swallowingLoss of appetiteReduced serum albumin levelReduced body mass indexReduced skinfold thickness

Box 4-6

medical health care of the elderly patient who ismedically compromised.

CONTROL OF SEQUELAE WITH THEUSE OF COMPLETE DENTURESThe essential consequences of wearing completedentures are reduction of the residual ridges andpathological changes of the oral mucosae. Thisoften results in poor patient comfort, destabiliza-tion of the occlusion, insufficient masticatory func-tion, and esthetic problems. Ultimately, the patientmay not be able to wear dentures and will receive adiagnosis of prosthetically maladaptive.

For the adverse sequelae of residual ridgeresorption to be reduced, the following should beconsidered:

1. Restoration of the partially edentulous patientwith complete dentures should be considered ifthis is the only alternative as a result of poorperiodontal health, unfavorable location of theremaining teeth, and economic limitations. Inthis situation, every effort should be made toretain some teeth in strategically good positionsto serve as overdenture abutments. The mainte-nance of tooth roots in the mandible is particu-larly important.

2. The patient with complete dentures should fol-low a regular control schedule at yearly inter-vals so that an acceptable fit and stable occlusalcondition can be maintained.

3. Edentulous patients should be aware of the bene-fits of an implant-supported prosthesis (see Part4). In young patients, the primary advantagewould be reduced residual ridge reduction. In eld-erly patients, the main advantages are improvedcomfort and maintenance of masticatory function.

The following precautions should be taken to pre-clude development of soft tissue disease:

1. Patients wearing overdentures supported by nat-ural roots or implants should follow a programof recall and maintenance for continuous moni-toring of the denture and the oral tissues. Ifpatient compliance is difficult to obtain, thismight indicate that it is necessary to see thepatient every 3 to 4 months.

2. The patient should be motivated to practiceproper denture-wearing habits such as not wear-ing dentures during the night.

Finally, it is important to remind and to explain toour patients that treatment with complete denturesis not a “definitive” treatment and that their collab-oration is important to prevent the long-term risksassociated with the consequences of wearing com-plete dentures.

BibliographyBudtz-Jørgensen E: Oral mucosal lesions associated with the

wearing of removable dentures, J Oral Path 10:65-80, 1981.Budtz-Jørgensen E: Prognosis of overdenture abutments in the

aged: effect of denture wearing habits, Community DentOral Epidemiol 20:302-306, 1992.

Budtz-Jørgensen E: Prognosis of overdenture abutments in eld-erly patients with controlled oral hygiene: a 5 year study, JOral Rehabil 22:3-8, 1995.

Budtz-Jørgensen E: Ecology of Candida-associated denturestomatitis, Microb Ecol Health Dis 12:170-185, 2000.

Budtz-Jørgensen E, Chung JP, Mojon P: Successful aging—thecase for prosthetic therapy, J Publ Health Dent 60:308-312,2000.

Canon RD, Holmes AR, Mason AB et al: Oral Candida: clear-ance, colonization or candidiasis? J Dent Res 74(5):1152-1161, 1995.

Carlsson GE, Lindquist LW: Ten-year longitudinal study ofmasticatory function in edentulous patients treated withfixed complete dentures on osseointegrated implants, Int JProsthodont 7:448-453, 1994.

Clifford TJ, Warsi MJ, Burnett SA et al: Burning mouth inParkinson’s Disease sufferers. Gerodontology 15:73-78, 1998.

Conny DJ, Tedesco LA: The gagging problem in prosthodontictreatment. Part I: Description and causes, J Prosthet Dent49:601-606, 1983.

Fenlon MR, Sherriff M, Walter JD: Factors associated with thepresence of denture related stomatitis in complete denturewearers: a preliminary investigation, Eur J Prosthodont RestDent 6:145-147, 1998.

Grushka M: Insights into burning mouth syndrome, PhD thesis,Toronto, 1986, University of Toronto.

Guggenheimer J, Hoffman RD: The importance of screeningedentulous patients for oral cancer, J Prosthet Dent74:141-143, 1994.

Hillerup S: Preprosthetic surgery in the elderly, J Prosthet Dent72:551-558, 1994.

Jahangiri L, Devlin H, Ting K et al: Current perspectives inresidual ridge remodeling and its clinical implications: areview, J Prosthet Dent 80:224-237, 1998.

Lombardi T, Budtz-Jørgensen E: Treatment of denture-inducedstomatitis: a review, Eur J Prosthodont Rest Dent 2:17-22,1993.

Main DMG, Basker RM: Patients complaining of a burningmouth, Br Dent J 154:206-211, 1983.


Mercier P, Vinet A: Factors involved in residual alveolar ridgeatrophy of the mandible, J Can Dent Assn 5:339-343, 1983.

Mericske-Stern R: Overdentures with roots or implants for elderlypatients: a comparison, J Prosthet Dent 72:543-550, 1994.

Newton AV: Denture sore mouth, Br Dent J 112:357-360, 1962.Newton JP, Yemm R, Abel RW et al: Changes in human jaw mus-

cles with age and dental state, Gerodontology 10:16-22, 1993.Ortman LF, Hausmann E, Dunford RG: Skeletal osteopenia and

residual ridge resorption, J Prosthet Dent 61:321-325, 1989.Reichart PA: Oral mucosal lesions in a representative cross-

sectional study of aging Germans, Community Dent OralEpidemiol 28:390-398, 2000.

Tallgren A: The continuing reduction of the residual alveolarridges in complete denture wearers: a mixed longitudi-nal study covering 25 years, J Prosthet Dent 27:120-132,1972.

Theilade E, Budtz-Jørgensen E: Predominant cultivablemicroflora of plaque on removable dentures in patients withdenture-induced stomatitis, Oral Microbiol Immunol 3:8-13,1988.

Theilade J, Budtz-Jørgensen E: Electron microscopic study ofdenture plaque, J Biol Buccale 8:287-297, 1980.

Tourne LPM, Fricton JR: Burning mouth syndrome, Oral Surg74:158-167, 1992.


C H A P T E R 5Temporomandibular Disorders inEdentulous PatientsThuan Dao

51

Temporomandibular disorders (or TMDs) is a col-lective term that is used to designate a group ofmusculoskeletal conditions affecting the temporo-mandibular area. These include muscular condi-tions, such as myofascial pain, and disordersaffecting the temporomandibular joint complex,such as disc displacement disorders and arthriticdiseases. The term TMDs was introduced byDworkin and LeResche (1992) and replacesnumerous misleading terms that were previouslyused.

EPIDEMIOLOGY OF TEMPOROMANDIBULAR DISORDERSIN EDENTULOUS POPULATIONSThe reported prevalence of TMDs in edentulouspopulations appears to vary considerably, rangingfrom 0% (Loiselle, 1969) to 94% (Agerberg andViklund, 1989). The wide discrepancies observedare largely due to differences in the criteria, or thelack of specific criteria, that were used to defineTMDs. Although the prevalence of TMDs in theedentulous population still needs to be ascertained,an appraisal of the epidemiological literature onTMDs and related symptoms from different popu-lation-based studies reveals consistently that it isprimarily a condition of young and middle-ageadults (mainly female) and that its prevalence tendsto diminish in the older-age group (LeResche,1997), where partial or complete edentulism pre-vails (MacEntee, 1985; Warren, Watkins, andCowen, 2002). These observations suggest thatTMDs are encountered in elderly and edentulous

subjects, but it is certainly not of the epidemic pro-portions reported in earlier studies.

ETIOLOGICAL FACTORSThe presumed association between edentulism andTMDs resulted from the traditional mechanisticnotions that tooth loss is a predisposing factor tomandibular dysfunction. This association has beenfurther reinforced by reports that the severity ofsuch dysfunction is positively correlated with theloss of occlusal support and the number of remain-ing teeth or occluding pairs of teeth. It is thereforenot surprising to see that the loss of vertical dimen-sion of occlusion has also been assumed to play animportant role in the etiology of TMDs in elderlyand edentulous patients. However, if tooth loss oredentulism is a direct cause of TMDs, the preva-lence of TMDs should be higher in the edentulouspopulation as compared with the dentate one. Thisis clearly not the case, and in the last decadenumerous reports have refuted this assumption(Bibb, Atchison, Pullinger et al., 1995; De Kanter,Truin, Burgersdijk et al., 1993; Gray, McCord,Murtaza et al., 1997). In addition, the lack of cor-relation between the number of remaining teeth andthe prevalence or severity of TMDS has beenrepeatedly reported (Bibb, Atchison, Pullinger etal., 1995; Tervonen and Knuuttila, 1988).

Although the effect of the dentition and eden-tulism on changes in the temporomandibular joints(TMJs) has been questioned, an age-relatedincrease in the prevalence of degenerative diseasesis a well-known fact, whether in the TMJs per se(Pereira, Lundh, and Westesson, 1994) or in other

body joints (Sowers, 2001). Therefore becauseedentulism is most prevalent among older persons,it is reasonable to assume that the presence ofdegenerative diseases in the edentulous populationis more likely to be associated with age than withedentulism itself.

A few studies have reported a higher preva-lence of TMDs in edentulous versus dentate sub-jects. However, the data either were notsubstantiated by statistical analysis (Tervonen andKnuuttila, 1988), or group differences failed toreach statistical significance (Harriman, Snowdon,Messer et al., 1990). There are also compelling datathat TMD-related signs and symptoms are mild inedentulous subjects (Bergman and Carlsson, 1985;Lundeen, Scruggs, McKinney et al., 1990; Raustia,Peltola, and Salonen, 1997; Wilding and Owen,1987) and are relatively low in those who do notwear dentures (Wilding and Owen, 1987). A lack ofcorrelation between the severity or presence ofTMDs and edentulism-related factors (duration,age, quality and number of complete prostheses,centric occlusion–centric relation coincidence, anddenture retention and stability) has also been fre-quently reported in the literature (Bibb, Atchison,Pullinger et al., 1995; MacEntee, Weiss, Morrisonet al., 1987; Raustia, Peltola, and Salonen, 1997).For instance, MacEntee (1987) reported no associ-ation between the clinical signs of dysfunction andocclusal instability or denture quality. In theirsearch for etiological factors for TMDs in edentu-lous denture-wearing patients, Faulkner andMercado (1990) failed to show significant associa-tion between the number of years that patients worecomplete dentures, the age of the denture, the cen-tric occlusion–centric relation coincidence, anddenture retention and stability. Their result is con-sistent with the current evidence-based view thatquestions the role of occlusion in the pathophysiol-ogy of TMDs (Greene, 2001).

Mechanistic etiological concepts have nowbeen eclipsed by biological variables, whichinclude cellular, molecular, neurophysiological,neuroendocrinological, immunological, and geneticmechanisms of joint diseases. Chronic orofacial andmuscle pains as unique foci for study have emergedfrom the related clinical and basic science research.The role of neuroendocrine peptides, cytokines, andlocal cell-derived mediators of pain and inflamma-

tion in arthritic pain and inflammation in the TMJshas received increasing attention (Kopp, 2001).Proposed neural mechanisms for TMD pain nowinclude impairments in central inhibitory mecha-nisms, disorders in pathways modulated by periph-eral baroreceptor afferent input, and alteration incentral nervous system processes that regulate thetemporal processing of pain (Maixner, Fillingim,Booker et al., 1995). In the case of muscle-relatedTMDs, sensitization of peripheral tissues, neuro-plasticity in pronociceptive and antinociceptive cir-cuits, and behavioral sensitization associated withincreased emotionality and with pain-specific neu-roendocrine and autonomic responsivity have beenalso been reviewed (Stohler, 1999). Some newerlines of evidence also suggest that the above painsystems may be modulated by the female hor-mones. One such example is the interactionbetween estrogen and neuroactive agents implicatedin both peripheral and central pain processingmechanisms (Dao, Knight, and Ton-That, 1998;Dao and LeResche, 2000). Moreover, the use ofexogenous hormones (e.g., oral contraceptives andhormone replacement therapies) has also beenreported to be associated with increased risks forTMDs, and a dose-response relationship was alsoevident (LeResche, Saunders, Von Korff et al.,1997). The role of female hormones in the patho-physiology of TMDs is an exciting research area;however, it must be recognized that the etiology ofTMD conditions is still unclear.

MANAGEMENT OF TEMPORO-MANDIBULAR DISORDERS IN THEEDENTULOUS PATIENTThe dental approach to TMD treatment in the eden-tulous patient has traditionally consisted of opti-mizing the stability, retention, and occlusion of thecomplete prostheses. This is still a valid approachto the adjunctive management of the TMDs.However, this does not imply a presumed occlusaletiology. Management of TMDs should primarilybe directed toward palliation of the condition. Theguidelines for management are well summarized inthe official Scientific Information Statement pub-lished by the American Association of DentalResearch (Greene, 2001).


Based on the evidence from clinical trials [ofTMDs] . . . it is strongly recommended that,unless there are specific and justifiable indica-tion to the contrary, treatment be based on theuse of conservative and reversible therapeuticmodalities. While no specific therapies havebeen proven to be uniformly effective, manyconservative modalities have provided at leastpalliative relief from symptoms without produc-ing harm.

In the absence of true understanding of the condi-tion and until development of specific therapies,correct and prudent conservative symptomaticmanagement of TMDs in denture wearers shouldbe similar to the management strategies prescribedfor most TMD patients. This includes patient edu-cation and reassurance about the benign nature ofthe condition, self-care, short-term pharmacother-apy (Dionne, 1997), physical modalities (Feine andLund, 1997), and cognitive and behavioral inter-vention (Dworkin, 1997).

REASSURANCE AND SELF-CARE REGIMENAlthough patients should be informed about thelimited knowledge of etiological factors, togetherwith reassurance about the relative frequent occur-rence of TMDs in the population, the good progno-sis of the condition, and the merits of prudentmanagement strategies. In addition, the patientshould be instructed to follow a home care programto promote tissue rest and self-healing that includesthe following: application of moist heat (10 to 20minutes, 4 times a day) or cold application (5 min-utes each time), soft diet, avoidance of musclestrain (e.g., avoid gum chewing or clenching), andidentification and avoidance of events that can trig-ger pain or discomfort. Encouraging patients toactively participate in the control of their conditionshould be an integral part of the managementstrategies because committed patients usually dobetter than passive recipients of care. This is sup-ported by recent evidence showing that whenpatients who participated in tailored self-care pro-grams were compared with patients who receivedthe usual TMDs treatment (e.g., physiotherapy,

patient education, medications, oral splints), theformer patients showed significantly decreasedpain, decreased pain-related activities, a reducednumber of painful masticatory muscles, andreduced additional visits for TMDs treatment(Dworkin, Huggins, Wilson et al., 2002).

PHARMACOTHERAPYPharmacotherapy may be required when the previ-ous strategies fail to increase the patient’s comfortlevel. For acute pain states, dentists most com-monly prescribe medications with analgesic prop-erties, as well as muscle relaxants, nonsteroidalanti-inflammatory drugs (NSAIDs), and therecently introduced selective cyclooxygenase-2(COX-2) inhibitor. These medications are particu-larly useful for the treatment of arthritic conditionsinvolving the TMJs. Patients should be followedclosely for the titration of the medication, to ensureadequate pain control and minimize unwanted sideeffects. It is important to note that although theshort-term efficacy of these medications is wellestablished, their long-term efficacy is not welldocumented. For persistent and neuropathic orofa-cial pain, management with antidepressants andopioids may play an important role. As for othermedications that are prescribed on a long-termbasis, however, the balance between their therapeu-tic benefit and toxicity should be carefullyweighed, and their administration should be sup-ported and coordinated with the family physicianor a pain specialist. The dentist should additionallybe aware of the potential interactions of the pre-scribed medications with other drugs that are usedby the patient for comorbid conditions.

PHYSICAL MODALITIESA wide range of physical modalities can be sug-gested to patients, including the use of heat andcold therapies, ultrasound, massage, joint mobiliza-tion, and passive stretching, and can be adminis-tered either by the patient or by a clinician.Although local heat application is widely used forpain relief, its benefit has been questioned becauseraised temperature increases tissue inflammation.On the other hand, the superiority of cold over heattherapy for reducing inflammation and swelling

Chapter 5 Temporomandibular Disorders in Edentulous Patients 53

has been documented (see review by Feine andLund, 1997). Although the long-term efficacy ofphysical modalities for musculoskeletal pain con-ditions has not been established, their safety, lowcost, and short-lived benefit in providing pain reliefjustify their use as palliative measures for TMDs.

BIOBEHAVIORAL MODALITIESAmong the biobehavioral therapies prescribed forchronic pain, the most commonly studied includebiofeedback, stress management, relaxation, hypno-sis, and education. As proposed by Dworkin, “Thelabel ‘biobehavioral’ refers to proven, safe methodsthat emphasize self-management and acquisition ofself-control over not only pain symptoms but alsotheir cognitive attributions or meanings and main-taining a productive level of psychosocial function,even if pain is not totally absent” (1997). In additionto modifying maladaptive habits, lifestyle patterns,and behaviors that may contribute to the perceptionof pain, biobehavioral therapies can also providepatients with coping skills for the control of pain andrelated disabilities. The efficacy of behavioral thera-pies in producing long-term relief has been suggestedfor many persistent pain conditions, and these thera-pies continue to be part of nearly all chronic paintreatment programs (Dworkin, 1997). However, theirlong-term efficacy in the management of TMDs hasnot been established.

SUMMARYTMDs can affect the edentulous and elderly popu-lation, although their prevalence and severity donot exceed those of the dentate subjects in a lower-age range. The shift from a mechanical etiologicalview to a biological one, including emphasis on thepossible etiological role of female hormones, hasalso resulted in a shift in treatment focus. Althoughprosthodontic treatment aims at achieving optimalprostheses and improvement of the patient’s orofa-cial comfort and function, the intervention per se isnot a specific therapy for TMDs.

ReferencesAgerberg G, Viklund L: Functional disturbances in complete

denture patients, Int J Prosthodont 2:41-50, 1989.

Bergman B, Carlsson GE: Clinical long-term study of completedenture wearers, J Prosthet Dent 53:56-61, 1985.

Bibb CA, Atchison KA, Pullinger AG et al: Jaw function statusin an elderly community sample, Community Dent OralEpidemiol 23:303-308, 1995.

Dao TT, Knight K, Ton-That V: Modulation of myofascialpain by the reproductive hormones: a preliminary report,J Prosthet Den 79:663-670, 1998.

Dao TT, LeResche L: Gender differences in pain, J Orofac Pain14:169-184; discussion 184-195, 2000.

De Kanter RJ, Truin GJ, Burgersdijk RC et al: Prevalence in theDutch adult population and a meta-analysis of signs andsymptoms of temporomandibular disorder, J Dent Res72:1509-1518, 1993.

Dionne RA: Pharmacologic treatments for temporomandibulardisorders, Oral Surg Oral Med Oral Pathol Oral RadiolEndod 83:134-142, 1997.

Dworkin SF: Behavioral and educational modalities, Oral SurgOral Med Oral Pathol Oral Radiol Endod 83:128-133, 1997.

Dworkin SF, Huggins KH, Wilson L et al: A randomized clini-cal trial using research diagnostic criteria for temporo-mandibular disorders-axis II to target clinic cases for atailored self-care TMDs treatment program, J Orofac Pain16:48-63, 2002.

Dworkin SF, LeResche L: Research diagnostic criteria for tem-poromandibular disorders: review, criteria, examinationsand specifications, critique, J Craniomandib Disord FacialOral Pain 6:301-355, 1992.

Faulkner KD, Mercado MD: Aetiological factors of cran-iomandibular disorders in completely edentulous denture-wearing patients, J Oral Rehabil 18:243-251, 1990.

Feine JS, Lund JP: An assessment of the efficacy of physicaltherapy and physical modalities for the control of chronicmusculoskeletal pain, Pain 71:5-23, 1997.

Gray RJ, McCord JF, Murtaza G et al: The incidence of tem-poromandibular disorder signs in patients wearing completedentures compared to patients with a natural dentition, EurJ Prosthodont Restor Dent 5:99-103, 1997.

Greene CS: The etiology of temporomandibular disorders:implications for treatment, J Orofac Pain 15:93-105; discus-sion 106-116, 2001.

Harriman LP, Snowdon DA, Messer LB et al: Temporo-mandibular joint dysfunction and selected health parametersin the elderly, Oral Surg Oral Med Oral Pathol 70:406-413,1990.

Kopp S: Neuroendocrine, immune, and local responses related totemporomandibular disorders, J Orofac Pain 15:9-28, 2001.

LeResche L: Epidemiology of temporomandibular disorders:implications for the investigation of etiologic factors, CritRev Oral Biol Med 8:291-305, 1997.

LeResche L, Saunders K, Von Korff MR et al: Use of exogenoushormones and risk of temporomandibular disorder pain,Pain 69:153-160, 1997.

Loiselle RJ: Relation of occlusion to temporomandibular jointdysfunction: the prosthodontic viewpoint, J Am Dent Assoc79:145-146, 1969.

Lundeen TF, Scruggs RR, McKinney MW et al: TMDs sympto-mology among denture patients, J Craniomandib Disord4:40-46, 1990.


MacEntee MI: The prevalence of edentulism and diseasesrelated to dentures–a literature review, J Oral Rehabil12:195-207, 1985.

MacEntee MI, Weiss R, Morrison BJ et al: Mandibular dys-function in an institutionalized and predominantly elderlypopulation, J Oral Rehabil 14:523-529, 1987.

Maixner W, Fillingim R, Booker D et al: Sensitivity of patientswith painful temporomandibular disorders to experimentallyevoked pain, Pain 63:341-351, 1995.

Pereira FJ Jr, Lundh H, Westesson PL: Morphologic changes inthe temporomandibular joint in different age groups: anautopsy investigation, Oral Surg Oral Med Oral Pathol78:279-287, 1994.

Raustia AM, Peltola M, Salonen MA: Influence of completedenture renewal on craniomandibular disorders: a 1-yearfollow-up study, J Oral Rehabil 24:30-36, 1997.

Sowers M: Epidemiology of risk factors for osteoarthritis: sys-temic factors, Curr Opin Rheumatol 13:447-451, 2001.

Stohler CS: Muscle-related temporomandibular disorders,J Orofac Pain 13:273-284, 1999.

Tervonen T, Knuuttila M: Prevalence of signs and symptoms ofmandibular dysfunction among adults aged 25, 35, 50 and65 years in Ostrobothnia, Finland, J Oral Rehabil15:455-463, 1988.

Warren JJ, Watkins CA, Cowen HJ et al: Tooth loss in the veryold: 13-15-year incidence among elderly Iowans,Community Dent Oral Epidemiol 30:29-37, 2002.

Wilding RJ, Owen CP: The prevalence of temporomandibularjoint dysfunction in edentulous non-denture wearing indi-viduals, J Oral Rehabil 14:175-182, 1987.

Chapter 5 Temporomandibular Disorders in Edentulous Patients 55

C H A P T E R 6Nutrition Care for the Denture-Wearing PatientMary P. Faine

56

Enjoyment of food is regarded as an importantdeterminant of an adult’s quality of life. Looseteeth, edentulism, or ill-fitting dentures may pre-clude eating favorite foods, as well as limit theintake of essential nutrients. Decreased chewingability, fear of choking while eating, and irritationof the oral mucosa when food particles get underdentures may influence food choices of the denturewearer. Conversely, the nutritional status of a patientwith dentures affects the health of the oral tissuesand the patient’s adaptation to a new prosthesis. Infact, well-designed and constructed dentures or animplant-supported prosthesis may prove to beunsatisfactory for a patient because of poor toler-ance by the underlying tissues and bone. Hence,denture failures can be due not only to imperfectdesign, but also to poorly nourished tissues.

Clinical symptoms of malnutrition are oftenobserved first in the oral cavity. Because of rapidcell turnover (every 3 to 7 days) in the mouth, aregular, balanced intake of essential nutrients isrequired for the maintenance of the oral epithelium.Inadequate long-term nutrition may result in angu-lar cheilitis, glossitis, and slow tissue healing. Theamount of alveolar bone resorption that occursafter tooth extractions may be exacerbated by lowcalcium and vitamin D intakes.

Nearly half of older individuals have clinicallyidentifiable nutrition problems. Undernutritionincreases with advancing age. Persons older than70 years of age are more likely to have nutritionallypoor diets. Dentate status can affect eating abilityand thus the diet quality. In elderly persons, oralhealth problems may contribute to involuntary

weight loss and a lower body mass index. Becausemost edentulous adults are of advanced age, a largenumber of patients with dentures can be expectedto have nutritional deficits. The nutritional status ofa denture wearer also is influenced by economichardship, social isolation, degenerative diseases,medication regimens, and dietary supplementationpractices (Figure 6-1). An understanding of thenutritional requirements, symptoms of malnutri-tion, and environmental factors that influence foodchoices will assist dental clinicians in identifyingdenture-wearing patients at risk for malnutrition.Dietary guidance, based on the assessment of theedentulous patient’s nutrition history and diet,should be an integral part of comprehensiveprosthodontic treatment. Nutrition support willimprove the tolerance of the oral mucosa to newdentures and prevent rejection of dentures. Becausedenture fabrication requires a series of appoint-ments, dietary analysis and counseling can be eas-ily incorporated into an edentulous patient’streatment plan.

THE IMPACT OF DENTAL STATUS ONFOOD INTAKEThe food choices of older adults are closely linkedto dental status and masticatory efficiency.Although an intact dentition is not a necessity formaintaining nutritional health, the loss of teeth oftenleads adults to select diets that are lower in nutrientdensity. Investigators in the United States andSweden have reported that adults with compromised

dentitions are overrepresented in groups with nutri-tionally poor diets. Furthermore, denture wearersreport that food such as raw carrots, lettuce, cornon the cob, raw apples with peels, steaks, and chopsare difficult to chew.

When compared to peers with 25 teeth ormore, edentulous male health professionals con-sumed fewer vegetables, less fiber and carotene,and more cholesterol, saturated fat, and calories.Denture wearers had lower serum β-carotene andascorbic acid levels than dentate subjects. A largenumber of denture wearers were among the 691healthy older persons studied by researchers at theUnited States Department of Agriculture’s (USDA)Human Nutrition Research Center on Aging inBoston. Nutritionally poorer diets were reported byadults who had low educational attainment, whohad low family income, or who wore partial orcomplete dentures. Male denture wearers hadpoorer nutrient intakes than female denture wear-ers. Specifically, mean intakes of calories, protein,vitamin A, ascorbic acid, vitamin B6, and folic acidwere lower in male denture wearers than in dentatemen. Calcium and protein intakes of female den-ture wearers were inferior to those of dentatewomen. In a subset of the USDA subjects, thenutrient intake of those who had one or two com-plete dentures was about 20% lower than that ofdentate subjects.

Age, oral motor function, adequate saliva, andthe number of occluding pairs of teeth in the mouthmainly determine an individual’s masticatory abil-ity. When compared to those with natural dentition,persons with removable complete dentures hadgreatly reduced chewing ability. Denture wearersmust complete a greater number of chewingstrokes to prepare food for swallowing. Even withadditional chewing, the average denture does notreduce foods to as small a particle size as does nat-ural dentition. The chewing ability of individualswith a complete denture in only one arch, opposedby a natural dentition, appears to be reduced tonearly the same extent as persons with completedentures in both arches. In a Veteran’s Admini-stration longitudinal study, dentition status andnutrient intakes were significantly related to masti-catory function. When new complete denturesreplace old ones that had poor retention, patientssubjectively reported that masticating performanceimproved; they chewed better and chewed differentfoods. However, nutrient intake was not improved.Chewing efficiency is determined by measuringparticle size after subjects have chewed a test foodas long as necessary to prepare the sample for swal-lowing.

Texture and hardness, rather than taste andsmell, determine acceptability of a food for manypatients with dentures. Generally, the intake of hardfoods (raw vegetables or fruits, fibrous meats, hardbreads, seeds, and nuts) is reduced, whereas theintake of soft foods (ground beef, breads, cereals,pastries, and canned fruits and vegetables) isincreased. Whether these changes in food selectionnegatively affect nutritional status depends onnutrient density of the food substituted, but softfoods are often lower in nutrient density and fiber.For example, replacing steak with ground beef pro-vides similar nutrients, but substituting applesaucefor a green salad results in lower nutrient intake.

Replacing a complete denture with osseointe-grated implants results in significant improvementin masticatory function. Increased intake of freshfruits and crisp bread was reported by a smallgroup of Swedish adults who received tissue-integrated prostheses in the lower jaw. Others whopreviously wore dentures reported that their chew-ing ability was markedly improved after insertionof a mandibular fixed prosthesis on osseointe-

Chapter 6 Nutrition Care for the Denture-Wearing Patient 57

Diabetes

Medications Smoking

Lownutrient intake

Lowcaloric intake

Alcoholabuse

Xerostomia Soft diet

UNHEALTHYORAL TISSUES

Figure 6-1 Maladaptive denture-wearing signs andsymptoms may include unhealthy oral tissues such ascracking at the corners of the lips and persistentsoreness of the tongue and oral mucosa. These may berelated to a low intake of essential nutrients, reducednutrient absorption, or altered nutrient metabolismdue to medications or alcohol abuse.

grated dental implants. However, improved oralfunction does not lead to selection of a higher qual-ity diet. Some individuals will eat a more varieddiet and increase their intake of fruits and vegeta-bles, but nutrient intake of implant wearers is gen-erally similar to complete denture subjects. Toimprove diet quality, individual patients undergo-ing prosthodontics need dietary counseling.

The inability to distinguish the sensory quali-ties of food reduces a patient’s enjoyment of eatingand may lead to reduced calorie intake. Because adecrease in taste and smell acuity frequentlyaccompanies aging, it is difficult to separate theeffects of aging and denture wearing on sensoryacuity. Nearly all denture wearers report a transientdecline in taste acuity when dentures are firstinserted. This is usually attributed to denture basecoverage of the hard palate. However, the ability totaste usually improves as the patient adapts to thedentures. When compared with the sensory percep-tions of dentate adults or partial denture wearers,subjective estimates of taste, texture acceptabilityof test foods, and perceived ease of chewing (bycomplex denture wearers) were rated the lowest. Inblind tests, denture wearers are significantly lessable to detect differences in texture and sweetnessof certain foods than dentate subjects can.

Dehydration is a major problem for seniorsbecause the ability to sense thirst is reduced in theelderly population. Hypotension, elevated bodytemperature, and mental confusion may occurwhen fluid intake is inadequate. The comfort ofwearing dentures is dependent on the lubricatingability of saliva in the mouth. If the oral mucosa isdry, chewing is difficult, denture retention is com-promised, and mucosal soreness or ulcerationsdevelop. Because salivary flow facilitates mastica-tion, formation of the food bolus, swallowing, anddigestion, it is a major contributor to the pleasureof eating.

Xerostomia, more commonly called dry mouth,is a clinical manifestation of salivary gland dys-function. Xerostomia may contribute to geriatricmalnutrition. There are several causes of drymouth: the use of medications, therapeutic radia-tion to the head and neck, diabetes, depression,alcoholism, pernicious anemia, menopause, vita-min A or vitamin B complex deficiency, HIV infec-tion, and autoimmune diseases such as Sjögren’s

syndrome. Aging as the sole cause of decreasedsalivary flow is unproven. The most common causeof dry mouth is the use of drugs to manage chronicdiseases. Xerostomia is a possible side effect asso-ciated with more than 400 drugs including antihy-pertensives, antidepressants, antihistamines,bronchodilators, antiparkinsonians, antispasmod-ics, anticholinergics, and sedatives. Mouthwashes,alcohol, tobacco, and caffeine may alter salivaryflow or cause dryness of the oral mucosa.

Management of xerostomia depends on thecause of the condition. If a drug is suspected to bethe cause, consulting with the patient’s physicianmay result in prescription of an alternate drug ormodification of the dosage schedule. Saliva substi-tutes provide temporary relief but have not provento be acceptable for many patients, and they areexpensive. Milk has been proposed as a saliva sub-stitute. Milk not only aids in lubricating the tissuesand increasing the pleasure of eating, but also hasbuffering capacity. This buffering capacity may bean important benefit if overdenture abutment teethare present. Because dry mouth may result in inad-equate nutritional intake, the use of milk not onlyserves as a saliva substitute but also is an excellentsource of nutrients.

Sialogogues (agents that stimulate salivaryflow) such as sugar-free gum, lozenges, or sugar-free candies containing citric acid may be recom-mended. Sorbitol- or xylitol-sweetened productsmay decrease the risk of candidiasis developing insusceptible adults. Additional recommendationsinclude beverages that may produce more salivasuch as water with a slice of lemon, lemonade, orlimeade. Carrying a sport bottle when leavinghome will allow for frequent sips of water. SuckingPopsicles or ice chips will increase comfort andprovide lubrication; sauces, gravies, and dressingswill moisten foods and make them easier to swal-low. Chewing fibrous foods such as celery orwhole grain breads will also increase saliva pro-duction. Making a conscious effort to consume atleast eight glasses of water, juice, or milk daily isthe most important measure to relieve dry mouth.

GASTROINTESTINAL FUNCTIONINGLittle research exists on the effect of tooth losson gastrointestinal function or the likelihood of


choking on food. The purpose of mastication is toreduce food particles in size so they can be swal-lowed and to increase the surface area of foodexposed to digestive juices and enzymes. Individualswith poor masticatory ability often swallow largepieces of food. Investigators have proposed thataccidental deaths occurring in restaurants havebeen inaccurately attributed to the “café coronary”when the true cause was choking on food. A reviewof autopsies performed on adults who died sud-denly while eating showed that the ratio of deathsdue to food asphyxiation to coronary disease was55:1. When a denture covers the upper palate, it isdifficult to detect the location of a food in themouth. Adults with such dentures are at a greaterrisk of having a large piece of food or a bone lodgein the air or food passage.

Inadequate mastication appears to cause gas-trointestinal disturbances. For example, the use oflaxatives, antacids, antireflux drugs, and antidiuret-ics was significantly higher in elderly edentulousCanadians with poor masticatory performance.Gastric distress and the use of laxatives in Finnishadults were reportedly reduced when ill-fittingdentures were replaced with well-fitting ones.Although a diet high in fiber helps prevent consti-pation, edentulous patients may avoid whole-grainbreads, fruits with skins, and vegetables.

NUTRITIONAL NEEDS AND STATUS OF OLDER ADULTSThere is a great diversity in the eating habits andfood intake of older adults. The nutrient needs ofolder persons vary depending on health status andlevel of physical activity. Thus it is difficult to gen-eralize about energy and vitamin and mineralrequirements appropriate for all older adults.Depending on body metabolism, an individual mayneed more, or less of, nutrients proposed in theDietary Reference Intakes (DRIs), which are quan-titative estimates of nutrient intakes for the individ-ual’s chronological age.

Energy needs decline with age because of adecrease in basal metabolism and decreased physi-cal activity. With aging, lean body mass is replacedby fat; this leads to a decrease in metabolic rate.The onset of chronic disease usually leads to adecline in physical exercise. Cross-sectional sur-

veys show that the average energy consumption isabout 1300 kilocalories (kcal) for 65- to 74-year-oldwomen and 1800 kcal for men of the same ages.This is lower than the caloric recommendation foradults 51 years of age and older (1900 kcal forwomen and 2300 kcal for men) but may be appro-priate if body weight is being maintained. Whencalorie intake is low, consumption of foods of highnutrient density such as legumes, vegetable soups,meat casseroles, fruit desserts, low-fat dairy foods,and whole-grain breads and cereals is important.

The best means of reducing calorie intake is toreplace foods high in fat and sugar with complexcarbohydrates, and these should be the mainstay forthe elderly person’s diet. In contrast to pastries,whole-milk cheeses, luncheon meats, salad dress-ings, and frozen desserts, the choice of nonfat dairyproducts, whole-grain breads, cereals, pasta, fruits,vegetables, beans, and legumes will provide impor-tant amounts of vitamins, minerals, and fiber.Patients with dentures who prefer soft foods suchas doughnuts, pastries, cakes, and cookies, whichare high in simple sugars and fat, should be advisedof the value of fruits, vegetables, grains, and cereals.An important component of complex carbohydratesis fiber, which promotes normal bowel function,lowers glycemic response, may reduce serum cho-lesterol, and is thought to prevent diverticular dis-ease.

Fats contribute about 33% of total calories inthe diet of the average adult. Because of growingepidemiological evidence of the link betweendietary intake of saturated fat, cholesterol, andoccurrence of hyperlipidemias, heart disease, cer-tain cancers, and obesity, adults are advised tomaintain their dietary fat intake at 20% to 35% oftotal calories. Because physiological stresses areassociated with age-related degenerative diseases,protein needs of older adults are thought to beslightly higher than those of younger persons. It isrecommended that 10% to 35% of total calories or1 g/kg of body weight come from protein. Thisconclusion is based on studies of serum albuminlevels and nitrogen balance studies in older adults.Surveys show that protein intake declines withage; in one national survey one third of seniors didnot meet the recommended intake. The proteinintake of denture wearers is lower than that ofdentate adults but is often adequate. If calorie or


protein intake is reduced, protein metabolism iscompromised.

Vitamin deficiencies in the elderly populationare apt to be subclinical, but any body stress mayresult in an individual having detectable symptoms.Individuals who have low-calorie intakes, ingestmultiple drugs, or have disease states that causemalabsorption are at greatest risk for hypovita-minosis. Free-living older persons often report lowdietary intakes of vitamin D, vitamin E, folic acid,calcium, and magnesium. Oral symptoms of malnu-trition are usually due to a lack of the vitamin Bcomplex, vitamin C, iron, or protein (Table 6-1). Inone study, clinical symptoms of burning mouthsyndrome (BMS) were resolved in 24 of 28 patientswith proven vitamin deficiency when vitamin Bcomplex supplementation was given. Folic acidplays an important role in cell division and in redblood cell formation; anemia results from an inade-quate folate intake. Many drugs and alcohol affectfolic acid absorption and metabolism. Individualswith a marginal intake of folic acid who are under-going long-term drug therapy are at greatest risk of

developing a deficiency of this vitamin. Oranges,cantaloupe, broccoli, spinach, asparagus, and driedbeans are good sources of folic acid.

With the measurement of serum metabolites ofvitamin B12, a high prevalence of undiagnosedvitamin B12 deficiency has been noted among theelderly population. Protein-bound vitamin B12 mal-absorption leads to a vitamin B12 deficiency moreoften than a low vitamin B12 intake or lack ofintrinsic factor. A vitamin B12 deficiency may leadto problems with dementia in older adults. VitaminB12 is found only in animal products. Syntheticvitamin B12 obtained from fortified foods or vitaminsupplements is better absorbed than protein-boundvitamin B12.

Because of its role in collagen synthesis, ascor-bic acid (vitamin C) is essential for wound healing.There is a wide variation in vitamin C intakes ofadults. In one survey, low ascorbic acid intakesassociated with low plasma levels were reported inone fourth of older individuals. Heavy smokers,alcohol abusers, or persons with high aspirin intakehave a higher daily requirement for ascorbic acid.The denture-wearing patient should be encouragedto consume foods rich in vitamin C daily such ascitrus fruits, peppers, melons, kiwifruit, mangos,papaya, and strawberries.

Vitamin E functions as an antioxidant in cellmembranes. By acting as a scavenger of free radicals,vitamin E prevents oxidation of unsaturated cellphospholipids. Dietary sources of vitamin E includevegetable oils, nuts, margarines, and mayonnaise.

Magnesium is a component of the body skele-ton, is a cofactor for more than 300 enzymes, andplays a role in neuromuscular transmission. Thehighest amounts of magnesium are found in veg-etables and unrefined grains. Milk is a moderatelygood source.

Alcohol abuse appears to be a serious healthproblem among some older persons. Although theactual incidence of alcoholism is unknown, esti-mates of alcohol abuse in independent-living olderpersons are 1% to 8% of those older than 60 years ofage. Alcoholism often is undetected and untreated.The loss of a spouse, loneliness, depression, retire-ment, loss of status, and reduced income all con-tribute to excess alcohol intake by older adults.Elderly persons tend to drink a smaller volume ofalcohol but drink more frequently. The substitution of


Table 6-1Oral Signs of Nutrient Deficiencies

Nutrient Lacking Oral Symptom

Protein Decreased salivary flowEnlarged parotid glands

Vitamin B complex, Lips:* iron, protein Cheilosis

Angular stomatitisAngular scarsInflammation

Tongue:EdemaMagenta tongueAtrophy of filiform papillaeBurning sensationSorenessPale, bald

Vitamin C Edematous oral mucosaTender gingivaSpontaneous bleeding of gingivalHemorrhages in interdental

papillae

*Vitamin B complex includes thiamin, riboflavin, niacin, pyridoxine,folic acid, and vitamin B12.

alcoholic drinks, which contain no nutrients, forfood usually results in multiple nutrient deficits.Deficiencies of thiamine, niacin, pyridoxine, folate(all B-complex vitamins), and ascorbic acid arecommonly seen in alcoholics. Osteopenia in maleswithout a history of bone disease may be due tolong-term alcohol intake. When efforts to resolvetissue intolerance to a prosthesis are unsuccessful,the misuse of alcohol should be considered.

CALCIUM AND BONE HEALTHBone loss is a normal part of aging that affects themaxilla and mandible, as well as the spine and longbones. Skeletal sites where trabecular bone (thealveolar bone, vertebrae, wrist, and neck of thefemur) is more prominent than cortical bone areaffected first. In a large screening study of healthyU.S. women age 50 or older, 40% had low bonemass. Several factors are thought to contribute toage-related bone loss that leads to osteoporosis:genetic background, hormonal status, bone densityat maturity, a disturbance in the bone remodelingprocess, a low exercise level, and inadequate nutri-tion. Low calcium intake throughout life is a con-tributor to osteoporosis. Osteopenia, loss of bone,affects women earlier than men because of loss ofestrogen at menopause and a smaller skeleton. Inwomen, bone loss begins during the fourth decadeof life or whenever estrogen secretion declines orceases. In 329 healthy postmenopausal women, apositive linear relationship between the number ofteeth and bone mineral density at the spine wasreported.

Trabecular bone in the alveolar process is asource of calcium that can be used to meet othertissue needs. It has been proposed that alveolarbone loss may precede loss of mineral from thevertebrae and long bones; thus the dentist maytherefore be the first health care provider to detectloss of bone mass. Mandibular bone mass hasbeen positively correlated with total body calciumand the bone mass of the vertebrae and wristof healthy, dentate postmenopausal and edentu-lous women with osteoporosis by some investiga-tors, but not all bone researchers concur. Inedentulous persons, local factors may have agreater influence on alveolar bone resorptionthan systemic factors linked to bone loss at other

body sites. This area of basic and clinical researchis clearly still developing.

Resorption of the alveolar ridge is a widespreadproblem among denture-wearing patients andresults in unstable dentures. Some remodeling ofthe alveolar processes occurs in response toocclusal forces associated with chewing. With lossof teeth the alveolar bone is no longer needed fortooth support; as a consequence, resorption isaccelerated and bone height is diminished. A greaterdegree of residual ridge resorption is observedin women than in men. Bone loss is acceleratedin the first 6 months after tooth extractions,and resorption is much greater in the mandiblethan in the maxilla. The loss of alveolar bone fre-quently makes it more difficult to construct amandibular denture that has good stability andretention.

Dietary calcium intake is critical to maintainingthe body skeleton. The most important means ofpreventing metabolic bone disease is acquiring adense skeleton by the time bone maturation occursbetween 30 and 35 years of age. A woman who hasa dense skeleton at 35 years of age will retain pro-portionately more skeletal mineral content and beless susceptible to fracture after menopause.Calcium intake of postmenopausal women is cor-related with mandibular bone mass. Patients withdentures who have excessive ridge resorptionreport lower calcium intakes. After age 35, about75% of U.S. women have inadequate calciumintakes. A chronically low calcium intake results ina negative calcium balance. For serum calcium lev-els to be maintained, calcium will be mobilizedfrom bone, and this leads to demineralization of theskeleton. Although a generous calcium intake byolder adults will not result in restoration of bonemass, it will improve calcium balance and slow therate of bone loss.

In 1997 the National Academy of Sciences rec-ommended that an adequate calcium intake formen and women 19 to 50 years of age is 1000 mgand 1200 mg for adults 51 years of age or older(Table 6-2). This recommendation far exceeds theusual calcium intake of U. S. women and men, 470and 610 mg/day, respectively. Both aging andmenopause lead to reduced calcium absorption andless body adaptation to changes in dietary intake inwomen. Oxalates found in rhubarb and spinach and


phytates found in whole-grain products andlegumes may form insoluble complexes with cal-cium, thereby reducing the amount of calciumabsorbed. High intakes of sodium, animal protein,and alcohol increase calcium losses in the urine.A moderate caffeine intake (300 mg or less perday) is recommended to prevent bone loss.

About three fourths of the calcium found in theAmerican diet is obtained from dairy foods. Majorsources of calcium are milk, cheese, yogurt, and icecream. Dairy foods are also a source of protein,riboflavin, vitamin A, and vitamin D. Collardgreens, kale, broccoli, oysters, canned salmon, sar-dines, calcium, fortified fruit juices and cereals, andtofu made with a calcium coagulant are nondairyfoods containing substantial amounts of calcium. Toreceive 1000 to 1200 mg of calcium, adults mustdrink three or four glasses of low-fat milk per day,eat 5 to 7 oz of hard cheeses, or consume very largequantities of nondairy foods. Lactose-intolerantadults who avoid milk may find yogurt or cheeseacceptable. This amount of dairy foods represents asignificant number of calories. Women with lowcalorie intakes should be encouraged to obtain atleast half their calcium needs from food sources andthe balance from calcium supplements.

Poor vitamin D status is an important publichealth problem. Adequate intake of vitamin Denhances calcium absorption in the intestine. Lowdietary intake, minimal exposure to sunlight, and alower rate of conversion to the active metabolite inthe liver and kidney are responsible for low plasmalevels of vitamin D in the elderly population. Theprimary dietary source of vitamin D is fortifieddairy products. To promote bone health, post-menopausal women and andropausal men ages 51to 70 should strive to obtain 10 μg of vitamin D (400IU) and increase intake to 15 μg at age 71 (600 IU).

If an individual lacks sun exposure, is lactose intol-erant, or dislikes dairy foods, a vitamin D supple-ment of 10 μg is desirable.

For those women who consume minimalamounts of dairy products, have lactose intoler-ance, or have allergies to dairy foods, calcium sup-plementation may be appropriate. Supplements arewell tolerated, are inexpensive, and have few sideeffects. The most common forms of supplementsare calcium carbonate, calcium citrate, calcium lac-tate, calcium gluconate, and calcium diphosphate.Calcium carbonate contains the highest concentra-tion of elemental calcium (40%), but in olderwomen, body absorption of calcium citrate is bet-ter. However, less elemental calcium is obtainedfrom each calcium citrate tablet. Calcium supple-ments that contain vitamin D to enhance absorp-tion of calcium in the gut are useful if vitamin D isnot obtained from other sources. A dose of 1000mg of elemental calcium taken with meals is com-monly prescribed. Chemically derived calcium car-bonate or calcium citrate is the safest source; bonemeal, oyster shell, and dolomite calcium supple-ments should be avoided because they may be con-taminated with heavy metals such as lead ormercury.

Few adverse affects of calcium supplementa-tion have been observed. Some older women havereported nausea, bloating, or constipation. Increasingcalcium intake results in higher urinary levels ofcalcium. A small percent of the population, mainlymen, are susceptible to forming kidney stones;however, a high intake of dairy foods does notappear to affect stone formation. A physicianshould monitor the use of calcium supplements bythese persons. The maximum calcium intake thatposes no risk of adverse effects is 2.5 g.

VITAMIN AND HERBALSUPPLEMENTATIONConsuming a variety of foods is considered the bestmeans of obtaining the balance of nutrients requiredfor good health. A varied diet also reduces the riskof chronic disease. The widespread use of vitamin-mineral and herbal supplements among NorthAmericans, especially among elderly persons, isdue partly to promotion efforts of the nutrient sup-plement industry. At least 50% of persons older


Table 6-2The 1997 Dietary Reference Intake Values for Calcium and Vitamin D*

Age (yr) Calcium (mg) Vitamin D (mg)

31-50 1000 551-70 1200 10>70 1200 15

*Adequate intakes.

than 65 years of age report using vitamin-mineralsupplements, and one fourth of adults use herbalsupplements. Persons who have high incomes andare well educated and those who perceive them-selves to be in good health are more likely to usedietary supplements. Many reasons are reported forusing nutritional supplements: to increase energylevel, to extend life, to prevent the onset of degen-erative diseases, to relieve the symptoms of chronicdiseases, and to make up deficits caused by unbal-anced diets. A large percentage of the supplementsingested are self-prescribed and unrelated to anyspecific physiological need. In fact, self-medicationby individuals may result in toxicity to the tissues orin a delay in seeking diagnosis and treatment for acurable condition. The U.S. Congress has restrictedthe Food and Drug Administration’s role in the reg-ulation of dietary supplements and the claims thatcan be made on labels.

Vitamin-mineral supplements without energyor fiber and only one third of the essential micronu-trients may foster a false sense of security in thepatient undergoing prosthodontics. Older adultsoften select a supplement that does not includenutrients most likely to be missing in their diet.Although the average adult intake of vitamin Cseems to be adequate, supplementation with ascor-bic acid is common. In contrast, low intakes of cal-cium, vitamin D, folate, and magnesium arereported among seniors. If clinical signs of malnu-trition are detected in the oral tissues of denture-wearing patients, referral to a physician fordefinitive diagnosis should occur (see Table 6-1).

In 1997, for the first time, the Food andNutrition Board of the National Academy ofSciences recommended that supplements or forti-fied foods could help some people meet their nutri-tional needs. Individuals who are at a greater riskfor the development of malnutrition and who maybenefit from taking a low-dose vitamin-mineralsupplement (≤100% of recommended dailyallowances [RDAs] or adequate intakes [AIs])include those consuming less than 1200 kcal/day orthose eating an unbalanced diet that lacks fruits,vegetables, or protein foods, and seniors with lowincomes or physical disabilities that hinder mobil-ity may limit access to food. Bioavailability of vita-mins and minerals also is affected by preexistingdisease, medications, fiber intake, emotional sta-

tus, and environmental stress. Digestion andabsorption is negatively affected in older personstaking several over-the-counter or prescriptionmedications. The person ingesting aspirin severaltimes a day may need more iron, vitamin C, andfolic acid. Individuals taking corticosteroids andcertain diuretics have increased calcium needs.Frequent use of laxatives and antacids results inincreased urinary excretion of minerals. For theolder person, synthetic vitamin B12 and folic acidhave higher bioavailability than those vitamins infoods. Supplemental sources of calcium and vita-min D will be needed by many seniors to ensureadequate intake.

For nutrients to be present in the proper ratio toone another, a multivitamin-mineral supplement ispreferable to single-nutrient tablets. For patients atrisk of nutritional deficits, the American DieteticAssociation recommends a multivitamin-mineralsupplement that does not exceed the RDAs or AIs.On the basis of nutrient deficiencies reported indenture-wearing patients, it may be reasonable toprescribe a low-dose multivitamin-mineral supple-ment for certain patients even though clinical signsof a nutrient deficiency are lacking. For patientsreceiving dentures, a generic one-a-day vitamintablet that includes vitamin D, folic acid, and vita-min B12 may be recommended. If intake of dairyfoods cannot be increased to meet daily needs,a calcium supplement is advised; because it isbulky, calcium must be taken in a separate tablet.

The use of megadoses of vitamins or mineralsby the elderly persons is a practice of great con-cern. When a high dose of a vitamin is taken, it nolonger functions as a vitamin but becomes a chem-ical with pharmacological activity. Adverse reac-tions from megadoses of nutrients are more likelyin the older adult because they are metabolized lessefficiently and excretion occurs more slowly. Highdoses of any nutrient are potentially toxic, butbecause the fat-soluble vitamins A and D are storedin the body, they are considered toxic at lower lev-els of intake. Megadoses of vitamin D can disturbcalcium metabolism, leading to calcification ofsoft tissues. High doses of dietary retinol (vitaminA) accelerate bone resorption, thereby increasingthe risk of hip fracture. The maximum level ofnutrient intake (Tolerable Upper Intake Level[UL]) that is unlikely to pose adverse health effects


has been determined for some vitamins and miner-als. The upper tolerable intake of vitamin D is 50μg, and the UL for preformed vitamin A is 3000 μgper day.

Although water-soluble vitamins are consid-ered nontoxic, well-documented toxicity syn-dromes are associated with megadoses of thewater-soluble vitamins, niacin, vitamin B6, andascorbic acid. Long-term intake of megadoses ofvitamin C can induce copper deficiency anemia,cause false-positive readings for glucose in theurine, and increase the risk of urinary stone forma-tion in susceptible individuals. A high niacin intakemay result in flushing, headaches, and itching skin.Peripheral neuropathies have resulted from highvitamin B6 intakes for long periods. Thus the den-ture-wearing patient should be cautioned againstindiscriminate use of megadoses of any nutrient orfiber.

Herbal supplements may have direct effects onthe outcome of oral surgery to remove remainingteeth before denture insertion. Herbs are medica-tions that may have adverse pharmacological sideeffects and should be used with caution. Herbs mayincrease the risk of bleeding, potentiate the action ofanesthetic agents, cause hypotension, or increase themetabolism of drugs being taken concomitantly.Herbal preparations are not standardized; thus theamount of active ingredient may vary among prod-ucts. Dentists should query patients about their useof herbal supplements and recommend they discon-tinue the use of herbals before surgery.

DIETARY COUNSELING OF PATIENTSUNDERGOING PROSTHODONTICTREATMENTThe quality of a denture-wearing patient’s diet canbe improved with nutrition counseling. One expec-tation of patients seeking new dentures is that theywill be able to eat a greater variety of foods. Suchpatients often are receptive to suggestions aimed atimproving their diet composition. The long-termrelationship dentists establish with their patientscan create an ideal situation for the identificationof older patients at nutritional risk, increasingnutrition awareness, and referral to a physician ordietitian. However, a single structured nutritional

interview is not likely to result in much change inchoice of foods.

It often is difficult, based on a visual inspectionor an interview, to identify patients in need of nutri-tional care. Most patients will tell the dentist thatthey eat a healthy diet. Patients receiving denturesshould be carefully screened for nutritional risk fac-tors at the first appointment so that counseling andfollow-up can occur during the course of treatment.The dentist and dental hygienist who have back-grounds in basic nutrition can provide nutritioncare. In the United States, clinical signs of frankmalnutrition are not seen very often. However, cer-tain denture-wearing patients are known to be atgreater risk for malnourishment (Box 6-1). Dietaryevaluation and counseling should be included intreatment if patients have any of the following phys-ical or social conditions: older than 75 years of age,low income, little social contact, involuntary weightloss, daily use of multiple drugs, or assistancerequired with daily self-care.

The main objective of diet counseling forpatients undergoing prosthodontics care is to cor-rect imbalances in nutrient intake that interferewith body and oral health. The dentist is notexpected to diagnose specific nutrient deficiencies,but to determine the general adequacy of the diet.If the patient reports involuntary weight loss orgain greater than 10 lb during the past 6 months,untreated hypertension, a diabetic state, or demon-strated oral tissue changes suggestive of malnutri-


Risk Factors For Malnutritionin Patients with Dentures

Eating less than two meals per dayDifficulty chewing and swallowingUnplanned weight gain or loss of more than 10

lb in the last 6 monthsUndergoing chemotherapy or radiation therapyLoose denture or sore spots under dentureOral lesions (glossitis, cheilosis, or burning

tongue)Severely resorbed mandibleAlcohol or drug abuseUnable to shop for, cook for, or feed oneself

Box 6-1

tion, referral to a physician should be made.Patients who express concern about obesity or lowbody weight or who report poor adherence to a dia-betic, reduced sodium, or low cholesterol diet canbe referred to a consulting dietitian.

Providing nutrition care for the denture-wear-ing patient entails the following steps:

● Obtain a nutrition history and an accuraterecord of food intake over a 3- to 5-dayperiod or complete a food frequency form

● Evaluate the diet; assess nutritional risk● Teach about the components of a diet that

will support the oral mucosa, bone health,and total body health

● Help patient establish goals to improve thediet

● Follow-up to support patient in efforts tochange food behaviors

Dietary questions can be incorporated into themedical history form or presented in a separatenutrition questionnaire administered at the firstappointment (Figure 6-2). Patients reporting nutri-tional risk factors are then instructed to prepare afood record. The dental counselor records the past24-hour food intake on the record. The patient isinstructed to record food intake for 2 or more days,which should include a weekend day at home. If afood frequency form is used, the counselor andpatient should complete it together. Patients mustclearly understand the purpose of diet counseling.Patients’ cooperation can be gained by advisingthem that dietary habits influence how well theiroral tissues will adjust to the new denture. The foodrecord is returned by mail or brought to the nextappointment.

When the record is received, the actual foodintake and quality of a patient’s diet is assessed. Ifa detailed food record is obtained, nutrient analysiscan be accomplished on the computer with adietary analysis software program, or reportedfoods can be classified into the five basic foodgroups described in the Food Guide Pyramid. Thetotal reported servings of each food group can becompared with the recommended number of serv-ings in the Food Guide Pyramid (Figure 6-3). Theminimum recommendations are three to four serv-ings from the dairy group, two servings each fromthe meat and fruit groups, three from the vegetable

group, and six from the bread-cereal group. Theminimum recommended number of servings ofeach food group will provide about 1600 kcal.Servings of processed foods high in sodium and fatshould be noted. Fish, ground meat, poultry, peanutbutter, soups, or casseroles made with beans orlegumes are high-quality sources of protein. Withinthe fruit and vegetable groups, one serving of a cit-rus fruit and one serving of a vitamin A–rich food,such as deep yellow or dark-green fruits and veg-etables, is needed daily.

At the second appointment, the relationship ofdiet to the health of the oral tissues and evaluationof the patient’s diet can be discussed. This will takeabout 30 to 45 minutes. Nontechnical terms shouldbe used when teaching patients about the diet–oralhealth relationship. Two concepts are to be stressed.First, the epithelial cells in the mouth have a rapidturnover. Second, the health of the mandible andmaxilla depends on a constant supply of calciumand vitamin D. Lack of calcium may acceleratebone resorption. The patient’s own radiograph canbe used to illustrate the amount of bone remainingin the mandible. This usually is enlightening forpatients because they have probably never consid-ered the systemic role of nutrients in maintainingthe oral tissues.

When discussing the quality of the patient’sdiet, always begin by pointing out positive aspects.Identify which food group quotas are being met. Ifthe diet is generally poor, focus on one or two ofthe most critical deficiencies. Low-calorie, fruit,vegetable, or dairy food intakes, or excessive use offat-soluble vitamin supplements would be of pri-mary concern. Do not overwhelm patients withinformation or alarm them by presenting a long listof dietary weaknesses. Remember that olderpatients with dentures often are particularly sensi-tive to possible threats to their health and maytherefore easily feel disconcerted. If serious dietaryproblems are detected, referral to a physician orregistered dietitian is advisable.

Nutrition goals for the denture-wearing patientare to eat a variety of foods, including proteinsources, dairy foods, fruits, vegetable, grains andcereals, and to limit salt, fat, and sugar intake (Box6-2). Lack of diet diversity, that is, omitting one ormore food groups from the daily diet, has beenassociated with greater risk of death over time.


Using the Food Guide Pyramid as a visual tool, thedentist can suggest desirable, nutrient-dense foodsto improve the diet, but patients must establish theirown dietary goals. Ask patients to describe whatfoods they could add or substitute in their diet toimprove the nutritional balance. Small changes thatare possible within the patient’s budget andchanges that respect food preferences are more

likely to be accepted. Adding one glass of milk ororange juice will make a significant contribution tonutrient intake. When it is determined what foodchanges can be made to improve the patient’s diet,the dentist or hygienist can prepare a diet prescrip-tion for the patient to take home. The results of thediet assessment and the diet prescription alsoshould be recorded in the patient’s dental chart so


DEPARTMENT OF PROSTHODONTICSNUTRITION HISTORY

Name: _______________________________________________ Date: ___________________Age: ________ Height: ________ Weight: ________ Desirable Weight: ____________

1. Do you consider your appetite to be: Good _______ Fair _______ Poor: ________2. How many meals do you eat each day? ___________________________________________ When are your meals eaten? ____________________________________________________ Where are most meals eaten? ___________________________________________________3. Do you eat alone? ___________, with family ___________, with friends ______________4. Do you usually snack between meals? Every day ______ Seldom ______ Never _________ What time of day? _____________ Common Snacks: ______________________________5. How often do you use gum, mints, cough drops? _____________________________________ What kind? __________________________________________________________________6. How much sugar do you add to coffee or tea? ______________________________________ What other beverages do you consume between meals? ______________________________7. Are you on a special diet? Yes _____ No _____If yes, what kind? _______Who recommended the diet? _______________________________________________________8. Are there any foods you cannot eat? Yes _____ No _____List: __________________________________________________________________________9. What kinds of medication, food supplements, or vitamin-mineral pills do you use, if any?( ) Medications: ____________________________________________________________

( ) Vitamins, minerals, other supplements: _______________________________________

( ) Antacids, laxatives, others: _________________________________________________10. Does your mouth get dry? Yes _____ No _____ When? _________________________What do you eat or drink to moisten your mouth? _______________________________________11. Do you have difficulty chewing or swallowing? Yes _____ No _____ Describe: _______________________________________________________________________________________12. How often do you use cigarettes, pipe tobacco, or chewing tobacco? _____________________11. How often do you use wine, beer, whiskey? Never _____ Daily _____ Weekly _____

Food Habits:

Figure 6-2 A nutrition history questionnaire that could be completed by the patient atthe time the health history is obtained.

that all members of the dental team can reinforcethe dentist’s goals.

Compliance with dietary advice is more likelyif follow-up is provided. Patients need a trial periodto try new foods and eating patterns. Dietaryprogress should be discussed at future appoint-ments. Roadblocks to modifying a patient’s dietshould be identified and addressed. Progress maybe slow, but modest dietary changes should bepraised. Small steps are more likely to result in per-

manent dietary improvement. With continued guid-ance and encouragement from the dental team,patients are more apt to make permanent changesin their food patterns. In fact, such nutrition careshould be an integral part of the overall prostho-dontic treatment.

For socially isolated or disabled older adults, thereare community-based nutrition programs includingfood stamps, home-delivered meals, and communalmeal programs served in local senior centers,


DIET EVALUATION SUMMARY

Food groups

Milk group (milk, cheese)3-4 servings/day

Portion size/serving

1 1/2 cups ice cream1 cup milk, yogurt1 1/2 oz cheddar cheese2 oz process cheese

1stday

2ndday

3rdday

4thday

5thday

Recom-mended5-daytotal

5*0+

5-daytotal Difference

Meat group (meat, fish, poultry, egg, dried peas, or beans)2-3 servings/day

2-3 oz cooked lean meat, fish, poultry2 eggs4 Tbsp peanut butter1 cup cooked dry beans or lentils

Fruit group2-4 servings/day

1 orange1/2 med grapefruit3/4 cup fruit juice

1 med apple, pear, banana1/2 cup cooked fruit

Vegetable group3-6 servings/day

1/2 cup cooked dark green, orange, or yellow vegetable

Bread/cerealgroup3-5 servings/day

1 pancake, 1 tortilla1 slice bread, 1/2 bagel1 oz dry cereal1/2 cup cooked cereal, rice, noodles, macaroni

*Adults 20-50 yrs +Adults >50 yrs

10

5

5

5

1/2 cup cooked peas, beans, corn, potatoes1 cup lettuce

10

30

Figure 6-3 Form used for evaluating a 5-day food diary submitted by the patient. Theaverage number of servings per day of each food group is compared with the recommendeddaily intake.

churches, or community centers. Nutrition educa-tion, as well as food, is provided. These nutritionservices can have a significant impact on nutrientintake and nutritional status of participating olderadults. Dental providers can refer patients to theseprograms.

DIETARY MANAGEMENT WHEN TEETHARE EXTRACTEDPatients who are candidates for implants or imme-diate dentures may require several tooth extrac-tions. The patient who is well nourished willexperience more rapid tissue healing and will beat lower risk of infection after surgery. If a patientappears poorly nourished (low body weight, weak,disoriented cognition, unexplained skin lesions,glossitis, cheilosis), surgery should be delayeduntil the individual’s body health improves.

Smokers, alcohol abusers, patients with uncon-trolled diabetes, and patients with untreated hyper-tension are at greater risk of having complicationsafter surgery. The smoker and drinker should beadvised to abstain or limit their habits for a fewweeks before and 1 month after surgery. Consultation

with the physician of the diabetic or hypertensivepatient will aid the dentist in determining if thepatient is stable enough to undergo the surgicalprocedure. The adequacy of a patient’s diet can beascertained with the steps just described. To sup-port body functioning and to improve the outcomeof surgery, malnourished patients should beinstructed to consume high-calorie, high-proteinfoods before surgery. Milk-based cooked cerealsand soups, canned fruits, mashed vegetables,yogurt, ice cream, cottage cheese, ground meat,and eggs are easy for patients with chewing diffi-culties to eat. A multivitamin containing 100% ofthe daily value can be prescribed for the high-riskpatient.

A generous supply of essential nutrients in thebody is basic to tissue healing. It has been clearlyshown that when the immune system is depressed,the risk of infection after surgery is greater.Protein, vitamins A and C, folic acid, pyridoxine,vitamin B12, iron, and zinc must be available tobody cells for the support of phagocytic activity,cell-mediated immunity, collagen synthesis, andregeneration of epithelial cells. The amount ofprotein and calories required by the postoperativepatient will depend on the amount of metabolicstress experienced during surgery. For the first24 hours after extractions, the patient shouldbe counseled to consume nutrient-dense liquids.A blender is useful in making cream soups, milk-shakes, fruit drinks, or instant breakfast drinkswith whole milk or milk with 2% fat. A high-protein milk can be made by adding one cup of drymilk powder to one quart of fluid whole milk. Thisfortified milk can be used for cooking, for addingto beverages, or for drinking by itself. By usingthis milk, the patient can boost calories, protein,vitamins, and minerals without increasing servingsize. However, milk is a poor source of vitamin C,an essential nutrient for collagen synthesis, so cit-rus fruit juices or another source of ascorbic acidmust be included in the diet. Small, frequent mealsthroughout the day (every 2 hours) may berequired to obtain adequate calories. This is not adesirable time for an adult to try to lose weight.

People’s tolerance for solid foods after surgeryvaries greatly. If blood clot formation is satisfac-tory, the patient should be encouraged to progressto soft foods by the third day. A variety of soft


Nutrition Guidelines forPatients Undergoing

Prosthodontics

1. Eat a variety of foods.2. Build diet around complex carbohydrates

(fruits, vegetables, whole grain breads, andenriched cereals).

3. Eat at least five servings of fruits and vegeta-bles daily.

4. Select fish, poultry, lean meat, eggs, or driedpeas and beans every day.

5. Consume four servings of calcium-rich foodsdaily.

6. Limit intake of bakery products high in fatand simple sugars.

7. Limit intake of prepared and processedfoods high in sodium and fat.

8. Consume eight glasses of water, juice, ormilk daily.

Box 6-2

foods (e.g., cereals, canned fruits, soft-cooked veg-etables, cottage cheese, casseroles, chopped meats,and puddings) can be recommended. Without somecounseling by the dentist, patients may slow theirrecovery by limiting themselves to juices, softdrinks, coffee, and tea.

For patients who cannot meet all of their nutri-tional needs with table foods, commercially pro-duced liquid dietary supplements are available.These products, high in calories and protein andfortified with vitamins and minerals, can be rec-ommended as between-meal snacks. There aremilk-based products, and for the lactose-intolerantpatient there are soy-based formulas. An 8-oz canprovides about 240 to 360 kcal and 10 to 15 g ofprotein. The use of a high-calorie liquid supple-ment has been shown to help maintain proteinstores and body weight after oral surgery. A lesscostly alternative is instant breakfasts that have apowdered-milk base.

SUMMARYDenture wearers are particularly vulnerable tocompromised nutritional health. The dentist who isaware of nutritional risk factors can identifypatients in need of nutritional guidance. Nutritionaldeficiencies may result from a combination of lowcalorie intake, poor chewing efficiency, the pres-ence of chronic disease, economic hardship, andpsychological problems. The ability of the oral tis-sues to withstand the stress of dentures is greater ifthe patient is well nourished. Dietary guidance isan integral part of treatment for the denture-wearingpatient.

Early in treatment, the dentist can assess thegeneral adequacy of the diet and address majordeficiencies or refer the patient for care. A patientwith dentures will probably not make sweepingdietary changes but will add nutritionally importantfoods if the need is clearly explained. If the den-tally impaired patients are counseled to eat moreslowly and chew longer, they can enjoy a wide vari-ety of foods with texture. Foods that require chew-ing stimulate salivation; saliva lubricates the oraltissues and increases denture comfort. The patientmust participate in developing nutrition goals andreceive continued encouragement if dietaryimprovement is to occur.

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Krall EA, Dawson-Hughes B, Papas AS et al: Tooth loss andskeletal bone density in healthy menopausal women,Osteoporos Int 4:104-109, 1994.

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Kribbs PJ: Comparison of mandibular bone in normal andosteoporotic women, J Prosthet Dent 63:218-222, 1990.

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73

DIAGNOSISDiagnosis for prosthodontic care requires the useof general diagnostic skills and accumulatedknowledge from other aspects of dentistry and itssupporting science. In this chapter emphasis isplaced on diagnostic procedures and findings thatare particularly relevant to edentulous and nearlyedentulous patients.

Familiarity with the Patient

The patient who is seeking prosthodontic care isprepared by past experiences, good or bad. If thepatient has a treatment history in the present prac-tice, both dentist and patient have the advantages ofprior knowledge. The dentist also has the potentialdisadvantage of proceeding on assumptions. Bothnew and returning patients need their completemedical history taken or reviewed and need toundergo thorough examinations.

Principles of Perception

Visual perception will be the primary mode of datagathering in the examination. A variety of theoriesof visual perception have been advanced, but it isperhaps easiest to think of its simplest componentsas seeing with the eyes and interpreting with thebrain. Typical of the tasks identified in this processare detection, discrimination, recognition, identifi-cation, and judgment. It is not difficult to extendthese tasks to the other senses, such as touch andhearing. If the tasks are interpreted in a little moredetail, then detection is merely noticing something

(i.e., determining its presence). Discriminationrequires distinguishing that which has been noticedfrom something else. Recognition requires decid-ing whether this, or at least something similar, hasbeen perceived on some previous occasion.Identification moves the process into specificity;what has been observed can now be communicated.Judgment allows something that has been observedto be placed within a spectrum of knowledge. Ineveryday life, these tasks usually proceed automat-ically, and certainly no attempt is made to fully per-ceive all aspects of the environment. In diagnosis,there is a professional responsibility to omit noth-ing of consequence. A consistent, methodicalapproach to examining patients is required.

The Setting

Health questionnaires and identification data can begathered in the reception area. The dentist’s reviewand clarification of the responses on the question-naire, as well as the examination of the patient, areappropriately carried out in the private operatory.The operatory should be comfortably equipped,tastefully decorated, and well lit. It should be free ofdistractions and provide patients with the senseof security and privacy that will allow them tocommunicate honestly and completely.

Problem Identification

Diagnosis, in its broadest sense, is an evaluation ofexisting conditions. More specifically, diagnosinginvolves identifying, and making judgments about,departures from a healthy state. These departures

C H A P T E R 7Diagnosis and Treatment Planning for Edentulous or Potentially Edentulous PatientsDouglas V. Chaytor

might simply be thought of as problems. Thedetection of these problems is the essential firststep, but the dentist’s perception of them mustmove through the perceptual tasks to judgment.The latter tasks may not be accomplished until afterthe examination. The dentist may have to use addi-tional resources to determine the exact nature of aproblem and whether it requires treatment. Mostimportant, the dentist cannot act on observationsthat have not been made. It is dangerous and inap-propriate to substitute assumptions for observa-tions. The importance of a thorough examinationwith accurately recorded observations cannot beoveremphasized.

Prognosis and Treatment Planning

Although logic suggests the tidy sequence of datagathering, interpretation into a diagnosis, thentreatment planning, the experienced clinician willbe thinking ahead during the data gathering and itsinterpretation. The consequences of both treatmentand no treatment will be borne in mind with partic-ular reference to how such action might change theprognosis. The objective of the process is the devel-opment of a treatment plan that specificallyaddresses the diagnosed needs of the patient andaccommodates treatment as it progresses.

CONTRIBUTING HISTORY: THE PATIENT’S STORYPlacing a patient’s prosthodontic needs in the broadercontexts of general health, socioeconomic status,lifestyle, and dental expectations will allow the den-tist to deliver treatment specifically appropriate forthat patient.

Social Information

A necessary first step for all patients is the estab-lishment of their identity. Information received inreferral letters, by receptionists over telephones, oreven on forms completed by the patient should beconfirmed. The staff can check administrativeinformation such as telephone numbers andaddresses. The dentist should address the patient byname and confirm more personal information suchas date of birth. Reviewing already completed

forms provides some opportunities for openingconversation and directly, or indirectly, confirmingthe contained information. A question about hoursof work might well prompt a patient who has givenan occupation of “school board employee” to say,“I work in the cafeteria, so I am off at 2:30.” Nowthe dentist not only knows when the patient mightbe available for appointments but also knows thatthe patient works in a high-risk area for frequenteating.

Knowledge of patients’ social settings can helpthe dentist understand patients’ expectations andthe evolution of their dental status. Family andsocial circle norms influence people. There are stillsectors of society that are not distressed by toothloss or by the prospect of wearing complete den-tures. Other patients come from unfortunate cir-cumstances where care has been inadequate, butgiven the resources, they would have done better.Most people have close friends or relatives whosejudgment they value. It is helpful to have patientsidentify these people during the examination and, ifpossible, gain some insight into their views.

An exploration of a patient’s habits will helpidentify those who might have contributed to theirpresent condition and those who will help ensuresuccess or failure for the treatment to be supplied.The potential for modification or reinforcement ofhabits should be noted for inclusion in the treat-ment plan. The dentist will like to know a patient’soral and denture hygiene procedures. The dentistcan also find out some of the patient’s less favor-able habits by explaining their significance fortreatment. Smoking is an example. A patient whohas not been convinced of the long-term detrimen-tal effects of smoking might respond when learningof its detrimental effects on wound healing and thedurability of tissue conditioners.

Patient expectations are founded in the realitiesand perceptions of the past and influenced byknowledge and emotions of the present but are val-idated only in the unknowns of the future.Prosthodontics is the most creative segment of den-tistry. Its intelligent use of modern techniques andmaterials justifies raising the expectations ofpatients with poor dental histories and inadequateknowledge of dentistry today. These patients can begreat practice builders when treatment exceedstheir expectations. Other people have expectations

74 Part Two Preparing the Patient for Complete Denture Treatment

that far exceed the possibilities for treatment byeven the most skilled professionals. If the dentistdoes not identify this discrepancy between expec-tations and reality before treatment is started, suc-cess will probably elude both dentist and patient.Educating patients is part of the dentist’s responsi-bility for providing dental care. Diagnosing theneed for education is as important as diagnosingthe need for prostheses.

Medical Status

As health care professionals, dentists are responsi-ble for the well-being of patients under their care.They are not entitled to “just make a denture.” Theymust be aware of each patient’s general health, espe-cially conditions that might influence the choice oftreatment or that can be aggravated by somethingthat might be done for the patient. Dentists shouldcollect this information early in the diagnosticappointment because of its potential to influenceeverything else that is done. Early collection ofthese data also allows the dentist to proceed withdiagnostic procedures without having to give undueemphasis to findings by asking related health ques-tions during the visual examination. Minor prepros-thetic oral surgery is a frequent requirement and canbe presented to the patient in a nonthreatening man-ner. The patient’s perception may be skeptical, how-ever, if at the same time the dentist has to ask aboutbleeding history or drug allergies.

The exploration of a patient’s medical history isa written and verbal art. A well-designed healthquestionnaire provides clues for more detailedexamination by the dentist. The primary objective isthe identification of conditions or incidents that haveimplications for current treatment. Other informa-tion assists the dentist in understanding the patient’scurrent condition and in developing a prognosis. Italso serves as a context for counseling.

A patient’s present conditions are most likely torequire accommodation if they physically disad-vantage the patient, require medication, or have thepotential for causing unfavorable reactions to treat-ment. Physical incapacity is not always visible.Inquiry may reveal back problems that prevent thepatient from tolerating long appointments.

Determination of vital signs will sometimesallow the dentist to find deviations from the

norm and in turn advise the patient to seek the serv-ices of a physician. It also provides a reference forthe patient’s record that can be used for comparisonshould a medical emergency occur during treatment.

Knowledge of all medications that a patient istaking is important to avoid any conflict in therapy.Such conflicts can range from interference witheffectiveness of a medication to the precipitation ofa medical emergency. Incidents of this nature result-ing from failure to elicit a medication history from apatient or from a failure to determine the signifi-cance and possible interactions of the medicationscannot be justified.

Mental Health

Patients seeking prosthodontic care arrive with anaccumulation of experiences and resulting atti-tudes. These may range from optimism throughresignation to despair. All may be set against abackground of psychoses or neuroses. When takingthe patient’s medical history and discussing condi-tions with the patient, the dentist must seek anunderstanding of the patient’s mental health, partic-ularly attitudes toward receiving new dentures.Much of this can be revealed through discussion ofthe reason for lost teeth, the importance of anyremaining teeth, and the patient’s experiences withdentistry, especially experience with any previ-ously worn prostheses. Danger lurks at both ends ofthe positive-negative spectrum. The overly opti-mistic patient may have unrealistically high expec-tations for success with all aspects of the dentures,such as esthetics and masticatory ability. At theother end of the spectrum is the patient who hasagreed to treatment only to please someone else,such as a spouse. In all instances, the dentist mustseek to improve patient understanding and strive toadjust expectations to reality.

Psychological inventories have been used toassess the personality characteristics of patientswho have difficulty wearing dentures. Such stud-ies have shown that many of these patients havehigh scores on indices of neuroticism. Neurosisis regarded as a chronic anxiety state at thephysiological level and is known to affect the per-formance of tasks requiring neuromuscular coor-dination. Both learning and skilled performanceshow optimal relationships with moderate levels

Chapter 7 Diagnosis and Treatment Planning for Edentulous or Potentially Edentulous Patients 75

of anxiety, whereas levels of anxiety that are toohigh or too low appear to be incapacitating.Although this suggests that only the most anxiouspatients should have trouble with their dentures,clinical experience suggests that such a conclu-sion may be narrow and restrictive. On the otherhand, cheerful extroverts are rarely found inthe ranks of patients who have difficulty withdentures and who complain unceasingly, althoughno causative factors can be found for theirproblems.

Dental Health

Success or failure in the provision of prosthodonticcare is frequently the direct result of how ade-quately the patient’s dental history has been gath-ered and analyzed. Through the telling of theirstories and responses to purposeful questions,patients will often provide the essence of a diagno-sis of their dental health and needs.

An understanding of the etiology of tooth lossby a patient will help a dentist estimate the patient’sappreciation of dentistry and contribute to theprognosis for prosthodontic success. Althoughpatients can change their attitudes and habits, it isreasonable to be suspicious that patients who havelost teeth in an accident might be much moreunhappy about their edentulous state than patientswho lost teeth as a consequence of decay resultingfrom neglect. Similarly, the expectations for theamount of alveolar bone remaining would begreater for the patient with a history of rapid toothloss from decay than for the patient with a longhistory of progressive periodontal disease.

Patients’ expectations will be strongly influ-enced by their denture experiences. Those experi-ences may be the source of both good and badhabits. Aside from biological compatibility andmechanical precision, success in prosthodontictreatment is largely dependent on matching patientexpectations to the treatment provided. Although itis important to strive to raise the quality of care tomatch the highest of patient expectations, it also isappropriate to lower the patient’s expectationsthrough education about denture wearing.

Considerable information can be gained fromobservations of dentures being used by patients orsaved from previous treatment. The warning to

beware of patients who have a “bag of dentures” iswidely known. The more appropriate warning isgrounded in diagnosis: the dentist should refrainfrom treating such a patient unless it is possible todetermine ways in which new prostheses can bemade significantly better than previous attempts.

Compromising Factors

Treatment planning is defined later in this chapteras a process of matching treatment options with apatient’s specific needs as determined by carefuldiagnosis. Part of that detailed diagnosis mustinclude identification of any factors that have thepotential to prevent the delivery of a desirable treat-ment. Detailed and analytical examination for thesefactors allows the dentist to move from generalknowledge to specific knowledge of the patientbeing examined. Some factors that should be exam-ined are anatomical, physiological, pathological,psychological, esthetic, and financial.

The examination of the patient’s anatomyfocuses on the head and neck, with emphasis on thedenture-supporting structures for the patient seek-ing prosthodontic care. However, the patient’sgeneral appearance should be observed for charac-teristics such as asymmetries, irregular gait, andphysical defects. Facial asymmetries, disparities injaw size and concentricity, interarch space, ridgeshape, sulcus depth, and muscle attachments areexamples of anatomical variations that can requirepreprosthetic correction or special accommodationin a treatment plan.

Normal physiological functioning contributesto denture success. For example, the successful useof dentures requires adequate neuromuscular con-trol. Deficiencies must therefore be noted and com-pensatory measures planned. The quality andquantity of saliva are also factors in a patient’s tol-eration of dentures. Thick, ropey saliva tends todislodge dentures, and thin saliva or low salivaryflows tend to provide an insufficient film for reten-tion of dentures or lubrication of the mucosa.Although these factors are unlikely to be modifiedfor prosthodontic purposes, an explanation of theireffects can help patients understand related prob-lems and thereby increase their willingness toaccept the associated limitations on treatmentsuccess.


Perhaps the most obvious, and certainly the mostcommon, objective of diagnosis is the identificationof pathoses. Classically, treatment first addresses theelimination of pain and infection. Neoplasms andother active problems also have to be identified forappropriate treatment. Decisions have to be madeabout inactive problems such as noninfected retainedroots. Aside from any immediate harm, considerationmust be given to the potential for posttreatment com-plications. Some potential complications can be suf-ficiently addressed by simply informing the patientabout them. Some problems relate frequently to den-ture wearing. These include hyperplasia of the den-ture-bearing area and tissues adjacent to dentureflanges, which frequently occurs in the area of therugae of the palate. This reactive tissue is cauliflower-like in appearance. The inflammation often is theresult of a superimposed infection with Candidaalbicans. Concomitant infections at the commissuresof the lips appear in many patients. Hyperplastic tis-sue also occurs at the borders of ill-fitting denturesand was formerly known as epulis Fissuratumbecause of its characteristic form and location.Dysplasia of the ridge crest makes an unstabledenture support.

All patients will be psychologically preparedfor treatment. The problem for the dentist is todetermine if that preparation is positive or negative.Some people will be approaching treatment withenthusiastic optimism; others will be merelyresigned to it as a necessity. Some will be coopera-tive and happy to participate in the decision makingand continuing care. Others will want to defer tothe dentist and avoid accepting responsibility fortheir own well-being. With reasonable care andeffort in patient management, most patients can besuccessfully treated. There are people who havereal psychological problems that require profes-sional help. Some of these problems can find focusin dental needs. The dentist should not assumethe role of the psychologist or psychiatrist.Consultations should be sought with appropriateprofessionals. Because of the sensitive nature ofthis type of referral, it usually is best to start withthe patient’s physician. If patients reveal that theyare already in the care of a psychologist or psychi-atrist, a direct consultation is in order. Danger liesmore in treating the undiagnosed patient than in thepatient undergoing therapy.

Desire for an esthetic appearance is a majormotivating factor for patients seeking new den-tures. Society places considerable emphasis onphysical appearance. Advertising uses the “perfectsmile” extensively. Preventive measures havehelped increasing numbers of people to preservenatural teeth into old age. Improvements haveenabled dentistry to provide lifelike prostheticreplacements for natural teeth. All these factorshave raised patient expectations. Success in treat-ment requires matching these expectations or mod-ifying them to meet the reality of currentprosthodontic care. It is therefore important for thediagnosis to address patient expectations foresthetic aspects of treatment. The consequences ofresponding to these expectations also must be con-sidered. The extraction of a few less-than-perfectteeth that retained a removable partial denture sat-isfactorily can produce a very difficult, and indeedunsatisfactory, complete denture situation. Anobvious example of this occurs in a patient who hasa Class II jaw relationship requiring a maxillarycomplete denture to replace a maxillary removablepartial denture, but has remaining overeruptedteeth in the anterior mandible. Although themandibular teeth can adequately retain a mandibu-lar removable partial denture, the esthetic require-ments for vertical and horizontal overlaps of theanterior teeth make the development of a stableocclusion very difficult.

Both the dentist and patient have reasons toconsider the financial implications of treatmentplans. The best treatment plans are useless if thepatient cannot afford the treatment. The diagnosismust therefore determine the significance ofproblems and the priority of the need for treat-ment to permit the development of a treatmentplan that addresses the patient’s needs in keepingwith an ability to pay. The diagnostic findingsmust be evaluated to allow consideration ofinterim care, deferred treatment, and alternativetreatment.

DATA COLLECTION AND RECORDINGAccurate diagnosis depends on the collection ofaccurate data. The means of collection and theform of the data will vary. To be useful, data mustbe stored in a readily retrievable format. They must


be respected for their contribution to the diagnosis.They must be kept confidential as a fundamentalprinciple of dentist/patient relations. Office staffmust be made aware of these principles. Theyshould know that no patient information should beshared with others, neither through conversationnor through careless exposure on computer screensor written records that can be viewed by otherpatients.

Record keeping is rapidly moving to computersinstead of the traditional paper chart. Computer-based record keeping offers some definite advan-tages in formatting, manipulation, and dataretrieval. Unfortunately, some programs can limitnatural expression and thereby present a risk oflimiting the scope and depth of information gath-ered. It is not the role of this text to debate the mer-its and technology of computerization. Thefollowing discussion of gathering and recordinginformation will not be specific to either format.

Questions

The gathering of information starts with the firstcontact about, or with, the patient. The informationmay come in a referral letter or a telephone callfrom the patient or another dentist. Whatever thesource, the record keeping should begin with thiscontact.

A registration form facilitates the capturing ofbasic information such as the patient’s name,address, and telephone number. The name andaddress of the patient’s physician, insurance infor-mation, referral source, and any other informationthat might need frequent or quick access also canbe recorded here. Gathering information withhealth questionnaires has several advantages, butthey should not be used alone. Their main advan-tages are consistency of predetermined questionsand ease of patient response. They therefore pro-vide a quick overview for the dentist. Staff shouldbe advised to try to detect people who might havereading problems arising from lack of education,learning disabilities, or language problems becausethe patient’s first language is different from the lan-guage used in the questionnaire. For most people, averbal administration of the questionnaire willovercome the problem, but for some people thehelp of family, a friend, or an interpreter may be

required. However completion of the questionnaireis achieved, the dentist should review it and discussit with the patient. Because the responses provideonly an overview derived from standardized ques-tions, the dentist must explore any suspicious orincomplete responses in more detail. Direct con-versation with people will probably be more reveal-ing than written communication. This is partly dueto its spontaneity and interactive nature. It alsoovercomes a natural reluctance by some people toput candid or confidential information in writing.The referring person is the first source of informa-tion. If this is another dentist, something of thepatient’s attitudes or behavior might be revealed. Ifthe referring person is a family member or friend, itis wise to be more cautious in the questioning.However, that person might reveal something ofthe new patient’s hopes and fears and, specifically,the reason for the referral. Given a chance, mostpatients will tell their own story. Indeed, mostpatients will have at least a lay idea of their diag-nosis and a possible treatment plan. The dentistwill learn this through careful listening. An inter-pretation of this information will assist the dentistin determining what the patients’ dental awarenessis and how much education will be required tohelp patients understand their problems and whatdentistry can do for them. Patients must beassisted in this process by addressing them at theirlevel of understanding, avoiding unnecessary den-tal jargon or an approach that might inhibit theconversation. Some patients are reluctant to revealinformation in their health or social histories thatthey feel is not pertinent to dentistry. A simpleexplanation of dentistry’s responsibility for thehealth of the whole patient as dental treatmentmight affect it, or might be influenced by it, usu-ally will help.

Records

Whether patients have been edentulous for long orshort periods, or are about to be rendered edentu-lous, it is important to review information abouttheir progression from a full complement of natu-ral teeth to their present state. The primary pur-pose of this review is to enable the dentist to baserestoration on original information and avoidreplication of errors in existing prostheses. Some


historical records will be available for mostpatients. The continuity of records is one advan-tage a patient gains from remaining in one prac-tice. Referring, or previous, dentists usually willbe helpful in supplying information. Informationnormally found in dental charts should bereviewed to provide background for current con-ditions and treatment needs. Charts should at leastprovide a chronology of previous treatment. Theyshould also contain some preextraction informa-tion such as tooth shade and vertical dimension ofocclusion. They also can provide previous healthhistory and an indication of patient compliancewith previously prescribed routines such as homecare or recall appointments.

Although radiographs reduce the three-dimen-sional oral structures to two-dimensional shadowpictures, somewhat enlarged and perhaps distorted,they do provide very useful information. They can,for example, contribute an indication of the relativesizes and arrangement of teeth. Old radiographsmight reveal how cysts or neoplasms influenced thetooth arrangement. The most valuable records toexamine are casts because they provide true three-dimensional information on tooth size and arrange-ment. Articulator mounted casts also reveal jawrelationships and interarch tooth relationships.Examination of old prostheses, coupled with dis-cussion with the patient, can reveal much aboutwhat the patient likes and dislikes and can or can-not tolerate. It is important to note characteristicssuch as the arch form of the teeth relative to thearch form of the residual alveolar ridge, the orien-tation of the occlusal plane, the relationship ofanterior teeth to the lips, denture base extensions,the thickness and contours of the flanges, and anywear patterns.

Systematically taken preextraction photo-graphs can be useful for determining tooth arrange-ment. Measurements of teeth also can be madefrom them. Observations on face form and jawrelations also can be made. Frequently, patients cansupply nonstandardized photographs that revealmuch of the same information. Age is not a seriousfactor in selecting teeth from preextraction infor-mation. The presence of natural teeth is importanteven if the patient’s mouth is closed. When askingpatients for such pictures, it helps to explainhow they will be used (i.e., for background infor-

mation and not necessarily as a blueprint for newdentures).

Visual Observations

Our primary data-gathering sense is vision. In dailylife, vision is taken for granted and used uncon-sciously. In a dental examination, it must be usedconsciously. Conditions should be designed foroptimal effectiveness. Adequate lighting is essentialfor making correct visual observations. Both qual-ity and quantity are important. Dentists routinelyuse task lighting to supplement ambient room light.To avoid eye strain, the gradient between the twomust not be too great. The ambient light should bediffuse to prevent the production of high-contrastshadows. The task lighting should not produceglare. Visual acuity diminishes with age, and higherlevels of lighting are required. Color balance isimportant for not only shade selection but also forthe correct evaluation of soft tissue.

Observing the patient should begin extraorally.There is much to be learned from watching thepatient entering the operatory and sitting in thedental chair. Are the patient’s movements sprightlyor impaired? Does the patient use a walking cane ortend to rest on furniture? Is there pallor or flushingof the face? Does the patient appear to be short ofbreath? Are there any signs of injury or impair-ment? Is the patient wearing eyeglasses? Is thepatient wearing a hearing aid? Do the patient’shands appear arthritic? Are there facial asymme-tries? Are circumoral tissues adequately supported?

After history taking and extraoral observations,the dentist begins the intraoral examination. Thesurface quality and contours of the soft and hardtissues are the objects of a careful visual examina-tion of the mouth. The dentist should adopt a rou-tine order for this examination to avoid omissions.Patients frequently will direct a dentist to theirchief complaint. This can distract the dentist from acomprehensive evaluation. It is wise to explain topatients what the value of the complete examina-tion is and how this allows for setting the chiefcomplaint in the context of the patient’s oral andgeneral health.

Often, aids to vision are helpful. The mouthmirror has been the symbol of dentistry’s diagnos-tic responsibilities for many years. It allows for


comfortable viewing angles. It also enables thedentist to direct light to structures and recesses ofinterest.

Magnification is a simple aid to vision. A hand-held lens will serve in some instances, but manydentists find loupes convenient for most tasks.Beyond magnification, loupes can improve theviewing distance and, with more sophisticatedoptics, can adjust the viewing angle. The latterfeatures enable the dentist to work using less stress-ful posture than might be possible with unaidedvision.

Still photography can be an aid in diagnosis andtreatment planning primarily by allowing the den-tist to have recorded images available for study dur-ing the development of a treatment plan.

Intraoral videography is promoted as a meansfor patient education. Its well-lit, magnified imagedisplayed on a monitor also provides the dentistwith an excellent image for immediate viewing orfor storage and retrieval. The stored images supple-ment other records for a variety of uses frompatient education to legal defenses. The ability toview such rich visual information when developinga treatment plan is a major asset.

Digitization of images makes computer-assisted vision possible. Although video imagescan be converted for this purpose, still digital pho-tography has developed to a practical state.

Radiography

The transition from emulsion-based film radiogra-phy to photostimuable phosphor-based films, CCD(charge couple device) and CMOS (complemen-tary metal oxide semiconductor) image sensing, iswell underway. This transition is reducing patientexposure to radiation; is eliminating image incon-sistencies related to concentrations, depletion, andtemperature of chemicals; and also is eliminatingchemical disposal as a problem. Experienced den-tists will find that displayed digital images differ inappearance from conventional radiographs viewedwith transmitted light on a viewbox. Direct viewingof the small film image gives the perception of pre-cision in the image that may appear to be lacking inthe enlarged digital image displayed on a monitor.The apparent lack of precision is a function ofmagnification and the resolution of the digital

image. Any digital image can be enhanced to bringout specific features.

Radiographs are important aids in the evalua-tion of submucosal conditions in patients seekingprosthodontic care. The presence of abnormalitiesin edentulous jaws, or in the edentulous segmentsof partially edentulous jaws, may be unsuspectedbecause of the absence of clinical signs or symp-toms. Abnormalities do occur and can be seen onradiographic examination. These may be foreignbodies; retained tooth roots; unerupted teeth; orvarious pathoses of developmental, inflammatory,or neoplastic origin. Radiographs aid in determin-ing the depth of periodontal pockets. They provideinformation about the bone surrounding the apicesof pulpless teeth. They can show the amount ofbone lost around the remaining teeth and in theedentulous regions (Figure 7-1). They also canshow the relative thickness of the submucosa cov-ering the bone in edentulous regions, the locationof the mandibular canal, and the mental foraminain relation to the basal seat for dentures. They cangive an indication of the quality of the bone thatsupports the teeth and will support the dentures.Unfortunately, this information is not always reli-able because of variations in radiographic tech-niques, exposure times, and developingprocedures. However, the denser (radiopaque) thebone appears to be, the better the bony foundation.Sharp spicules of bone on ridge crests and spinyridges also are apparent on dental radiographs.These conditions may affect decisions about thetypes of impressions and denture-base design thatshould be used.

Extraoral radiographs can provide a general sur-vey of a patient’s denture foundation and surround-ing structures. Panoramic dental radiography isreadily available for the convenient examination ofdentulous and edentulous patients. The dentist mustbe aware that such radiographs incorporate inaccu-racies resulting from the tomographic principles ofthis type of radiograph. Modern machines haveadjustments to compensate for some of these prob-lems, but they do not produce precisely accuratepictures of the anatomical structures. Magnificationof structures is common with this technique and isof the order of 25%. Because the machines are pro-grammed to capture a predetermined “slice” ofanatomy, structures outside that slice can be missed.



A B

C

DFigure 7-1 Radiographic evidence can be combined with clinical observations to enable thedentist to prescribe optimal treatment. The patient in A and B and the one in C are partiallyedentulous, and each requested complete denture treatment. In A and B, clinical and radiographicexaminations indicate that all the teeth can be retained and a maxillary removable partialoverdenture can be prescribed, rather than a complete denture. In C and D, a minimum of twobilaterally located and suitable abutments to support an overdenture is not present. This patient wastherefore treated with immediate dentures because of the untreatable periodontal disease present.

This can happen most easily for small structuressuch as ectopic root tips. Knowledge of the locationof anatomical structures, as they are normally pro-jected on panoramic radiographs, is an essentialprerequisite for reading panoramic radiographs.Suspicious areas should be examined in more detailwith intraoral radiographic techniques. Special filmholders and central ray aiming aids are available formaking some radiographs. Cephalometric and tem-poromandibular joint (TMJ) radiography are exam-ples. Some large-format views, such as the lateraljaw projection, can be obtained by having thepatient hold a cassette loaded with film against theface while exposure is made with the regular chair-side dental x-ray machine.

Intraoral radiography is the most frequently usedformat in dentistry, with the periapical approachconsidered essential for caries detection and theevaluation of periodontal support. Although periapi-cal radiography is convenient, it also has diagnosticadvantages. The small film size allows placementclose to the structures of interest, resulting inless magnification than panoramic radiography.Similarly, the small films can be kept flat and thusavoid distortion of the image. Although these fea-tures suggest the value of this format when teeth arepresent, this format should not be overlooked inedentulous patients. Maxillary tuberosities, forexample, often are not clearly seen in panoramicradiographs but can be clearly seen in profile onperiapical films. In fact, this format should be usedto further explore any suspicious areas not clearlyseen on large-format films. Although the word filmhas been used here, the same comments will apply tothis format when recorded by means of direct digitalradiography. Occlusal format films are designed tobe held on the occlusal surface of the teeth andexposed appropriately from above or below the jawsto provide a view of a whole arch. Like the periapi-cal approach, it captures all structures in the path ofradiation. The profile it provides is particularly help-ful for diagnosing apparent expansion of the bonebuccally or lingually, such as may occur with cystsor retained roots.

Palpation

Although it is important to use all senses in diag-nosis, touch is probably second only to vision in

importance. For submucosal structures, it competeswith, or perhaps more correctly, complements,radiography. A sensitive finger will detect abnor-malities such as displaceable structures, disconti-nuities, and enlargements of structures. It willreveal textural differences and unusual contours.A light touch should be used for most of the exam-ination, but patient response to pressure also is help-ful. Certain areas, such as sharp residual alveolarridges and mylohyoid ridges, typically are tender.Before patients are palpated, they should be told toexpect pressure. They should be assisted in distin-guishing the normal sensation of pressure from painand tenderness. Tenderness or pain, in apparentlynormal areas, may indicate underlying pathoses andshould be investigated radiographically.

Dentists should follow a routine pattern ofintraoral palpation to avoid omissions. Typically,one might start with lips and cheeks, moving to thedenture-supporting areas, the floor of the mouth,and the tongue. Aside from noting the features ofeach area, it is important to also note asymmetrieswith the contralateral structures.

Both primary and secondary denture supportareas should be palpated. The sides of residualalveolar ridges should be palpated in addition tothe ridge crest. Irregularities and patient reactionsshould be noted. The contents of the floor of themouth are best palpated with one finger from onehand inside the mouth and two fingers of the otherhand applied extraorally. The outside fingers pre-vent the displacement of the structures duringpalpation by the intraoral finger. The patency ofWharton’s duct and the production of saliva by thesubmandibular gland should be demonstrated bywatching for the expression of saliva from theduct orifice as the gland and duct are gentlysqueezed. Palpation of the tongue is essential fora thorough examination and should be done insequence with the visual examination. The patientis asked to protrude the tongue onto gauze. Aidedby the gauze, the dentist can hold the tongue whileusing a mirror to examine it. Palpation of thetongue should be done both left to right and rightto left. Obviously, this must be done quickly. Thetargeted areas are the lateral borders and theregion of the vallate papillae. The dentist will useextraoral palpation to corroborate intraoral find-ings and explore other structures such as the TMJ


and associated muscles. It has been said that theexposed head and neck are areas of responsibilityfor dentists. This may not be a view shared bypatients if they are unaware of the need to look forstructures such as lymph nodes in the neck.Extraoral palpation requires explanation to thepatient to avoid misunderstanding of the dentist’spurpose.

Measurement

Classification of some structures as large or small,and sulci or fossae as deep and wide, or shallowand narrow, is adequate for a general appraisal of apatient’s anatomy. However, some structures andspaces require more precise recording. Studentsnew to the field of prosthodontics will find meas-uring helpful in developing their abilities to esti-mate size. Recorded measurements often arehelpful in the laboratory for fabrication of prosthe-ses. They also allow the dentist to verify the attain-ment of some treatment objectives. Later theyserve as references for reevaluation of prosthesesduring recall examinations.

The most fundamental extraoral measurementis the vertical dimension of occlusion. A little moredifficult to establish, but also important, is the ver-tical dimension of rest. Techniques for makingthese measurements often suggest making arbitrarymarks on the nose and chin for reference. However,such references disappear at the end of the appoint-ment. Anatomical references such as menton andthe columella of the nose remain with the patientand therefore allow repeated comparative measure-ments at future appointments. The anatomical ref-erences used should be noted in the patient’s chart.Consistency of technique by the dentist will fosterreliability of these repeated measurements. Otherextraoral measurements relate to specific proce-dures such as tooth selection. For example, thepatient’s true interpupillary distance can be com-pared with the interpupillary distance on a photo-graph of the patient; a ratio can be calculated andthen used to calculate a replacement tooth sizefrom the patient’s tooth size measured on thephotograph.

A periodontal probe or dividers and a ruler orBoley gauge can be used to make intraoral meas-urements. Size is a factor to be considered in mon-

itoring any traumatic lesion or other lesions of themucosa. Measurements also are helpful in design-ing prostheses or items used in their constructionsuch as impression trays. In the latter instance,measurements of sulcular depth can be transferredto casts to indicate the height of tray flangesrequired. Of course, some measurements of intrao-ral structures can be made more easily on the diag-nostic casts, for example, the size of remainingteeth.

Diagnostic Casts

Diagnostic casts are at least a convenience and, inmost instances, a necessity. They allow for an eval-uation of anatomy and relationships in the absenceof the patient. The mounting of casts on an articu-lator allows for a dynamic evaluation of theinterarch relations. A facebow can be used to con-veniently relate the casts to an approximate hingeaxis. Eccentric records can be made to set thecondylar guidances. The mounted casts can be sur-veyed and analyzed at the dentist’s convenience.The casts may reveal new information or confirmthat which has already been observed intraorally.The dentist will be looking at arch size and sym-metry, interarch space, arch concentricity, antero-posterior jaw relationship, and lateral jawrelationships, especially posteriorly where anocclusal crossbite might be indicated. The dentistalso will be looking for signs of underlying abnor-malities. Measurement and a determination of rela-tionships to other structures will assist in makingdecisions on preprosthetic surgery. Undercuts maybe observed unaided, or their significance can bedetermined more precisely with the aid of a dentalsurveyor. Even soft tissue disease may be moreobvious on a cast than intraorally when saliva andcolor may obscure it. The rugae provide an exam-ple. Displacement from the pressure of an old den-ture can be more obvious on a dry cast than in themouth.

SPECIFIC OBSERVATIONSExperienced dentists use the full spectrum of data-gathering techniques and aids in accomplishing acompilation of complete information to use indeveloping a diagnosis for a patient. Regardless of


how the information is obtained, the objective isthe gathering of specific information from specificobservations.

Existing Dentures

The patient’s existing dentures should be examinedcarefully. The objectives of this examination are todetermine exactly the quality of the dentures andhow that relates to the experiences cited earlier bythe patient and to determine the potential forimprovement. If the dentist cannot identify specificattributes of the dentures that can be improved toalleviate specific problems, embarking on the mak-ing of new dentures is tantamount to embarking ona sailing voyage without a navigation chart. Thesame rocks and shoals that spoiled the last voyageare probably going to produce failure again. Base,framework, and tooth material can be determinedby visual inspection or light scratching with ametal instrument. Transmitted light will reveal theretentive pins of porcelain teeth. Set against the ageof the denture and the material of the opposingocclusion, some estimates of patient use and abuseof the prostheses can be made. For example, porce-lain teeth are more wear resistant than acrylic resinteeth; thus the resin teeth will show more wear thanporcelain teeth over the same period of use.However, porcelain teeth are more brittle; they willlikely be chipped if the patient has not been care-ful, especially when cleaning them. Chipping alsomay be the result of lack of harmony in the occlu-sion. An evaluation of the fit of a denture willdetermine how well it is adapted to the denture-bearing area, how well the flanges fill the sulci,how correct the border extensions are, and wherethe posterior palatal seal is located. Dentures withflanges that are deficient in extent or thickness failto achieve their potential for support, stability, andretention. A variety of proprietary products can beapplied to the tissue surface of the denture beforeseating that will reveal the distribution of tissuecontact. These products include pressure-indicatingpastes and special formulations of silicone impres-sion materials. A thin mix of irreversible hydrocol-loid impression material also works. A clue to poordenture-base fit is the finding of plaque on selectedsites of the tissue surface of the denture. The tissuesurface of the labial flange is a typical location.

The most important observation that must be madeof the occlusion is whether the occlusion is in har-mony with the patient’s jaw relations. Large dis-crepancies will be immediately obvious if thepatient is guided into centric relation and the occlu-sion is observed as the patient brings the teethtogether and subsequently is guided into eccentriccontacts. Small discrepancies may only be sug-gested by tooth wear patterns. The level and orien-tation of the occlusal plane must be assessed—somust the tooth-to-tooth and tooth-to-ridge relation-ships. The length of the plane relative to the sizeand shape of the denture-bearing area also must beassessed. Denture teeth set over the slope of themandibular ridge as it approaches the retromolarpad are recognized as a source of denture instabil-ity. Tissue trauma and a patient’s inability to suc-cessfully use dentures can frequently be traced toerrors in occlusion.

An evaluation of the esthetics of existing den-tures should be approached first from the perspec-tive of the knowledge and professional judgment ofthe dentist. Second, there must be an evaluation inthe light of information about the patient’s naturalteeth. The third phase of the evaluation must takeinto consideration the patient’s views. These per-spectives must all be reconciled to achieve successin the making of new prostheses. A patient willsometimes be satisfied with esthetically inappro-priate dentures because of conditioning throughlong-term use. These patients often are reluctant tohave significant changes made because they wouldbe noticeable to other people. Patients who desirechange must have their expectations clarifiedbecause these expectations may not correspondwith the dentist’s intentions or abilities. Theesthetic appropriateness of a patient’s existing den-tures and the possibilities for improvement can bedetermined by comparing the observed and con-templated characteristics with the recommenda-tions made later in this book for selecting andarranging prosthetic teeth.

Soft Tissue Health

Complete dentures are entirely dependent for sup-port on soft tissue (mucoperiosteum) and underly-ing hard tissue (bone). The health and quality ofthose tissues are therefore very important determi-


nants of success in the wearing of complete den-tures (see Plates 7-1 and 7-2). The dentures are sur-rounded by the cheeks and lips, which are coveredby lining mucosa. This mucosa moves in intimatecontact with the dentures during functioning of therelated facial and masticatory muscles. The liningmucosa of the lips and cheeks and floor of themouth is relatively thin and easily traumatized. It isalso the site of a variety of pathoses. The lingualand palatal surfaces of the dentures are in intimatecontact with the tongue and its specialized mucosa.The specialized mucosa covering the tongue issometimes said to be a “window” on systemic dis-orders. All these tissues must be examined in detailfor individual anatomy and for abnormalities,irregularities, and pathoses. The term masticatorymucosa has been applied to the mucosa coveringthe residual alveolar ridges and palate. It usually isattached to the underlying periosteum. When it isnot attached, denture instability can be a problem.The area of attachment diminishes with ridgeresorption. The mandibular ridge is more suscepti-ble to this problem. A total loss of attachment isoften first seen above the mandibular symphysis.This loss can be demonstrated by pulling the lowerlip and watching the floor of the mouth move.

Diagnosis of abnormalities of the mucosarequires the recall of the normal appearance.Shape, color, and texture are significant character-istics. Some variations occur frequently with nosignificance and are therefore accepted as normal.These include Fordyce’s granules in the buccal fatpads and varicosities in the floor of the mouth ofelderly patients. Initially, knowledge of normalappearance is learned from anatomy texts and thestudy of surface anatomy. However, the requiredmental picture becomes well developed onlythrough careful examination of many healthymouths. General knowledge of the anatomy of themouth provides a background for the examiningdentist to focus on the specific details of theanatomy of each patient. The simple questions ofpresence or absence of the normal structures mustbe followed by determinations of the detailed char-acteristics of the structures. The hard palate isexamined for its shape, its height, its width, and thequality of the mucosa and submucosa covering it.Does it have a high vault that will resist lateral dis-placement of a denture? Is the hard palate wide as

to supply denture support and surface area forretention? The soft palate accommodates the poste-rior palatal seal and distal border of a completedenture and is included in the discussion of bordertissues. The cheeks are examined primarily todetermine if they are pathoses free. If traumaticlesions are found, their relationship to existing den-tures must be determined. The general contour ofthe cheeks should be noted. Are they full, fillingthe buccal spaces, which indicates a need for con-cave buccal contours on the dentures? Does the fullshape result from underlying fat (e.g., retainedjuvenile buccal fat pads) or from well-exercisedmasseter muscles such as is seen in gum chewers?The latter must be accommodated in the buccalflange contours through the impression making.

The tongue is an important factor in denturesuccess or failure. The size and activity are themain concerns. The tongue will expand into eden-tulous spaces. The introduction of a new denturewill then be met with dislodging competition fromthe tongue. An edentulous patient who has not beenwearing a mandibular denture often will use thetongue as an antagonist for the maxillary arch inmastication. In these situations, the tongue canbecome enlarged and very strong. Examinationof the floor of the mouth includes examination ofdeep structures. The surface contours are importantbut can change as a result of underlying activity.Contraction of the mylohyoid muscles will raise thefloor of the mouth. This will dislodge a completedenture made from an impression that did notrecord the floor of the mouth with the mylohyoidmuscle in a contracted state. The visual examina-tion requires that the depths of mucosal folds beexposed to be sure hidden lesions are not missed.The patency of the submandibular ducts should bechecked. Bidigital palpation should express salivafrom the duct. This technique helps identify abnor-malities such as sialoliths in the submandibularduct, fibrosed glands, and enlarged lymph nodes.Many types of pathological lesions can be found inand around the oral cavity, including lesions of themucous membrane and tissues under it. They maybe in the bone or glandular tissue; on the softpalate, hard palate, lips, cheeks, tongue, or floor ofthe mouth; or in the throat. Like mechanical cutsand abrasions, pathological lesions should be diag-nosed and treated before impressions are made.


Among the more common lesions found in themouth of edentulous patients are pseudoepithe-liomatous hyperplasia, papillary hyperplasia, apht-hous ulcers, lichen planus, hyperkeratosis,leukoplakia, and epulis fissuratum (hyperplasia).Other lesions may be more serious; for example,lumps and ulcers can be evidence of malignancies.These may be found anywhere in the oral cavity. Ifthey are not detected, serious consequences canresult for the patient and for the dentist. If suspi-cious lesions are found, adequate steps must betaken to determine their precise nature. Theseinclude biopsy and referral for further tests. Oralmalignancies are most common in people who areold enough to need complete dentures, but theymay occur in people of all ages. The obligations ofdentists for maintaining health do not end when theteeth are gone. Instead, they become more impor-tant. Patients must be questioned about theirknowledge of any suspicious findings. Questioningshould start with the patient’s awareness of theabnormality and progress through symptoms, dura-tion, and any home remedies that might have beenapplied. The patient’s perception of whether alesion is healing or spreading is important.

The color of the mucosa will reveal much aboutits health. The differences in appearance between ahealthy, pink mucosa and red, inflamed tissue willbe apparent. The cause of any inflammation mustbe determined. Is it the result of trauma from an olddenture? Is it a manifestation of infection?Abrasions, cuts, or other sore spots may be foundin any location under the basal seats of the existingdentures or at the borders. They may be the resultof overextended or even underextended borders.Malocclusion is also a major source of tissuetrauma. Sharp or overextended denture borderswill produce red lines of inflammation or ulcera-tions. Evidence of cheek biting will appear at thelevel of the occlusal plane. It often will be whitescar tissue indicating a mucosa that has been trau-matized and is now healing. Sometimes sorenessresults from something as simple as a berry seedgetting under the denture. At the time of the exam-ination, the causes should be determined to allowcorrection before impressions are made. Althoughinfections may arise from a variety of sources, fun-gal infections are common in edentulous patients.Concomitant inflammation of the corners of the

mouth should raise suspicions of C. albicans infec-tion. A cytosmear may be made easily and exam-ined for pseudohyphae. Smears also may becultured to confirm the clinical diagnosis.

Hyperplasia of the tissue associated with ill-fit-ting dentures is a common finding. Hyperplastictissue will be found in relation to edentulous ridgesand border tissues, as a reaction either to trauma orto the resorption of supporting bone. When boneresorbs, it leaves a void in the denture foundationas defined by the existing denture. This space oftenwill remain at least partially filled with hyperplas-tic tissue. This condition seems to appear more fre-quently in the maxillary arch. On the mandible, it isseen most frequently in the anterior region whenthe posterior regions are relatively stable but thedentures were not relined in more recent anteriorextraction sites. Occlusal trauma from decreasedvertical dimension of the jaws and posterior toothwear is concentrated in the anterior regions andcontributes to this problem. Border tissues chroni-cally traumatized by overextended flanges, or byflanges of dentures that have settled as result of lostridge support, often will produce a reactive hyper-plasia that has commonly been referred to as epulisfissuratum. Similarly, tissue will proliferate insidea loose-fitting flange. The labial surface of themaxillary residual alveolar ridge is a common site.Papillary hyperplasia is cauliflower-like in appear-ance and tends to occur on the anterior of thepalate, in the area of the rugae, of long-term den-ture wearers. Often this tissue is inflamed and isthen referred to as inflammatory papillary hyper-plasia. The deep crevices of papillary hyperplasiaare prone to infection. The infection frequently isfound to be C. albicans. Obviously, infection mustbe treated before new dentures are made, but recur-rence is likely unless the hyperplastic tissue isremoved.

Excess fibrous tissue commonly occurs undervery normal-appearing mucosa. Although it issometimes quite firm, it does not provide sounddenture support. This is in part due to its unevendistribution. The maxillary tuberosities, if fibrous,may not only provide poor denture support but mayalso be so large as to interfere with the correctplacement of the occlusal plane. If they are mobile,they will diminish the stability of the denture. Theanterior region of the maxillary residual alveolar


ridge also may be fibrous, but usually it is flabby ifbone resorption has occurred and the denture hasnot been relined to compensate for the loss. A ridgesupporting a complete denture opposed by onlyanterior teeth in the mandible seems to be especiallyprone to this type of deterioration. Resorption of themandibular residual alveolar ridge sometimes leavesa tight band of fibrous tissue above the ridge crest.This too is nonsupportive for a complete denture andis difficult to record accurately in an impressionbecause of its displaceability.

Hard Tissue Health

Teeth All teeth should be examined and evalu-ated carefully. The loss of all remaining teeth canbe a terrible psychological shock to patients, eventhough some of them may not admit it.Consequently, the dentist should be empathetic topatients who must lose their teeth. Every possibil-ity for saving them should be explored. Whenpatients recognize that the dentist does not wantthem to lose their teeth, a necessary feeling of con-fidence can be developed. Even patients who saythat they cannot wait to get rid of their teeth so thatthey will not have to see dentists anymore usuallydo not really want to lose their teeth. Often they areonly trying to prepare their defenses against futuredifficulties they do not understand. If the dentistremoves teeth without adequate reason, physical,mental, and even legal problems may arise. Theanswer as far as the dentist is concerned is simple:get all the facts and consider all possibilities beforemaking the decision to remove the remaining teeth.Many diagnostic factors are involved. To ignore orfail to recognize any of them can lead to incorrectdecisions. Valid reasons for extractions mayinclude one or more of the following conditions:

1. Advanced periodontal disease with severebone loss around the teeth

2. Severely broken-down crowns (subgingival)that cannot be adequately restored

3. Fractured roots4. Periapical or periodontal abscesses that can-

not be successfully treated5. Unfavorably tipped or inclined teeth that

pose problems for their use as abutments forfixed or removable prostheses

6. Extruded or tipped teeth that interfere withthe proper location of the occlusal plane

The number and location of remaining teeth mustbe carefully noted. Perception sometimes fulfillsexpectations, as was mentioned earlier. Driftedteeth can masquerade as missing neighbors. Eachtooth should be identified and notations should bemade of drifted or malaligned teeth. The coronalstructure of remaining teeth should be examined forthe quality of both the natural components and anyrestorations. The fracture or ditching of restorations,the extent of caries, and the presence of cracks,especially vertical cracks extending into the root,should be determined. The questions to be answeredinclude the following: Is this tooth satisfactory tosurvive on its own? Can it support a removable par-tial denture? Can it be restored? Can it be used as anoverdenture abutment? Periodontal support isanother major factor in the decision to preserveteeth or render a patient edentulous. If significantperiodontal disease is found, its extent and theprognosis for treatment become factors in decidingon retention or extraction of the affected teeth.

Bone Bone is the firm, yet physiologicallydynamic, support for teeth and prostheses. Itsexternal form and internal structure are influencedby systemic and local factors. Even though wholebones are permeated with other structures such asblood vessels, bone tissue is primarily a collage-nous protein matrix impregnated with mineralsalts. Its stability is dependent on good nutritionand hormone balance. A thorough discussion ofbone diseases of systemic origin is beyond thescope of this book, but the dentist must be alert totheir negative influence on the success of prostho-dontic treatment. Patients may reveal these diseasesin their health histories. Alternatively, they may beunaware of the problem yet exhibit symptoms onexamination. Commonly identified metabolic bonediseases are osteosclerosis, osteomalacia, and osteo-porosis. Osteosclerosis refers to increased amountsof calcified bone. It can be associated withmetastatic tumors or hypoparathyroidism. A defi-ciency in the amount of minerals relative to theamount of matrix is referred to as osteomalacia.Osteoporosis is a decrease in bone mass but with anormal ratio of minerals and matrix. Adult women,


especially after menopause, are particularlyinclined to have osteoporosis. Local bone diseaseand anatomy can be significant factors in prostho-dontic care. Retained roots of teeth, abscesses,cysts, and neoplasms have to be identified and dif-ferentially diagnosed. Appropriate treatment mustthen be planned. Some retained roots will be par-tially resorbed and difficult to distinguish from sur-rounding bone. Attempts to remove these surgicallyoften are frustrating and only partially successful.If such roots are asymptomatic and apparently cov-ered completely in bone, they are usually best leftundisturbed. The patient should be made aware oftheir presence and the rationale for leaving them.Roots covered only by mucosa and roots withclearly defined periodontal ligaments, associatedcysts, or abscesses should be removed. Neoplasmsrequire complete diagnosis and treatment.

The anatomy of structures particularly relatedto the provision of prosthodontic treatment isdescribed and illustrated in later chapters. Diagnosisin preparation for new dentures requires a detailedexamination of the specific anatomy of the individ-ual patient. Many variations will be found. Somewill present no special problems. Others willrequire accommodation in impression making. Stillothers will require surgical correction. Sharp andspiny residual alveolar ridge crests can be productsof preextraction bone destruction, trauma duringextractions, or postextraction resorption. Crestalbone irregularities and increasing radiolucencytoward the ridge crest suggest this in radiographsshowing the ridge in profile. Palpation usually willreveal the sensitivity of the mucoperiosteum overthe crest. Because of the sensitivity, spiny ridgecrests cannot contribute much to the support of adenture. Surgical reduction is tempting and some-times indicated, but the reduction in ridge heightadversely affects the stability of a denture. Theridges can sometimes be kept for their contributionto stability if they are relieved of direct pressure byusing a selective pressure impression techniquethat gains support for the denture from other areas.Severe resorption will expose the mental foraminaon the crest of the mandibular residual alveolarridge. This may be seen radiographically. Theexposed mental nerve is sensitive to pressure. Thepatient wearing dentures may report a sporadicshooting pain in the distribution area of nerve.

Palpation will produce the same pain. Relief of thedenture to bridge over the nerve must be providedbut is not completely effective because conven-tional complete dentures move in function.Stabilization of dentures with implants has over-come this problem. The location and size of themandibular canal usually are important only if sur-gery, such as the placement of implants, is contem-plated. Enlarged maxillary sinuses preclude, or atleast complicate, reduction of maxillary residualalveolar ridge height such as might be needed toallow correct orientation of the occlusal plane.Placement of implants in the region of the maxil-lary sinuses will usually require the grafting ofbone to the inner wall of the sinus by a proceduregenerally referred to as a sinus lift.

Tori are benign bony enlargements found insome patients at the midline of the hard palate or onthe lingual aspect of the mandible in the premolarregion. They vary in size. Small ones may beaccommodated by relief of the denture base. Othersare so large that their interference with denturedesign warrants their surgical removal. Tori are cov-ered with a thin mucoperiosteum; consequently,they are very hard and sensitive to pressure. A torusin the midline of the maxillary arch, torus palatinus,may appear to be nothing more than a prominentmidline suture but may be so large that it fills thepalate to the level of the occlusal plane. Generally,surgical removal of a torus palatinus should beavoided, but if the torus is so large that it extendsbeyond the vibrating line and over part of the softpalate, it should be removed or reduced in size.When the torus extends very far back, it can inter-fere with the development of a posterior palatal seal(see Figure 8-9). Mandibular tori occur singly or inrows just above the floor of the mouth. It often isdifficult to provide adequate denture relief for thembecause it would break the border seal of the den-ture. If adequate accommodation through relief can-not be anticipated, surgical removal is indicated.Because a torus has a thin covering of cortical bone,the interior cancellous bone will be exposed by sur-gery. The formation of a new cortical plate takes2 to 6 months.

Bony undercuts can be found on maxillary andmandibular residual alveolar ridges. They are sig-nificant only if the denture base cannot be manipu-lated into place over them. This usually requires


opposing undercuts. A typical example is a railwaytrack–like mandibular residual alveolar ridge withlingual and buccal undercuts. Another typicalexample is seen when buccal undercuts appear atthe distal of the maxillary right and left residualridges. Although some of these undercuts resultfrom true exostoses, many, such as the maxillaryexample, arise from inadequate management of thealveolar bone at the time of extractions. Forcepsextraction of teeth usually spreads the alveolus.The buccal and lingual plates require repositioningafter this occurs; otherwise, the socket will fill withnew bone supporting the cortical plates in a splayedrelationship.

Biomechanical Considerations

A number of biomechanical factors influence thechoice of methods to be used and the difficultiesthat will be encountered in providing completedenture service. These factors must be recognizedeven though sometimes not much can be done toeliminate the problems or their causes. Instead, it issometimes necessary to alter the technical proce-dures to minimize the adverse effects of theunfavorable conditions.

Jaw Relations Unobtrusive observation usuallywill provide the first indication of the patient’s jawrelations. A later chapter deals with the determina-tion of jaw relations during treatment. Some ofthese approaches can be applied at the diagnosticappointment. The vertical dimensions of the face atrest and occlusion, as well as the anteroposteriorjaw relations, must be estimated during diagnosisto permit provision for their acceptance or correctionbeing included in the treatment plan.

The available amount of support for completedentures is directly related to the size of the mandibleand the maxillae. Although dentists are expected tostrive for accuracy in all aspects of denture con-struction for all patients, it is obvious that errors inpatients with small arches can take on more signif-icance than would be the case for patients withlarge arches. This will be true from impressionmaking to finalization of the occlusal scheme anddenture bases. The arch form as it appears from anocclusal viewpoint should be noted. This informa-tion is used in several steps of denture construction

(e.g., stock tray selection for preliminary impres-sions). In the absence of precise information, archform can be used as a factor in tooth selection. Italso may assist in decisions on the arrangement ofteeth. If the arches are asymmetric, problems oftooth arrangement and occlusion may occur.Harmony in size and form between maxillary andmandibular jaws allows for the most desirable tootharrangements and occlusion. However, somepatients have large maxillary jaws and smallmandibular jaws, or the opposite disharmony.These conditions arise from genetic factors andfrom imbalance in growth and development. Whenthe natural teeth were present, these patients wouldhave had severe malocclusions, unless they hadbeen treated with orthodontics. The replacement ofteeth for people who had a Class II or Class IIImalocclusion presents some special problems.Generally, the artificial teeth should occupy thesame positions as the natural teeth. This requires theocclusion to be planned in relation to the dishar-mony. The modifications from an ideal occlusion toa crossbite occlusion or one with an excessive hori-zontal overlap of the upper teeth over the lower teethwill require time to develop. These difficultiesshould be recognized and anticipated when thediagnosis is made. The cross-sectional contour of aresidual alveolar ridge has an important influenceon the selection of an impression procedure.Resorption of a residual ridge after the removal ofteeth radically changes its cross-sectional form.When the teeth are first removed, the ridge is broadat its occlusal surface, but as resorption occurs, theresidual ridge becomes progressively narrower andshorter. The ideal ridge has a broad top and paral-lel sides. As the ridge becomes narrower, itbecomes sharper and consequently is unable towithstand as much occlusal pressure as a broaderridge. Ridge relations change as shrinkage occurs.Therefore the amount of resorption that hasoccurred after teeth have been lost affects the rela-tionship between the maxillary and mandibularsupport areas. The bone of the maxillae resorbs pri-marily from the occlusal surface and from the buc-cal and labial surfaces. Thus the maxillary residualridge loses height, and the maxillary arch becomesnarrower from side to side and shorter anteroposte-riorly. The mandibular ridge resorbs primarily fromthe occlusal surface. Because the mandible is wider


at its inferior border than at the residual alveolarridge in the posterior part of the mouth, resorption,in effect, moves the left and right ridges progres-sively farther apart. The mandibular arch appears tobecome wider, while the maxillary arch becomesnarrower. The cross-section shrinkage in the molarregion is downward and outward. The cross-sectionshrinkage in the anterior region at first is downwardand backward. Then, as shrinkage continues, theanterior part of the basal seat for the mandibular den-ture moves forward. These changes must be noted atthe time of the examination to plan for the resultantproblems of leverage, occlusion, and tooth positionfor esthetics.

Denture stability is enhanced by parallelism ofthe primary denture-bearing areas. When naturalteeth contact in centric occlusion, the surfaces ofthe maxillary and mandibular arches are, in effect,parallel. This is a very stable relationship. Eventhough denture teeth will be set to contact evenly incentric occlusion, the surface of the arches thatsupport the dentures may be resorbed out of paral-lelism. This diminishes the stability of the dentures.This problem must be noted at examination forconsideration in denture design. For example,implant-supported dentures are especially helpfulin this situation. To determine this relationship, thepatient should be coached to position the jaws atthe vertical dimension of occlusion and hold theposition while the examining dentist parts the lipswith fingers and mouth mirror to observe theridges. The relationship also will be obvious onmounted diagnostic casts. Mounted diagnosticcasts also will reveal the amount of interarch space.This is important information because a lack ofspace can lead to denture failure from improperlypositioned teeth. Excessive space usually is relatedto severe ridge resorption. The resulting instabilityalso limits denture success. Even when severe ridgeresorption indicates excessive interarch space inthe anterior of the mouth, the posterior should beexamined to determine if there is sufficient space.If some teeth are present, they must not interferewith the placement of the occlusal plane. Extractionmay be indicated if a tooth is so extruded that itsocclusal surface is above the desired occlusalplane, unless it can be shortened sufficiently to beon the same plane with the other teeth in that dentalarch.

If the maxillary tuberosities are so large thatthey will prevent the correct location of the occlusalplane or require the omission of some teeth or pre-vent the correct distal extensions of the denturebases, they could be surgically reduced. The factthat a patient may have been wearing dentures doesnot rule out these difficulties. Denture-base wearon old dentures over the retromolar pads and themaxillary tuberosities suggests an interarch spacedeficiency. Radiographs will show whether largetuberosities are bone or an overgrowth of fibrousconnective tissue. Where possible, the reductionshould be limited to the fibrous tissue. The result-ing closed soft tissue wound heals quickly andpredictably. Should bone have to be removed,remodeling is initiated, making the result less pre-dictable and prolonging the healing. Sometimesspace can be gained by dissecting out nonessentialcontents from large retromolar pads.

Border Tissues Retention of a complete dentureis partially dependent on an effective border seal.The seal is created by closely adapting the dentureto its surrounding tissues. Therefore the tissues thatwill surround the denture flanges and the spacesthat will accommodate them should be examinedthoroughly. Noting their specific anatomical char-acteristics and dimensions during the diagnosiswill help in designing the denture, in determiningthe size and shape of a custom tray, and in evaluat-ing of the impressions.

The labial sulci anterior to the buccal frenulaare often obliterated by the lips resting against theresidual alveolar ridges. With severe ridge resorp-tion, the lingual boundary is undefined. An esti-mate of the depth and labiolingual width of eachsulcus will help by setting an objective for impres-sion making and ultimately for the height andthickness of the labial flanges. The goal is to pro-vide a denture flange that correctly supports, butdoes not distort, the lips while also creating a bor-der-sealing contact with the boundary tissues with-out impingement. Essentially the same can be saidof the buccal sulci, which are located distal to thebuccal frenula. However, some related structuresmust be examined for their influence on the space.Lateral jaw movement will advance the coronoidprocess of the mandible toward the maxillarytuberosity. In so doing, it may obliterate the sulcus,


indicating that a very thin denture flange will beneeded. This diminished space will have to berecorded during impression making. The massetermuscle, when contracting, can act through the buc-cinator muscle and impinge on the buccal sulcus.This effect usually is much more pronounced in themandibular buccal sulcus. The external obliqueline of the mandible defines the lateral boundary ofthe buccal shelf and frequently defines the buccalboundary of the mandibular buccal sulcus.However, sometimes the tissues of the cheek areeasily displaced and will allow a wider mandibularbuccal flange.

The alveolingual sulcus lies between the tongueand the residual alveolar ridge and body of themandible. The mylohyoid muscle underlying itsfloor modifies its depth and shape during function.The sulcus should therefore be observed duringmovements of the tongue. Having the patient lickthe lower lip from side to side with the tip of thetongue can raise the floor of this sulcus to a rea-sonable level. The retromylohyoid fossa is thepouch forming the posterior terminus of the alve-olingual sulcus on each side. The few mylohyoidmuscle fibers found here are usually weak and dis-placeable. However, the posterior wall of the fossais the retromylohyoid curtain, which contains thesuperior constrictor of the pharynx. Contraction ofthis muscle will alter the shape of the fossa; so toowill protrusion of the tongue. An estimate of usablespace must be made. Having the patient place thetongue tip in the opposite buccal sulcus usually willdemonstrate the usable space. It may be necessaryto use a mouth mirror to control the tongue to per-mit observation.

The anatomy of the soft palate usually willdetermine the location of the distal border of themaxillary complete denture and its posterior palatalseal. A soft palate that turns down abruptly limitsthe distal extension of the denture. A palate thatslopes down gradually allows more discretion inlocating the denture border. The vibrating line isused as a guide to this location. It is the area oftransition from immovable palatal tissue to themovable soft palate. Observation of the palate withthe mouth open and the patient attempting to saythe letter “k” usually will reveal the vibrating lineand the extent of palatal movement. The depth towhich the tissue anterior to the vibrating line can be

displaced will determine the depth of the posteriorpalatal seal. The hamular notches, which appearbetween the maxillary tuberosities and the hamularprocesses of the medial pterygoid plates, should bedemonstrated. Even though these bone boundariesare covered by soft tissue, they usually can be pal-pated. Between them, the soft tissue is quite dis-placeable, thus affording a location for theposterior palatal seal of the maxillary denture.However, the pterygomandibular raphe originatesin this area; it must not be encroached upon by thedenture. The various sulci are traversed by frenula.Some contain muscles. Others are moved by neigh-boring muscles. If they are displaced by the denturebase, the denture will be dislodged when the mus-cles contract. If the notches made in the denturebase to accommodate the frenula are too large, aseal will not be achieved, and air will leak in andbreak the potential vacuum that helps retain thedenture. The potential for these problems must beestimated at the diagnosis. If it is determined thattheir location, size, or activity will adversely affectdenture retention, surgical repositioning or removalshould be considered. Each labial and buccal frenu-lum must be examined to make specific determina-tions. The lingual frenulum also must be examined,but surgical correction often has to involve thefloor of the mouth, making it uncomfortable for thepatient and hence less desirable. An important con-sideration is interaction between the lingual frenu-lum and the mandibular labial frenulum. If there isinsufficient attached mucosa on the ridge betweenthe frenula to prevent movement of one causingmovement in the other, the area of attachment mustbe improved surgically. Otherwise, the mandibulardenture will be unstable because its mucosal sup-port is unstable.

Saliva Saliva often does not receive the attentionit deserves. Both the flow rate and the viscosity areimportant to denture success. Normal resting sali-vary flow is about 1 ml/min. A flow of medium vis-cosity at this rate lubricates the mucosa and assistsretention of complete dentures. Many factors canaffect the flow rate, but aging is no longer consid-ered to be a primary factor in diminished flow.Many patients of denture-wearing age, however,take medications that can reduce salivary flow.Patients who have received radiation therapy in the


region of the salivary glands usually have glandulartissue destruction with resulting reduction in sali-vary flow. In the absence of a history of radiationor antisialagogue drugs to explain diminishedflows, further investigation is warranted. Theglands themselves may be diseased or ducts can beblocked, although the latter would usually produceacute distress. Often the palatal glands aredestroyed in patients who have worn a completemaxillary denture for many years. The cause isreally pressure atrophy resulting from lost residualalveolar ridge support of the denture.

Muscular Development

The oral cavity is surrounded by muscles. Jaw andsoft tissue movements are the products of muscleactivity. If the muscles are strong and their activitywell coordinated, they will help the patient use a cor-rectly designed denture. Conversely, poor denturedesign, weak muscles, and poor muscle coordinationall detract from denture stability and retention.

Muscle Tonus The tone of the facial tissues iscritical to several steps of denture construction.Tissue tone that is either too strong or too weak isunfavorable. As a result, completing clinical proce-dures may require more than the usual amount oftime. If the muscles are too tense, cheek and lipmanipulations will be difficult; if too slack, the lipsand cheeks may be displaced easily by impressionmaterials. Patients may take more time than usualto learn to use the dentures. Optimal functioning ofthe postural and facial expression muscles requirescorrect support from the natural teeth and ridges orfrom correctly designed and built prostheses.

Neuromuscular Coordination Good muscularcontrol and coordination are essential to the effec-tive use of complete dentures. They also are helpfulin denture construction. For example, when tonguemovements are used for border molding the lingualflanges of a mandibular impression, the timing,direction, and amount of movement are critical tothe success of the molding. Similarly, coordinationof jaw movements is important during denture con-struction and use.

A patient lacking ability to move the mandibleto the right place at the right time reveals the poten-

tial for problems in making jaw relation recordsbefore they are attempted. To make an observationof muscular control, the dentist can ask the patientto open the mouth about halfway and move thelower jaw from left to right, then to put the tongueinto the right cheek and into the left cheek, to stickit out, and to put it up and back inside the mouth.The ability, or lack of ability, to do these move-ments on demand will be apparent. The treatmentschedule can be modified accordingly. If the den-tist feels the problems are significant, the patientcan be asked to practice jaw movements at home.Emphasis can be placed on deliberate border move-ments ending in centric relation. Practicing in frontof a mirror will allow the patient to visually coor-dinate the movements.

Patients with one or more of the followingsymptoms usually are considered to have a tem-poromandibular disorder (TMD). The symptomsinclude (1) pain and tenderness in the muscles ofmastication and the TMJs, (2) sounds duringcondylar movements, and (3) limitations ofmandibular movement. Quite logically, the TMJsshould be healthy before new dentures are made.

Unhealthy TMJs complicate the registration ofjaw relation records. If it is to be a functional posi-tion, centric relation depends on the structural andfunctional harmony of osseous structures, theintraarticular tissue, and the capsular ligaments. Ifthese specifications cannot be fulfilled, the patientwill not be able to position the mandible in a cor-rect centric relation or, for that matter, provide thedentist with a repeatable one; thus the importanceof the routine evaluation of a patient’s temporo-mandibular function as an integral part of com-plete denture treatment. The diagnosis andmanagement of TMDs were addressed in detail inChapter 5.

Tongue Apart from the example of tonguemovement coordination during impression makingpreviously mentioned, tongue position and coordi-nation are significant in complete denture func-tioning. A retruded tongue position deprives thepatient of a border seal of the lingual flange in thesublingual crescent and also may produce dislodg-ing forces on the distal regions of the lingualflanges. Normally, the tongue should be expectedto rest in a relaxed position on the lingual flanges,


which, if properly contoured, will allow the tongueto help retain the denture. A tongue thrust tends todislodge a lower complete denture by raising thefloor of the mouth and, in so doing, lifting the lin-gual flanges and by exerting pressure on the ante-rior teeth. Attempts at retraining may not be verysuccessful but will at least make patients aware ofthe problem and help them to understand theadverse effects.

Dentists should have a basic knowledge ofspeech, particularly its articulatory component.Articulation is the modification of speech soundsby structures of the throat, mouth, and nose.Fortunately, the neuromuscular activity that pro-duces speech can adapt to, or accommodate, somestructural change. The relationship of the positionsteeth, lips, and tongue have to each other in thearticulation of speech is discussed later (seeChapter 19). An assessment must be made duringdiagnosis to identify existing problems and deter-mine the potential for improvement.

A patient’s protective gag reflex can compromisedental treatment. A thorough history and oral exami-nation will reveal the presence of an overly activereflex early in the patient/dentist relationship. Thedentist can then assess the possible cause of the prob-lem as being attributable to iatrogenic factors, organicdisturbances, anatomical anomalies, biomechanicalinadequacies of existing prostheses, or psychologicalfactors. Effective management of gagging tends to bebased on experience and anecdote, with combina-tions of distraction techniques, prosthodontic man-agement, and medication. Usually, counseling,reassurance, and kind handling of the patient prove tobe useful therapeutic adjuncts. However, patientswhose gagging cannot be controlled by counseling ordistractions may need the services of a psychologist.

Cheeks and Lips The external form of the cheeksand lips is dependent on their internal structure andtheir underlying support. This support may be nat-ural teeth and ridges or denture teeth and bases.The muscles in the cheeks and lips have a criticalfunction in successful use of dentures. The dentureflanges must be properly shaped to aid in main-taining the dentures in place without consciouseffort by the patient. This involves the develop-ment of the correct arch form and tooth positions,as well as the shape of the polished surfaces and the

thickness of the denture borders. The amount ofdenture space must be considered carefully if afixed implant-supported prosthesis is plannedbecause it does not usually provide a tissue-supporting base.

Patients with very thick cheeks may presenttechnical problems during some clinical steps.Thick cheeks often do not allow easy manipulationfor border molding of impression materials.Various characteristics of the lips not only are sig-nificant for denture retention but also are promi-nent in considerations of esthetics and phonetics.Fortunately, phonetics involving the lips does nottend to pose many independent problems whenesthetic requirements are satisfied. If the tissuearound the mouth has wrinkles and the rest of theface does not, lack of lip support can be suspectedand significant improvement can be expected.A rolled-in vermilion border is evidence of inade-quate lip support and historically has characterizeddenture wearing. If the problem appears to be ante-rior teeth set too far lingually or palatally, the lackof support can be tested by adding wax to the labialsurfaces. If the addition of wax improves theappearance of the lip, plans can be made to bringthe new teeth further forward and thus provide thenecessary support to help eliminate the wrinkles. Ifthe wrinkles, especially the vertical lines in thelower half of the lip, are long-standing, they willnot disappear at once, and patients should bewarned about this. Questions about the prominenceof the natural upper anterior teeth may reveal thatthe residual alveolar ridge was reduced when theteeth were removed “to get rid of the buck teeth Inever liked.” Attempts to reduce the horizontaloverlap of anterior teeth by setting the teeth back“under the ridge” and through surgery usually leadto a lack of lip support that produces vertical linesas tissue tone deteriorates later in life. Patientsshould be told that for a short time their mouthsmight appear to them to be too full because of thesudden change. The danger insofar as the dentist isconcerned is that too much support for the lipsmight be provided in an attempt to eliminate thevertical lines in the upper lip. The apparent fullnessof the lip is directly related to the support it getsfrom the bone or denture base and the teeth behindit. Lip fullness should not be confused with lipthickness, which involves the intrinsic structure of


the lip. A denture with an excessively thick labialflange may make the lip appear to be too full ratherthan displaced. Excessively thick denture basesalso can make the lip appear thick or short. Anobliterated philtrum or mentolabial fold suggestsexcessive support. The problem with lip fullness isin the patient’s reaction to changes. If the existingdentures have the teeth set too far palatally, thepatient may feel that the new and corrected tootharrangement makes the lip too full. Extra time willbe needed at the try-in of the wax dentures.

Patients with thin lips present special problems.Any slight change in the labiolingual tooth positionmakes an immediate change in the lip contour. Thiscan be so critical that even overlapping of teethmay distort the surface of the lip. Both the archform and the individual tooth positions areinvolved. Thick lips give the dentist a little moreopportunity for variations in the arch form andindividual tooth arrangement before the changesare obvious in the lip contour.

The evaluation of anterior tooth position iscomplicated by short or incompetent lips. Thepatient may ask for a less-than-natural show ofteeth. Long lips tend to hide the teeth, thus pre-senting the dentist with a temptation to set the teethtoo long to make them visible. Awareness of theseproblems can help the dentist overcome them.A patient with a short upper lip may expose all theupper anterior teeth when properly set and much ofthe labial flange of the denture base as well.

INTERPRETING DIAGNOSTIC FINDINGSAfter all the intraoral and general physical and den-tal conditions have been recorded and radiographs,casts, and other visual aids are at hand, they can beinterpreted, and the treatment plan can be devel-oped. This includes which teeth are to be saved andhow, which teeth are to be extracted, the tooth-removal sequence, the type and extent of oral sur-gery that might be required, and the type ofprosthesis that is indicated. Should it be an over-denture, an immediate overdenture, a conventionalimmediate complete denture, or an interim imme-diate denture, or even a transitional denture? Is itthe unusual situation where all the teeth should beremoved and a waiting period allowed so that thetissues can heal somewhat before new dentures are

made? Is the ultimate goal an implant supportedprosthesis?

Obvious, Congruent, or Incongruent?

Some diagnostic findings have obvious signifi-cance and suggest treatment that is just as obvious.The incidence of this will increase as a dentistbecomes more experienced in treating edentulousand partially edentulous patients. These apparentlyeasy decisions become the basis for developing atreatment plan. However, such a treatment planshould be looked on as a hypothesis in need of test-ing. The testing may lead to modifications. Thefirst test of the obvious is to determine if such find-ings are consistent with other findings that havebeen made. Is there congruency between the dis-ease that appears to be present and the probable eti-ology? Incongruity of information gathered about apatient signals the need for further investigation.

Summary

A diagnosis must be based on adequate informa-tion and must account for the findings from the his-tory and examination. Where findings cannot beaccounted for, further investigation may be incor-porated into the treatment plan, provided suchaction would not be injurious to the patient. A sum-mary of the points addressed in developing a thor-ough diagnosis can serve as a primer ondetermining patient problems (Box 7-1).

TREATMENT PLANNINGTreatment planning is the process of matching possi-ble treatment options with patient needs and system-atically arranging the treatment in order of prioritybut in keeping with a logical or technically necessarysequence. The process requires a broad knowledge oftreatment possibilities and detailed knowledge ofpatient needs determined by a careful diagnosis.A dentist approaching treatment planning with adeficiency in either of these categories of knowledgeplaces the patient in jeopardy of receiving inadequateor inappropriate treatment. The dentist also mustresist the natural tendency to include in a treatmentplan only that treatment that the dentist feels compe-tent to deliver. Patients requiring treatment beyond


the competency of the treatment planner should bereferred to more competent colleagues or specialists.When presented with adequate explanations, patientsappreciate referrals as expressions of the dentist act-ing in the patients’ best interests. Failure to makesuch referrals is unethical and can lead to litigation.The consequences of both treatment and no treatmentmust be considered. Treatment planning must have aparallel process of developing a prognosis. Treatmentplanning is driven by the diagnosis but must takeother factors such as a prognosis, patient health, andattitudes into account.

WHY TREATMENT PLANA treatment plan is required to specifically state thetreatment that will address a particular patient’s

needs (Figure 7-2). That treatment will be stated ina logical sequence and will include adjunctive care.Its detail and clarity will permit estimates of oper-atory time and laboratory time, as well as associ-ated fees. Failure to have such a plan makesinformed consent by the patient impossible.Proceeding without informed consent exposes thedentist to problems ranging from loss of patientconfidence to difficulty with fee collection or evento litigation. Inadequate plans also make it difficultor impossible for staff to do their part in maintain-ing a smooth delivery of patient care.

Treatment Planning Is Problem Solving

Problem-solving techniques usually involve care-ful analysis of a problem, breaking it into compo-nents where possible, then generating and weighing alist of possible component solutions to ultimatelyconstruct a comprehensive solution. The problemsare not solved until the solutions are implemented.Untried solutions might reasonably be thought ofas hypotheses in need of testing. Dental treatmentplanning might be thought of in the same manner.The first step is a careful analysis of the diagnos-tic findings, paying particular attention to specificcomponents (see Box 7-1). With knowledge ofthese needs, the second step involves developing alist of possible means of addressing them (Box7-2). Although this may be a mental exercise, thereare times when a written list assists thinking. Theintegration of these component solutions into acomprehensive treatment plan requires an estima-tion of the impact of the components on eachother.

The Matching Process

The information that should be gathered on indi-vidual patients and the techniques for gathering itare discussed earlier in this chapter. The details ofthe specific observations determine the detailsof the treatment required (Figure 7-3). A decision tosupply a set of complete dentures to an edentulouspatient does not require very sophisticated think-ing. Left at that level, the results might be equallyunsophisticated. Truly professional care requiresthe dentist to consider all information gatheredand appropriately address it in the treatment plan.


A Primer on Determining Patient Problems

History: The Patient’s StorySocialMedicalMentalDentalCompromising factorsSpecific ObservationsExisting dentures

MaterialsFitOcclusionEsthetics

Soft and hard tissue healthLining and specialized mucosaMucoperiosteumTeethBone

Biomechanical considerationsDenture supportInterarch relationsBorder seal areas

Muscular developmentMuscle tonusNeuromuscular coordinationCheeks and lips

Box 7-1


enables dentist to

enables patient to

dentist delivers

patientreceive

Estimate• Operating Time• Laboratory Time• Calendar Time• Fees

Delivered Care• patient specific

Informed Consent• Treatment• Time• Fees

Treatment PlanAddresses patient's needsLists Specific TreatmentSpecifies logical sequence

Figure 7-2 Why treatment plan.

A Primer on Treatment Options

Box 7-2

Adjunctive CareElimination of infectionElimination of pathosesSurgical improvement of denture supportand spaceTissue conditioningNutritional counseling

Prosthodontic CareThe patient destined to become endentulous

Removable partial dentureConventionalInterim

Hybrid complete denture/removablepartial dentureTransitional

Complete dentureImmediate or conventionalDefinitive or interimTooth, implant, or soft tissue supported

The edentulous patientComplete denture

Soft tissue supportedImplant supportedFixedRemovable

There are many occasions when the patient willbenefit from preparatory care such as the treat-ment of candidiasis, the repositioning of frenula,and the reduction of fibrous maxillary tuberosi-ties. The presence of active periodontal diseasemay make prediction of the form of the postex-traction ridge impossible and thereby suggest theuse of an interim immediate denture for thepatient who is about to have remaining teethextracted. A history of denture dissatisfaction, thefinancial means to afford quality care, and find-ings of a deficient, denture-supporting foundationbut adequate bone suggest the patient would ben-

efit from implant-supported prostheses. Design,fabrication, and delivery of prostheses as thefocus of prosthodontic care are discussed later inthis book. The dentist must customize the care foreach patient.

The information accumulated from the diag-nosis must be systematically analyzed to identifyeach patient’s problems and to determine theirrelated needs. A problem list for a patient mightinclude (1) large areas of edentulous residualalveolar ridges and (2) three remaining teeth thatcan be restored only with the aid of endodonticand periodontal treatment. When a patient is


Determine Patient

Select Treatment

RequiresSpecific Knowledgeof patient from complete diagnosis

RequiresBroad Knowledgeof treatment options, delivery and management

match

History - The Patient's Story• Social• Medical• Mental• Dental• Compromising Factors

Specific Observations Existing Dentures • materials • fit • occlusion • aestheticsSoft and Hard Tissue Health • lining and specialized mucosa • mucoperiosteum • teeth • boneBiomechanical considerations • denture support • inter-arch relations • border seal areasMuscular development • muscle tonus • neuro-muscular coordination • cheeks and lips

See Primer on

DeterminingPatient

Adjunctive Care• Elimination of infection• Elimination of pathoses• Surgical improvement of denture support and space• Tissue Conditioning• Nutritional counselling

Prosthodontic Care• Types of prostheses - the patient destined to become endentuous - Removable Partial Denture conventional interim hyrid Complete Denture/Removable Partial Denture transitional - Complete Denture : immediate or conventional : defintiive or interim : tooth, implant or soft tissue suppported - the edentuous patient > Complete Denture : soft tissue supported : implant supported - fixed - removable

See Primer on Treatment

Options

Figure 7-3 The treatment planning process.


Patient Education:an initial and continuing activity integral to, and supportive of, a treatment plan

Purposes• inform the patient of their dental health and its significance.• give the patient understanding of significance of edentulism.• match the patient's expectation with reality of treatment potential.• explain nature, use, and shortcomings of prostheses.• identify alternative treatments and their consequences.

Will help patient understand• diagnostic procedures• diagnostic results• treatment plan• treatment to be provided• use of prostheses• continuing care• fees

Should facilitate• acceptance of treatment• acceptance of fees• continuing care

Figure 7-4 Patient education.

unhappy with his or her appearance and expressesa desire for replacement of missing teeth, the den-tist might be tempted to decide the patient needsextensive endodontic, periodontic, and prostho-dontic treatment to address all problems.However, if the patient has limited financialresources, he or she is more likely to translate theproblems into a need for extractions and completedentures. Agreement must be reached on the

needs and the treatment options to be applied.This may require modifications in a treatmentplan as first conceived by a dentist. One mightthink of this process as transforming a dentist-oriented treatment plan to patient-oriented treat-ment plan in light of a variety of influencing factorssuch as accessibility and finances. However, themodifications should not be such that they wouldjeopardize the health of the patient.

Patient Preparation

All patients seeking dental services do so withsome degree of understanding and experience. Theextent of the experience and the validity of theunderstanding will vary greatly. This diversity mustbe recognized by the dentist and addressed in thetreatment plan and its presentation. Respecting thepatient’s uniqueness, the dentist must use the treat-ment plan as an educational tool to raise thepatient’s level of understanding of dentistry andtheir understanding of how the proposed treatmentwill meet their individual needs identified throughdiagnosis. Patient education is an essential elementin patient care that should start with the initial con-tact with the patient (Figure 7-4).

SUMMARYThe treatment plan developed for a patient shouldreflect the dentist’s best efforts at interpreting thediagnostic findings and addressing the patient’sneeds in keeping with their appreciation for den-tistry and their ability to accept the proposed treat-ment. The presentation of a treatment plan to apatient is an offer to contract with a patient for theprovision of treatment. It is therefore helpful to thepatient, and prudent for the dentist, to supply awritten summary of the treatment plan and patientobligations associated with its acceptance.Licensing boards and insurance companies reportthat the underlying reason for complaints bypatients can frequently be traced to dentists’ inade-quate communication with patients, especially con-cerning an explanation of treatment and fees. Thetreatment plan therefore not only provides directionfor the dentist but also contributes a measure ofprotection by aiding the patient in understand-

ing the care that will be provided and the obliga-tions that go with it. It is well to remember thatgood treatment plans are conducive to good careand to mutual understanding between dentists andpatients.

BibliographyBarsh LI: Dental treatment planning for the adult patient,

Philadelphia, 1981, WB Saunders.Bohay NB, Stephens RG, Kogan, SL : A study of the impact of

screening or selective radiography on the treatment andpostdelivery outcome for edentulous patients, Oral SurgOral Med Oral Pathol Oral Radiol Endod 86:353-359, 1998.

Coleman GC, Nelson JF: Principles of oral diagnosis, St Louis,1993, Mosby–Year Book.

Ganong WF: Review of medical physiology, ed 16, Norwalk,Conn, 1993, Appleton and Lange.

Goaz PW, White SC: Oral radiology: principles and interpreta-tion, ed 3, St Louis, 1994, Mosby–Year Book.

Hall WB, Robert WE, LaBarre EE: Decision making in dentaltreatment planning, St Louis, 1994, Mosby–Year Book.

Ivanhoe JR, Cibirka RM< Parr GR: Treating the modern denturepatient: A review of the literature, J Prosthet Dent 88: 631-635, 2002.

Little JW: Dental management of the medically compromisedpatient, ed 5, St Louis, 1997, Mosby–Year Book.

McCord JF, Grant AA: Identification of complete denture prob-lems: a summary, Br Dent J 189:128-134, 2000.

Miles DA, Razamus TF, Van Dis ML: Basic principles of oraland maxillofacial radiology, Philadelphia, 1992, WBSaunders.

Morris RB: Principles of dental treatment planning,Philadelphia, 1983, Lea & Febiger.

Owall B, Kayser AF, Carlsson GE: Prosthodontics:principle and management strategies, London, 1996,Mosby–Wolfe.

Papas AS, Niessen IC, Chauncey HH: Geriatric dentistry: agingand oral health, St Louis, 1991, Mosby–Year Book.

United States Pharmacopeial Convention: Drug information forthe health care professional, ed 6, Rockville, Md, 1996, TheUnited States Pharmacopeial Convention, Inc.

Wood NK, Goaz PW: Differential diagnosis of oral and max-illofacial lesions, ed 5, St Louis, 1997, Mosby–Year Book.


C H A P T E R 8Preprosthetic Surgery: Improving thePatients’ Denture-Bearing Areas andRidge RelationsGeorge A. Zarb, S. Ross Bryant

100

The vast majority of patients for whom completedenture therapy is prescribed have already beenwearing dentures. As suggested earlier, there is a riskin patients wearing dentures for prolonged periods.This risk, or biological price, manifests itself ina number of adverse changes in the dentures’ founda-tions. Consequently, several conditions in the edentu-lous mouth should be corrected or treated before theconstruction of complete dentures. Often, patients areunaware that tissues in the mouth have been damagedor deformed by the presence of old prostheses. Otheroral conditions may have developed that must bemanaged to increase the chances for success of thenew dentures. The patient must be made cognizant ofthese problems, and a logical explanation by thedentist, supplemented with radiographs and, whererequired, diagnostic casts, usually will convince thepatient of the necessity for the suggested treatment.

Treatment methods to improve the patient’sdenture foundation and ridge relations are usuallyeither nonsurgical or surgical in nature, but can bea combination of both methods.

NONSURGICAL METHODSNonsurgical methods of edentulous mouth prepara-tion include the following methods.

Rest for the Denture-Supporting Tissues

Rest for the denture-supporting tissues can beachieved by removal of the dentures from themouth for an extended period or the use of tempo-rary soft liners inside the old dentures. Both proce-

dures allow deformed tissue of the residual ridgesto return to normal form (Figures 8-1 and 8-2).Clinical reports and experience also support themerits of regular finger or toothbrush massage ofdenture-bearing mucosa, especially of those areasthat appear edematous and enlarged.

It has been demonstrated that tissue abuse causedby improper occlusion can be made to disappear by(1) withholding the faulty dentures from the patient,(2) adjusting/correcting the occlusion and refittingthe denture by means of a tissue conditioner, or (3)substituting properly made dentures. When the latteris undertaken, it is necessary to allow the soft tissuesto recover by removing the dentures for 48 to 72hours before impressions are made for the construc-tion of new dentures. However, it generally is not fea-sible to withhold a patient’s dentures for an extendedperiod while the tissues are recovering. Thereforetemporary soft liners have been developed as tissuetreatment or conditioning materials. The softness ofthese materials is maintained for several days whilethe tissues recover. Tissue conditioners consist ofa polymer powder and an aromatic ester-ethanolmixture (see Chapter 12). They have been widelyused in dentistry for years and provide the dentistwith an expanded scope for short-term resolution ofpatient problems.

The major uses of these tissue-conditioningmaterials are tissue treatment, liners for surgicalsplints, trial denture-base stabilizers, and optimalarch form or neutral zone determinants. Clinicalexperience indicates that soft liners also can be usedas functional impression materials when relining orrefitting complete dentures (see Chapter 24).

It is well recognized that denture-bearing tissuesdemonstrate microscopic evidence of inflammation,even if they appear clinically normal. Consequently,tissue rest for at least 24 hours and preferably theuse of tissue conditioners are essential preliminariesto each prosthetic appointment. Tissues recoverrapidly when the dentures are not worn or whentreatment liners are used. The method of achieving

optimal health of the denture-bearing tissues is notas important as the result (the tissues being madehealthy). Many dentures fail because the impres-sions or registrations of the relations are made whenthe tissues are distorted by the old dentures. Thesame error is frequently committed when denturesare relined without adequate denture-bearing tissuerest or tissue treatment.

Chapter 8 Preprosthetic Surgery: Improving the Patients’ Denture-Bearing Areas and Ridge Relations 101

100

80

Per

cent

of o

rigin

al ti

ssue

thic

knes

s

60

40

20

00 2 4 6 8 10 12 14 16 18

Minutes

240(4 hr)

Constant pressure applied Pressure removed

Instantaneouselastic recovery

Initial thickness

Delayed elasticrecovery

Delayed elasticcompression

Instantaneouselastic compression

Figure 8-1 Typical behavior of tissue under a constant pressure load for 10 minutes.Notice the 90% recovery within 8 minutes after removal of the pressure. Total recoveryrequires 4 hours. (From Kydd WL, Daly CH, and Wheeler JB: Int Dent J 21:430-441, 1971.)

100

80

Tis

sue

thic

knes

s in

perc

ent o

f orig

inal

thic

knes

s

60

40

20

00 2 4 6 8 10 12 14 16 18

Minutes

20

Constant pressure applied Pressure removed

70 yr /

24 yr ?

Figure 8-2 Comparison of responses to tissue loading and removal of the load in anelderly adult and a young adult. The compression curve is essentially the same. However, theremoval of load shows definite differences in rate of recovery. The load was 11 g/mm2. (FromKydd WL, Daly CH, and Wheeler JB: Int Dent J 21:430-441, 1971.)

Occlusal Correction of the Old Prostheses

An attempt should first be made to restore anoptimal vertical dimension of occlusion to the den-tures presently worn by the patient with an interimresilient lining material. This step enables thedentist to prognosticate the amount of verticalfacial support that the patient can tolerate, and itallows the presumably deformed tissues to recover.The decision to create room inside the denturedepends on its fit and the condition of the tissues.The tissue treatment material also permits somemovement of the denture base, so its positionbecomes compatible with the existing occlusion,apart from allowing the displaced tissues to recovertheir original form. Consequently, ridge relationsare improved, and this improvement facilitates thedentist’s eventual relation registration procedures.*

It also may be necessary to correct the extent oftissue coverage by the old denture base so allusable supporting tissue is included in the treat-ment. This correction can easily be achieved by useof one of the resin border-molding materialscombined with a tissue conditioner.

Good Nutrition

A good nutritional program must be emphasizedfor each edentulous patient. This program is espe-cially important for the geriatric patient whosemetabolic and masticatory efficiency may becompromised (see Chapter 6).

Conditioning of the Patient’s Musculature

The use of jaw exercises can permit relaxation ofthe muscles of mastication and strengthen theircoordination and help prepare the patient psycho-logically for the prosthetic service. If at the initialappointment the dentist observes that the patientresponds with difficulty to instructions for relax-ation and coordinated mandibular movement,a program of mandibular exercises may be pre-scribed. Clinical experience indicates that sucha program may be beneficial and the subsequentregistration of jaw relations facilitated.

SURGICAL METHODSFrequently, certain conditions of the denture-bearingtissues require edentulous patients to be treated sur-gically. These conditions are the result of unfavorablemorphological variations of the denture-bearing areaor, more commonly, result from long-term wear ofill-fitting dentures. The objectives of prescribinga preprosthetic surgical procedure are listed in Box8-1. It must be emphasized that these interventionsare infrequently mandatory undertakings. It is oftenfar easier to make alterations in the prosthetic tech-niques and materials used than to subject thepatient to a surgical intervention. The key consid-eration is whether a good prosthodontic prognosiswill result from the surgical outcome. In fact, it isonly the provision of dental implants that has beenshown to have the best prognosis for morphologi-cal problems associated with maladaptivedenture-wearing behavior.

Correction of Conditions That PrecludeOptimal Prosthetic Function

Hyperplastic Ridge, Epulis Fissuratum, andPapillomatosis The premise underscoring surgi-cal intervention is that mobile tissues (e.g., a


*This will in turn facilitate an occlusal adjustment that can be accom-plished intraorally or extraorally (with an articulator).

Objectives of PreprosthodonticSurgical Prescriptions

1. Correcting conditions that preclude optimalprosthetic functionLocalized or generalized hyperplastic replace-ment of resorbed ridgesEpulis fissuratumPapillomatosisUnfavorably located frenular attachmentsPendulous maxillary tuberositiesBony prominences, undercuts, and ridgesDiscrepancies in jaw size relationshipsPressure on mental foramen

2. Enlargement of denture-bearing area(s)VestibuloplastyRidge augmentation

3. Provision for placing tooth root analogues bymeans of osseointegrated dental implants

Box 8-1

hyperplastic ridge), tissues that interfere withoptimal seating of the denture-localized enlarge-ment of peripheral tissues (an epulis), or tissuesthat readily harbor microorganisms (a papillomato-sis) are not conducive to firm, healthy foundationsfor complete dentures. Whenever possible, thesetissues should be rested, massaged, or treated withan antifungal agent before their surgical excision.If the patient’s health or a personal choice pre-cludes surgical intervention, the impression tech-

nique and design of the denture base have to bemodified to accommodate the mobile tissue andminimize its distortion.

Frenular Attachments and Pendulous MaxillaryTuberosities Frena are fibrous bands of tissueattached to the bone of the mandible and maxillaeand are frequently superficial to muscle attach-ments. If the frenum is close to the crest of the bonyridge (Figure 8-3), it may be difficult to obtain the


A

BFigure 8-3 Preoperative (A) and postoperative (B) views of the maxillary buccal frenum(arrowhead) in an edentulous patient with an unrepaired palatal cleft. Excision allowed foroptimal extension of the denture flange into this area.

ideal extension and border of the flange of thedenture. The upper labial frenum in particular maybe composed of a strong band of fibrous connec-tive tissue that attaches on the lingual side of thecrest of the residual ridge. This tissue shouldusually be removed surgically. Frena often becomeprominent as a result of reduction of the residualridges. If muscle fibers are attached close to thecrest of the ridge when frena are removed, themuscles usually are detached and elevated ordepressed to expose the amount of desired ridgeheight. The frenectomy can be carried out beforeprosthetic treatment is begun, or it can be done atthe time of denture insertion when the new denturecan act as a surgical template. The former is pre-ferred because the patient will not have to contendwith postoperative discomfort along with adjust-ment to the dentures.

Pendulous fibrous maxillary tuberosities(Figure 8-4) are frequently encountered. They occurunilaterally or bilaterally and may interfere withdenture construction by excessive encroachment on

or obliteration of the interarch space. Surgical exci-sion is the treatment of choice (Figure 8-5), butoccasionally maxillary bone must be removed. Caremust be used to avoid opening into the maxillarysinus. In those instances in which the sinus dipsdown into a pneumatized and elongated tuberosity,it may be possible to collapse the sinus floor upwardwithout danger of opening into it. This techniquealso is used when a bony undercut exists on thebuccal side of the tuberosity and the sinus has pneu-matized into the undercut (Figure 8-6).

Bony prominences, undercuts, spiny ridges,and mandibular tori may have to be removed toavoid painful denture flange impingement and toachieve a border seal beyond them against the floorof the mouth (Figure 8-7). They frequently occur soclose to the floor of the mouth that a border sealcannot be made. On the other hand, maxillary toriare rarely removed. Satisfactory dentures can bemade over most of them by careful relief of thepalatal denture base material. The following areindications for the removal of maxillary tori:


A

CFigure 8-4 A, A pendulous, fibrous, mobile right maxillary tuberosity that is easilydisplaced. B, Two elliptic incisions undermine the mass (C) and allow for approximation ofthe mucosal surfaces (D) over a firm, bony base.

B

D


A

B

C

D

E

F GFigure 8-5 Procedure for reducing the vertical height of a maxillary tuberosity.A, Incisions are made in the fibrous tuberosity. B, A wedge of fibrous tissue is removed. Thetuberosity is less bulky but is still as vertically long as before. C, Incisions made just underthe mucosa permit removal of all unwanted fibrous connective tissue. D and E, Thin mucosalflaps are fitted, trimmed, and sutured. This technique decreases vertical length of thetuberosity. F and G are clinical views of C and E.


A B

C D

E F

G HFigure 8-6 Legend on opposite page.

1. An extremely large torus that fills the palatalvault and prevents the formation of an ade-quately extended and stable maxillary denture(Figure 8-8)

2. An undercut torus that traps food debris,causing a chronic inflammatory condition; sur-gical excision is necessary to create optimal oralhygiene

3. A torus that extends past the junction of the hardand soft palates and prevents the development ofan adequate posterior palatal seal (Figure 8-9)

4. A torus that causes the patient concern

Exostoses may occur on both jaws but are more fre-quent on the buccal sides of the posterior maxillarysegments (Figures 8-10 and 8-11). They may creatediscomfort if covered by a denture and usually areexcised. It must be emphasized that routine excisionof all mandibular exostoses is rarely recommended(see Figure 8-10, B). Frequently, the denture can beeasily relieved to accommodate the exostoses, ora permanent soft liner can be used.

Sometimes the genial tubercles are extremelyprominent as a result of advanced ridge reductionin the anterior part of the body of the mandible(Figure 8-12). If the activity of the genioglossusmuscle has a tendency to displace the lower dentureor if the tubercle cannot tolerate the pressure orcontact of the denture flange in this area, the genialtubercle is removed and the genioglossus muscledetached. If it is clinically necessary to deepen thealveololingual sulcus in this area, the genioglossusmuscle is sutured to the geniohyoid muscle belowit (see Figure 8-12).

Residual alveolar ridge undercuts (Figure 8-13)are rarely excised as a routine part of improvinga patient’s denture foundations. Usually, a path ofinsertion and withdrawal of the prosthesis can bedetermined together with careful adjustment ofa denture flange, which enables the dentist to use theundercuts for extra stability. Diagnostic casts can besurveyed as a guide in the assessment of the minimalamount of tissue to be removed. Considerable evi-dence exists that residual ridge surgery causes exces-sive bone reduction. However, the dentist maycomfortably choose to remove a severe undercut thatoccurs opposite the lingual side of mandibular secondand third molars and is tender to palpitation (Figure8-14). Such an undercut is caused by a sharp mylo-hyoid ridge that (usually) is covered by very thinmucosa. When painless undercuts occur in this area,they can help achieve added stability for the denture(Figure 8-15). The path of insertion in such a situationis altered to allow for distal placement of the lingualflanges with a downward and forward final seatingmovement. Alternatively, one undercut area can berelieved in the denture to permit engagement of theremaining undercut area for retentive purposes.

Discrepancies in Jaw Size Impressive advancesin surgical techniques of mandibular and maxillaryosteotomy have enabled the oral and maxillofacialsurgeon to create optimal jaw relations for patientswho have discrepancies in jaw size. The patientwith prognathism frequently places considerablestress and unfavorable leverages on the maxillarybasal seat under a complete denture. This maycause excessive reduction of the maxillary residualridge. Such a condition is even more conspicuouswhen some mandibular teeth are still present.A mandibular osteotomy in these cases can createa more favorable arch alignment and improve theappearance as well (Figure 8-16). However,changes in the soft tissues of the face tend to beaccentuated by such a procedure (as shown by thepatient in Figure 8-16). Usually, an adjunctiveface-lifting procedure in this type of patient pro-duces impressive results. Alternatively, thesepatients may be considered for implant-supportedor retained dentures to address their prosthodonticproblems. Such a procedure would less invasive,but its outcome is determined by host bone site andesthetic considerations.


Figure 8-6 Reduction of a huge pneumatizedtuberosity (T). A, Preoperative diagnostic cast. B, Castmade 2 years after surgery. C, Clinical view of theenlarged and exposed bony tuberosity. D, Thetuberosity 2 years after surgery. E, Dental radiographsof the patient’s right and left maxillary molar regions.F, Radiograph of the enlarged pneumatized tuberosity. G, Radiograph shows the buccal undercut ofa pneumatized sinus (arrow). H, Another radiograph, 2 years after surgery.


A B

C D

E

Figure 8-7 Conspicuous mandibular tori (A) are surgically exposed (B). A mucoperiostealflap (C) is replaced and sutured interdentally. D, Prominent mandibular tori on anedentulous cast (arrowheads). E, Intraoral view of the tori that must be excised beforedenture construction.

Pressure on the Mental Foramen If bone resorp-tion in the mandible has been extreme, the mentalforamen may open near or directly at the crest of theresidual bony process (Figure 8-17). When thishappens, the bony margins of the mental foramen

usually are more dense and resistant to resorptionthan the bone anterior or posterior to the foramen is.This causes the margins of the mental foramen toextend and have very sharp edges 2 to 3 mm higherthan the surrounding mandibular bone. Pressure

from the denture against the mental nerve exiting theforamen and over this sharp bony edge will causepain. Also, pressure against the sharp bone will causepain because the oral mucosa is pinched between thesharp bony margin of the mental foramen and thedenture. The most suitable way of managing this is toalter the denture so pressure does not exist. However,in rare instances it may be necessary to trim the boneto relieve the mental nerve of pressure. Pressure onthe mental nerve is reduced by increasing theopening of the mental foramen downward toward the

inferior border of the body of the mandible. Sucha change permits the mental nerve to exit the bone ata point lower than it had previously, thereby takingpressure off the nerve.

Occasionally, the anterior part of the residualridges becomes so resorbed that it is extremely thinlabiolingually, and it may have a sharp knife-edgewith small spicules of bone protruding from it(Figure 8-18). Careful denture relief in these areasfrequently overcomes this problem. If, however,constant irritation develops as a result of the softtissue being pinched between the denture and thebone, the spicules and the knife-edged ridge mustbe surgically reduced.

A lack of parallelism between the maxillaryand mandibular ridges can be encountered and, onoccasion, may require surgical correction. This lackof parallelism may be caused by an absence oftrimming of the tuberosity and ridge behind the lastmaxillary tooth when it is removed or may be theresult of jaw defects, unequal ridge reduction, orabnormalities of growth and development. Mostclinicians favor parallel ridges for their denturefoundations because the resultant forces generatedare directed in a way that tends to seat the denturerather than dislodge it. Also, the height of theocclusal plane of the upper denture can be elevatedposteriorly to improve the denture esthetically.

Virtually all the surgical procedures describednecessitate the use of a surgical template effect. The


A BFigure 8-8 The sheer bulk of a torus may prevent conventional palatal coverage by thedenture base (A). This situation can be ameliorated in a partially edentulous mouth bymodification of the design of major connectors (B), or (less frequently) the torus may beconsidered for surgical removal.

Figure 8-9 A large maxillary torus that extendsdistally past the proposed posterior palatal seal area.

patient’s old dentures can usually be modified andlined with a tissue conditioner to function as such. Theuse of a soft-lined prosthesis protects the operatedarea from trauma and enables the patient to continuewearing the dentures. All the surgical interventionsmentioned in this chapter must be considered in thecontext that there are potential effects on residualridge resorption and that extensive surgical prepara-tion of the edentulous mouth is rarely necessary. Infact, clinical experience indicates that careful pros-thetic technique and design can frequently precludea surgical intervention. The obvious exception to thisobservation is the use of implants, which have signif-icantly improved treatment outcomes for patients withmaladaptive denture experience.

Enlargement of Denture-Bearing Areas

The surgical techniques of vestibuloplasty andridge augmentation have been largely eclipsed by

osseointegrated implant modalities. However,some explanatory observations about the rationaleare relevant.

Vestibuloplasty The reduction of alveolar ridgesize is frequently accompanied by an apparentencroachment of muscle attachments on the crestof the ridge. These so-called high (mandibular) orlow (maxillary) attachments serve to reduce theavailable denture-bearing area and to underminedenture stability. The anterior part of the body ofthe mandible is the site most frequently involved:the labial sulcus is virtually obliterated, and thementalis muscle attachments appear to “migrate”to the crest of the residual ridge (Figure 8-19). Thisusually results in the dentist’s arranging the teeth ina position more lingual than the position of theformer anterior teeth. Such lingual crowding maynot be tolerated by the patient, and when the absentsulcus is accompanied by little or no attached


A

B CFigure 8-10 Bony exostoses (arrows) on the right buccal aspect of the maxillary residualridge (A) and on the labial and buccal aspects of the anterior mandibular ridge (B and C).

alveolar mucosa in this area, it is virtually impossi-ble for a lower denture to be retained. Myoplastyaccompanied by sulcus deepening has been pro-posed in an attempt to improve denture retention.With this operation the oral surgeon detaches theorigin of muscles on either the labial or the lingual,or both, sides of the edentulous residual ridges.This allows for an increase in the vertical exten-sions of the denture flanges. When horizontal bonyshelving is present in the mentalis muscle region,the surgical procedure is less successful, and itsrelative efficacy is attributable to the modificationof the powerful mentalis muscle’s activity. The riskof altered lower lip and chin sensation may alsoresult from such mandibular intervention.

Over the years close cooperation between thetwo involved disciplines has resulted in a clearerunderstanding of what the surgical interventionshould achieve. A wide and deep sulcus is notessential for success (Figure 8-20, A and B), andthe vestibuloplasty can be restricted to the interpre-molar region because the buccinator muscles arenot the major cause of the problem (see Figure8-19, D and E). Displacement of the mentalismuscle and adjacent muscle slips allow for the pro-duction of a looser lower lip, along with a lowwound margin down in the sulcus and an increasein both stability and depth of the labial flange. Thesituation varies in the maxillae, where a musclecomparable to the action of the mentalis in itsunstabilizing potential is not encountered.A broader vestibuloplasty is indicated here.

Although a lingual vestibuloplasty can providefor a major denture dimensional increase, the pro-cedure is traumatic, particularly in frail and elderlypatients; therefore the procedure is only very infre-quently recommended. The long-standing clinicalimpression that free-skin grafts lose resiliency anddevelop nuisance crinkling has been confirmed inseveral reports. Skin grafts tend to result ina noticeable increase in parakeratosis, with subse-quent clinical sogginess. Furthermore, they seem toexhibit poor cohesion and adhesion qualities withacrylic resin when compared with mucosa. Wheneverpossible, mucosal grafts are preferred.

The use of customized acrylic resin templates orthe modified previous denture to support vestibulo-plasty in the mandible is essential. These templatesare usually fastened to the mandible with circum-mandibular wires for 1 week or longer. Carefully


1 1

2

3 3

4

2

4

A BFigure 8-11 Incorrect (A) and correct (B) methodsfor trimming an exostosis of the crest of the alveolarprocess labial to the mandibular incisors. The exostosisshould be removed before the incisor teeth areremoved. (In A an undesirable loss of bone occurs ifa labial undercut is trimmed after the tooth isremoved. 1, Tooth in position [notice the labial bonyprominence]; 2, the removed tooth leaves an undercut;3, removal of the undercut shortens the labial plate ofbone; 4, the end result is a lingually placed sharpresidual ridge. The correct method [B] is to removea labial undercut before the teeth are removed. Thisconserves bone and leaves a larger and more desirableresidual ridge. 1, Tooth in position, with a labial bonyprominence; 2, the bony prominence is removed, butthe height of bone is retained; 3, tooth removed; 4, theresulting residual ridge is favorable.)


A B

C

D EFigure 8-12 A prominent and painful superior genial tubercle (A, arrowheads) issurgically exposed (B) and excised (C). Cephalometric radiographs (D and E) show thethinness of the mandible. In D, notice that the superior genial tubercle (arrow) is higherthan the crest of the bony ridge. Notice also the extreme interarch distance at the rest position.E, After the tubercle had been removed.

designed splints will reduce inflammation, reducepostoperative scarring, and maintain muscles in thedesired position, thereby improving the result. Theeffect of mandibular vestibule-extension surgery onmuscle activity and prosthesis retention has beeninvestigated. The electromyographic activity of thementalis and inferior orbicularis muscles was shownto undergo only slight changes despite the mentalismuscle’s being severed completely from its origin inthe mandible. The presumed cause of this minorchange was that the mentalis muscle was given a neworigin in the lower lip, with mainly the same activitypattern. However, a variable change in the apparentprominence of the chin can result. The alteredappearance has been described as a “witch’s chin.”


Figure 8-13 Anterior mandibular alveolar ridgeundercuts (arrowheads) are rarely excised.

A BFigure 8-14 Undercuts frequently occur on the lingual of the mandibular second andthird molars. Occasionally, they are very tender, and a sharp mylohyoid ridge of bone mustbe excised (A, arrowheads). B, A surveyor is used to emphasize the undercut that such a ridgecan create.

A BFigure 8-15 Posterior mandibular lingual undercuts (A, arrows), occur frequently andcan be used to enhance mandibular denture stability (B) via selective reduction of the acrylicresin flange(s).


A B

CFigure 8-16 Preoperative (A) and postoperative (B) views of a man who underwentmandibular osteotomy. C, The preoperative diagnostic cast.

Continued


D E

F GFigure 8-16 cont’d Preoperative (D) and postoperative (E) profiles and cephalometricviews (F, G) of a woman treated in a similar manner. (Courtesy Dr. P. Symlski.)

Another result of excessive alveolar bone loss orreduction is obliteration of the hamular notch. This“anatomical cul-de-sac,” with its potential for dis-placement, makes it an important part of the poste-rior palatal seal of the maxillary denture. Its absencecan severely undermine retention of the denture, anda small, localized deepening of the sulcus in thisarea may be attempted. The patient’s old denture ora surgical template is used after the surgery to helpretain the patency of the newly formed, yet smallsulcus, or notch.

Ridge Augmentation For many years oral andmaxillofacial surgeons have attempted to restore

advanced jaw residual ridge resorption by placingonlay bone grafts from an iliac or rib sourceabove or below the mandible. Unfortunately,follow-up reports suggest that the result generallyleaves much to be desired with respect to pre-dictable recovery of ridge height and minimalmorbidity as a treatment outcome. Considerablecaution is recommended with these proce-dures because they are a formidable undertaking,particularly for elderly patients. Nevertheless,current surgical reports suggest promise for com-bining grafts with implants to rectify serious resid-ual ridge resorption problems, particularly in themaxilla.


A

BFigure 8-17 Intraoral (A) and radiographic (B) views of an edentulous mandible withsuperficially placed mental foramina (arrowheads), resulting from extensive residual ridgereduction. The foramina usually are quite palpable in such situations.

Replacement of Tooth Roots withOsseointegrated Dental Implants

Whenever complete dentures are prescribed, theoptimization of a denture-bearing area is a logicaland compelling objective. For some patients thisdemands a preprosthetic surgical prescription. Twodecades of studies about treatment outcome withosseointegration have provided irrefutable evidenceto support this type of preprosthetic surgery. Thisscientific advance has ushered in a new era of effi-cacy and effectiveness in preprosthetic surgery. Thedenture-bearing area is no longer the prime or exclu-sive source of support, and the focus has now shiftedto an endosseous one. Different numbers ofimplants are prescribed for different prosthesisdesigns, such as an electively fixed prosthesis,which is entirely implant borne (Figure 8-21), or anoverdenture, which relies both on implant and resid-ual ridge support (Figure 8-22). Implant manage-ment of edentulous jaws is described in Part 4.


A

BFigure 8-18 A, The slender knife-edge mandibularalveolar ridge is covered by a thin and nonresilientmucosa. B, The working cast clearly demonstrates theknife-edged character of the ridge (arrowheads).


Origin

Insertion

MM

Origin

Insertion

1

2

A B

D

C

EFigure 8-19 Legend on opposite page.


Figure 8-19 Sagittal sections through the lower lipand anterior part of the mandible (A and B) show thespace available for a labial flange and the effect of thementalis muscle (M) on this space. The muscleoriginates on the bone and inserts into the skin.Contraction of the muscle lifts the lip and reduces thespace available for the flange of a denture. A lateralcephalogram (C) shows the contour of the residualalveolar ridge immediately after tooth extraction (1)and at the origin of the mentalis muscle (simulated at 2). When 1 resorbs to its present level, the relativelocale of origin of this muscle now obliterates thelabial sulcus. D and E, A mandibular vestibuloplastyprovides for dramatic increase in the labial flangeextension.

A B

C DFigure 8-20 Deepened facial mandibular (A and B) and maxillary vestibules (C) with skingrafts in place. Note that current procedures do not aim at achieving such a wide area ofoperation and restrict the intersection to interforamina site in the mandible. Mandibulardentures before and after sulcus deepening are compared (D).


A B

C DFigure 8-21 A, After two preprosthetic surgical stages, the osseointegrated implants areused as abutments for an electively removable fixed prosthesis. Prosthetic cylinders arematched to the implants and joined together by means of a wax scaffolding (B), which is castto provide support for the final prosthesis (C and D). Notice that access to the retainingscrews allows for ready removal of the prosthesis and that the gingival surface design allowsfor hygiene maintenance as with standard fixed prostheses.


A

C

D

B

Figure 8-22 A, Stabilization of a complete denture by means of three osseointegratedimplants joined together with a cast gold bar (B). Clip attachments inside the mandibularprosthesis ensure retention and stability without compromising the esthetic result (C and D).The quality of a patient’s prosthetic experience can be greatly enhanced by prescribing thiscost-effective method.

BibliographyBjörlin G, Palmquist J, Ahlgren J: Muscle activity and denture

retention after vestibular extension surgery, Odontol Rev18:179-190, 1967.

Cawood JI, Howell RA: A classification of the edentulous jaws,Int J Oral Maxillofac Surg 17:232-236, 1988.

de Koomen HA, Stoelinga PJW, Tideman H et al: Interposedbone-graft augmentation of the atrophic mandible,J Maxillofac Surg 7:129, 1979.

Harrison A: Temporary lining materials: a review of their uses,Br Dent J 151(12):419-422, 1981.

Hillerup S: Preprosthetic mandibular vestibuloplasty withsplit-skin graft: a two-year follow-up study, Int J OralMaxillofac Surg 16:270-278, 1987.

Hillerup S, Hjørting-Hansen E, Eriksen E et al : Influence of skingraft pathology on residual ridge reduction after mandibularvestibuloplasty: a 5-year clinical and radiological follow-upstudy, Int J Oral Maxillofac Surg 19:212-215, 1990.

Hjørting-Hansen E, Adawy AM, Hillerup S: Mandibularvestibulolingual sulcoplasty with free skin graft: a five-yearclinical follow-up study, J Oral Maxillofac Surg 41:173-176, 1983.

Hopkins R: A colour atlas of preprosthetic oral surgery,London, 1987, Wolfe Medical Publications.

Lytle RB: Complete denture construction based on a study ofthe deformation of the underlying soft tissues, J ProsthetDent 9:539-551, 1959.

Møller JF, Jolst O: A histologic follow-up study of free autoge-nous skin grafts to the alveolar ridge in humans, Int J OralSurg 1:283, 1972.

Quayle AA: The atrophic mandible: aspects of technique inlower labial sulcoplasty, Br J Oral Surg 16:169-178, 1979.

Taylor RL: A chronological review of the changing conceptsrelated to modifications, treatment, preservation, and aug-mentation of the complete denture basal seat, AustProsthodont Soc Bull 16:17-39, 1986.

Weingart D, Strub JR, Schilli W: Mandibular ridge augmenta-tion with autogenous bone grafting and immediate implants:a 3-year longitudinal study (abstract), Abstracts from thefifth International Congress of Preprosthetic Surgery,Vienna, 1993.

Wowern N. Bone mineral contents of mandibles: normal refer-ence values—rate of age-related bone loss, Calcif Tissue Int43:193-198, 1988.


C H A P T E R 9Immediate DenturesNancy S. Arbree

123

An immediate denture is “a complete denture orremovable partial denture fabricated for placementimmediately after the removal of natural teeth”(according to the Glossary of Prosthodontic Terms,Academy of Prosthodontics, 1999). An immediatedenture can also be an overdenture. One of the firstreferences to immediate dentures in the literaturewas that of Richardson in 1860 (Seals, 1999).

Immediate dentures are more challenging tomake than routine complete dentures for both thedentist and the patient. Because a try-in is not pos-sible beforehand, the patient may not be completelycomfortable with the resulting appearance and fiton the day the immediate denture is inserted. Thedentist must explain and the patient must fullyunderstand the limitations of the procedure beforebeginning treatment.

Immediate dentures may be either single imme-diate dentures or upper and lower immediate den-tures in the same patient. The latter should be madetogether to ensure optimal esthetics and occlusalrelationships.

DEFINITIONS IN CURRENT PRACTICECurrently, there are two popular types of immedi-ate dentures:

1. Conventional (or classic) immediate denture(CID): After this immediate denture isplaced and after healing is completed, thedenture is refitted or relined to serve as thelong-term prosthesis.

2. Interim (or transitional or nontraditional)immediate denture (IID): After this immedi-ate denture is made and after healing is com-

pleted, a second, new complete denture isfabricated as the long-term prosthesis. TheGlossary of Prosthodontics Terms definesinterim prosthesis as a prosthesis designedto enhance esthetics, stabilization and/orfunction for a limited period of time, afterwhich it is replaced by a definitive prosthe-sis (Academy of Prosthondontics, 1999).

Practically speaking, the CID is usually selectedwhen only anterior teeth remain or if the patient iswilling to have the posterior teeth extracted beforeimmediate denture procedures begin. The IID isused most often when anterior and posterior teethremain until the day of extraction and placement ofthe immediate denture.

An abbreviated type of IID has been called the“jiffy” denture (Raczka and Esposito, 1995). It issimilar to the IID because it is replaced by a secondcomplete denture after healing. Some dentists use itwhen the immediate denture needs to be fabricatedvery quickly (in one day or session) because ofextenuating emergency circumstances or medicalindications. It differs from the IID in that the den-ture “teeth” are usually made with tooth-colored,autopolymerizing acrylic resin (Hay, 1998; Raczkaand Esposito, 1995; Seals, Kuebker, and Stewart,1996; Pence, Lee, and Baum, 1992; Rayson andWesley, 1970) or portions of the patient’s preexistingfixed or removable partial denture(s) (Cohen andMullick, 1994; Zalkind and Hochman, 1997). Thesetooth/prosthesis components are converted with theuse of irreversible hydrocolloid impressions, stonecasts, and either autopolymerizing or light-cured,tooth-colored and pink resins (Khan and Haeberle,1992) into an IID.

The low cost and efficiency with which thesejiffy dentures can be made allow their fabricationin extreme circumstances. Refer to the literaturereferences for the precise techniques for theseIIDs. They are not described here because they donot usually use conventional denture teeth andprocessing techniques. The main disadvantage of“jiffy dentures” is that the materials used are notas long lasting (e.g., in wear and color stability)as conventional denture teeth and processedbases.

ADVANTAGES AND DISADVANTAGESFOR ALL TYPES OF IMMEDIATEDENTURESAdvantages

1. The primary advantage of an immediatedenture is the maintenance of a patient’sappearance because there is no edentulousperiod.

2. Circumoral support, muscle tone, verticaldimension of occlusion, jaw relationship,and face height can be maintained. Thetongue will not spread out as a result oftooth loss.

3. Less postoperative pain is likely to be encoun-tered because the extraction sites are pro-tected. Some authors have discussed whetherimmediate dentures reduce residual ridgeresorption (Heartwell, 1965; Johnson, 1966;Kelly, 1958; Campbell, 1960; Carlsson,1967).

4. It is easier to duplicate (if desired) the natu-ral tooth shape and position, plus arch formand width. If desired, the horizontal and ver-tical positions of the anterior teeth can bemore accurately replicated.

5. The patient is likely to adapt more easily todentures at the same time that recovery fromsurgery is progressing. Speech and mastica-tion are rarely compromised, and nutritioncan be maintained.

6. The availability of tissue-conditioning mate-rial allows for considerable versatility in thecorrection and refinement of the denture’sfitting surface, both at the insertion stageand at subsequent appointments.

7. Overall, the patient’s psychological and socialwell-being is preserved. The most compellingreasons for the immediate denture prescriptionare that a patient does not have to go withoutteeth and that there is no interruption of a nor-mal lifestyle of smiling, talking, eating, andsocializing. The reasons are supported by astudy (Jonkman, Van Waas, and Kalk, 1995),which found that 1 year after denture place-ment, a majority (76% to 79%) of patientswith immediate dentures (when comparedwith two groups of control subjects, one whohad immediate overdentures and one who hadtooth-attachment overdentures) could eatproperly and had easily adapted to wearing thedenture. No difference in denture satisfaction,comfort, chewing ability, esthetics, and gen-eral satisfaction was found among the threegroups.

Disadvantages

Immediate dentures are a more challenging modal-ity than complete dentures because the presence ofteeth makes impressions and maxillomandibularpositions more difficult to record.

Specific disadvantages include the following:

1. The anterior ridge undercut (often severe)that is caused by the presence of the remain-ing teeth may interfere with the impressionprocedures and therefore preclude alsoaccurately capturing a posteriorly locatedundercut, which is important for retention.

2. The presence of different numbers ofremaining teeth in various locations (anteri-orly, posteriorly, or both) frequently leads torecording incorrectly the centric relationposition or planning improperly the appro-priate vertical dimension of occlusion. Anocclusal adjustment, or even selective pre-treatment extractions, may be needed tomake accurate records at the proper verticaldimension of occlusion.

3. The inability to accomplish a denturetooth try-in in advance on extractions pre-cludes knowing what the denture will actu-ally look like on the day of insertion.Careful planning, operator experience,


attention to details of the technique, andexplanation to the patient best address thisinherent problem.

4. Because this is a more difficult and demand-ing procedure, more chair time, additionalappointments, and therefore increased costsare unavoidable.

5. Functional activities (e.g., speech and masti-cation) are likely to be impaired. However,this is a temporary inconvenience.

Additional Comparative Advantagesand Disadvantages

The CID and the IID have advantages and dis-advantages when the two techniques are comparedwith each other. Many of these are described inTable 9-1. Advantages are as follows:

1. The CID will usually have better initial reten-tion and stability because fewer teeth are usu-ally extracted on the day of placement.

2. The CID has an easier surgical session onthe second surgical (denture placement)date.

3. The overall cost of the CID is less.4. The IID technique results in two dentures,

which is advantageous for some patients.5. The IID has only one surgical visit.6. The IID procedure takes less overall time,

from the dentist’s meeting the patient toplacing the denture.

7. Patient with IIDs can use all their teeth orwear their existing removable partial den-ture(s) up until the day of extraction.

8. The IID lends itself better to complex treat-ment plans, especially in a patient who needsan upper immediate denture opposing alower transitional removable partial denture.

9. The IID is better for less experienced practi-tioners because a second denture can correctany imperfections.

The following are disadvantages:

1. The CID technique results in only one den-ture.

2. The CID technique requires two surgicalvisits.

3. The CID technique includes a period of pos-terior partial edentulism, which impairsmastication and compromises esthetics.

4. The CID takes longer to fabricate, espe-cially in complex treatment plans.

5. The single surgical visit for the IID is moreinvolved and lengthy than for a CID.

6. The retention and stability of the IID is lessat insertion. However, modern tissue condi-tioning techniques negate this disadvantage.

CONTRAINDICATIONSA few patients are not good candidates for imme-diate dentures. They include (1) patients who are inpoor general health or who are poor surgical risks(e.g., postirradiation of the head and neck regions,systemic conditions that affect healing or bloodclotting, cardiac or endocrine gland disturbances,and psychological disorders) and (2) patients whoare identified as uncooperative because they cannotunderstand and appreciate the scope, demands, andlimitations to the course of immediate denturetreatment.

On occasion, patients will not object to goingwithout teeth during the healing period. This isespecially true if these patients have extensivetooth loss (or teeth decoronated by decay) already.For these patients, immediate extractions followedby conventional complete denture treatment aresimpler and less expensive.

DIAGNOSIS, TREATMENT PLANNING,AND PROGNOSISWhich Type of Immediate Denture Should BePrescribed?

Scrupulous treatment planning and patient educa-tion, plus meticulous clinical performance aidedby the careful use of tissue conditioners, will vir-tually ensure a predictable treatment outcome formost CIDs (see candidate for upper and lowerimmediate dentures in Figure 9-1). With well-planned monitoring and modifications, thesedentures can become the definitive prostheses forlong-term wear. Such results can be achieved rou-tinely. In some cases, the presence of numerousposterior teeth and the need for other hard and

Chapter 9 Immediate Dentures 125

soft tissue related procedures can complicatetreatment. In some patients, the sequelae ofadvanced periodontal disease, including aberrantocclusal relationships, might require a “staged”surgical approach to the final objective of adefinitive prosthesis. Extracting the posteriorteeth and performing other necessary proceduresfirst in these patients can lead to predictableresults for the CID.

However for other patients, the idea of a periodwithout posterior teeth is impossible to imagine.The IID essentially reconciles these considerations:(1) expediency for the patient where smile, occupa-tion, and preference demand a full display of teethat all times and (2) recognition of the educatedguesswork necessitated by this type of service. Theproviso (agreed to by both patient and dentist) is

that if the esthetic and occlusal outcome is not sat-isfactory, a new definitive prosthesis will be made.In this manner, a patient can be reassured while thedentist acknowledges the inherent risks in this typeof service.

More and more patients are opting for the con-venience of the IID choice. If the dentist performsthe technique meticulously and the patient is coop-erative, the resulting IID can be very successful.The second denture procedures allow optimizationof the end result.

The final decision as to which type of immedi-ate denture best suits the treatment needs and socialhistory of the patient can be confusing. Table 9-1summarizes a comparison of the CID and IID forassistance during preliminary patient discussionsand at the final treatment-planning visit.


Figure 9-1 Advanced (Class III—McGarry, Nimmo, and Skiba, 2002) candidate forimmediate denture treatment. A, Natural tooth display. B, Teeth in centric occlusion.C, Maxillary occlusal view.

A C

B

Continued

Explanation to the Patient

A careful explanation to the patient of the limita-tions of immediate denture service should alwaysbe given. It is helpful to have a list including allpossible difficulties (Box 9-1). Practitioners shouldalso include an informed consent with wordingspecific to the nature of the immediate denture(Box 9-2). At this stage of diagnosis and treatmentplanning, patients should be provided with writteninformation (to take home) concerning dentures,

immediate dentures, or both so that they have timeto ask questions at a subsequent visit when treat-ment procedures begin.

Oral Examination

The usual full mouth series of radiographs shouldbe taken. The dental and medical history of thepatient should be reviewed. A head and neckexamination is performed. During the normal


Figure 9-1 cont’d D, Mandibular occlusal view. Panoramic (E) and full mouth (F).

D E

F

Table 9-1Comparative Indications for the Conventional (or Classic) Immediate Denture versus the Interim (or Transitional or Nontraditional) Denture

Conventional Immediate Denture (CID) Interim Immediate Denture (IID)

Intended as definitive or long-term prosthesis Transitional or short-term prosthesisAfter healing is complete, it is relined After healing, a second denture is made; the IID is kept

as a spare denture and may be relined for use as aspare

At the patient’s initial presentation, usually only anterior At initial presentation, usually both anterior and teeth (plus possibly premolars) are remaining posterior teeth are remaining

Usually has good retention and stability at placement, Usually has only fair retention and stability at which is possible to maintain during healing insertion, which must be improved by provisional

relines (tissue conditioning) during healingThe overall cost of CID treatment is less than IID The overall cost of IID treatment is greater than CID

treatment because it is the cost of the CID plus a reline treatment because it includes the cost of the interimdenture and a second denture

Treatment process takes longer than the IID because Treatment process takes less time than the CID as there is a delay of 3-4 weeks for the posterior teeth denture fabrication procedures can begin right awayextraction areas to heal partially before making the final impression.

Generally indicated when only anterior teeth are Generally indicated when there are multiple anterior present or few posterior teeth remain that do not and posterior teeth remaining or full arch extractions support an existing removable partial denture and/or these teeth support a removable partial denture

that the patient desires to retain until insertionGenerally indicated when patient can function without Generally indicated when the patient cannot or will not

posterior teeth for approximately 3 months go without posterior teeth or an existing removable (3-4 weeks posterior area healing time plus 2 months partial denture because of esthetic or functional to fabricate and place the CID) concerns

At placement of the CID, usually only anterior teeth are At placement of the IID, usually both anterior and extracted (possibly also one premolar on each side posterior teeth are extractedthat had been retained to preserve the vertical dimension of occlusion)

Indicated when two extraction visits are feasible Indicated when only one surgical visit is preferable (e.g., to meet “one hospital surgical visit” insurancebenefits or when the patient’s medical conditionwarrants) only one surgical and/or hospital visit.

Esthetics of the CID cannot be changed The second denture procedure after the IID allows an alteration of esthetics and any other factors ifindicated.

At the end of the treatment, the patient has one denture. At the end of the treatment, the patient has a spare denture to use in case of extenuating circumstances

If all posterior teeth are initially removed, the vertical Because posterior teeth need not be removed before dimension of occlusion is not preserved; opposing fabrication of the IID, the vertical dimension ofpremolars can be maintained for this purpose occlusion may be preserved

Contraindicated for a patient who has a complex Indicated when the patient will become edentulous in treatment plan (e.g., periodontal therapy, crowns, one arch and become partially edentulous in the fixed partial dentures and removable partial dentures opposing arch for the first time or complex in the opposing arch) or for changes in the vertical procedures are needed (such as crowns, fixed partial dimension of occlusion dentures, and removable partial dentures) or changes

in the vertical dimension of or changes in the verticaldimension of occlusion; an upper IID against atransitional lower partial denture can be made; then any periodontal procedures, crowns, and fixed partialdentures can be done during the initial healing stage

Not useful for converting existing prostheses such as Can be useful in converting existing prostheses to an IIDremovable partial dentures

intraoral examination, the dentist should includeand record periodontal probings, a full charting ofall the teeth, and a note of need for frenumrelease, tori reduction or any other hard and softtissue surgery, if necessary. When possible, teethshould be selected for retention as overdentureabutments. A careful evaluation and palpation ofthe potential denture-supporting tissues and theposterior palatal seal area should be carried out.The patient should be classified according to thepartially edentulous classification system of theAmerican College of Prosthodontists (McGarry,Nimmo, and Skiba, 2002) or another system. Thisaids in the determination of prognosis.

The shade and mold of the existing teethshould be determined. A gingival shade should betaken with denture-base shade tabs. Patientsshould be asked if they like their current shade andtooth position and what changes they would makeif any. This discussion should include decidingwhether to preserve diastemata, rotations, andoverlapping of teeth for a more natural transitionand a more natural-looking denture. This initialesthetic dialogue will streamline the final toothselection process at a later visit. It also is best toinclude photographs as part of the permanentrecord, including full-size face and profile, lips

closed and smiling, and an intraoral view of theteeth in maximum occlusion.

Time should be spent evaluating the lip support,philtrum shape, position of high lip line, low lipline, and amount of tooth exposure in functionwhile the patient is both silent and talking. Notationof the following factors will help in later visits:

1. The patient’s existing midline and need formodification of its position (existing teethmay have drifted, especially if a nearby toothhas been lost for some time)

2. The patient’s existing vertical dimension ofocclusion and amount of interocclusal dis-tance (freeway space) and the need for con-forming to or changing it, according towhether the patient’s existing maximumocclusal position coincides with the plannedcentric relation position for the immediatedentures and how difficult it is to manipu-late or achieve that position for recording

3. The present amount of horizontal and verti-cal overlap of anterior teeth

4. An estimate of the Angle’s classification ofocclusion for the patient

5. Display of posterior tooth in the buccalcorridor


Explanation to the Patient Concerning Immediate Dentures

Box 9-1

1. They do not fit as well as complete dentures.They may need temporary linings with tissueconditioners and may require the use of dentureadhesives.

2. They will cause discomfort. The pain of theextractions, in addition to the sore spots causedby the immediate denture, will make the firstweek or two after insertion difficult.

3. It will be difficult to eat and speak initially, almostlike learning to eat and speak all over again.

4. The esthetics may be unpredictable. Without ananterior try-in, the appearance of the immediatedenture may be different from what you or thedentist expected.

5. Many other denture factors are unpredictablesuch as the gagging tendency, increased saliva-

tion, different chewing sounds, and facial con-tour.

6. It may be difficult or impossible to insert theimmediate denture on the first day. Every effortwill be made to do so. If it is not possible, it willbe inserted or remade as quickly as possible.

7. Immediate dentures must be worn for the first 24hours without being removed by the patient. Ifthey are removed, they may not be able to bereinserted for 3 to 4 days. The dentist will removethem at the 24-hour visit.

8. Because supporting tissue changes are unpre-dictable, immediate dentures may loosen up dur-ing the first 1 to 2 years. The patient isresponsible for all fees involved in refitting orrelining the dentures.

Examination of Existing Prosthesis

Any existing prostheses should be examined forshade, mold, tooth position, lip support, and smileline. The shade of the denture base should also benoted.

Tooth Modification

Many immediate dentures will require modificationof opposing teeth to correct the occlusal plane or toeliminate prematurities in centric relation. Occlusalplane adjustment is necessary because the factorsthat necessitate tooth extraction (e.g., extensivecaries, periodontal disease, and extrusion or drifting)often are associated with occlusal discrepancies(Figure 9-2). These can affect the correct registrationof centric relation, especially when they interferewith guiding the patient into the centric relation

position. They can also interfere with the properdetermination of the occlusal vertical dimension.These tooth modifications should be made to thepatient in advance of the final impressions.

At times it is determined that the analysis of theocclusion and the plane of occlusion is best madeby performing a diagnostic mounting of the pre-liminary casts (impression technique for these isdescribed later) to carefully evaluate the plannedchanges. The esthetic dialogue initiated at the oralexamination visit can be recorded and marked onthe mounted diagnostic casts. These casts are alsoused to plan and mark the occlusal tooth modifica-tions that will need to be done at the final impres-sion visit later (Figure 9-3). These preliminarycasts also serve as a preextraction record.

Prognosis

All of the foregoing features will allow the dentistto determine a prognosis for the immediate den-ture. The professional fee should be quoted onlyafter this thorough examination. At this point, therewill be a good indication of the best type of imme-diate denture for the patient, the anticipated diffi-culties (e.g., inability to achieve a reliable centricrelation position), esthetic demands on the part ofthe patient, a compromised residual ridge for den-ture support, systemic diseases and medicationsthat may affect denture success, sensitive tissues orsharp, bony prominences that may necessitate moresore spot adjustment, and other concerns. TheAmerican College of Prosthodontics Classificationfor Partially Edentulous Patients (McGarry, Nimmo,Skiba et al., 2002) should be noted; it is helpful toboth the dentist and the patient to use this system tounderstand the nature of the patient’s diagnosis andprognosis. It also serves as a basis to refer to special-ists (prosthodontists) when indicated. Once thepatient understands and accepts the diagnosis, treat-ment plan, and prognosis, treatment can begin.

Referrals/Adjunctive Care

If other dentists are to be involved in thepatient’s treatment, referrals for required consul-tations are requested at this time. When required,a surgical consultation should occur early in thetreatment to establish good communication


Example of Informed Consent forImmediate Dentures

An immediate denture is a denture that isinserted immediately on extraction of yourremaining teeth. The fit, appearance, or com-fort of such dentures is very difficult to predict.There is no way that teeth can be fitted inadvance to show you what the denture will looklike, how well you will be able to bite and chew,and how they will fit.

Immediate dentures often require tissue con-ditioning or temporary liners during the heal-ing phase as the natural process of gum andbone shrinking takes place. After severalmonths, the immediate denture will need adefinitive reline or a new denture. The costs ofthese liners, relines, or the new denture are notincluded in the fee for the immediate denture.The fee for each of these services has been dis-cussed with you.

Every effort will be made to duplicate orimprove on the position of your natural teeth,but if the immediate denture is not quite whatyou expected, you may have to have a seconddenture made, even if a reline was what wasoriginally planned.

Box 9-2

among the patient, practitioner, and the surgeon.Common preprosthetic surgical procedures areconsidered (Terry and Hillenbrand, 1994). Awritten referral with a copy of the radiographsshould be sent to the surgeon in advance.Requests for surgery, where not to do surgery(e.g., when bone trimming is not needed or whensaving teeth for overdenture abutments), andfuture surgical considerations (e.g., dentalimplants) are also identified.

This surgical consultation visit will further reas-sure the patient as to events that will occur on the sur-gical date(s). If the patient desires any type ofsedation anesthesia, the details of this can be workedout in advance. The surgeon and the practitionershould communicate after the consultation so thatthey can arrange a mutually convenient surgical dateand so that the practitioner can receive input and sug-gestions from the surgeon’s examination of thepatient.

An endodontic consultation concerning anytreatment needed for planned overdenture abut-ments should be done, if necessary. The endodon-tic treatment can start at any time. Periodontalconsultations should also be scheduled for anyremaining teeth in the opposing arch or overden-ture abutments as needed. It is usually preferableto do any needed periodontal therapy after theplacement of the immediate denture. Clinical

experience indicates that the removal of periodon-tally compromised adjacent teeth frequentlyimproves and even reduces the periodontal treat-ment that may be required for the remaining teeth.

Oral Prophylaxis

The patient should have a general scaling of theteeth to minimize calculus deposits. This willreduce the postoperative edema and chance ofinfection.

Other Treatment Needs

Often, patients with single immediate dentures alsorequire restorations, crowns, or removable partialdentures. Restorations are usually performed coin-cident with the immediate denture procedures.

For the patient with a single CID, restorationsand crowns can be completed during the 3 to 4weeks of healing after the first surgical visit andalso coincident with the immediate denture proce-dures. For the patient with a single IID, restora-tions, crowns, and the definitive removable partialdentures procedures for the opposing arch aredone after placement of the IID. The only excep-tion to this is if a transitional removable partialdenture is planned for the opposing arch; this isfabricated coincident with the immediate dentureprocedures.


Figure 9-2 A, The lower anterior teeth requiring modification to correct them to an evenplane of occlusion. B, Note the supereruption of the upper right molar (mirror view), whichmust be corrected in the final planned prosthesis

A B

CLINICAL AND LABORATORYPROCEDURESThe procedures for fabrication of immediate den-tures are similar to those for making complete den-tures, with some modifications. If overdentureabutments are planned, endodontic treatment ispreferably completed coincident with the immedi-ate denture procedures. The abutments can bemorphologically modified when the denture isready to be inserted. Final preparation of overden-

ture abutments and placement of any copings orattachments should be done after the immediatedenture is inserted and the patients’ ridge healing iscomplete.

First Extraction/Surgical Visit

If a clinical decision is made to undertake pre-liminary extractions (CID technique), the patientshould have the identified (usually posterior)teeth removed as soon as possible. Opposing


Figure 9-3 Mounted diagnostic casts of the patient in Figure 9-1 can help evaluate theplane of occlusion, extruded teeth, diastemata, and rotated teeth. They can be marked forsmile line, midline, posterior limit, and planes of occlusion such as interpupillary andala-tragus. They serve as a permanent preextraction record. A, Front view with marks formidline, interpupillary line, and smile line. B, Right lateral view with ala-tragus line. C, Leftlateral view.

A B

C

premolars may be retained to preserve the verti-cal dimension of occlusion, although canines orother anterior teeth may provide the required so-called centric or vertical stops. Any otherrequired hard and soft tissue operation is alsousually done at this first surgical visit. Examplesinclude tori reduction, tuberosity reduction, andfrenectomy.

These posterior extraction and other operated-on areas are allowed to heal for a short time, usu-ally only 3 to 4 weeks, before the preliminaryimpressions are made. If any posterior teeth areproposed as overdenture abutments, and if thepatient does not object, the endodontic treatmentcan be done earlier and these teeth reduced beforethe impression appointment.

Preliminary Impressions and Diagnostic Casts

Impressions are made in irreversible hydrocolloid(alginate) in stock metal or plastic trays. The trayshould be selected based on its ability to reach allperipheral tissue borders and posterior extensions,such as the retromolar pad on the mandibular archand the posterior limit (hamular notches and post-dam area) on the maxillary arch. Periphery (rope)wax is adapted to the borders of the tray to reachtoward the vestibule and into the often-extensiveundercuts accentuated by the presence of teeth. Thepalatal surface of the upper tray needs to have waxadded to reach the palatal tissues (Figure 9-4).Location of the posterior limit can be marked in thepatient’s mouth with an indelible stick. This oftenwill transfer to the impression surface, or it can bedrawn (copied from the mouth) on the impressionlater before pouring.

The wax may show through these initialimpressions, but this will not significantly alterthe cast accuracy because of the softness of thewax. The impressions should be free of voids andshould record the full extensions planned for thedenture prosthesis. These impressions are pouredin stone and are used to make custom trays forthe final impressions. If an IID is planned, thesepreliminary impressions and casts will contain allof the remaining teeth (Figure 9-5, A and B, andFigure 9-6, A and B). If a CID is planned, these willcontain only anterior teeth (Figure 9-5, C and D,and Figure 9-6, C and D).

Loose Teeth

Several authors have made suggestions for protect-ing loose teeth from extractions during preliminaryor final impression procedures for immediate den-tures. Loose teeth can be blocked out by addingperiphery wax at the cervical areas, by generouslyapplying a lubricating medium to the teeth, by plac-ing copper bands over the loose teeth (Soni, 1999),by placing a vacuum-formed plastic over the teeth(Vellis, Wright, Evans et al., 2001), or by placingholes in the tray and using an amalgam condenser torelease the tray over loose teeth (Goldstein, 1992).

Custom Trays, Final Impressions,and Final Casts

Many successful tray types and impression tech-niques for immediate dentures are described in thedental literature. There are two basic ways to fabri-cate the final impression tray, depending on the loca-tion of the remaining teeth and operator preference.Both are successful as long as they are done properly.

Type One: Single Full Arch Custom ImpressionTray The type one method more closely resem-bles a routine custom impression tray for remov-able partial dentures. It can be used in the CIDtechnique. It is the only tray that can be used for theIID technique. This type of tray is effective whenonly anterior teeth are remaining or when anteriorand posterior teeth are remaining.

The process for tray fabrication is as follows:

1. The areas of the casts with remaining teethare blocked out with two sheet wax thick-nesses as for a fixed partial denture customimpression tray; undercuts in the edentulousareas are blocked out as for a complete den-ture custom tray. In the IID technique, bothanterior and posterior teeth areas are blockedout with two thicknesses of wax (Figure 9-7,A and B). In the CID technique, only anteriorteeth are blocked out in this manner.

2. A stop effect is established by providingholes through the wax anteriorly (CID andIID) or posteriorly (IID only) on one or twoteeth and posteriorly in the tuberosity orposterior palatal seal areas (CID and IID).


3. The tray is outlined to be 2 to 3 mm short ofthe vestibular roll and to extend and includethe posterior limit (posterior palatal seal andhamular notch area).

4. Autopolymerizing acrylic resin or light-cured resin is adapted over the cast, into thestops, and to the planned outline. A handle isadded to the anterior palate or to the mid-palate. The latter is regarded as advanta-geous because if the anterior handle is toolong, it may interfere with proper anteriorvestibule border molding. A sketch of thecross section of a full arch tray for a CID isshown in Figure 9-8. The full arch tray foran IID would be similar except that it wouldhave teeth under the posterior section as

well as under the anterior section. The tray isallowed to polymerize (Figure 9-9).

5. As with the usual technique in completedentures (see Chapters 13 and 14), the trayis polished, tried in, and relieved. Bordermolding is accomplished, the appropriateadhesive added, and a final impression ismade in any preferred elastomeric material(irreversible hydrocolloid, polysulfide rub-ber base, polyvinyl silicone, or polyether)(Figure 9-10).

Type Two: Two-Tray or Sectional CustomImpression Tray The type two method is used onlywhen the posterior teeth have been removed (CID). Itcannot be used in the IID technique because usually


Figure 9-4 A, Maxillary tray border molded with periphery (rope) wax to extend intoundercuts and onto the vestibular roll area and palatal area (B). C, Mandibular tray similarlyprepared.

A B

C

there are posterior teeth present. It involves fabricat-ing two trays on the same cast—one in the posterior,which is made like a complete denture tray, and onein the anterior (backless tray). Some operators elimi-nate the anterior tray.

1. Outline the borders of the tray(s) again to be 2to 3 mm short of the vestibule but coveringthe posterior limit and/or the retromolar pads.

2. Use melted wax to block out tissue under-cuts, interdental spaces, and undercutsaround the anterior teeth. Note: A doublesheet of wax is not used because intimateadaptation of the tray is desired.

3. Adapt autopolymerizing acrylic resin orlight-cured resin to the posterior edentu-

lous areas. This section or posterior trayshould cover the lingual surfaces of theteeth (only) and extend up beyond theincisal edges of the teeth to include a han-dle (Figure 9-11).

4. For the anterior section or tray, there are vary-ing techniques: one is to adapt a custom tray,and another is to cut and modify a plasticstock tray (Figure 9-12). Alternately, someoperators prefer to not use a tray. Instead, theyadapt plaster impression material or a heavymix of an elastomeric impression materialdirectly in the mouth. The anteriorsection/impression material must cover thelabial surfaces of the teeth and the vestibule.All variations can be used successfully.


Figure 9-5 Maxillary (A) and mandibular (B) preliminary impressions for the IID tech-nique and maxillary (C) and mandibular (D) preliminary impressions for the CID technique.CID, Conventional immediate denture; IID, interim immediate denture.

C D

A B

5. The posterior sectional tray is tried in,relieved as with a complete denture tray,border molded, and adhesive applied; thenthe posterior impression is made in anyimpression material desired (zincoxide–eugenol paste, polysulfide rubberbase, polyvinyl silicones, polyether)(Figure 9-13). This material does not haveto be elastomeric because it will not lockinto tooth undercuts because it includesonly the lingual areas of the teeth and theposterior ridge. If severe posterior ridgeundercuts are present, an elastomericmaterial should be used.

6. The posterior impression is removed andinspected. Excess material is removed,

and it is replaced in the mouth. The anteriorsection of the impression is made to it byone of the variations described in step 4.Figure 9-14 shows the sectional custom traytechnique for a patient with a CID.

7. The most important consideration in the sec-tional tray technique is the careful, properreassembly of the two separate componentsof the impression. Care must be taken not todistort this assembly during removal fromthe mouth and during the pouring of theimpression. The method of boxing theimpression with a mixture of plaster andpumice is suggested as least likely to causedistortion (Figure 9-15). The final casts aretrimmed (Figure 9-16).


Figure 9-6 Preliminary maxillary (A) and mandibular (B) casts for IID technique.Preliminary maxillary (C) and mandibular (D) casts for the CID technique. CID, Conventionalimmediate denture; IID, interim immediate denture.

C D

A B

Another tray variation is the maxillary Campagna tray(Campagna, 1968). It looks like a full arch tray with ahole cut out where the remaining anterior teeth are(CID technique). A stock tray is used over the full archtray to capture the anterior teeth in the impression.

Note: At the final impression visit (preferable)or at the jaw relation record visit, the teeth selectedearlier for the patient should be shown to thepatient for his or her approval. A change can bemade at this time if necessary.

Location of Posterior Limit and Jaw RelationRecords

The procedures for locating the posterior limit andjaw relation records are identical to those for com-plete dentures (see Chapter 15). If there are enoughanterior and posterior teeth remaining (in somepatients with IIDs), there may not be a need for arecord base and occlusion rim. If not (as in somepatients with IIDs and all patients with CIDs),


Figure 9-7 Wax block-out of maxillary (A) and mandibular (B) casts for an interimimmediate denture (IID).

Optional

CA

B

Figure 9-8 Sketch of outline and wax block-out of a single full arch custom impressiontray for a conventional immediate denture (CID). A, Wax for spacer. B, Stop. C, Wax block-out.

A B


Figure 9-10 Border molding (A) and final impressions (B) for maxillary (C) and mandibu-lar (D) immediate dentures (IID) in full arch custom impression trays. In the CID technique,posterior teeth would not usually be present in the full arch final impression. CID,Conventional immediate denture; IID, interim immediate denture.

Figure 9-9 Maxillary (A) and mandibular (B) full arch custom impression trays. This viewwould look the same for either a CID or an IID. In the IID, teeth would also be present under theposterior sections. CID, Conventional immediate denture; IID, interim immediate denture.

A B

C D

A B

record bases and occlusion rims are made on themaster casts.

1. Undercut areas around teeth and on eden-tulous areas are blocked out with wax, andautopolymerizing acrylic resin or light-cured resin is adapted to the edentulousareas of the cast as for complete dentures.Wax occlusion rims are added to theproper height and width. The remaining

teeth and anatomical landmarks, such asthe retromolar pad, can serve as a guide tothe height of the rim (Figure 9-17). It isimportant that these record bases be stableand strong enough to record jaw relations.

2. The record bases and occlusion rims are triedin for patient comfort. They are removed. Theposterior limit is marked as discussed inChapter 15 and transferred to the upper recordbase and then to the cast. Alternatively, if a


5 mm10 mm A

Figure 9-11 Sketch of the two-tray or sectional custom impression tray method, whichcan be used only when there are no posterior teeth present (CID). A, Posterior tray; dottedline, anterior tray/impression material; CID, conventional immediate denture.

Figure 9-12 Sectional tray techniques use a posterior custom impression tray, which can becovered by an anterior custom impression tray (A) or a stock tray (B). (Courtesy Dr. Arnold Rosen.)

A B

record base was unnecessary, this transfer alsocan occur “by eye.”

3. An evaluation of the patient’s existing verti-cal dimension of occlusion is accomplished,determining if it should be retained. Onoccasion, the operator may wish to restore itby opening because the patient’s uneventooth loss, loosening of the remaining teeth,and tooth wear created overclosure. Attimes, the vertical dimension of occlusionwill have to be closed because drifting andextrusion of the patient’s teeth opened it.

The latter can be accomplished by grindingthe natural or stone teeth on the master cast.

4. The occlusion rims (and teeth if necessary)are trimmed to the desired vertical dimen-sion of occlusion. A face-bow transfer anda recording of centric relation are made(see Chapter 16).

5. The casts are mounted on the articulator(Figure 9-18).

6. Protrusive relation records are made, ifdesired, to transfer to the articulator in orderto set the condylar guidance.


Figure 9-13 The posterior component of the sectional impression technique (conven-tional immediate denture [CID]). Maxillary posterior section is border molded (A), and thefinal impression is made (B). C, Mandibular border molding. D, Impression.

C D

A B

Setting the Denture Teeth/Verifying JawRelations and the Patient Try-in Appointment

The articulated casts are used for setting any ante-rior/posterior teeth that are missing so that a try-incan be accomplished with the patient. A try-in isnot always possible (e.g., when all teeth in the archare present as in some patients with IIDs), but themounting should still be confirmed at a patientvisit. In Figure 9-19, the posterior teeth are missing(CID) so that a try-in is possible.

1. Set the posterior teeth as described in Chapter17. Set the teeth in tight centric occlusion.

2. The trial denture bases are tried in the mouth andused to verify vertical dimension of occlusionand centric relation as with complete dentures. Ifnecessary, the lower cast is remounted with a newcentric relation record until the articulatormounting and the patient’s centric relation coin-cide. Teeth are reset to any new mounting andtried in again. For patients where a try-in is notpossible, a verifying centric relation recordshould be taken to confirm the jaw relationship.

3. Now it is important to take time with the patientto record landmarks on the casts and to confirmthe patient’s esthetic desires. Much of what fol-lows has already been done as a preliminary


Figure 9-14 The anterior component of the sectional impression technique andreassembly with posterior section (conventional immediate denture [CID]). A, Maxillary poste-rior impression reseated in the mouth. B, Try-in of the anterior section of maxillary tray.C, Sectional maxillary final impression removed (by unhinging) together and reassembled.D, Mandibular completed final sectional impression.

C D

A B

measure at the diagnostic or diagnostic mount-ing phase. If available, the mounted diagnosticcasts should accompany this visit to serve as areference.a. The midline or newly selected midline is

recorded on the base area of the master casts.The middle of the face is usually the bestchoice for the midline, but this should be con-firmed with the patient. It should be pointedout to the patient if the selected midline doesor does not coincide with the middle of thephiltrum or the midline of the lower teeth.Some patients will prefer that it does.

b. The anterior plane of occlusion (using theinterpupillary line as a guide) is determinedand marked on the base of the cast. Theremaining canines may not be coincidentwith this plane. Two teeth should be foundthat are parallel to the desired anterior planeof occlusion. If posterior teeth are still pres-ent at this stage, they may be extruded,which would distort the desired occlusalplane. Intraoral landmarks that correspondto the ala-tragus plane should be located andnoted. These can be used as an aid to drawan ala-tragus line on the base of the cast. Ifposterior teeth are missing at this stage, it iseasy to establish and record the ala-tragusline with the posterior tooth set up.

c. The high lip line should be determined.A discussion can then occur with the patientas to the display of tooth/gingiva that willbe attempted or the need for a localizedanterior alveolectomy if too muchtooth/gingiva display is anticipated (seepatient in Figure 9-1, A). Also note andshow the patient the posterior tooth displayin the buccal corridor. Make sure the patientsees and approves this.

d. A discussion of placement of diastemata,rotated teeth, notches, and other naturalarrangements should occur so that thepatient is actively involved in the estheticdecisions. Some patients want perfect-look-ing teeth because they never had them,whereas other patients will prefer a morenatural arrangement. They may not wantfriends and colleagues to know that anychange has occurred.

e. Note the existing anterior vertical and hori-zontal overlap. Often, in patients in whomdrifting and excursion have occurred, thiswill be severe. Most patients will want toduplicate the position of their natural teeth,but some do have rather unesthetic arrange-ments, the result of advanced periodontaldisease and drifting of teeth.

Determine how much vertical overlapneeds to be maintained for esthetics and pho-netics. Deep vertical overlaps are detrimentalto denture stability. If it is excessive, discusswith the patient the possibility of dentureretentive loss during excursions. Using aposterior anatomical tooth or increasing thehorizontal overlap to minimize the incisalguidance may be able to help here.

If horizontal overlap is excessive, deter-mine if maxillary anterior teeth need to beplaced farther back into the mouth to elimi-nate an unesthetic position or if the horizon-tal overlap needs to be preserved for lipsupport and phonetics. Lower anterior den-ture teeth can be tipped forward to eliminatesome of the excess horizontal overlap.Discuss with the patient the fact that anteriorteeth in dentures do not have centric relationcontact; this will be especially true if thehorizontal overlap is excessive. Make notes


Figure 9-15 Plaster and pumice (50:50) mix forboxing is the method least likely to cause distortion ofsectional impressions. Boxing wax is applied to this tocomplete the boxing before pouring the impression.

and mark the casts with planned changesafter receiving the patient’s approval.

4. Reevaluate any further tooth modifications fora smooth occlusal plane or for better centricrelation.

5. The casts are marked with all the informationjust listed and with information gathered duringthe initial oral examination. This should includepocket depths, free gingival margins, a linemarking the interproximal of each tooth, and adrawing of where the new tooth position shouldbe. One should duplicate these markings on thediagnostic casts for a back-up reference. The

tooth selection is confirmed with the patient(Figure 9-20).

6. A discussion of the surgical and denture place-ment protocol should occur to prepare thepatient further and to answer any questions thatthe patient may have had after reading the writ-ten instructions given earlier. It is always wiseto mention to the patient that circumoral tissueswill become edematous and discolored in thefew days or even weeks after insertion. Once theinflammatory response is resolved, the patientwill still experience a local sense of upper lippuffiness, due to the presence of a flange, which


Figure 9-16 Maxillary (A) and mandibular (B) final casts produced from the single fullarch custom impression tray method shown in Figure 9-10, for interim immediate dentures(IIDs). The final casts for a maxillary (C) and mandibular (D) conventional immediate denture(CID) are also shown.

C D

A B

is necessary for denture retention. This can bethinned after sore spots are eliminated, and thepatient should be reassured that the full upperlip sensation is usually temporary until the softtissues adapt.

7. If a change in the vertical dimension of occlu-sion is desired, and indeed feasible, the dentureteeth are reset or modified to the preferred ver-tical dimension of occlusion.

Setting the Anterior Teeth: Laboratory Phase

Setting anterior teeth for immediate dentures differsfrom that for complete dentures. An alternative or

“every other” tooth setup is suggested even ifduplicating the exact position of the remainingtooth is not the goal. Some authors have suggestedthe removal of all the teeth at this stage and then asetting of the denture teeth with the desired tootharrangement irrespective of where the natural teethwere. However, this method eliminates much valu-able information provided by the remaining teeth.The following tooth set-up technique is suggested:

1. Mark with an “X” (overdenture abutmentscan be marked with an “O”) and removewith a saw or cutting disk every other ante-rior tooth (in the case of IIDs, every otherposterior tooth as well) from the cast,


Figure 9-17 A, Mandibular record base with occlusion rim for an IID that uses theremaining teeth and halfway up the height of the retromolar pad as a guide to location ofthe posterior plane of occlusion. Maxillary (B) and mandibular (C) final casts and record basesfor conventional immediate dentures (CIDs).

B C

A


Figure 9-18 A, Mounted casts for immediate upper and lower dentures (IID). Rightlateral view (B) and left lateral view (C). For upper and lower CIDs, D, Frontal view.E, Right lateral view. F, Left lateral view. CID, Conventional immediate denture; IID,interim immediate denture.

C D

E F

A B

leaving at least one canine, central incisor,and lateral incisor. Trim the extraction siteon the cast with a carbide bur (wide, flutedones designed for stone trimming are best)as if the tooth had been removed and a smallclot had formed in the site. In other words,the resulting area should be concave and notconvex (Figure 9-21). Be conservative inthis trimming (Jerbi, 1966), using the pocketdepths as guides. The facial (only) portionof the extraction site can be further trimmedconservatively to the pocket depth line witha bur or a knife blade. The lingual or palataltissues should not be trimmed because they

will not collapse to the pocket depth afterextraction.

Overdenture abutments are trimmed toa dome shape to approximately 3 mmabove the free gingival margin or slightlyhigher than the final form (1 to 2 mmabove the gingival margin) planned. In theforegoing description, it is assumed thatlittle or no bone will be removed duringthe extraction. If an anterior alveolectomyis needed, the casts should be trimmedaccording to esthetic requirements and asdictated by careful radiographic scrutinyand surgical operator input. The maximum


Figure 9-19 A and B, Posterior tooth setup for a try-in for conventional immediate dentures(CIDs).

Figure 9-20 A, Casts and land areas marked with the new midline, anterior plane ofocclusion (interpupillary), high lip line, gingival margins, interproximals, and pocket depths.B, Tooth selection is confirmed with the patient.

A B

A B

amount of trimming possible is usuallyabout halfway between the buccal and thepalatal gingival margins. Final smoothingof the cast must be completed at the waxboil-out stage, often by the dental techni-cian. The prescription to the technicianshould note that this trimming should beconservative and serve only to smoothsharp edges and blend in the trimmedareas.

2. Set every other tooth in the maxilla first andthen the mandible, referring to the notes andmarks made at the try-in visit. The goal is anoptimal esthetic result.

3. Then remove the remaining teeth and com-

plete the entire setup. Bring posterior teethforward, close diastemata if desired, andfinalize the setup for a balanced occlusionas needed (Figure 9-22). A Boley gauge orvisualization can be used to compare thepreexisting distance between the canines onthe preextraction diagnostic cast and thenew tooth arrangement (Figure 9-23).

4. An extra visit to recall the patient fora look at the final wax-up is a good ideaat this time. This serves to reassuresome apprehensive patients and mayeven provide them an opportunity to intro-duce minor artistic refinements in thesetup.


Figure 9-21 A, Use an “X” to mark an alternate tooth for removal, an “O” to mark anoverdenture abutment, lines to mark interproximals, lines to mark the free gingival margin,and a line on the tooth to mark any planned raised position. B, The extraction site istrimmed conservatively. C, The extraction site should be convex (not concave). Note themidline and interpupillary line, which has been transferred to the base of the cast.

A

B C

Wax Contouring, Flasking, and Boil-Out

1. The wax contour is similar to that for completedentures, although the immediate denture maybe thinner, especially in the anterior. Make surethat wax is added to provide a thickness of

material for strength during future deflasking.Also, when denture insertion is first attempted,it will undoubtedly bind on undercut areas.Thickness of the acrylic resin is needed toprovide room to trim from the inside to relievethe sore spot or to seat the denture.


Figure 9-22 A, Every other tooth is set on the maxillary and the mandibular casts.B, The remaining teeth are removed. C to F, The setup is completed and waxed-up.

C D

E F

A B

2. A remount cast to preserve the face-bow shouldbe done for later patient remounting 2 to 4weeks after delivery.

3. The casts are flasked in the usual mannerfor complete dentures. At boil-out, the castshould be smoothed with a knife to a harmo-nious rounded contour (Figure 9-24). Customcharacterization of the denture bases also ispossible at this time.

Surgical Templates

A surgical template is a thin, transparent formduplicating the tissue surface of an immediatedenture and is used as a guide for surgically shap-ing the alveolar process (Farmer, 1983). It is aprescription for the surgical procedure and isessential when any amount of bone trimming isnecessary.

This template is fabricated (usually by the den-tal technician) by the following procedure:

1. Make an irreversible hydrocolloid (alginate)impression of the edentulous ridge after the casthas been trimmed at boil-out.

2. Pour the impression in stone.3. Make a clear resin template on this duplicate

cast by any of these four methods:a. Vacuum form method (a hole is placed in the

center of the cast and a clear sheet is vacu-umed onto the cast)

b. Sprinkle-on technique (a clear acrylic[orthodontic] resin is used)

c. Process template in clear acrylic resin (cre-ated by waxing up, flasking, and heat pro-cessing [Figure 9-25])

d. Fabricate the template in light-cured, clearmaterial


Figure 9-23 The preextraction casts and the final immediate denture wax-up can becompared. A, Maxillary. B, Mandibular.

A B


Figure 9-25 A surgical template is made at boil-out from the master cast (A) by makingan irreversible hydrocolloid (alginate) impression. B, This is poured in stone. C, A wax-up isdone. D, This can be processed in clear acrylic resin.

A B

C D

Figure 9-24 At boil-out, a knife is used to smooththe extraction sites to a harmonious rounded contour.

Processing and Finishing

1. The immediate dentures are processed andfinished in the usual manner of completedentures. If desired, a laboratory remountcan be accomplished before removing thedentures from their casts and finishing. Keepthe undercut areas of the denture slightlythick at this point to allow for insertion overundercuts. Using an upward/backward pathof insertion of the immediate denture atplacement may allow insertion without trim-ming; regardless, these areas can be thinnedlater before sending the patient home.

2. It is best to keep all posterior undercuts atthis point because often they do not needreduction but can be well managed byselecting an alternate path of insertion andwithdrawal of the denture combined withjudicious trimming of the width of theinside of the resin flange in these areas atthe placement visit. Any bumps inside theimmediate denture resulting from over-trimming of the cast should be reduced toallow for a convex ridge healing. Theseprocedures are duplicated on the surgicaltemplate.

3. Both the immediate denture and the surgicaltemplate should be placed in a chemicalsterilizing solution in a bag for delivery.

Surgery and Immediate Denture Insertion

1. The patient can see the practitioner first forreduction of any overdenture abutments(Figure 9-26) or sectioning of any preexist-ing fixed partial dentures. The dentistperforming the operation then extracts theremaining teeth, taking care to preservethe labial plate of bone. Usually, no bonetrimming is done.

2. The surgical template is used as a guide toensure that the prescribed bone trimming isdone adequately. The template should fitand be in contact with all tissue surfaces.Inadequately trimmed areas planned forbone reduction will blanch from the pres-sure and be seen through the clear template.

The template is removed and the bone orsoft tissue trimmed until the template seatsuniformly and completely. This indicatesthat the denture will seat as it was originallyintended, to ensure proper occlusion andminimally induced discomfort.

3. Sutures are placed where necessary (Figure9-27). (With simple extractions, none arepreferred.)

4. If the overdenture abutments must bereduced after the extractions, the extractionsockets can be protected during preparationby covering them with Burlew foil.

5. Usually, the dentist or surgeon places thedenture so that it seats well with good firmbilateral occlusion and no gross deflectivecontacts. Pressure areas inside the denture(indicated by rocking) can be located withpressure-indicating paste and trimmed. Ifthe occlusion is not correct, the dentureshould be rechecked for seating, particu-larly distally, the so-called denture heelareas, which are checked for interference.When occlusal prematurities are verified, aquick occlusal correction is done to allowsimultaneous bilateral contact (Figure 9-28). Further refinement of the occlusionusually is done at a later date. The frenashould be checked for proper relief.


Figure 9-26 The overdenture abutments are bestreduced by the application of a rubber dam to preventamputated crowns from entering the throat or airway.

6. On occasion, the denture will be found tobe inadequately retentive. This is fre-quently the case when both anterior andposterior teeth were extracted. A tissue-conditioning liner can be placed at thisstage, but the material should not beallowed to get into the extraction sites.Burlew foil can be used to cover the extrac-tion sites for this procedure. Carefullycheck the extraction sites before dismissingthe patient. Also trim any bumps or projec-tions of tissue conditioning material insidethe denture with a rounded hot instrument.If this is overlooked, normal socket healingwill be compromised, and the ridge willheal with small concavities overlying the


Figure 9-27 A, It was determined that this patient needed an anterior alveolectomy.B, The seated stent will show blanched areas where bone has not been trimmed adequately.C, After proper bone trimming, the template will seat uniformly. D, Sutures can then be placed.

Figure 9-28 At placement, good bilateral contactsshould be present.

A B

C D

extraction sites. A knuckle-shaped residualridge will result.

Some authors (Woloch, 1998) recommend thatinstead of extracting the remaining anterior teeth,decoronation (with pulpectomy as indicated) of thecrowns should be done instead. The advantagescited are better visualization (less blood), shorterplacement visit, no need for surgeon on the dayof placement, minimal pain and swelling, andease of distinguishing sore spots at adjustment vis-its (versus pain from extraction sites). The rootsare removed after several days through 2 to 3weeks. Disadvantages are that there is no tissuecollapse that can be planned when setting dentureteeth and extraction might be more difficult insome instances without the clinical crown.Contraindications include acutely infected teethand severe bilateral undercuts.

Postoperative Care and Patient Instructions

First 24 Hours The patient should avoid rins-ing, avoid drinking hot liquids or alcohol, and notremove the immediate denture(s) during the first24 hours. Because inflammation, swelling, anddiscoloration are likely to occur, their partial con-trol can be helped with ice packs (20 minutes on,20 minutes off) on the first day. Because ofswelling, premature removal of the immediatedenture could make its reinsertion impossible for3 to 4 days or until reduction of swelling. In addi-tion, if swelling occurs and the denture can bereinserted, the amount of sore spots created willbe increased. The patient should be reminded thatthe pain from the trauma of extraction would notbe eliminated by removal of the dentures from themouth. Analgesic medications are prescribed asrequired (Holt, 1986).

Patients should be alerted to expect minimalblood on their pillow during the first night, buttroublesome hemorrhaging is rare because thedenture acts as a bandage. The diet for the first24 hours should be liquid or soft, if tolerated.

The following should occur at the 24-hour visit(Figure 9-29):

1. Ask patients where they feel sore. Warnthem that you are going to remove the den-

ture and that this will cause some discom-fort. Have some dilute mouthwash readyfor the patient to rinse with. Remove thedenture and wash it.

2. Quickly check the tissues for sore spotsrelated to the denture; these will appearas strawberry-red spots. Usually, theseareas include canine eminences, lateral totuberosities; posterior limit areas; andretromylohyoid undercuts as well as anyother undercut ridge areas.

3. These areas may be related to the denturebases visually or with the adjunctive use ofpressure indicator paste. The correspondingareas are relieved in the acrylic resin. Thedenture should be kept out of the mouthonly for a very short time.

4. Adjust any gross occlusal discrepancy incentric relation or excursions.

5. Reevaluate the denture for retention. Place atissue conditioner if denture retention isunsatisfactory.

First Postoperative Week Counsel the patientto continue to wear the immediate denture atnight for 7 days after extraction or until swellingreduction. This ensures that a recurrence of noc-turnal swelling will not preclude reinserting thedenture in the morning. Starting immediatelyafter the 24-hour visit, the patient should beshown how to remove the denture after eating toclean it and to rinse the mouth at least three tofour times daily to keep the extraction sites clean.The denture should then be quickly reinsertedand worn continuously. After 1 week, sutures canbe removed (Figure 9-30), and the patient canbegin removing the denture at night.

Further Follow-up Care

During the first month after insertion, the patientis seen on request or else weekly as required forsore spot adjustments. Denture adhesives can beused during this period as an aid if retention islost between visits. After 2 weeks, remount castsare poured, the maxillary denture is related to itssemiadjustable articulator using the remountmatrix made before flasking, a centric relation



Figure 9-30 Patient’s healing after 1 week in the maxillary (A) and mandibular (B) arch.A B

A CFigure 9-29 The patient (A) and the maxillary (B) and mandibular (C) arches 24 hoursafter extraction. Sore spots are evident on the mandibular anterior buccal ridge.

B

record is used to remount the mandibular denture,and refinement of the occlusion is performed(Figure 9-31).

If the opposing arch is not a denture, a cast ofthe opposing restored or unrestored arch is madein an irreversible hydrocolloid (alginate) impres-sion and related to the immediate denture on thearticulator in a manner similar to the one justdescribed.

Subsequent Service for the Patient with anImmediate Denture

After the sore spots are eliminated and the tissueshave healed, a recall program for changing the tis-sue-conditioner liner is organized. Ridge resorptionis fastest during the first 3 months (Tallgren, Lang,and Walker, 1980). The frequency of changing theseliners varies from patient to patient and is influencedby denture hygiene frequency and methods, diet, andsmoking habits. New light-cured soft liners may lastlonger in some patients. The major determinants ofthe frequency of changing temporary liners are therate and amount of ensuing bone resorption and theability of the patient to keep the liner clean.

Research shows that complete socket calcifica-tion is complete at 8 to 12 months after tooth extrac-tion and that bone volume of the ridge is reduced20% to 30% during the first 12 months. The resorp-

tion in the lower ridge is about twice that for theupper ridge (Tallgren, Lang, and Walker, 1980)Practically speaking, patients with CIDs frequentlyprefer to have a definitive reline (laboratory acrylicor chair side acrylic or light-cured resin) done withinthe first 3 to 6 months. This is acceptable, butpatients should be told that their denture-supportingarea will continue to remodel and that further relineswill probably be necessary (at an additional fee forservice). Regular visits and adjustments are neededthroughout the first year (Tallgren, Lang, andWalker, 1980).

Patients with IIDs can have their second denturestarted within 3 to 6 months if desired. Again, thissecond denture may need a reline (laboratory acrylicor chair side acrylic or light-cured resin) after tissuescomplete their full healing. The advantage here is thatthe IID can be worn as a spare if a laboratory relineis selected for the second denture.

Change in Plans

Infrequently, imperfect results demand thatthe patient with a CID become the patient with theIID by default, or after the fact. This may be due toprocessing errors or unmet expectations forthe CID. In such situations, a new second denture(instead of a reline of the CID) is fabricated.Because of this possibility, all patients with CIDsshould be informed that there is always the remotechance that the CID could turn out to be an IID anda second denture may need to be made. The feestructure would be adjusted because clearly, a sec-ond denture is more expensive than a reline.

In a similar manner, a planned IID can turnout to be the final prosthesis (as in the CID).When all goes well, the dentist and the patientmay be so pleased with the interim denture thatit is relined as the final denture.

Overdenture Tooth Attachments, Implants,or Implant Attachments

When patients with immediate overdentures havean indication for an overdenture attachment, itshould be accomplished after healing and beforethe definitive prosthesis so that attachment compo-nents can be processed into the second denture orreline (Figure 9-32).


Figure 9-31 All dentures should be remountedafter delivery. Remounting the immediate dentureshould occur after swelling has subsided, betweenweek 1 and week 2 postoperatively.


Figure 9-32 A, Patient for whom immediate overdentures with lower attachments areplanned if the retention of the lower overdenture is not as expected. B, Denture try-in atcorrect vertical dimension of occlusion. C, Placement of immediate upper and loweroverdentures. D, Zest Anchor attachments are done after healing and before reline or seconddenture (E) so that attachment components can be processed into the definitive prosthesis.(D, Zest Anchor, Inc, Irvine, Calif.)

B

A

C

D E


Figure 9-33 Candidate for maxillary immediate denture who would like an implantretained overdenture as her final treatment outcome. A, Patient’s smile with her remainingteeth. B, Teeth in occlusion. C and D, Preoperative radiographs. E, Final mounted interimdenture maxillary cast against opposing arch. Denture tooth position planning must occur atthis stage for the eventual placement of the four implants and bar assembly. F, Placement ofthe interim denture (IID).

A B

C D

E F

Continued

If the patient’s treatment plan includesimplants, such as an implant retained overdenture,the implants can be placed and allowed to healunder the immediate denture. Care should be takento avoid wearing the prosthesis for the determinedtime after implant surgery (usually 1 to 2 weeks).The immediate denture can be reinserted afterrelieving and tissue-conditioning procedures.

After implant uncovering, the immediate den-ture is relieved to accommodate the healing abut-ments and serve as the prosthesis until replacementby the implement prosthesis. Figure 9-33 shows

an immediate denture patient who illustrates thissequence of events.

SUMMARYImmediate dentures fulfill an important role intoday’s treatment modalities by providing thepatients with esthetics, function, and psychologicalsupport after extractions and during the healingphase. The technique is more demanding than reg-ular complete dentures for both the patient and thedentist. If the patient is well prepared and the


Figure 9-33 cont’d G, A clear resin duplicate of the interim denture serves as a surgicaltemplate. Its placement on the preliminary cast helps to plan the best implant/bar assemblylocation. H, After implant placement and healing, try-in of final implant bar assembly. I, Finalimplant attachment overdenture. J, Patient’s smile with (second) implant overdenture. Ifplanned well, the patient’s interim denture can also be relined to “fit” the bar assembly.

G H

I J

appropriate type of immediate denture is selected(conventional or interim), the resulting prosthesiscan be a success.

ACKNOWLEDGMENTSGratitude is expressed to Dr. Arnold Rosen for hisslides in Figure 9-12, Dr. Victor Fong for his treat-ment/laboratory procedure shown in his patientthroughout the chapter, and Mr. David Baptistefor his tinting and processing of the photographeddentures.

ReferencesAcademy of Prosthodontics Editorial Staff. The glossary of

prosthodontic terms: seventh edition, J Prosthet Dent 81:76,78, 1999.

Campagna SJ: An impression technique for immediate dentures,J Prosthet Dent 20:198-202, 1968.

Campbell RL: A comparative study of the resorption of the alve-olar ridges in denture wearers and non-denture wearers,J Amer Dental Ass 60: 146-148, 1960.

Carlsson GE, Bergman B, Hedegard B: Changes in contour ofthe maxillary alveolar process under immediate dentures: alongitudinal clinical and x-ray cephalometric study covering5 years, Acta Odontol Scand 25: 45-75, 1967.

Cohen BD, Mullick SC: Conversion of a fixed/removable partialdenture into an immediate provisional complete denture, J NJ Dent Assoc 65:19-21, 1994.

Farmer JB: Surgical template fabrication for immediate den-tures, J Prosthet Dent 49:579-580, 1983.

Goldstein GR: An alternative immediate complete dentureimpression technique, J Prosthet Dent 67:892-893, 1992.

Hay CD: Direct provisional immediate denture is comfortabletransition, J Indiana Dent Assoc 77:14, 1998.

Heartwell CM and Salisbury FW: Immediate dentures: an eval-uation, J Prosthet Dent 15(4): 616-618, 1965.

Holt RA Jr: Instructions for patients who receive immediatedentures, J Am Dent Assoc 112:645-646, 1986.

Jerbi FC: Trimming the cast in the construction of immediatedentures, J Prosthet Dent 16(6): 1048-1051, 1966.

Jonkman RE, Van Waas M, Kalk W: Satisfaction with completeimmediate dentures and complete immediate overdentures:a 1-year survey, J Oral Rehabil 22:791-796, 1995.

Kelly EK, Sievers RF: The influence of immediate dentures ontissue heating and alveolar ridge form, J Prosthet Dent 9(5):739-742, 1958.

Khan Z, Haeberle CB: One appointment construction of animmediate transitional complete denture using visible light-cured resin, J Prosthet Dent 68:500-502, 1992.

McGarry TJ, Nimmo A, Skiba, JF et al: Classification systemfor partial edentulism, J Prosthodont 11:181-193, 2002.

Payne SH: A transitional denture, J Prosthet Dent 14:221-2241964.

Pence B Sr, Lee MW, Baum L: Transitional dentures: a betterimmediate prosthesis leads to successful restoration,General Dentistry 40:319-23, 1992.

Raczka TC, Esposito SJ: The “jiffy” denture: a simple solutionto a sometimes difficult problem, Compendium ofContinuing Education in Dentistry 16: 914, 1995.

Rayson JH, Wesley RC: An intermediate denture technique,J Prosthet Dent 23:456-463, 1970.

Seals RR Jr, Kuebker WA, Stewart KL: Immediate completedentures, Dent Clin North Am 40:151, 1996.

Soni A: Use of loose fitting copper bands over extremely mobileteeth while making impressions for immediate dentures,J Prosthet Dent 81:638-639, 1999.

Tallgren A, Lang BR, Walker GF et al: Roentgen cephalometricanalysis of ridge resorption and changes in jaw and occlusalrelationships in immediate complete denture wearers, J OralRehabil 7:92, 1980.

Terry BC, Hillenbrand DG: Minor preprosthetic surgicalprocedures, Dent Clin North Am 38:193-216, 1994 (review).

Vellis PA, Wright RF, Evans JH et al. Prosthodontic manage-ment of periodontally compromised patient, N Y State DentJ 67:16-20, 2001.

Woloch MM: Nontraumatic immediate complete dentureplacement: a clinical report, J Prosthet Dent 80:391-393, 1998.

Zalkind M, Hochman N: Converting a fixed partial denture toan interim complete denture: esthetic and functional consid-erations, Quintessence Int 28:121-125, 1997.


C H A P T E R 10OverdenturesGeorge A. Zarb, Rhonda F. Jacob, John P. Zarb

160

Dentists have long recognized the difference thatthe presence of teeth makes to preservation of alve-olar ridge integrity (Figure 10-1). It appears thatthe presence of a healthy periodontal ligamentmaintains alveolar ridge morphology, whereasa diseased periodontal ligament, or its absence, isassociated with variable but inevitable time-dependent reduction in residual ridge dimensions(see Chapter 2). In the past the extraction of entiredentitions with complete denture replacementsused to be promoted as an inexpensive and perma-nent solution for oral health care. The legacy ofthis approach has become a major oral morpholog-ical problem: advanced residual ridge resorption(RRR). Ongoing and frequently rapid reduction inedentulous ridge size appears to be multifactorialand is imperfectly understood. However, clinicalexperience and compellingly documented researchhave underscored the merits of retaining naturalteeth to serve as abutments under complete den-tures or else under extensive or distal extensionareas of removable partial dentures. The premise isthat occlusal forces of a functional and parafunc-tional nature that exert an adverse influence ondenture-supporting tissues need to be attenuated orreduced and that attempts to clinically address thisproblem are an important part of the RRR para-digm that the dentist can control. Thus we have thetechnique of designing overdentures, which alsohave been described as hybrid dentures, or teeth-supported or assisted complete dentures. Theretained teeth abutments may be few or numerous,coronally modified or restored, and frequentlyendodontically prepared. The objective is to dis-

tribute stress concentration between retainedteeth abutments and denture-supporting tissues(Figure 10-2).

The overdenture technique was originally intro-duced to reconcile a need for maximum support inmorphologically compromised dental arches witha desire to improve equally compromised estheticappearance resulting from undersupported circum-oral tissues. Consequently, patients with congenitalanomalies such as cleft palates or those with seque-lae of maxillofacial trauma were the usual candi-dates for the service (Figure 10-3). Eventually, themerits and ingenuity of the technique encourageddentists to prescribe it for patients who had worndentitions or anomalies that included missing teethand when unfavorable jaw size or position couldnot be rectified by orthognathic surgery (Figures10-4 and 10-5). Above all, the technique was incor-porated into the management of patients withpartial or terminal dentitions, especially whencomplete dentures seemed a likely therapeuticoption. In fact, in today’s dental practices, it is mostunlikely that immediate dentures are ever pre-scribed without diligent efforts made to retain abut-ment teeth (even if provisionally) for an immediateoverdenture service (see Chapter 9).

Most prosthodontic educators and researchersnow recognize that the technique helps reduce theimpact of some of complete denture-wearing con-sequences: RRR, loss of occlusal stability, under-mined esthetic appearance, and compromisedmasticatory function. The technique has also beenregarded as a gentler transition to the completelyedentulous state.

Van Waas et al. (1993) randomly assigned74 subjects to immediate complete dentures versusimmediate complete overdenture prostheses sup-ported on two mandibular canines. They evaluatedthe loss of bone in the canine area using cephalo-metric radiographs. The authors reported a reduc-tion of 0.9 mm in the overdenture group and1.8 mm in the denture group; in the molar area theloss of bone was 0.7 mm and 1.9 mm, respectively,with all measurements being statistically signifi-

cant. The clinical retention of bone surrounding theabutments has been clinically observed by most cli-nicians using this technique.

ADVANTAGES AND DISADVANTAGESDemonstrated, cited advantages of overdenturesinclude the following: (1) There is maintenance ofmore residual ridge integrity than if an “unsup-ported” denture is worn. This results from presumed

Chapter 10 Overdentures 161

pm

spNL

ba

a

b

MLgn

A B

CFigure 10-1 A, Dramatic residual ridge reduction (RRR) of the mandibular edentuloussegments contrasts sharply with integrity of the alveolar ridge where the incisors are present.B, Virtual absence of the upper and lower alveolar ridges in the mandible of a 13-year-oldboy whose dentition was congenitally absent. C, Measurements of ridge reduction/resorption.The anterior height of the upper and lower alveolar ridges at two stages of observation (a andb). The difference (a and b) represents reduction of the ridges between observations. Shadedarea denotes the resorption. (C, Modified from Tallgren A: J Prosthet Dent 27:120-132, 1972.)

improved occlusal stress distribution. (2) Denturestability and even retention (particularly in themandible) may be enhanced. (3) Patients’ subjec-tive perceptions regarding a retained “naturalfeeling” tend to be positive ones. This may translateinto better occlusal awareness, biting force, andconsequent neuromuscular control than if the abut-ments in the overdenture were absent. (4) The tech-nique is a viable and simple alternative to completedenture therapy, and it is frequently self-reported asproviding immense psychological support forpatients. (5) Its application is virtually unlimitedand depends on the dentist’s judgment and skilland, above all, on the patient’s motivation to main-tain an impeccable oral environment (Figure 10-6).There are also disadvantages to the technique, andit is prudent to regard it as a likely provisional one.The likely time-dependent transition to completedenture treatment is largely related to the patient’soral hygiene commitment and the nature of theselected abutments. It must be emphasized that thecovered teeth abutments’ environment is not con-ducive to maintaining a plaque-free milieu with itsserious risk of adverse sequelae. Furthermore, theage-related inability to apply a scrupulous hygiene

protocol and the presence of refractory periodontaldisease are serious deterrents to successful teethretention outcomes. Thus many clinicians fre-quently cite significant occurrence of caries andperiodontal disease around abutments. Caries can,of course, develop rapidly, with different degreesof susceptibility recorded, particularly amongolder persons. However, some studies have alsoemphasized the feasibility of controlling cariouslesions through nutritional counseling, sustainedprogram of oral hygiene, and regular fluorideapplications.

The prevention of gingival and periodontaldisease is a very compelling concern because itremains the patient’s responsibility, and scrupuloushygiene accompanied by biannual professionalmonitoring is mandatory to ensure continued abut-ment-supporting tissues’ health. This entails a rigidand frequent recall appointment protocol with itsimplied additional expense, and it is one that isincreased in the context of endodontic and frequentrestorative requirements. Furthermore, availableinterarch space is sometimes judged inadequate ontechnical convenience grounds, and extensive abut-ment or design modifications will be required to


A BFigure 10-2 The entire notion of the classic overdenture technique is depicted in A andB. Two mandibular canines are morphologically altered after root canal therapy andextraction of adjacent teeth that demonstrated advanced periodontal disease. Their retentionand use as overdenture abutments ensure dentogingival support for the complete dentureand an expected reduction in residual ridge resorption (RRR) at least around and between theabutments. Overdenture treatment planning reconciles clinical decisions regarding numberand location of potential abutments, their restorative and endodontic status, and their usefor retention and support. A management strategy for their continued health status is alsoa required consideration.


A

B C

D EFigure 10-3 Clinical management strategy carried out on this 54-year-old man whosecongenital anomaly was surgically repaired in his youth (A to E). Note that congenitallyimpaired horizontal and vertical dimensions of the facial profile were esthetically correctedwith an overdenture.

expedite treatment. Potential weakness in the acrylicresin denture base also will need to be determined,and extra laboratory steps such as a cast metal super-structure fabrication can lead to additional expenses.

The increased costs associated with the tech-nique are, however, justified because overdenturesare a superior health service compared to the stan-dard complete denture.

INDICATIONS AND TREATMENTPLANNINGThe versatility of the overdenture service isdemonstrated in Figures 10-2 to 10-8. Thesepatient examples were selected to emphasize therange of treatment possibilities. Above all, they

underscore the logic of including the method as anintegral part of every dentist’s treatment-planningrepertoire. In general, there are two major groupsof patients who benefit from the technique. Group1 comprises patients with a few remaining teeththat may be healthy or with reversible periodontaldisease, that are coronally intact, or that are malpo-sitioned or morphologically compromised. Theseteeth can be modified for use as abutments.Treatment here is conceptually and technicallystraightforward with minimal preprosthodonticintervention needed. Analysis of articulated diag-nostic casts, full-mouth radiographs, and overallpatient concerns will enable the dentist to deter-mine potential abutment teeth’s restorative andendodontic requirements (if any) in the context of


A

B

C DFigure 10-4 A to D, Congenitally missing teeth have undermined both the appearanceand the functional efficiency of this patient. A maxillary overdenture resolved the problemand created a normal appearance. Note that minimal horizontal labiofacial support wasrequired here.


A B

CFigure 10-5 Patients with vertical or horizontal dimension deficits of their maxillaryarches can be managed prosthodontically by overlaying their maxillary dentition. Thisapproach permits improved horizontal facial support and increased vertical dimension ofocclusion. A, B, D, and E, Pretreatment views of a patient whose complaint of compromisedmasticatory function and poor esthetic appearance was attributable to a discrepancy in facialdevelopment. C and F, Post-treatment results were achieved without surgical orthognathicinterventions. Continued

the proposed overdenture’s design. Particular con-sideration should be given to those patients inwhom the overdenture will oppose a natural orrestored natural dentition (see Chapter 21). Thepresence of overdentured abutments in an other-wise edentulous arch will reduce the considerablerisk inherent in the stresses associated with anunbalanced hammer and anvil effect simulated bysingle complete denture therapy (see Chapter 2).

Group 2 comprises patients who received a diag-nosis of so-called mutilated or severely compromiseddentitions. These patients appear to be heading in anedentulous direction, and their treatment is definedby the complexity, expense, and time implications ofthe intervention. Selected extractions will need to becarried out, keeping in mind that retention of teethwith good alveolar support will preserve bone at theselected sites. Conversely, retention of periodontallycompromised teeth can only risk further depletion of

bone levels if such teeth are retained—thus the needfor their early extraction. Such an initiative could alsoserve to improve the periodontal status of the adja-cent retained teeth.

SELECTION OF ABUTMENT TEETHSpecific critical factors that influence the selectionof abutment teeth include periodontal status,mobility, location, and endodontic and prosthodon-tic considerations, with costs an ever-present andoften overriding consideration. The treatment planis defined by the number and required interven-tions on the retained teeth, as well as the following:

1. Periodontal and mobility status: An abut-ment root or tooth must be chosen that issurrounded by healthy periodontal tissues.The tissues may already be healthy or


D E

FFigure 10-5 cont’d

rendered so by appropriate periodontaltherapy (see Figures 10-6 and 10-7).Compromised teeth with a good treatmentprognosis are popularly regarded as suitablecandidates, even when horizontal bone lossis present. Conversely, significant verticalbone loss, particularly if accompanied bytype 2 or 3 mobility, generally precludesa tooth’s selection. Slight tooth mobility perse is not a contraindication because a favor-able change in the crown-root ratio mayameliorate this sign. A circumferential bandof attached gingiva, albeit a narrow one, isregarded as a mandatory requirement forabutment selection.

2. Abutment location: Because the anteriormandibular alveolar ridge appears to be mostvulnerable to time-dependent RRR, caninesor premolars are regarded as the best overden-ture abutments to reduce adverse forces at thissite. This conviction applies to the maxilla aswell, although incisors are also frequentlyused. The latter is particularly desirable if themandibular arch is intact or is a naturallyrestored one. Clinical experience supports therecommendation of at least one tooth perquadrant. If this recommendation is exceeded,retained teeth should preferably not be adja-cent ones, or there should be several millime-ters of space between the reduced tooth forms.


A B

C DFigure 10-6 This example of mandibular overdenture treatment in a 45-year-old womanwith periodontal disease underscores the simplicity of the technique as well as its advantagesand disadvantages. The panoramic views in A and B are separated by an interval of 7 years.Although such radiographic precision is not scientifically quantifiable, it still suggests animpressive retardation in residual ridge resorption (RRR). C, The prepared root surfaces wereleft “bare,” but no caries activity or increased periodontal disease progress was noted. Clearly,the patient’s home maintenance program, which included fluoride gel use, has yieldeda very good treatment outcome (D). The status of the prosthesis has been well monitored.

This will minimize the risks of compromise insoft tissue health. Some authors haveexpressed serious concerns about preservingor restoring balance of forces between theopposing arches. This notion underscores theimportance of the dentist’s reconciliation ofthe number and location of retained abutmentsin either arch and the status of the opposingone. Ultimately, this must be assessed in thecontext of the status of the mandibular“hammer” and maxillary “anvil” concept dis-cussed earlier. Considerations for selectingmaxillary overdenture abutments are summedup in Table 10-1.

3. Endodontic and prosthodontic status:Anterior single-rooted teeth are easier andless expensive to manage endodontically.Whenever pulpal recession to the extent ofcalcification has occurred, endodontic treat-ment usually can be avoided. The clinicalcrowns can be modified for technical con-venience and treated with sealant restora-tions or fluoride applications. In recent yearsthe use of cast copings has been largelyeclipsed by composite and alloy restorations,with or without adjunctive retention.

Various methods and devices have been proposedfor preparing abutment teeth to receive an over-


A B

C DFigure 10-7 A and B, The presence of severe adult periodontal disease necessitatedextraction of selected teeth and subgingival root planing of retained overdenture abutments.C and D, Endodontic treatment and alloy restorations ensured 6 years of excellentprosthodontic rehabilitation. With ongoing clinical monitoring and good home care, weanticipate a good prognosis for this patient’s treatment outcome.


Table 10-1Considerations in Selection of Maxillary Teeth as Overdenture Abutments

Maxillary Teeth Advantages Disadvantages

Central incisors Ideal location, provide protection Proximity and alveolar prominence may complicate of the premaxilla utilization

Lateral incisors Widely separated, facilitating Diminished root surface areaplaque control

Tissue undercuts do not pose a problem

Path of placement/removal is not compromised

Ability to create a flange/peripheral seal

Canines Longest root of the anterior teeth Diverging facial tissue undercutsOvercontoured flangesExcessive lip supportPotentially uncomfortable placement/removal of

prosthesisComplicates placement of prosthetic teethInternal relief to accommodate canines may weaken,

create a food trap, compromise the peripheral seal

From Nelson DR, von Gonten AS: Biomechanical and esthetic considerations for maxillary anterior overdenture abutment selection, J Prosthet Dent72:133-136, 1994.

denture. It is our impression that the essentialfeature in this technique is not the type of attach-ment used per se but the following basicprinciples:

1. Maximum reduction of the coronal portionof the tooth should be accomplished.A better crown-to-root ratio is established,and minimal interference will be encoun-tered with the placement of artificial teeth.The routine use of endodontic therapyincreases the coronal reduction that can beachieved. Patients with advanced pulpalrecession, usually combined with extensivetooth wear, can undergo coronal reductionwithout the need for endodontic treatment(see Figure 10-8). A clinical decision toleave the prepared abutment tooth “bare” or“unprotected” versus “to protect” it witha coping has fiscal and design implications.Frequently, a devitalized and broken-downtooth can be restored with an alloy or a com-posite, reshaped, and polished with finesandpaper disks. In most situations, a baretooth root preparation can provide adequate

long-term service for both immediate andreplacement overdentures and is the selec-tion of choice. This preparation is madewhen time is needed to evaluate the status ofselected abutment teeth and when a patient’s(usually an elderly one’s) general health pre-cludes several dental appointments. It is alsothe least expensive option, and a coping’spresumed protective qualities can probablybe exceeded with fluoride gel application,maintenance of an excellent level of oralhygiene, the use of chlorhexidine mouth-washes, and appropriate adjunctive restora-tive therapy. Study results are ambiguous atthis time as to whether alloy, resin compos-ite, glass ionomer, or resin-modified glassionomer materials are the recommendedmaterial for filling endodontic openings. Allthese materials have produced clinical suc-cesses. Fluoride release of glass ionomershas not been compellingly evaluated in anoverdenture population, and use of thismaterial should not preclude additionaldaily fluoride regimens. Success of any ofthe materials requires routine follow-up to

A

B C

D EFigure 10-8 A and B, Advanced, symptomatic teeth wear and pulpal recession ina patient whose dentition showed considerable morphological changes and neglect. C and D,Three maxillary anterior teeth were retained, and an overdenture was constructed (E). Someof the badly worn anterior mandibular teeth were reduced/reshaped, polished, and partially“restored” with a cast removable partial denture of the overlay type.

evaluate the integrity of the restoration, andmoreover, to evaluate home care of the abut-ment. The clinician is encouraged to contin-ually evaluate current dental literature onthis topic of dental materials for abutmentrestoration.

2. The need for a gold coping or a crown-and-sleeve coping retainer depends onseveral factors. Occasionally, a gold copingis necessary and can be prepared with orwithout a post or retentive pins, dependingon the amount of tooth structure remainingabove the gingival attachment. Often thecoping preparation can extend into theendodontic preparation to gain increasedsurface area. The gold coping (Figure 10-9)

does involve an additional expense, butsome patients are uncomfortable with thesight of discolored and “unprotected” rootsin their mouth. The patient’s susceptibility tocaries must also be considered because pro-vision of a coping does not guaranteereduced caries activity. Tooth preparation issimilar to that for a complete gold crown,with or without additional pin retention, andit includes a combination of shoulder andchamfered gingival margins as dictated bythe amount of residual tooth structure. Itmust be emphasized that the main objectivein preparing and restoring overdenture abut-ments is to prolong the useful life span ofthe retained abutments and the preservation


A B

CFigure 10-9 A, Gold copings to protect and partially restore the mandibular canines. B, An overdenture has been modified out in these areas to conform to the abutmentcontours. C, The cosmetic merits of the complete denture are in no way compromised.

of alveolar bone; it is not necessarily tointroduce a technique for more retentivedentures. Consequently, a simple, short,convex abutment preparation (with orwithout a casting) appears to be the optimalroot surface preparation.

3. Provision of some sort of attachment mech-anism on a cast coping also is popular(Figure 10-10). This is an extension of theprecision-retained abutment concept used inremovable partial dentures and modified foruse with overdenture abutments. It is a tech-nically ingenious idea and offers a diversityof techniques, for example, intracoronal and

extracoronal attachments, chairside attach-ments, or indirect attachments with castcopings. Several of these attachments areavailable in resilient and nonresilientdesigns. The notion of underscoring the useof such attachments shifts the overdenturedesign from stability and retardation ofRRR concerns to major emphasis on pros-thesis retention. Apart from the increasedexpense, the risks are increased technicaldemands and difficulties, particularlywhen repairs are required, oral hygienemaintenance requirements may be moredemanding, and esthetic plus interarch


A B

C DFigure 10-10 Although attachments in general may not be needed, they can improvesupport, stability, and retention of the overdenture. Some clinical examples are shown. A andB, The Dalbo Rotex chairside attachment system: male portion cemented in the abutmentteeth and female housing embedded in the acrylic of the overdenture. C and D, TheCeka-Revax attachment system: the male stud-type attachment is soldered to a coping.Fixation is achieved by the female housing embedded in the (maxillary) overdenture.

space concerns are usually more severe.Nonetheless, attachment systems expand thescope of the overdenture technique inselected specific situations in which reten-tion concerns dominate in the context ofavailable design considerations.

Gold copings and telescopic crowns are a methodof improving overdenture retention. These may beconical crowns with a friction adaptation at themarginal area of the abutment or milled crownswith larger surface area for frictional retention.Frictional retention is more commonly used inexclusively tooth-supported overdentures that arenot supported by soft tissue. In overdenture situa-tions where the prosthesis also rests on resilientedentulous ridges, the copings and telescopiccrowns are usually designed with a relief areaof 0.3 to 0.5 mm, allowing tissue-ward movementand lateral movements. Retention is obtained byother devices. The remainder of the edentulousridge is covered by acrylic resin bases. The tele-scopic crowns resemble porcelain crowns, and theyare incorporated in the overdenture. Wenz et al.(2001) have described these methods with both (1)complete tooth-supported and (2) tooth- and tissue-supported dentures. Tooth- and tissue-supporteddentures had an average of three or fewer abut-ments. The total of both groups in the Wenz studywas 125 subjects with 460 abutments. A total ofonly 16 subjects lost 38 abutments, and the proba-bility of keeping all abutments was similar in bothgroups, with 84% (95% confidence interval [CI],67-94) at 5 years and 66% (95% CI, 38-84) at10 years. We stress that these abutments should bein very good health when considered for thisrestoration technique.

LOSS OF ABUTMENT TEETHSeveral studies have reported loss of abutmentteeth during varying observational follow-upperiods. After 5 to 6 years, about 10% of abutmentteeth supporting overdentures were lost. The mostfrequent causes were periodontal disease (about70%), caries (about 25%), and endodontic compli-cations (about 5%). Many of the long-term clinicalstudies of overdenture populations have beenfraught with logistical problems of poor clinical

follow-up and poor patient compliance in homecare. Therefore their projection of abutment loss isa suspect point estimate, but one that can beexplained through little fault of the investigators orclinicians. This patient population is usually older,with other health problems, social problems offinances and transportation, and an overall lack ofperceived dental need. Many authors reported thatalthough yearly or biannual examinations wereplanned, after a few years, more than 25% of pop-ulations ceased evaluations or were sporadic inattendance. The level of compliance with homecare was also sporadic and at times nonexistentbecause this was a patient population that likelyhad long-standing habits leading to a terminal den-tition that culminated in the overdenture treatmentplan. What is compelling in this population is thepossible vulnerability of the abutments, and it isclear that the success of overdenture treatmentdemands effective prevention of caries and peri-odontal disease. Regular follow-up visits are essen-tial, and oral health maintenance measures areperiodically reviewed and revised as necessary.

Ideally the patient must be well motivated tomaintain the hygienic phase of periodontal care. Ithas been amply demonstrated that inadequate oralhygiene is a major contributor to abutment loss.Given the fact that this population may lack dexter-ity and motivation for adequate hygiene, one mightconsider the many mechanical toothbrushes thatare available. Lack of patient compliance and pre-dicted lack of motivation should not excludea patient from overdenture therapy. Griess,Reilmann, and Chanavaz (1998) described men-tally challenged subjects who maintained 81% ofthree-teeth telescopic overdentures at 8 years.Unfortunately actual “loss of dentures” was morea problem then loss of abutments. One-toothmandibular overdentures were not as well tolerated,and patients often discarded these dentures.

Long-term monitoring of patients with over-dentures reveals the occasional need for removal ofone or more abutment teeth. This must be expected,and the cause is usually a periodontal abscess.Removal of the affected tooth, with appropriatefilling in of the contacting site in the overdenture,can be done readily and inexpensively, without lossof the prosthesis. Caries accounts for the remainderof maintenance issues and abutment loss. Fluoride


gel is prescribed for daily application to the insideof the overdenture to bring the fluoride into inti-mate contact with the natural tooth structure. It isunderstood that the effectiveness of fluoride onroot and dentinal surfaces has not been as welldefined as fluoride remineralization and incorpora-tion in enamel. Studies of root surface caries inpatients exposed to lifelong fluoridated watersupply reveal a decrease in caries activity. Its usehas been prescribed for patients with overdenturesand seems to decrease caries activity. As in enamel,the greater the fluoride concentration, the greaterthe efficiency of the fluoride.

An in vitro evaluation was performed byEttinger et al. (1997) to simulate overdenture abut-ment root surface caries, and the depth of reminer-alization bands were evaluated with polarized lightmicroscopy. Fluoride preparations were 5000-ppmacidulated phosphate fluoride (pH 5.6), 5000-ppmneutral sodium fluoride, and 1000-ppm neutralsodium fluoride, with a distilled water control.Over 18 days the extracted teeth with exposed rootsurfaces were repeatedly placed in fluoride for4 minutes, then in a demineralizing solution for6 hours, and then in a remineralizing solution for17 hours. The lesions in the 5000-ppm preparationhad statistically shallower lesions. All groupsexcept the control group exhibited remineraliza-tion bands. Reduction of demineralization wasfound to have a dose response in favor of thegreater 5000 ppm. These findings are consistentwith in vivo fluoridated dentifrice studies on rootsurface caries.

Given these findings, one should consider thepreparations with greater fluoride concentrations.There are also dentifices with 5000-ppm fluoridethat can be prescribed. The role of preparation pHis also being questioned in root surface cariesmodels. The thought that the tissues may beseverely irritated by the daily use of fluorides withlow pH is an unlikely scenario because patientsundergoing irradiation have been using daily stan-nous fluoride preparations (pH 4.0) in tray applica-tors for 10 minutes daily for many years withoutnoticeable tissue irritation or patient complaints. Inaddition, stannous fluoride (SnF2) preparationshave been shown to inhibit plaque formation andperiodontal microorganisms in multiple periodon-tal studies. If patients complain about tissue irrita-

tions, neutral preparations can be considered. Theclinician should continue to evaluate the commer-cially fluoride preparations and the fluoride litera-ture as it relates to root surface caries andoverdenture abutments.

CLINICAL PROCEDURESThe procedures will vary depending on whethera tooth-supported complete denture is being con-structed or a tooth-supported immediate-insertioncomplete denture is planned (see Chapter 9).

Tooth-Supported Complete Denture

The important principles of complete denture con-struction must be respected and when required,matched to the technical and laboratory dictates ofselected attachment type. These principles areidentical to those described in subsequent chapters,and they should be meticulously observed.

One frequently encountered problem oftooth-supported complete denture service is thetendency for an unfavorable gingival responsearound the abutment teeth (Figure 10-11). The fol-lowing may cause gingival irritation: (1) movementof the denture base (more apparent in mandibulardentures), with the development of a loading factor


Figure 10-11 Gingivitis (arrowheads) around theabutments of an overdenture caused by inadequatehygiene measures of the patient. If untreated, thecondition may precipitate a series of adverse changesand actually progress to periodontal disease.

at the gingival margins; (2) poor oral hygiene withfailure to remove plaque or to pay sufficient atten-tion to tissue rest and periodic recall assessments;and (3) excess space in the prosthesis around thegingival margins of the abutment teeth, whichleads to the development of a “dead space” (apotential source of inflammation and tissuehypertrophy).

Clinical experience suggests that a slight spacearound the gingival margin is essential to avoidoverloading this particularly vulnerable site, espe-cially with mandibular dentures because theyappear to become dislodged more easily than max-illary dentures. On the other hand, a dead spacemay lead to a combined hypertrophic/hyperplasticresponse of the gingival margin similar to thatelicited by a relief chamber in a complete maxillarydenture. One way to avoid this is to hollow out anarea in the resin overdenture over the abutment siteand line it with a tissue conditioner at the time ofdenture placement. The resiliency of the liner,combined with its need for frequent replacement,can create an optimal schedule for recall appoint-ments. However, there also may be subsequentdeterioration of the material and, with it, the risk ofgingival tissue damage. Our preference thereforeis to use an autopolymerizing hard acrylic resinto reline the abutment area at delivery of theprosthesis.

Tooth-Supported Immediate-InsertionComplete Denture

The procedures for immediate tooth-supportedcomplete dentures are identical to those describedin Chapter 9, except that the coronal reduction ofthe selected abutment teeth is done at the time theremaining teeth are extracted. The teeth to beretained are prepared on the master cast to theapproximate shape of the pending abutment, andthe remaining teeth are trimmed from the cast inthe usual manner. The processed immediatedenture thus demonstrates depressions on itsimpression surface that will conform to the teeththat are being retained. The endodontic treatment iscompleted during one or more appointments beforethe immediate denture insertion or just before thecombined surgical-prosthetic appointment. Somedentists prefer the latter because removal of the

tooth crown facilitates the endodontic procedures.Immediate denture insertion and follow-up arecarried out in the usual manner (see Chapter 9).The need for refining the impression surface of thedenture in the operated on and abutment sites, bythe addition of a treatment resin, is essentialbecause rapid tissue changes are to be anticipated.When healing has occurred and tissues and remod-eling bone have achieved a stable contour, addi-tional coping preparation may be necessary withrefitting of the prosthesis in this area.

TREATMENT OUTCOME STUDIESThe desire to prolong the useful life of at leasta few of our patients’ teeth led to a dramatic surgeof interest in the overdenture concept. Severalreports endorsing the technique have been pub-lished and many anecdotal claims made, but untilrecently there has been a lack of well-documented,long-term clinical follow-up of these patients.Current research appears to endorse the claim thatoverdentures are an effective alternative to conven-tional complete denture therapy, and their use inroutine practice continues to be endorsed.However, the very nature of overdenture design andits relationship to plaque must always be kept inmind if this treatment modality is to fulfill itspotential. Furthermore, the impressive and virtu-ally morbidity-free outcomes reported inimplant-supported overdenture studies are nowbeginning to eclipse the traditional role ofteeth-supported overdentures.

SUMMARYRelatively short-term favorable outcomes with theoverdenture technique are well demonstrated andendorse routine prescription of the technique.Furthermore, the recent introduction of theosseointegration technique created the possibilityof converting patients with maladaptive completedentures into ones with adaptive overdentureswhen implants are used to stabilize “offending”prostheses. As a result, the twin techniques (tradi-tional complete denture fabrication with naturalteeth abutments or with implants) now offer den-tists and patients a new standard of prosthodontictherapy (see Part 4).


ReferencesBecker CM, Kaldahl WB: An overdenture technique designed to

protect the remaining periodontium, Int J Periodont RestorDent 4:28-41, 1984.

Budt-Jörgensen E: Prognosis of overdenture abutments inelderly patients with controlled oral hygiene: a 5 year study,J Oral Rehabil 22:3-8, 1995.

Derkson GD, MacEntee MM: Effect of 0.4% stannous fluoridegel on the gingival health of overdenture abutments,J Prosth Dent 48:23-26, 1982.

Ettinger RL, Jakobsen J: Caries: a problem in an overdenturepopulation, Community Dent Oral Epidemiol 18:42-45,1990.

Ettinger RL, Krell K: Endodontic problems in an overdenturepopulation, J Prosthet Dent 59:459-462, 1988.

Ettinger RL, Olson RJ, Wefel JS et al: In vitro evaluation oftopical fluorides for overdenture abutments, J ProsthentDent 78:309-314, 1997.

Ettinger RL, Taylor TD, Scandrett FR: Treatment needs of over-denture patients in a longitudinal study: five-year results,J Prosthet Dent 52:532-537, 1984.

Geertman ME, Slagter AP, Van Waas MAJ et al: Comminutionof food with mandibular implant-retained overdentures,J Dent Res 73:1858-1864, 1994.

Gotfredsen K: ITI-implants with overdentures: a prevention ofbone loss in edentulous mandibles? Int J Oral MaxillofacImplant 5:135-139, 1990.

Griess M, Reilmann B, Chanavaz M: The multi-modal prosthetictreatment of mentally handicapped patients-necessity andchallenge, Eur J Prosthodont Rest Dent 6:115-120, 1998.

Hussey DL, Linden GL: The efficacy of overdentures in clinicalpractice, Br Dent J 161:104-107, 1986.

Jensen ME, Kohout F: The effect of a fluoridated dentifrice onroot and coronal caries in an older adult population, J AmerDent Assoc 117:829-832, 1988

Johnson GK, Sivers JE: Periodontal considerations for overden-tures, J Am Dent Assoc 114:468-471, 1987.

Kalk W, Käyser AF, Witter DJ: Needs for tooth replacement, IntDent J 43:41-49, 1993.

Keltjens HMAM, Creugers TJ, Mulder J et al: Survival andretreatment need of abutment teeth in patients with overden-tures: a retrospective study, Community Dent OralEpidemiol 22:453-455, 1994.

Keltjens HMAM, Creugers TJ, Schaeken MJ et al: Effects ofchlorhexidine-containing gel and varnish on abutment teeth

in patients with overdentures, J Dent Res 71:1582-1586,1992.

Keltjens HMAN, Creugers TJ, van’t Hof MA et al: A 4-yearclinical study on amalgam, resin composite and resin-modi-fied glass ionomer cement restoration in overdenture abut-ments, J Dent 27:551-555, 1999.

Keltjens HMAM, Schaeken MJM, Van der Hoeven JS et al:Caries control in overdenture patients: 18-month evaluationon fluoride and chlorhexidine therapies, Caries Res24:371-375, 1990.

Keltjens HMAM, Schaeken MJM, Van der Hoeven JS et al:Effects of chlorhexidine gel on periodontal health of abut-ment teeth in patients with overdentures, Clin Oral ImplantsResh 2:71-74, 1991.

Lauciello FR, Ciancio SG: Overdenture therapy: a longitudinalreport, Int J Periodont Restor Dent 5:62-71, 1985.

Mericske-Stern EA, Mericske-Stern R: Overdenture abutmentsand reduced periodontium in elderly patients: a retrospectivestudy, Schweig Monatssche Zahnmed 103:1245-1251, 1993.

Mushimoto E: The role in masseter muscle activities of func-tionally elicited periodontal afferents from abutment teethunder overdentures, J Oral Rehabil 8:441-455, 1981.

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C H A P T E R 11Building Rapport: The Art ofCommunication in the Management ofthe Edentulous PredicamentHoward M. Landesman

177

There is an overwhelming amount of research datato confirm the enormous success achieved throughincorporating implants for managing the edentu-lous predicament. Accordingly, it is easy to con-clude that it is no longer necessary for thepractitioner to spend countless hours with patientsdiscussing how to adapt to a removable prosthesis.

The dentist can assume that the objectives oftherapy for the edentulous patient—retention, sta-bility, support, and esthetics—can be satisfied bythe use of implants. In fact, those dentists whothroughout their professional career declined toaccept edentulous patients now use implants toachieve the same optimal result in much the samemanner as restoring a partially edentulous spacewith a fixed prosthesis. It is a “dream come true”for the technically oriented dental professional. Is ittherefore possible for the practitioner to declarevictory in his or her need to communicate withpatients, and can effective communication skills beminimized?

This author wishes to convey to the reader thatcommunication is more than transmitting infor-mation. Communication is essential because it isan act of sharing. It is a participation in a rela-tionship that involves a deep understanding of thepatient. It includes an ability to listen, empathize,and ultimately establish a trusting doctor/patientrelationship.

Dentists are taught to be masters in technicalskills and to provide quick solutions to problems.However, many problems require “patience withpatients” through effective communication tech-niques and listening to the needs of those who seek

dental help. The purpose of this chapter is to sensi-tize the practicing dentist to the importance of thedoctor/patient relationship by building rapportthrough effective communication skills.

In his acceptance speech for the Nobel Prize forliterature, John Steinbeck noted that “. . . they areoffered for increased and continuing knowledge ofman and of his world—for understanding and com-munication. . . .” Steinbeck was, of course, referringto categories of the Nobel Prize; however, evena cursory reading reveals that his words are equallytrue of his art with its offering of human diversity.Communication and understanding are not the solepurview of the literary artist, however, but are nec-essary components of all human life from theindividual to the familial, social, and professional.

For health care professionals, in particular,such skills are as essential as impeccable clinicaltechnique because communication and understand-ing are tools of healing. Despite ever-increasingevidence that effective communicative skills areessential to the practice of even the most science-based and technical-helping professions, commu-nication is often underemphasized in the curriculaof medical, dental, and other health care colleges.This scarcity is no doubt attributable to the monu-mental proportions of biological and physical sci-ences to be absorbed from a weighty curriculumand the equally daunting task of acquiring andhoning clinical skills to competency within a pre-scribed time frame. The unfortunate, but avoidable,result is too often uncomfortable and unproductiveconfrontations with those “problem patients”encountered by adept practitioners.

This chapter does not aspire to offer a crashcourse in effective communication. Rather it isdesigned to give an overview of the subject coloredby the precepts of humanistic psychology. The aimis to evoke within the thoughtful clinician an appre-ciation of and interest in communicative skills byoffering an elemental framework from which topractice, with the hope of inspiring further inquiry.To these ends, it addresses the following questions:(1) What is communication? (2) Why is it impor-tant? (3) What are the techniques of effective com-munication? and (4) What is the specialsignificance of doctor/patient communication?

WHAT IS COMMUNICATION?Scope

In the beginning was the word: the Latin communi-care, which means to share, impart, and partake.The 1989 edition of the Oxford English Dictionarycites 10 definitions for the English verb communi-cate and 12 for the noun communication. Thesemeanings are layered, like an onion, with, forexample, high-tech informatics outermost and spir-itual communion at the core. The multiplicityimplies an organic universality.

Communication is ubiquitous—the thread thatweaves an individual pattern into the universal web.In the arts, for example, a poet perceives the windcommunicating with trees, and a deaf composerhears a symphony performed by the orchestrawithin his mind. In science, the biologist knowsthat the waters lead salmon to the spawning groundby means of subtle chemical messages and thatmigrating birds navigate by electromagnetic broad-casts from the Earth’s poles. In quantum physics,an observer measuring a particle’s position ormomentum is aware that the very act of observa-tion will influence the outcome. This interactionbetween subject and object implies somethingcommunicated; there is an informational transac-tion between bird and earth, between physicist andsubatomic particle.

Among the multitude of communicators,human beings are by far the most complex, themost prolific, and the most likely to be misunder-stood. Humankind alone consciously experiencesthe misunderstanding and separation, the alienationand longing, identified and defined by the existen-

tialists. Martin Buber wrote the following: “Manwishes to be confirmed in his being by manand wishes to have presence in the being of theother . . . secretly and bashfully he watches fora Yes which allows him to be and which can cometo him only from one human person to another.”

Human beings are separated from other ter-restrial species by consciousness, reflectiveness,and the ability to create and communicatethrough the medium of language. As Buber sug-gests, they are dependent on quality interactionswith others for spiritual, mental, emotional, andphysical well-being, for integration and affirma-tion. Communication is the medium throughwhich individuals are able to transform a sense ofalienation into the sense of self, of community,and of union.

The existential plea continues to be addressedby theologians and philosophers, by social scien-tists and psychologists, striving to create new para-digms rooted in a holistic view of the human being.Those helping professions oriented predominatelyby bioscience (medicine and dentistry, for example)are responding by incorporating new themes suchas the “person centeredness” advocated by thehumanistic psychologist Carl Rogers.

The scope of communication extends from theindividual to society. If (1) the well-being of theperson is related to the quality of his or her com-munication and (2) society is composed of persons,then (3) a measure of that society’s health is thequality of its communications.

A Model of Communication

Communication among human beings is a transac-tional process used to impart or share ideas andother information. Its most commonly recognizedvehicle is language.

If evolutionary theory is accepted, it becomesreasonable to suppose that since appearing on theplanet, the genus Homo struggled to conveymeaning to fellow primates through symbolic ges-tures, grunts, and other sounds that eventually ledto assigning common significance to specific vocalsymbols and language. By the time animals andcrops were domesticated, in 9000 BCE, spoken lan-guage was the norm. Written language appeared in3100 BCE in the form of pictographs, and the


Phoenicians invented alphabetical script about1200 BCE.

Until the nineteenth century, Western culturesubscribed to the notion that language was a giftfrom God and that human behavior was divinelydirected. Consequently, any inquiry into communi-cation or the other social sciences was based onreligious dogma. In the twentieth century, speechcommunication studies were instituted because ofan interest in politics and persuasion during WorldWar II, not surprisingly because propaganda is animportant weapon of war.

From the social unrest of the late twentiethcentury and with the emergence and increasinginfluence of humanistic psychology, interest incommunication expanded to include the dynamicsof the transaction among individual human beings.Results of current studies continue to reveal newinformation.

Figure 11-1 offers an animated model of com-munication, which consists of nouns and verbs,things and actions. The nouns are (1) participants,(2) messages, (3) channels or vehicles, (4) noise,and (5) environments. The verbs or actions are(1) encoding, (2) sending, (3) receiving, (4) decoding,and (5) responding.

Let us examine the model using the example ofa man and a woman conversing. In this sample, theinitiating participant or sender, the woman, experi-ences thoughts, feelings, or other mental imagesshe wishes to convey to the man, or receiver.Before this intent can be actualized, the internalimages must be translated or encoded into lan-guage. Although this process involves complexneurological activity, it usually occurs withouteffort or awareness. When, however, the womanpauses before speaking to seek a word appropriateto the internal experience she wishes to share, sheis afforded an opportunity to become aware of theact of encoding.

Encoded, the message is sent, traveling by wayof the selected channel or vehicle to the receiver. Inthe example dialogue, the channel is vocalized lan-guage. Other examples of channels include tele-phoning, writing a letter, or typing an e-mailmessage.

The man receives the message through theauditory sense. Neurons in his brain engage intranslating the words into thoughts or other person-ally meaningful internal experience; he decodes themessage. Even as the decoding process occurs, theman assumes the role of sender, responding to his

Chapter 11 Building Rapport: The Art of Communication in the Management of the Edentulous Predicament 179

Noise Noise Noise

NoiseNoiseNoise

Participant

(Sends andreceives)

Participant

(Sends andreceives)

Channel(s) Channel(s)

Encodes/Decodes

Encodes/Decodes

Messages

Figure 11-1 Communication is a continuous, irreversible, transactive process involvingparticipants who occupy different but overlapping environments and are simultaneouslysenders and receivers of messages, many of which are distorted by external, physiological,and psychological noise. (From Adler RB, Towne N: Looking out/looking in, ed 5, New York,1987, Holt, Rinehart and Winston.)

interpretation of the message and sending inten-tional or unintentional signals or verbal feedbackor nonverbal messages to the woman, who becomesthe receiver, then the sender as she responds. Par-ticipants send and receive messages simultane-ously.

The purpose of the dialogue is to exchangeinformation that is understood. Consequently, theoutcome of successful communication is a conso-nance of the mental images of each participant. Allcommunicative efforts do not succeed because thiscongruence is dependent on the participants’ability to express and interpret accurately.

These capabilities are affected by the twofactors known to social scientists as environmentand noise. Environment is twofold: in addition tothe physical locale, it encompasses the internalenvironment or personal history each participantbrings to the dialogue. As Figure 11-1 illustrates,internal environments overlap, but only to theextent that the participants’ experience and knowl-edge are shared. If the English-speaking womansays “fork,” the English-speaking man receives thecorrect mental image. If one or the other under-stands only French, the message is aborted by con-flicting internal environments.

The major portion of each internal environmentis not common to both participants. Differences inage, life experience, socioeconomic status, andinterests, among many others, create varied inter-nal environments that affect accurate communica-tion. In the sample scenario, the quality and contentof the interaction will be affected if the woman’sinternal environment is that of a chief executiveofficer of a major corporation and the man worksas a day laborer. What if he is fascinated by base-ball and she is uninterested in it, or she is an80-year-old grandmother and he is a 40-year-oldbachelor?

The second factor affecting the success of com-munication, noise, also has two aspects: the exter-nal and internal. The effects of external noise areobvious. Loud music, for example, hinders thecommunicants’ ability to hear and, consequently,the quality of their vocal interaction.

Less obvious, internal noise is attributed tophysiological and psychological factors. Theformer affects reception and stems from the partic-ipant’s physiological condition (e.g., is he ill? is she

hearing impaired?). The latter includes elementssuch as a participant’s preoccupation, emotionalstate, and defensiveness. In short, anything hap-pening in a participant’s consciousness that distortsattention or distracts it from the communicativeprocess is psychological noise and impinges onboth the accuracy of expression and of reception.Adler and Towne define this transactional model ofcommunication as “a continuous, irreversible,transactive process involving participants whooccupy different but overlapping environments andare simultaneously senders and receivers of mes-sages, many of which are distorted by external,physiological, and psychological noise.”

WHY IS COMMUNICATIONIMPORTANT?“Man is the talking animal.” Speech and gesturesaturate every facet of human existence. Why arethe only animals that obviously and continuouslyengage in symbol making so occupied with thiscomplex activity? Since the first tribal groupagreed that certain noises would represent speci-fied external objects or internal states of being,Homo sapiens have used language as a tool for ful-filling needs.

Abraham Maslow set forth a hierarchical tax-onomy of human needs: (1) life, (2) safety, (3)belongingness and affection, (4) respect andself-respect, and (5) self-actualization or the real-ization of individual potential. On the most basiclevel (need for life), the ability to communicate, toshare sensory impressions, played a substantiverole in the success of the species by expanding thelimits of individual perception to include sensorydata from others’ nervous systems and by support-ing the cooperative activity necessary to survival.People warned one another of danger by shoutingwords that meant “watch out”; they shared andpassed to their progeny stores of knowledge tofacilitate life. Part of a tribal repertoire that wasshared by symbols included information such aswhat plants to eat or make soap or baskets from andwhat dangerous animals or places to avoid.Through verbal and nonverbal exchanges withimmediate family, shamans, and chiefs, peoplelearned and fulfilled needs for safety, inclusion,affection, and esteem. Because the basic needs


(integral to all human beings since the origin ofthe species) have been satisfied over millenniathrough personal interaction with the external envi-ronment, human beings are dependent on theirhabitat and social structure—the components ofthis environment.

In contemporary Western society, practicallyspeaking, communication continues to servehumanity by permitting people to tell the dentistwhich tooth hurts, to order a favorite meal, and toask directions from a passerby. Psychologically,our interactions with others mold the sense of iden-tity and the concept of self. Personal value andworth are equated by inclusion in the group, byesteem, and by recognition. People influence theirsocial environment by conveying needs and desiresthat can then be fulfilled and, conversely, byresponding to needs communicated by others.

Ultimately, as these basic, species-widerequirements are met, the need at the apex of thehierarchy enters awareness. Once thirst isquenched, hunger is sated, and the person is snug inthe esteem of a group, there is an opportunity forthe person to listen and respond to the uniqueaspects of the individual psyche. This urge to seekself-actualization is nourished by interaction withthe internal environment and is characterized bypersonal uniqueness and independence. It revealswho we are and what we can offer to others. Thussymbol making can free the individual from totaldependence on, and consequent attention to, thesupporting external environment and allow thespontaneity, creativity, and holistic sense ofbelonging within the cosmos that distinguishesself-actualization.

The importance of communication lies in itsfunctions. It is the nexus between human beingsand the universal context, the external and internalenvironments that nourish. It enabled the cavedweller to thrive and proliferate; it makes possiblethe sophisticated business of contemporary lifepractically, socially, professionally, and spiritually.

WHAT ARE THE ELEMENTS OFEFFECTIVE COMMUNICATION?Social science describes myriad elements thatoverlap psychological principles and combine toinfluence this art. These factors include dissonant

and confirming relational climates, defensiveness,selective perception, social intelligence,self-image, genuineness, and empathy. An in-depthexamination of the many psychosocial dynamicsacting on the exchange of information amongpeople is not possible within the confines of onechapter. Therefore this discussion is limited to anexamination of some of the skills used byhigh-level communicators. Because communica-tion is an art, the maestro becomes proficient inspecific techniques that include self-awareness,genuineness, attending behavior, listening,empathy, self-disclosure, and deep understanding.

Self-awareness is the cornerstone of effectivecommunicative skill. Abraham Maslow describedthe self as “ . . . a kind of intrinsic nature which isvery subtle, which is not necessarily conscious,which has to be sought for, and which has to beuncovered and then built upon, actualized, taught,educated.” Carl Jung went so far as to suggest thatfull understanding of human nature may not bepossible without a similarly intelligent species forcomparison.

Human beings are singular among animalsbecause their inner natures and consequent behav-iors are not obviously and completely dictated byinstinct. Other animals express their biologicalnatures confidently without thought or attention.All cats, for example, hunt, groom themselves, andsleep copiously; they announce “catness” effort-lessly and unconsciously. On the other hand, whatdefines humanity is an elusive and complexquestion. Knowing oneself is not an easy task.

Maslow postulates a three-faceted humannature: instincts common to the species; individualuniqueness; and a higher, spiritual or actualizedself. To achieve the full, meaningful expression andunderstanding necessary for expert communica-tion, one needs to be in touch with these threeaspects and to be tuned in to the feelings,self-concept, ideas, attitudes, and values that makeup the inner environment.

Because feelings are basic to all facets of theself and are not always articulated with ease, theycan serve as a model for this discussion. Socialroles and taboos, perceived risks, and difficulty ofexpression combine to suppress the sharing ofemotions. Cultural admonitions such as “anger isbad” lead to misunderstanding and even fear of


feelings. Unexpressed emotions are likely to beignored and may ultimately be relegated to therealm of the unconscious. The inaccurate and oftennegative mythology surrounding the acceptanceand expression of emotion can close the door onself-awareness. For example, people often believethat their feelings come from others. “You make mehappy” or “You make me angry” are commonexpressions. However, emotions, which are basedon thoughts in response to situations and circum-stances, are generated from within. We are respon-sible for how we feel. Replacing “you” statementswith “I” statements, such as “I feel happy (angry)when you call,” conveys the notion of responsibil-ity and defuses the threatening implication of emo-tional control from without and resultantdependency. In addition, “I” statements reduce therisk that the receiver will react defensively.

Another common myth is the belief that beingaware of a feeling or expressing it is synonymouswith acting on it. Acknowledging anger does notcommit one to yelling and throwing things. Ratherthan a call to immediate action, a feeling isa message from the inner self, an invitation toself-awareness. How or if to act on it is subject tothe discretion of the individual relative to thesituation.

Awareness of physical reactions, followed byintrospection, assists in recognizing and definingfeelings. Strong emotions elicit rapid heartbeat,perspiring, and a shaky sensation—signs of bothfear and anticipation. Subtle feelings are most fre-quently felt in the solar plexus or heart. A flutteror a pang here is a feeling message. Another wayto tune in on feelings is to monitor inner dialogue.What are you saying to yourself: that you areworthy and capable? Feedback fr om others canalso bring emotions and other unknown aspects ofself into awareness and clarity. Genuineness,a quality of self-awareness, is expressed whencommunication accurately portrays inner experi-ence. Sir Francis Bacon stated the essence of gen-uineness when he wrote, “Be so true to thyself asthou be not false to others.” Communicators whodisplay genuineness inspire trust by exhibiting spe-cific behaviors. They are free from playing roles;that is to say, they do not disguise themselves orplay games to manipulate others. They are awareand accepting of personal strengths and weak-

nesses; they tend not to react defensively; and theyare open and consistent in thought, feeling, andbehavior.

Attending behavior means paying attention toor being with another and communicating this non-verbally with physical proximity; relaxed, openposture; turning toward the partner; and eyecontact. It includes sensitive interpretation of non-verbal messages. Attending behavior speaks ofaffection, respect, and esteem.

Listening, which is closely related to attendingskills, is not merely hearing the other’s words whilewaiting impatiently for a turn to talk. Effective lis-tening means being committed to understandinganother. It also requires attention to, and accuratedecoding of, both verbal and nonverbal messages.Nonverbal language (proxemics, kinesics, and par-alanguage) conveys feelings and attitudes. Prox-emics is the study of the space betweencommunicators; kinesics concerns postures andfacial expressions; and paralanguage is the use ofsounds other than words, such as pause, pitch, andintonation. Accurate decoding of nonverbal lan-guage requires understanding that its messages areambiguous and sensitivity to their meaning withinthe context of the situation. Listening is essentialfor empathetic responding.

Empathy is the ability to see a situation fromanother’s frame of reference and to understand andappreciate someone else’s feelings, perceptions, orattitudes. It does not necessarily connote agreementbut does relay respect or the belief that the other isa worthwhile and capable individual. It functions topromote and communicate understanding, layingthe groundwork for trust. It is a difficult skillbecause personal feelings and attitudes must beexchanged for openness and acceptance.

Self-disclosure broadens the base of under-standing and increases rapport. Persons revealthemselves continuously through nonverbal behav-ior, but people frequently feel that self-disclosuremeans confessing faults and weaknesses. It is moreaccurately a sharing of experience and resultingfeelings within the context of an interaction.Self-disclosure promotes trust in a relationship andencourages others to respond in kind.

Deep understanding combines the skills ofattending, listening, and empathy to perceive andcommunicate information about another that may


be unknown or unclear to that person. For instance,if a friend shows a pattern of self-criticism, onecould intuit a lack of self-esteem. If the hunch isaccurate, expressing it appropriately to the friendcan stimulate insight. Deep understanding letspeople know how others perceive them, which aidsself-awareness. To be effective, one must under-stand it as intuition and express observations tenta-tively as a personal perception, rather than asabsolutes or judgments.

Self-awareness, genuineness, attending behavior,listening, empathy, self-disclosure, deep understand-ing, and other techniques used by high-level commu-nicators are underscored by the principles of concreteexpression, discipline, and person centeredness.

Concrete expression adds clarity and capturesthe meaning of experience. It is characterized bydescribing perceptions, rather than stating infer-ences. For instance, to say, “I see you are angry,” isinferred from perceived behavior. Instead, saying,“Your face is red, jaw clenched, and you’re yelling.It looks like you’re angry,” is concrete. Such state-ments check accuracy with a summation or ques-tion that encourages the other to clarify, refute, oracknowledge the truth of the observation.

Discipline implies that a communicator pos-sesses a wide variety of communicative behaviorsand the social intelligence to know which is mostappropriate in a particular situation. A skilled com-municator does not articulate emotions indiscrimi-nately, but expresses those feelings and thoughtsthat suit the occasion and individuals involved.Discipline tempers self-disclosure and reducesrisks involved in talking about feelings. A qualityof discrimination, it boosts courage and confidence.

Person centeredness is an attitude that unitesthe attributes of communication in a matrix ofrespect and esteem. Based on acceptance, it isfeeling that others are of value and worthy of atten-tion by virtue of their humanness, and it fuels thecommunicator’s skills.

SPECIAL SIGNIFICANCE OFDOCTOR/PATIENT COMMUNICATIONDentists are in significant agreement that successor failure in fabricating dentures is not exclusivelypredicated on a patient’s residual form, but on thepatient’s attitude toward the prosthesis as well. It

has been noted that the body schema (the psycho-logical image of the physical self) is heavilyinvested with emotional meaning. Significantchanges in body image result in varying degrees ofemotional instability that affect adaptive compe-tence. Given time, most people can absorb thetrauma involved in body changes and develop newadaptations to changed circumstance. Although itappears that most patients adapt to the denture-wearing experience, many do not. They comprisea group of people who are more emotionally fragileand who find that they cannot adjust to the physi-cal change or else cannot cope with the tissues’complex adverse response to prostheses. Theloss of teeth in both general patient groups, mor-phologically or emotionally maladaptive, is anobstacle they cannot surmount despite provision ofexcellent prosthetic replacements.

There are many critical elements to consider inmanaging the adaptive and maladaptive patientswith dentures. The two most important are thebehavior of the doctor and the iatrosedative inter-view, both of which involve a skillful handling ofverbal and nonverbal communication.

THE DOCTOR’S BEHAVIORFor the emotionally maladaptive patient with den-tures, the sense of loss and the prospect of a life ofdiscomfort and discontent are powerful feelingsthat may create a sense of hopelessness. The doctor,on whom the patient is dependent to make a signif-icant change in his or her life, becomes an impor-tant figure. The patient must have an alliance withthe doctor to cross over to adaptability. Conse-quently, there are strong feelings associated withsuch a doctor. They will be powerfully positive ornegative, depending on the doctor’s behavior andattitude. Those feelings will become “incorpo-rated” into the denture. If the patient distrusts andresents that behavior and attitude, the resultingdenture will be “contaminated” by those feelings.The consequence is rejection of the denture as wellas the doctor. On the other hand, if the doctorcreates a warm, trusting relationship, the goodwillbecomes embedded in the denture, resulting inpatient acceptance of it along with acceptance ofthe doctor. Trust and a warm relationship will over-ride the mechanical and psychological factors that


ordinarily create a maladaptive response to the pros-thesis. The first few minutes of an interaction arecritical in creating trust. A warm relationshipshould be generated at the greeting before theinitial interview starts. This is accomplished byempathetic nonverbal and verbal communications,a skill some doctors have intuitively and othershave acquired in learning the role of a doctor anddedicating themselves to mastering it.

Bowlby’s research suggested that attachmentbehavior is among the instinctive responses thatappear at birth. This response is biologically presetand therefore not dependent on prior learning.Attachment behavior is defined as “seeking andmaintaining proximity to another individual.”Attachment behavior is one set of instinctiveresponses that operates in the service of speciessurvival. For the remainder of one’s life, seekingand maintaining proximity to another individualwill be a matter of central importance to existence.

All relationships of consequence includeattachment behavior and trust if they are to effec-tively survive. When patients require the help ofcare providers (such as a dentist or physician) tocare for their most prized possession (effectivephysical functioning), attachment and trust needsare activated. The way in which the clinician rec-ognizes and responds to such needs can makea crucial difference in outcome.

A patient may view a prosthesis prescriptionwith some degree of alarm. Others regard the pre-scription as the ultimate disaster because previousexperiences have indicated a maladaptiveresponse. This can be the case even when an initialprosthetic experience is an adaptive one, only toundergo a prognostic change as a result of a con-tinuum of adverse morphological sequelae. Hope-fully, latent attachment behaviors are stimulated asthe patient looks for a caretaker who is confident,caring, sensitive, and supportive. The dentist whocan satisfy these attachment behaviors is likely tohave a considerable advantage in preparinga denture that is acceptable to the patient, bothphysically and emotionally.

THE IATROSEDATIVE INTERVIEWThe iatrosedative interview is designed to helpdentists mobilize their resources so that they

operate in the most efficient way to create theclimate of involvement and trust indispensable toaltering maladaptiveness.

The iatrosedative model is a systematic, prag-matic, “cherished” interaction used to reduce oreliminate most of the dental fears encountered inpractice. The definition of iatrosedation is“making calm by the doctor’s behavior.” The wordis a combination of iatro (doctor) and sedation(the act of making calm). The goal of iatroseda-tion is to create a relearning experience whereinthe feelings originally learned will be unlearnedand a new set of feelings generated as a conse-quence of the interaction between the doctor andthe patient. The iatrosedative interview is com-posed of four parts: (1) recognizing and acknowl-edging the problem, (2) exploring and identifyingthe problem, (3) interpreting and explaining theproblem, and (4) offering a solution to theproblem.

RECOGNIZING AND ACKNOWLEDGINGTHE PROBLEMThe following example started as an open-endedinitial interview. The patient immediately indicatedthat emotional factors were an important compo-nent of her request for a new denture. The doctorrecognized this and acknowledged it by shifting intoan iatrosedative interview. Had the doctorresponded to the patient’s opening statement byasking, “Well, what’s the problem with yourdenture?” this would indicate nonacknowledgmentand the desire to move the interview into the tech-nical-anatomical arena.

Example

A 57-year-old woman has an appointment to seea dentist concerning her inability to adapt todentures. Other than this information, he knows vir-tually nothing about this patient. When he enters theoperatory, his first impression is of an attractive,petite woman who seems younger than her statedage. She is seated, her face is expressionless, and thedoctor infers that she is anxious or depressed. Hebegins with a greeting and some brief pleasantries,the continues:

Doctor: What kind of difficulties are you having?


This type of opening permits the patient to tellher story in the way she wishes. An open-endedquestion often elicits the patient’s dominantconcern.

Patient: I am awfully unhappy. (Pauses.)Doctor: Unhappy?The patient chooses to convey her emotional

uneasiness as a primary complaint. The doctorrepeats the significant word, indicating to thepatient that he wishes to hear more. This alsoconveys to the patient his willingness to considerpsychological factors as well as physical ones. Thisis a first step toward developing a strong workingrelationship.

Patient: I have grown into an old woman longbefore my time. The day they removed my teeth, Ifelt I had aged 20 years.

The patient is defining one potentially majorfactor in her maladaptive response to dentures.There may be others, but she has provided thedoctor with an important diagnostic clue.

Doctor: That feeling must be quite distressing.However, you do not give the appearance of an oldwoman.

The doctor again recognizes the emotional issuesand indicates his acknowledgment by providingsome support in making a realistic appraisal of herappearance. To go beyond this limited observationmay make the patient feel that the doctor is trying tomake her feel better but is in reality insincere. Hewill continue to explore the emotional factors.

Exploring the Problem

Patient: Yes, everyone tells me that, but that’snot how I feel.

(She smiles for the first time.) And that is whatcounts. The doctor’s observation has been vali-dated, but she emphasizes that the only thing thatmatters is how she feels. Again, she underscoresthe importance of her inner state. The smile signalsthat her earlier tension is probably receding, andthe doctor’s style of communication is beginning tohave an effect.

Doctor: I agree with you. In the end, it is onlyhow we feel that really matters. (He waits to see ifthe patient will respond to this remark. She doesnot.) Aside from the fact that the loss of teeth and

the denture makes you feel like an old woman, howare you having difficulty with the denture?

The doctor agrees with this very realisticassessment by the patient, that is, the nature ofone’s feelings. No matter how fine the prosthesis,all is for naught if the patient feels miserable. Hepauses to see whether the patient wants to add any-thing more to this point. If she does not, he nowshifts his focus from the generalized emotionalstate to ask what specific complaints there are. Thiswill lead shortly to an interruption to evaluate theoral condition and the dentures.

Patient: I find it very uncomfortable. It slips. Ihave a burning sensation. My food seems tasteless.But I wear the denture all the time despite the dis-comfort because I’m shocked by how I look without it.

She mentions physical difficulties but indicatesthat the discomfort is overridden by the dread ofappearing aged. Even when she is talking aboutphysical factors, the pull is always back to emo-tional distress.

Doctor: I see. Your emotional discomfort is evengreater than your physical discomfort. But can yougive me more details about the physical difficulties?

The doctor makes explicit what is implicit inthe patient’s observations. This is another way ofindicating to the patient that she has been heard andunderstood. Because the doctor needs more infor-mation about physical difficulties, he shifts back tothis area.

Patient: The denture seems to move in mymouth. When I chew, it seems to slip from side toside. The only time it doesn’t is if I eat soft foods.But my gums seem to be sore all the time. Seemslike a burning sensation. Spicy foods make it muchworse. I have given up all alcohol because it nowseems to burn my mouth.

The physical symptoms that accompany theemotional ones have now been clarified. In a briefperiod of time, the doctor has acquired someknowledge of the patient’s emotional and physicalsymptoms. This seems an appropriate time togather information about previous attempts to fab-ricate dentures.

Doctor: As I understand it, you’ve had severalother dentures made.

Patient: Yes, none of them worked. Dr. L didtwo, and Dr. Y did the other two. Each one didn’twork, and I don’t know why. To be honest, I really


don’t know why I came to see you. If two perfectlycompetent specialists could not make one denturethat I could wear comfortably, I really don’t knowwhat I could expect from you.

During the early part of the interview thepatient appeared tense and anxious. Her emo-tional state has shifted to a more aggressive posi-tion in which the edge of sarcasm and challengecan be detected in both the tone of her voice andher words. The doctor has two possible responses.The first is to simply ask her why she requesteda consultation despite her pessimism. A secondpossibility is to pick up on her thinly veiled anger.For the moment, the doctor chooses the firstmaneuver. However, he will keep in mind theanger and the challenge for another point in theinterview.

Patient: Well, I haven’t given up. Somehow Ihave the feeling that someone must have theanswer to my problem. (Long pause.) You can help.

Her pessimism is not total, but the doctor mustbe cautious. What happened with the previous“very competent dentists” who she says failed,could also be the fate of this doctor.

Doctor: You are not very happy with the previ-ous dentists you went to?

As noted earlier, her manner indicated anger atthe previous practitioners. Is there something ofconsequence he can learn from her past encoun-ters? The dentist puts the question directly to thepatient in looking for the doctor-behavior link tomaladaptiveness.

Patient: Each one was quite confident that hecould make a denture that I would be happy with. Iremember telling them that I hated wearinga denture, but they just said that they could makeone that would fit.

The statement is at the crux of the matterbecause the previous dentists and this patient weretalking at different levels. In each instance, thedentist was focused on fit, but she was talkingabout emotional fit.

Doctor: You were talking about your emotionaldistress mostly.

The doctor explicitly interprets what the patienthas been telling him. At this point, he realizes thatif there is any chance of success, he must hear bothlevels and set up a treatment plan that incorporatesboth aspects.

Patient: Exactly. I must say, doctor, I am some-what encouraged because you seem to appreciatewhat I’m going through.

This is a positive movement in cementinga relationship. The doctor is now fully aware thatattention to the psychological factors will beimportant because emotional concerns will alwaysbe present. This is an appropriate time to interruptthe interview and examine the dentures in themouth to determine whether the burning and sore-ness of the tissues are related to any pathosis suchas lesions or inflammation; whether there are anyproblems with inadequate ridges; and whether thedenture is well fabricated. If all of these factors arewithin a satisfactory range, the question of nonac-ceptance maladaptiveness arises. (The oral exami-nation revealed that the patient was wearingmandibular and maxillary dentures. The ridgeswere more than adequate in size and shape, and thedentures were well fabricated and adapted. Nolesions were visible, and the mucosa was free ofinflammation. The tentative diagnosis was “mal-adaptive Class II, unable to adapt psychologicallyand physically.”)

Part of the exploration of the problem wasstated in the previous portion of the interview.Some of the feelings were revealed, and the previ-ous doctors’ behaviors seemed to have been limitedto technical aspects of the problem. It is probablethat some of the patient’s hostility may be related tothese experiences. Further exploration is necessaryto determine whether previous learning has condi-tioned the patient and, if so, how the recommenda-tion of total tooth loss and complete denturesaffected her. In addition, what were her feelingswhen the teeth were extracted and the denturesplaced?

Doctor: You mentioned that you hate wearingdentures. Before we talk more about that, I’d liketo ask if your parents or grandparents haddentures.

Patient: Yes, my mother did, and she suffered sowith them. I remember as a child that she wasunable to wear them and had several sets made.She was unable to eat with them, and I was fright-ened because I thought that this might happen tome. I am so much like my mother.

Doctor: That must have been terrifying to youas a child. Did you ever get used to the idea?


The doctor makes an understanding statementand follows it with a facilitative question to getmore information about her feelings.

Patient: No, no, I never did. I’ve never forgottenthe first time I saw my mother with her denturesout. Her face fell in—it was so shrunken that I pan-icked. And when the doctor told me that I had tohave my teeth pulled, that horrible image flashedthrough my mind.

Doctor: Did you tell the doctor how you felt?Patient: Yes, I did, but he didn’t seem to care too

much and repeatedly said that I should get used toit and get along just fine.

Doctor: How did that make you feel?Patient: It made me angry and frightened me

even more than I was.This example represented the most common

basis for maladaptiveness as a result of depressionand anxiety related to toothlessness and dentures.Whatever feelings are expressed—the depressionand fears of aging, loss of body integrity, femininity,masculinity, youthfulness, or beauty—may be thecore around which the explanatory and interpretivesegment of the interview will be built. The responsesto the questions about the feelings associated with thedoctors’ behaviors will provide insight as to the prob-able effect on adaptiveness and also will be used inthe explanatory interpretive phase of the interview.

INTERPRETING AND EXPLAINING THE PROBLEMThere is more than one way to use the informationgarnered by the exploration of the feelings andevents preceding and following the advents of toothloss and replacement by artificial substitutes. Thedoctor’s style will determine this. The iatrosedativemodel is a vehicle to create mutual involvement bya combination of expressions of feelings of confi-dence and trust by both parties, the inclusion of thepatient as participating in achieving success, andthe use of the acquired information to suggest thatfeelings may affect success or failure in adapting todentures. The sincerity of the tone the doctor bringsto the situation probably will have a profoundeffect on the patient.

Doctor: I feel that you have suffered a greatdeal at the loss of your teeth. It was a terrible blow,and it seems as if you have never really gotten over

it. You were frightened as a child when your motherlost her beautiful teeth and her face sunk in,making her look very old suddenly. You learned tofear dentures because of this, and because of thisfear, you fought to avoid losing your teeth. Unfor-tunately, you did lose them. The dentures are a con-stant reminder of that loss, and your feelings mayhave an effect on your being able to accept them.You may have learned to fear having denturesbecause of your mother’s unhappy experience. Thismay have set the stage for your not being able toaccept dentures for yourself. Furthermore, the con-dition, or quantity and quality of your denture-sup-porting tissues, may not be optimal for an adaptivedenture experience. A thorough examination willenable me to determine whether adjunctivemethods of denture support, such as implants, maybe required in your particular case. What do youthink? Does this make sense to you?

Patient: Yes, that sounds possible. (The exami-nation is carried out.)

Doctor: I want you to know your feelings canchange, and with that change we can expect you tobe able to wear the dentures with comfort. Yourgums, although tender, are healthy. They are notinfected, but the stress of your unhappiness with thedentures can and does affect the way your gumstolerate the pressure of the dentures. With your newdentures and a new set of feelings, it is likely thatyou will not have the soreness you have now. Let’stalk about what we can do.

OFFERING A SOLUTION TO THE PROBLEM

Doctor: We will work together in making newdentures, and I am quite confident that, as we workthings out together, your feelings about yourselfand your dentures will change so that you will beable to live with them comfortably. It is going totake time to fabricate well-fitting dentures for you.It may take as long as 3 to 4 months.

Patient: Doctor, why so long?Doctor: It takes time to make dentures that are

well fitting, dentures that you will be able to func-tion with properly, and I want you to know that theday I place the dentures in your mouth is in essencethe first day of treatment. From that time on, I willbe available to help make you comfortable.


Patient: I really appreciate that, doctor. Theother doctors were so impatient with me and didn’tseem to realize that I was suffering so much emo-tionally. I feel hopeful and would like us to start.

The patient is grateful that the dentist is willingto spend the necessary time to make a good set ofdentures. The great advantage is that the patientwill get involved with the dentist as the helping,understanding, and supportive figure, realizing thatthe dentist is extremely concerned about herlong-term well-being. She also realizes that thisdentist is maintaining an open-door policy. Thiscontinues the building process toward anever-more-positive trusting relationship.

Doctor: Good. I am glad you feel optimisticabout our working together. Let’s set up anappointment to start treatment. I would like you tobring some photographs of you when you had yournatural (own) teeth. They will be of great help toboth of us in determining what your teeth lookedlike before and also help us in determining how toarrange the new teeth.

Patient: I’ll start looking for them. I think Ihave wedding pictures when I had a big smile onmy face.

The patient is now involved in the fabricationof the new dentures, which adds another incrementof relationship building. If, after a considerableamount of treatment, it becomes apparent that thepatient’s adaptive ability is not increasing suffi-ciently, it would be in her best interest and thedentist’s to address the issue. The timing is impor-tant here. This is a difficult issue. Most patientsreject the initial recommendation of dealingdirectly with the emotional aspects of the problem.Nevertheless, with an understanding approach,coupled with a strong relationship, such as existswith this patient, an initial rejection may change toacceptance.

Doctor: I am very concerned about ourprogress at this point. We have done everything thatwe can together, and things are not going as wellfor you as they should. My experience has beenthat most patients would be able to manage thesedentures. I am quite confident that the stress youhave undergone in losing your teeth and strugglingwith the dentures is still affecting you. Therefore Ithink we should bring someone in to help us withthose stress factors.

Patient: No, I don’t think I want to do this. Idon’t think I am emotionally disturbed.

Doctor: I did not mean to imply that you werean emotionally disturbed individual. We all havespecific areas in our lives that are upsetting, andfor many people, accepting dentures is very diffi-cult. I need to discuss this with you at this pointbecause without solving this emotional aspect, wechance failure again, and you may be spendingtime, effort, and money unnecessarily. What Iwould like you to do is think about it because I sin-cerely believe it would be in your best interest.Perhaps share these thoughts with someone who isparticularly close to you and whose opinion youvalue. Call me next week, and let us discuss thisover the phone. One last point: next week you maystill be opposed to my suggestion; however, in 4 or6 months you may feel differently about it and wantto explore my suggestion further. If that happens,feel free to call me, and I’ll be happy to help you inany way I can.

There are a small percentage of patients whocannot adapt because they need their symptoms.Patients maintain symptoms for a variety ofreasons. The symptoms may represent a way ofrationalizing other problems and manipulatingpeople, and they may be an exhibitionistic attemptto draw sympathy from other people. These symp-toms may be absolutely necessary to maintaina precarious psychological equilibrium. If thepatient cannot relinquish such symptoms, thedentist will fail.

SUMMARYSome patients are maladaptive because morpho-logical or neuromuscular deficits preclude success-ful wearing of dentures. Other patients areemotionally maladaptive. For these patients, effec-tive verbal and nonverbal communication is signif-icant in maximizing an effective doctor/patientrelationship and minimizing the maladaptiveresponse. Often, patients who seek technicaladvice relative to a prosthesis are seeking emotionalsolutions.

If the patient is maladaptive, the dentist cannotconclude that the patient is “neurotic” and beyondthe dentist’s capacity to help. The dentist who shutsoff the patient’s desire to share his or her feelings


about wearing a denture is putting obstacles in thepath to achieving a successful outcome. It is notthe denture that is the problem; it is the patient’sfeelings about that particular denture.

A major aspect of the solution is the dentist’sability to first listen and gather information andthen communicate effectively. In general, dentistsare excellent communicators in the areas of physi-cal and anatomical problems, but reticent when theissues are emotional.

The iatrosedative interview is an effectivemethod of communication to help patients who areunable to adapt to dentures. It creates an indispen-sable trusting relationship in the process of deter-mining the factors responsible for the problem andoffers a solution.

It is worth reiterating that dentists becomemasters in technical skills and very adept at pro-viding quick solutions to problems. However,many practice problems require significant com-mitment to “patience with patients.” Effectivetechniques of communication remain an indispen-sable determinant of favorable managementoutcomes.

ACKNOWLEDGMENTSThe author is indebted to Dr. Nathan Friedman,who coauthored previous manuscripts that influ-enced this chapter’s preparation. The significantassistance received from Ms. Virginia S. Watsonalso is gratefully acknowledged.

BibliographyAdler RB, Towne N: Looking out/looking in, ed 5, New York,

1987, Holt, Rinehart and Winston.

Bowlby J: Attachment and loss, vol 1, p 194, New York, 1979,Basic Books.

Capra F: The Tao of physics, New York, 1984, Bantam Books.Cassell EJ: Talking with patients, vol 1, The theory of

doctor-patient communication, Cambridge, Mass, 1985, TheMIT Press.

Covici P, editor: The portable Steinbeck, New York, 1971, TheViking Press.

Davis AJ: Listening and responding, St Louis, 1984,Mosby–Year Book.

Egbert L, Battit G, Turndoff H, et al: Value of the preoperativevisit by an anesthetist, JAMA 195:553, 1963.

Friedman N: Iatrosedation: the treatment of fear in the dentalpatient, J Dent Educ 47:91-95, 1983.

Friedman N, Landesman HM, Wexler M: The influence of fear,anxiety, and depression on the patient’s adaptive response tocomplete dentures, Part I. J Prosthet Dent 58:687-689,1987; Part II. J Prosthet Dent 59:169-173, 1988.

Hayakawa SI: Language in thought and action, New York, 1972,Harcourt Brace Jovanovich.

Hirsch B, Levin B, Tiber N: The effect of patient involvementand esthetic preference on denture acceptance, J ProsthetDent 28:127-132, 1972.

Kelly EW Jr: Effective interpersonal communication: a manualfor skill development, Washington, DC, 1979, UniversityPress of America.

Kirschenbaum H, Henderson VL: Carl Rogers: dialoges,Boston, 1989, Houghton Mifflin.

Lefer L, Pleasure MA, Rosenthal L: A psychiatric approach tothe denture patient, J Psychosom Res 6:199-207, 1962.

Maslow AH: Toward a psychology of being, New York, 1968,D Van Nostrand.

The Oxford dictionary of quotations, ed 3, Oxford, 1980, OxfordUniversity Press.

Pitts WC: Difficult denture patients: observation and hypothe-sis, J Prosthet Dent 53:532-534, 1985.

Rogers C: A way of being, Boston, 1980, Houghton Mifflin.Welch ID, Tate GA, Richards F, editors: Humanistic psychology:

a source book, Buffalo, NY, 1978, Prometheus Books.Zunin L: Contact: the first four minutes, p 194, New York, 1979,

Basic Books.


C H A P T E R 12Materials Prescribed in the Management of Edentulous PatientsRanda R. Diwan

190

The selection of materials is based on a reconcilia-tion of their biocompatibility, optimum physicaland mechanical properties and, where indicated,their superior esthetic qualities. A fundamentalknowledge of the properties, as well as the limita-tions of dental materials is crucial, so that dentistscan carefully manipulate those materials to the bestbenefit of the patient. This is further underscoredby the fact that none of the materials used in den-tistry or medicine are totally inert. Biodegradationof materials in the oral environment has been fre-quently related to chemical or mechanical factorsprevailing in the oral cavity such as bacteria, saliva,and other oral fluids.

The aim of this chapter is to present a synthesisof key information regarding biomaterialsprescribed in the management of the edentulouspatient. It is organized in five sections: denturebase materials, denture teeth materials, liningmaterials, denture cleansers, and cast metalalloys.

Fulfilling the requirements listed in Box 12-1may be a challenge for dental practitioners, consid-ering the number of new materials available on thedental market, often with unproven claims of supe-riority in biocompatibility, physical, and mechani-cal properties. The clinical efficiency of allprosthodontic materials should essentially be basedon long-term, large-scale clinical trials, as well asstrict adherence to internationally recognized spec-ifications and standards that gauge the quality andproperties of those materials to ensure maximumsafety, durability, and effectiveness.

DENTURE BASE MATERIALSOver the years a variety of materials have beenused for the fabrication of denture bases. The mostcommonly used materials are polymers such aspolymethylmethacrylate (PMMA) or acrylicresins. Popularity of PMMA accrues from the factthat the material exhibits favorable working char-acteristics, has acceptable physical mechanical andesthetic properties, and is easy to fabricate withinexpensive equipment. However, as with all otherknown denture base materials, acrylic resin has itsinherent limitations and does not fulfill all therequirements of a hypothetically ideal denture basematerial (Box 12-2).

The polymerization process of PMMA involvesthe conversion of low molecular weight monomers tohigh molecular weight polymers. Denture base resinsare formed by a process of additional polymerizationthrough the release of free radicals. The reactionpasses through three stages, namely, activation andinitiation, propagation, and finally, termination. Aninitiator like benzyl peroxide yields free radicals,which sets off the chain reaction. Activation of theinitiator can be achieved through the application ofheat (heat-activated or cured PMMA), chemicals,such as tertiary amines (chemically activatedPMMA), or by other sources of energy, such asvisible light-activated (VLC) urethane dimethacry-late, or through electromagnetic radiation such as inthe case of microwave-activated resins.

Copolymers are formed when monomers oftwo or more compatible types are joined. The vast

majority of today’s dentures are made of heat-activated PMMA and copolymers, such as rubberreinforced PMMA. The latter is a high-impactacrylic resin, where the PMMA forms graftcopolymers with polystyrene-butadiene rubber.The rubber inclusions significantly improveimpact strength of the polymerized denture base.

Polymers with chemical bonds between differ-ent chains are termed cross-linked. This processaffects physical properties of the polymer. In thecase of PMMA, it increases rigidity as well as crazeresistance, which is the tendency of resins to formminute surface cracks, and reduces the resin’s solu-bility in organic solvents. The chemical composi-tion of frequently used denture base resins is listedin Box 12-3.

Chapter 12 Materials Prescribed in the Management of Edentulous Patients 191

General Requirements ofBiomaterials for Edentulous

Patients

1. The material must be biocompatible:No harmful effects on the oral tissuesNontoxic, nonirritantNonallergenic, noncarcinogenic

2. The material must fulfill clinical objectives:Optimum physical and mechanical properties:

Adequate hardness, rigidity, strengthHigh abrasion resistanceAdequate thermal propertiesAdequate viscoelastic propertiesChemical nondegradability

Superior esthetic propertiesHigh cleansabilityEasy to fabricate and manipulateReadily available and economical to usePermits easy and inexpensive maintenance

such as repairs and additions

Box 12-1

Requirements of an IdealDenture Base

Biocompatible (nontoxic, nonirritant)Adequate physical and mechanical properties:

High flexural and impact strengthHigh modulus of elasticity for better rigidityLong fatigue lifeHigh abrasion resistanceHigh craze resistanceHigh creep resistanceHigh thermal conductivityLow densityLow solubility and sorption of oral fluidsSoftening temperature higher than that of

oral fluids and foodDimensionally stable and accurate

Superior esthetics and color stabilityRadiopacityGood adhesion with denture teeth and linersEase of fabrication with minimum expensesEasily repaired if fracturedReadily cleansable

Box 12-2

Chemical Composition ofDenture Base Resins

Heat-Activated PMMAPowder-liquid systemPowder: prepolymerized spheres of PMMA

Initiator: benzoyl peroxide (~0.5%)Pigments and dyed synthetic fibers

Liquid: methyl methacrylate monomerInhibitor: hydroquinone (traces)Cross-linking agent: ethylene glycol dimetha-

crylate (~10%)Activator-NN-dimethyl-p-toluidine*

Microwave-Activated PMMAPowder-liquid systemSimilar to heat-activated PMMA: with slight

modifications to accommodate the micro-wave activation procedure

Light-Activated Resins (single component,premixed composite sheets and ropes)Matrix: urethane dimethacrylate, microfine silicaFiller: acrylic resin beadsPhotoinitiator: camphoroquine-amine

*Only in chemically activated resins.PMMA, Polymethylmethacrylate.

Box 12-3

Technical Considerations and Properties ofDenture Base Resins

Heat-Activated PMMA These resins are commonlyprocessed in a brass flask using a compression-molding technique (dough technique). The polymerand monomer are mixed in the proper ratio of 3:1by volume or 2.5:1 by weight. The mixed materialgoes through four stages: first, a wet, sandlike stage;second, a tacky fibrous stage as the polymer dis-solves in the monomer; third, a smooth, doughlikestage, suitable for packing into a mold; and fourth,a stiff, rubberlike stage. Dough formation isassisted by internal plasticizers chemicallyattached to the polymer beads that locally softensthem and facilitates monomer diffusion.

After wax elimination, the dough is packed in agypsum mold. The flasks are placed, under pres-sure, in a time-temperature controlled water bath toinitiate polymerization of the resin.

The polymerization reaction is exothermic innature and should be carefully controlled to avoid amarked increase in temperature, which may exceedthe boiling point of unreacted monomer (100.8˚C),leading to denture porosity. Gaseous porosity dueto rapid heating and monomer evaporation appearsas fine, uniform spherical pores, localized moreoften in the thicker portions of the denture.

Inadequate pressure during flask closure, aninsufficient amount of dough present on packing ofthe mold, or improper mixing of powder/liquidcomponents may also result in denture porosity.The resulting porosity will inevitably compromisethe physical properties and denture esthetics andmay promote the accumulation of denture deposits,which could adversely affect the health of thedenture-supporting tissues.

In general, heat-activated acrylic resins arepolymerized by placing the flasks in a constant-temperature water bath at 74˚C (165˚F) for 8 hoursor longer with or without a 2- to 3-hour terminalboil at 100˚C. A shorter cycle involves processingthe resin at 74˚C for approximately 2 hours thenboiling at 100˚C for 1 hour or longer.

Rapid-cure type resins have been recentlyintroduced in the market. The resins are polymer-ized by rapidly heating the packed dough in boilingwater for 20 minutes. The materials are hybridacrylics, in which activation of the polymerization

reaction is carried out through both chemical andheat activators, allowing rapid polymerizationwithout porosity.

It should be noted, however, that processing attemperatures that are too low or for shorter timesincreases the residual monomer content in theprocessed denture base. Excess residual monomerin the polymerized resin base could lead to tissueirritation, sensitivity, or even allergic reactionsin some patients. The plasticizing effects ofexcess monomer could also adversely affect theproperties and dimensional stability of the denture.Fortunately, allergies to residual monomer arerelatively rare, and most patients are well able totolerate the 0.2% to 0.5 % of residual monomer thatoften remains, even in a properly polymerized base.

After the polymerization procedure, the dentureflasks are cooled slowly to room temperature toallow adequate release of internal stresses and thusminimize warpage of the bases. Deflasking thenfollows and should be done carefully to avoid frac-ture or flexing of the dentures.

The popularity and relative simplicity of thecompression molding technique are usually over-shadowed by the high-processing stresses that areinduced in the resins during polymerization. Thesestresses result from various factors. First, polymer-ization shrinkage, which occurs as polymer chainsare formed, accounts for a volumetric shrinkage ofabout 7%. Second, thermal shrinkage follows asthe resin cools. In addition, differences in thermalcontraction of the resin and gypsum mold collec-tively yield stresses in the resin. It is tempting toassume that the release of such cumulative stressesmay give rise to dimensional changes and inaccu-racies in the fit of the denture base. However, thesechanges have been found to be clinically insignifi-cant in the fit of heat-activated acrylic resin denturebases, and in most instances they do not cause dis-comfort to the patient. Occlusal errors that arecommonly encountered after processing are effec-tively corrected and the predetermined verticaldimension of occlusion restored through routinelaboratory remount procedures.

Denture base resins are also subjected to avariety of stresses during function. Midline frac-tures of dentures during function have been consid-ered a flexural fatigue failure because of cyclicdeformation of the base during function. This is


usually more evident in ill-fitting or poorlydesigned dentures. Impact fracture, on the otherhand, may result from accidental dropping of thedentures by the patients. Denture fractures or dis-tortions may be expected considering the far-from-ideal mechanical properties of conventionalunmodified heat-activated resins, particularly theirinferior tensile, flexural, and impact strength aswell as poor fatigue resistance.

Other physical and biological considerationsof conventional heat-activated resins include thefollowing points:

1. Denture bases undergo water absorption,mostly through diffusion, which resultsin linear expansion. The resulting expan-sion has been found to offset the thermalshrinkage that occurs during polymerization.Similarly, conventional acrylic base resinsdo dry out, causing shrinkage. Patients areroutinely cautioned to store their dentures inwater when out of the mouth.

2. Acrylic resin dentures have a low thermalconductivity, portrayed as a substantialdecrease of thermal stimulation of thepatient’s oral tissues under the denturebase. This could be a source of inconven-ience, particularly to first-time denturewearers.

3. Denture base resins deform under load withtime. This viscoelastic property, termedcreep, is minimized, but not entirely elimi-nated, especially under high stresses, by theaddition of cross-linking agents.

4. One of the main advantages of heat-activated resins is their excellent chemicalbond with acrylic resin denture teeth. This isa result of the increased rate of diffusion ofmonomers into polymers at the high temper-atures involved in processing, leading to theformation of chemical welts between theteeth and the bases. On the contrary, adhe-sion of acrylic polymers to metal anduntreated porcelain is weak and can only beeffectively accomplished through mechani-cal retention. Treatment of the ridge lap areaof porcelain teeth with organosilane com-pounds and the use of adhesive primers tochemically bond acrylic resin to metal

alloys has been advocated to overcome thisproblem.

5. Biocompatibility of acrylic resin in the sur-rounding oral environment is considered anattribute to the material. However, waterabsorption of the bases is usually associatedwith the ability of certain organisms to col-onize the fitting surface of the denture (e.g.,Candida albicans), particularly in associa-tion with poor denture hygiene. Frequentcleansing and soaking the dentures in chem-ical cleansers is usually sufficient to mini-mize this problem. The use of chlorhexidinegluconate has been recommended to effec-tively eliminate C. albicans, as well as treat-ing the resin surface with nystatin.

Heat-activated PMMA is less frequently processedusing an injection-molding technique. The resinmix is injected into a closed, sprued flask undercontinuous pressure. The resulting dentures usuallydemonstrate minimum polymerization shrinkage.Other plastics that are injection molded includepolycarbonates, nylon, and polyvinyl acrylics. Thelatter plastics could be considered in patientswith a confirmed allergy to the methacrylatemonomer. However, high capital costs and sensitiv-ity of the technique limit its application for denturefabrication.

Chemically Activated Resins

These resins are often referred to as cold-curing,self-curing, or autopolymerizing resins. As pointedout earlier, the methyl methacrylate monomer con-tains a chemical initiator, a tertiary amine, whichactivates the polymerization process without theneed of any heat. Chemically activated resins aremuch less frequently used for denture fabricationas compared with the heat-activated resins.Processing of the resins could be carried out bycompression molding in a flask, where initial hard-ening of the resin occurs within 30 minutes of flaskclosure. The resins could also be used to producedentures using a pour or fluid resin technique.The principal difference in chemical compositionof the resins used in this technique is the smallersize of the powder particles necessary to ensurefluidity of the mix.


The pour technique involves pouring the fluidmix into a sprued mold made of a reversible hydro-colloid material (agar agar). The flask is placedunder pressure at room temperature or at a slightlyhigher temperature (45˚C). Polymerization is com-pleted in about 30 to 45 minutes. The technique isobviously simpler and cleaner with regard to flask-ing and deflasking but is prone to problems, suchas shifting of denture teeth during pouring of theacrylic into the mold. The use of a hydroflaskincreases atmospheric pressure around the mold,minimizing air inclusions in the mix, thus yieldinga denser resin base.

In comparison with heat-activated resins,chemically activated resins do, in general, have ahigher residual monomer content of 3% to 5%.Polymerization in those resins is never as completeas in heat-activated resins. This results in inferiormechanical properties and dramatically compro-mises biocompatibility of the denture bases.The materials exhibit higher solubility; they haveinferior color stability, due to oxidation of theamine accelerator; and creep rates are usually high,especially under increased stresses. However,chemically activated resins, particularly when com-pression molded, display less shrinkage on poly-merization than their heat-activated counterparts,leading to greater dimensional accuracy. This couldbe attributed to a reduction in the residual stressesinduced during the processing cycle.

Microwave-Activated Resins

Microwaves are electromagnetic waves in themegahertz frequency range that have been recentlyadvocated to activate the polymerization process ofacrylic resin base. The procedure was greatly sim-plified in 1983, with the introduction of a specialglass fiber–reinforced plastic flask, suitable for usein a microwave oven. The acrylic resin is mixed inthe proper powder/liquid ratios, and the composi-tion of the liquid monomer is usually modified tocontrol the boiling of monomer, in a very shortcuring cycle of about 3 minutes. In this techniqueheat is rapidly generated within the monomer as aresult of numerous rapid intermolecular collisions.As the degree of polymerization increases,monomer content decreases proportionally, and asenergy is further absorbed, the remaining monomer

is converted into a polymer. Careful control of thetime and wattage of the oven is essential to yieldporous-free resins and still ensure complete poly-merization. The technique is more time efficientand cleaner than the conventional technique.However, its limitations are related due to its cost-effectiveness for a wide production base, particu-larly because of high equipment expenses andfragility of the plastic flasks, which are easily proneto damage. Microwave-activated resins have com-parable physical and mechanical properties to con-ventionally heat-activated resins, with claims ofeven greater dimensional stability. This could beattributed to the excellent temperature control inthe resin and equal distribution of temperaturethroughout the resin and gypsum mold, respec-tively.

Light-Activated Resin Bases

Light-activated resins, also termed VLC resins, arecopolymers of urethane dimethacrylate and anacrylic resin copolymer along with microfine silicafillers. The polymerization process is activated byplacing the premixed, moldable resin on the mastercast on a rotating table, in a light chamber andexposing it to high intensity visible light of 400 to500 nm, for an appropriate period of about 10minutes. In this technique, after an initial cure ofthe resin base, the teeth are repositioned on thebase using a light-cured template, and contouring iscarried out, followed by a final cure in the lightchamber. The resin is coated with a nonreactivebarrier compound to prevent oxygen inhibition ofthe polymerization process. Light-activated resinscontain no methacrylate monomer and could bereadily used in monomer-sensitive patients. Theproduced resin contains high molecular weightoligomers, which results in smaller polymerizationshrinkage, reportedly half that of conventionalresins. The physical and mechanical properties ofthe resins compare well with conventional heat-activated resins, particularly in regard to impactstrength and hardness. Some studies, however, havereported lower elastic moduli and slightly lowerflexural strength for VLC resins, which couldincrease deformation of the dentures during func-tion. The inferior bond strength of VLC resins toresin denture teeth has been a main concern;


however, significant improvement of this bond hasbeen achieved with the use of bonding agents.

Modified Acrylic Resin Bases

For the prevention of shortcomings in the mechan-ical properties of conventional heat-activatedacrylic resins, modifications have been introducedinto the structure of the polymers to improvemechanical properties, such as flexural, tensile,and impact strengths, as well as fatigue resistance.Chemical modifications to produce graft copoly-mer resins, through the incorporation of a rubberphase, have been attempted. The resulting resinconsists of a matrix of PMMA in which is dis-persed an interpenetrating network (IPN) of rubberand PMMA. The resins absorb more energy athigher strain rates before fracture occurs, resultingin a significant increase in impact strength.However, this modification has been shown to beaccompanied by a reduction in the stiffness orrigidity of the resins.

Rubber reinforcement of PMMA is a success-ful alternative to conventional resins. However, thehigh cost of the material restricts its routine use fordenture fabrication. Mechanical reinforcement ofacrylics has also been attempted through the inclu-sion of fibers such as glass, carbon, aramid(Kevlar) fibers, nylon and ultra high modulus poly-ethylene (UHMPE) polymers, as well as metalinserts (wires, plates, fillers). The resulting resinshave demonstrated an increase in impact and flex-ural strength, as well as a significant improvementin fatigue resistance, effectively minimizingdenture fractures.

Various problems have been associated withthis route of reinforcement of PMMA resins. Thisincludes tissue irritation from protruding glassfibers, poor esthetics associated with dark carbonfibers (black), or straw-colored Kevlar fibers.Other limitations relate to an increase in productiontime, difficulties in handling, precise orientation,placement, or bonding of the fibers within theresin. In the case of metal inserts, failure due tostress concentration around the embedded insertshas been reported.

The availability and quality of fibers fordenture reinforcement are improving very quicklywith great promises for better results in the near

future. Attempts to improve radiopacity of thedenture bases have been carried out to facilitatethe detection of fragments of resin bases that maybe accidentally ingested or, more seriously, inhaledby the patient. These attempts included the use ofmetal inserts, radiopaque salts and fillers, andorganometallic compounds. Examples are bariumsulphate (8% wt), bismuth (10% to 15% concentra-tions), halogen-containing copolymers, or addi-tives such as 2,3-dibromopropyl methacrylate.Unfortunately, many of those attempts have beenaccompanied by adverse effects on the estheticsand strength of the denture base resins or, moreseriously, cytotoxic effects that may endanger thepatient. Table 12-1 provides a summary of com-monly used denture base resins, their processingtechniques, and properties.

MATERIALS USED IN THEFABRICATION OF PROSTHETICDENTURE TEETHProsthetic or denture teeth are produced in a varietyof molds and shades and are available as vacuum-fired porcelain, acrylic resins, modified acrylic,and composite resins. In general, teeth used in thefabrication of dentures should demonstrateoptimum physical and mechanical properties towithstand rigorous demands of masticatory func-tions, such as chewing, biting, shearing, or crush-ing of food, and simultaneously exhibit superioresthetics, particularly in the anterior region of themouth (Box 12-4).

Acrylic Resin Teeth

Acrylic resin (PMMA) denture teeth are manufac-tured either by the compression-molded doughtechnique or by injection molding. Some teethcontain an IPN. Such resins exhibit low creep andflow rates, and minimum dissolution in solvents,which is an important requirement for resin teeth.Most resin teeth are highly cross-linked in thecoronal portion to provide resistance to crazing, butwith little or slight cross-linking in the gingival orbody portion to improve bond to the denture base.A significant advantage of acrylic resin teeth is thatthey bond chemically to the denture base, provided


Table 12-1Processing Techniques and Properties of Denture Base Resins

Processing Technique/Denture Base Resin Method of Activation Advantages Disadvantages

Conventional heat- Compression-molded/dough Good biocompatibility Low Low thermal conductivity Low activated PMMA technique density impact and flexural

Flask and gypsum mold Good esthetics, color strengths Water bath short or stability, surface finish Short fatigue life long cycles Insoluble in oral fluids Low abrasion

Chemical bond with resin resistance teeth Radiolucent

Acceptable dimensional stability

Easily repaired/modified Easy to fabricate/low cost

Heat-activated rubber Compression molded High impact strength Reduced stiffness/rigidity reinforced PMMA Water bath short or long More expensive than

cycles conventional PMMA

Heat-activated fiber Compression molded High impact and flexural Unesthetic color of Carbon reinforced PMMA Water bath short or long strengths and Kevlar fibers

cycles Good fatigue resistance Inferior surface finish High stiffness Increased production time

Difficulty in handling and placement of fibers

Chemically activated Compression-molded/dough Dimensionally accurate High residual monomer PMMA or pour/fluid resin Pour resins easy to deflask content

Agar mold Processing is less time- High creep rates Chemically activated consuming Reduced stiffness

Lower impact/fatigue strengthColor instability High solubilityTooth movement/tooth bond

failures in pour resins

Microwave-activated Compression molded Short processing time High capital cost PMMA Fiber reinforced plastic flask Processing technique Flasks easily fractures/

Microwave energy in an easy/clean limited serviceability oven at 500-600 W Dimensional accuracy Porosity if time/temperature

Curing time as short as Comparable physical/ of oven not controlled3 minutes mechanical properties

to conventionally processed resins

Light-activated PMMA No flask required Simple processing technique High capital cost High intensity visible light Short processing time Inferior bond to resin

(wavelength 400-500 nm) No methacrylate monomer dentureIn special light chamber Low polymerization Decreased elastic Curing time 10 minutes shrinkage teeth modulus Slightly

Improved fit lower flexural strengthComparable impact strength

and hardness to conven-tionally processed resins

PMMA, Polymethylmethacrylate.

that the tooth surface was thoroughly dewaxed.This in turn facilitates grinding of the teeth toaccommodate the available interocclusal spacesand allows reshaping of the teeth to fit small spacesfor esthetic purposes, without fear of destroying thebond to the base. The use of adhesive promoterssuch as (4-methacryloxyethyl trimellitic anhydride[4-META]) has been recently advocated to facili-tate bonding of highly cross-linked acrylic teeth toresin bases. Adhesive resin cements containing thiscompound have also been used to facilitatebonding of resin bases to base metal alloys.

The esthetic qualities of acrylic resin teethhave improved significantly over the years, andclinically they are quite acceptable. The teeth areprepared in layers of different shades with lightershades towards the incisal or occlusal portions,thus increasing their translucency. Both acrylicand porcelain teeth can also be characterized withsurface stains to enhance their natural appearance.A specifically great advantage of acrylic resinteeth is the ease of their occlusal reshaping toachieve the desired articulation needed for variousocclusal schemes. Resin teeth have high resiliencyand are tougher than porcelain teeth, making themless liable to fracture or chipping on impact.Unfortunately, they exhibit inferior abrasion resist-ance, which could lead to alteration in the vertical

dimension of occlusion, particularly in long-timedenture wearers. However, newer, chemicallymodified acrylic resin teeth are more wear resist-ant and stain much less than earlier-used resinteeth.

Composite resin teeth have also been intro-duced as a suitable material for fabrication ofdenture teeth. They contain microfine filler parti-cles of silica and have demonstrated wear proper-ties that are clinically acceptable. Continuedimprovements in the polymer structure may facili-tate its widespread use by most clinicians in thefuture.

Porcelain is another material that has been quitepopular for fabrication of denture teeth for manyyears. Porcelain teeth, in general, exhibit superioresthetic qualities, excellent color stability, and highabrasion resistance. They are mechanicallyattached to resin bases by means of pins or diatoricholes, and this attachment precludes their ability tobe ground, or reshaped, to fit limited interarchspaces. Bonding of porcelain teeth to acrylic baseshas been recently enhanced by a combination ofmicromechanical retention and chemical bonding.This is carried out by treating the ridge lap area ofthe tooth with an etchant such as hydrofluoric acidgel, followed by a silane-coupling agent.

Another limitation of porcelain teeth includestheir ability to cause significant wear of opposingenamel and metallic occlusal surfaces. The teethare quite brittle, can easily crack or chip on impact,and are difficult to grind for occlusal adjustmentsbecause they lose their surface glaze and repolish-ing is quite difficult. Porcelain teeth produce noisyclicking sounds on contact with each other.However, the teeth are not without merits. They aredimensionally stable; are hard, in comparison withthe softer acrylic resins; exhibit no permanentdeformation under occlusal loading; and are insol-uble in oral fluids and in most organic solvents.

In the selection of denture teeth for completedentures, and considering the recently mentionedproperties of the various materials, the dentistshould avoid combining posterior resin teeth withporcelain anterior teeth. The significant differencesin abrasion resistances in both materials, withacrylic resin wearing more rapidly than porcelain,would potentially create destructive occlusal forcesin the anterior region of the mouth. Table 12-2


Requirements of ProstheticDenture Teeth

1. Durable bond with the denture base material2. Resistance to oral fluids/solvents3. High impact strength to withstand forces

during mastication4. High abrasion resistance with little or no

wear to maintain the predetermined verticaldimension of occlusion and withstandparafunctional movements

5. Esthetically pleasing, inconspicuous, ade-quate translucency, color stability, goodsurface texture, and ease of characterizationto produce a natural appearance

6. Easily adjusted and refined by grinding andeasily polished

Box 12-4

compares the properties of acrylic and porcelainteeth.

DENTURE-LINING MATERIALSDenture-lining materials are used to refit the sur-faces of complete dentures and to help conditiontraumatized tissues, providing an interim or perma-nent cushionlike effect. These materials are gener-ally classified into the following types:

1. Short-term soft liners (tissue conditioners)2. Long-term soft liners

Soft denture liners are polymers with a glass tran-sition temperature (Tg) that is below that of mouthtemperature. The Tg is the temperature at which apolymer ceases to be glossy and brittle and changesto a rubberlike form. The soft resilient nature ofthese materials inside the mouth provides themwith a whole range of diagnostic, adjunctive, and

treatment purposes in the management of edentu-lous patients.

Short-Term Soft Liners (Tissue Conditioners)

These materials are soft, resilient materials com-monly used as temporary liners and have beenwidely used in dentistry to manage a multitude ofpatient problems and for various clinical applica-tions (Box 12-5).

Tissue conditioners are provided mostly as apowder/liquid system, but preformed sheets ofacrylic gels are also available. The powder containsa polymer, a polyethylmethacrylate (PEMA), or itscopolymers, and the liquid contains a mixture ofethyl alcohol (solvent) and an aromatic ester(dibutyl phthalate), which acts as a plasticizer thatlowers the Tg of the polymer rendering it a soft gel.The gelation of tissue conditioners is a physicalprocess, which is devoid of any chemical reactionor any monomeric substances that could causetissue irritation. Upon mixing the powder and


Table 12-2Advantages and Disadvantages of Acrylic Resin and Porcelain Teeth

Property Acrylic Resin Teeth Porcelain Teeth

Bond with resin base Chemical bond Mechanical via pins or diatoric holesMechanical properties Less brittle than porcelain Very brittle/chipping occurs on impact

High resilience and toughnessSolubility in oral fluids and Insoluble; some dimensional Insoluble; inert in oral fluids; no

dimensional changes changes dimensional changesMaintenance of vertical Poor abrasion resistance; wear is Excellent abrasion resistance; hard,

dimension (VDO) significant, wear can result in wear is insignificant; VDO tends to reduced VDO be maintained

Effect on opposing occlusion Can oppose natural teeth or Abrades opposing tooth enamel/metallic occlusal surfaces metallic surfaces

Tooth contouring/occlusal Relatively easy Difficult, may result in loss of surface adjustment/repolishing glaze

Grinding of ridge lap areas Easy to grind without compromising Difficult to grind; compromises tooth-resin bond tooth-resin bond; difficult to

position or retain in limitedinterarch spaces

Esthetic properties Excellent, can be characterized as Excellent, can be characterized as required required

Clicking sounds None on contact with opposing teeth Noisy, clicking occurs with opposing porcelain teeth

liquid, the alcohol/plasticizer mix diffuses into theswellable acrylic beads. Gelation involves theentanglement of outer polymer chains of swollenbeads, resulting in a tacky set gel with high cohe-sive properties, which enhances its retention to thefitting surface of the denture. The set gel has vis-coelastic and elastic properties that allow it to actas a shock absorber. The temporary nature of tissueconditioners stems from the fact that both thealcohol and the plasticizer leach out and are par-tially replaced by water. The material thus hardenswithin a considerably short time, which varies froma few days to a week or two, and gradually loses itsproclaimed cushioning effect. In addition, the mate-rial becomes increasingly vulnerable to surfacedeterioration, contamination, and fouling bymicroorganisms, which in turn can lead to furtherirritation to the already abused mucosal tissues.

Ideally, for adequate cushioning, a tissue condi-tioner should be replaced with a fresh mix every 2to 3 days. This procedure should continue until fullrecovery of the tissues has occurred. The gelationcharacteristics and viscoelastic properties of tissueconditioners vary due to differences in their com-position and structures, such as powder particlesize and ethyl alcohol content. Some materials are

formulated to remain soft and resilient for longerperiods. The mechanism of action of tissue condi-tioners is related to their specific viscoelastic prop-erties, which is a combination of both viscous fluidand elastic solid behavior. Viscous behavior allowsadaptation of the gel to the inflamed/irritatedmucosa underlying the denture, which greatlyimproves the fit of the denture. After an initial easyflow, the gel becomes highly viscous, and its flowthereafter is affected by the magnitude of the loadapplied on the denture as well as its duration. Thisconsequently affects stress distribution in themucosa. Concurrently, under cyclic/intermittentloading such as during chewing, the materialdemonstrates a time-dependent elastic behaviorthat allows it to recover initial deformation, absorb-ing impact forces and cushioning the underlyingtissues. Thus viscoelastic and elastic properties oftissue conditioners result in an even distributionof load on the underlying mucosa and a cushioningof cyclic forces of mastication. This in turn allowsthe traumatized mucosa to recover, particularlyunder an ill-fitting denture.

Short-term soft liners can also be used as func-tional impression materials. Requirements for thisclinical application differ slightly from thoserequired for tissue conditioning.

For traumatized tissues to be effectively condi-tioned, a tissue conditioner should demonstrateadequate flow and elastic properties. Maintenanceof this viscoelastic behavior is the key to its clini-cal success. A functional impression material, onthe other hand, should display good flow but withminimal elastic recovery. The material should flowreadily under functional stresses, ensuring contin-ual adaptation to the underlying soft tissues as theyare altered under stresses. However, for guaranteedaccuracy of the impression, the material mustundergo minimum elastic recovery and shouldexhibit adequate dimensional stability in terms ofweight change, water sorption, and solubility. Castsshould be poured immediately after removal of theimpression from the patient’s mouth. Functionalimpressions are routinely removed from thepatient’s mouth after a few days. Results of recentstudies recommend even shorter periods of 24hours to obtain optimum results.

Materials that are available as short-term softliners vary considerably in their compositions and


Indications for Short-Term SoftLiners/Tissue Conditioners

1. Treatment and conditioning of abused/irri-tated denture supporting tissues lining ill-fitting dentures allows the tissues to rest andregain their health prior to impressionmaking for new dentures

2. For provisional adjunctive/diagnostic pur-poses such as recovery of the vertical dimen-sion of occlusion and correcting occlusion ofold prosthesis; also to assess the necessity ofusing a permanent soft liner for patientswith chronic pain or soreness associatedwith denture wearing

3. Temporary relining of immediate den-tures/immediate surgical splints

4. Relining cleft palate speech aids5. Tissue-conditioning during implant healing6. Functional impression materials

Box 12-5

properties; some fulfill the requirements of anoptimum functional impression material more effi-ciently than others. The choice of materials shouldbe based on a thorough understanding of theirproperties in conjunction with their effective clini-cal applications.

Self-Administered Home Relines

Numerous over-the-counter temporary reline mate-rials are available for patients’ use and are mar-keted as “home relines.” The materials allow thepatient to adjust the fit of their dentures. They aresupplied as preformed thermoplastic pads or in apowder/liquid form and have a similar compositionand manipulation as treatment liners. The mainlimitation and danger of these materials are thehigh potential for their misuse. Improper adherenceto manufacturer’s instructions on the proper mixingof the components or long-term use of these linerscan lead to trauma, can cause irritation to theunderlying tissues, may adversely affect thedenture base materials, and may cause occlusalerrors. There is a unanimous consensus thatpatients should be strongly discouraged from usingthese materials as a substitute for seeking properprofessional help.

Long-Term Soft Liners

Long-term/permanent soft liners are mostly used asa therapeutic measure for patients who cannot tol-erate the stresses induced by dentures. There isstrong theoretical evidence to justify the use ofthese materials in the management of edentulouspatients who suffer from chronic pain, soreness, ordiscomfort due to prolonged contact between therigid denture base materials and the underlyingtissues. Such as the case in patients with sharp,thin, or heavily resorbed ridges or those with severebony undercuts. In these situations a viscoelastic softliner would be a welcome adjunct to compensate forthe dramatically depleted mucoperiosteal support.The liner permits wider dispersion of forces andabsorption of impact forces that are involved in func-tional and parafunctional movements.

Materials available as permanent soft linersinclude plasticized acrylics, silicone rubber, plasti-cized vinyl polymers and copolymers, hydrophilic

polymers, polyphosphazine fluoropolymers, fluo-roethylene, and polyvinyl siloxane addition sili-cones. Currently, the most commonly usedmaterials are plasticized acrylics and siliconerubber, which are either chemically or heat acti-vated. Requirements of an ideal permanent softliner are presented in Box 12-6.

Plasticized Acrylics

Heat-activated plasticized acrylic liners are sup-plied as preformed sheets or in a powder/liquidform. The powder consists of a higher methacrylatepolymer (PEMA) and benzoyl peroxide as an ini-tiator. The liquid consists of a higher methacrylatemonomer (such as ethyl, n-butyl or 2-ethoxyethylmethacrylate) together with a plasticizer, commonlya phthalate ester. The plasticizer lowers the Tg ofthe resin and acts as a lubricant betweenthe polymer chains, enabling them to deform moreeasily. The liner is processed in the laboratory,usually at the time of processing a new denture.

Chemically activated acrylic resins are alsoavailable as soft liners. Their chemical compositionis similar to that of heat-activated resins, but theyare polymerized by a peroxide-tertiary aminesystem. These materials are applied as chairside


Requirements of an Ideal Long-Term Soft Liner

1. Biocompatibility2. Good dimensional stability3. Low water sorption and water solubility4. Good wettability by saliva5. Permanent softness/compliance/viscoelas-

ticity6. Adequate abrasion resistance and tear

resistance7. Good bond to the denture base8. Unaffected by aqueous environment and

cleansers, easy to clean9. Simple to manipulate

10. Color stable and exhibits good esthetics11. Inhibits colonization of fungi and other

microorganisms

Box 12-6

relines, and polymerization usually takes a fewminutes. However, as with other mouth-curedliners, they can only be used on a temporary basisbecause of their tendency to foul and debond fromthe denture within a few weeks, a major drawbackthat limits their clinical application. The presenceof free monomer also results in inferior mechanicalproperties and reduced biocompatibility.

Silicone Soft Liners

Another commonly used long-term soft liner is sil-icone rubber. Silicone liners are provided with heatactivation or room temperature vulcanization(RTV).

Heat-activated silicone is supplied as a singlepaste that consists of poly(dimethyl siloxane), aviscous liquid to which silica is added as a filler,and benzoyl peroxide as an initiator. The liner setsby a cross-linking reaction that is catalyzed by heatand the peroxide initiator. It is processed againstthe acrylic dough of the new denture. The additionof an adhesive usually enhances the bond betweenthe liner and the acrylic resin base.

RTV silicones, on the other hand, use a con-densation cross-linking process catalyzed by anorgano-tin compound. The materials are suppliedas paste and liquid and are also laboratoryprocessed to the fitting surface of the denture base.The fact that these materials achieve a lower degreeof cross-linking than their heat-activated counter-parts certainly compromises many of their attrib-utes as long-term liners.

Advantages and Disadvantages ofPermanent Soft Liners

Despite the vast clinical benefits that have beenrecognized for plasticized acrylics and silicones assoft liners, both materials exhibit properties thatare by far short of fulfilling requirements of anideal permanent liner. This fact has limited theirefficacy and life expectancy, reportedly to amaximum of 1 year of serviceability.

Plasticized acrylic soft liners exhibit good,durable bond strength to the acrylic base, have beenshown to exhibit higher tear and abrasion resist-ance, and can achieve a much better polish than sil-icones.

However, biodegradation of plasticized acrylicsin the oral environment is their main weakness. Theplasticizer and other soluble materials in the linerleach out in saliva resulting in a progressive loss ofresiliency, diminishing their cushioning effect. Theresulting hard, rough surface of the liner then pro-motes calculus and food accumulation and under-goes fouling with microorganisms, as well as colorchanges and staining.

The major drawback of silicones as soft linersis their intrinsic inability to bond with the denturebase resin, which is more evident around the bordersof the denture. High water sorption by the lineraccentuates this problem further, detrimentallyaffecting the adhesion between the liner and resinbase. This is a particular problem in RTV silicones,which tend to swell, split, or peel off the denturebase. Attempts to enhance the bond with resinbases include adding bonding agents; using specialprimers applied to the acrylic base, as in the case ofRTV silicones; or confining the borders of the linerto end within the denture border, rather thanextending it to the periphery of the denture base.However, such a design may be accompaniedwith the risk of decreasing the shock absorbabilityof the liner.

Despite their shortcomings, silicone rubbers,particularly those that are heat activated, have amyriad of properties that enhances their clinicalpreeminence over plasticized acrylics, mostly theirhigh resilience and prolonged elasticity over time,which in turn, enables them to maintain their cush-ioning effect longer than other soft liners.

Most challenging in the use of long- and short-term soft liners is their tendency to support growthof C. albicans and other microorganisms on andwithin the liners. The porous nature, particularly ofsilicones, reportedly facilitates water absorptionand diffusion of nutrient materials. This is furthercomplicated by the difficulty of cleaning most ofthese liners with routine mechanical or chemicalmethods, such as brushing, or hypochlorite andperoxide denture cleansers (Figure 12-1).

Excellent oral and denture hygiene and the useof antimicrobial agents can effectively minimizefungal/microbial colonization of liners. Cleaningof soft liners can be carried out with a soft brush inconjunction with a very mild detergent or nonabra-sive dentifrice. Alternatively, the external surface


of the denture can be cleaned as described, but theliner itself can be wiped with cotton under coldwater. Box 12-7 provides a comparison of proper-ties of plasticized acrylics versus silicone rubber.

Clinical experience indicates almost universaltissue tolerance of soft liners and acceptable patientreactions. However, currently, the materials have tobe considered as temporary expedients becausenone of the advocated permanent soft liners has alife expectancy comparable to that of the resindenture base. Improved strength, permanentresiliency, improved adhesion to the denture bases,the ability to inhibit growth of microorganisms,and chemical stability continue to be the mainfocus of ongoing research. These attempts includesurface coatings of liners with sealants such as flu-orinated copolymers and integration with antifun-gal components. Silicone rubbers, when properly

used, may be the most appropriate of the varioustypes available, but they too are only temporaryexpedients and must be inspected regularly by thedentist and replaced when unsatisfactory. Aspointed out earlier, the application of propercleansers and home care habits has contributed tothe use of these materials with significantly bene-ficial results. It must be emphasized, however, thatusing these materials does not preclude adherenceto the fundamental principles of complete dentureconstruction. Nevertheless, when used intelli-gently, soft liners are an excellent adjunct in remov-able prosthodontics.

DENTURE CLEANSERSEducation of patients is crucial to enhance theirawareness of both limitations and inherent weak-


A B

CFigure 12-1 A, Recently completed resilient liner on a mandibular denture. B, A 6-month-old resilient liner with foci of yeast colonies already apparent. C, A neglected12-month-old resilient liner with almost total coverage by yeast colonies.

nesses in the physical and mechanical properties ofthe inserted prosthesis. Furthermore, it must beemphasized that improper care of dentures canhave serious detrimental effects on the health of thedenture-supporting tissues. Most patients areunaware of the risks of microbial plaque accumula-tions around and under the denture-tissue inter-faces and the potential for promoting adversepathological mucosal reactions such as denturestomatitis and angular cheilitis.

The presence of denture deposits and their rateof accumulation are directly related to the pres-ence of a protein-rich saliva and the microporousnature of the polymeric base, which facilitatesmicrobial plaque formation and ensuing calculusdeposition. The organic portion of calculus consistsof microproteins that bond the deposits to thedenture surface, whereas the inorganic portionmostly contains calcium phosphate and calcium

carbonate. Maintenance of adequate denturehygiene, through mechanical or chemical methods,or both, is essential to minimize and preferablyeliminate adverse tissue reactions. It must be anintegral component of postinsertion patient care.

Denture cleansing materials and techniquesinclude mechanical brushing, the use of chemicalcleansers, or both. Commonly available denture clean-sing materials include (1) oxygenating cleansers, (2)alkaline hypochlorite solutions, (3) dilute mineralacids, (4) abrasive powders and pastes, and (5)enzyme-containing materials (proteases) (Box 12-8).

Mechanical Techniques

Patients are routinely instructed to clean their den-tures by light brushing with a soft denture brush ora multifluted soft nylon brush with rounded endsand soap and water. The mechanical cleaningaction of the brush is usually sufficient to removeloosely attached soft food debris, without abradingthe denture base and teeth. However, it is ineffec-tive for denture disinfection. The removal of hardcalculus deposits, plaque, and stains require morevigorous measures such as the daily use of immer-sion chemical denture cleansers or brush-on dilutedacid cleansers.

The use of hard bristle brushes, forceful brush-ing, or abrasive dentifrices, such as calcium car-bonate or hydrated silica, may cause abrasion ofpolymeric materials or result in scratches on theirsurface. The rough, irregular surfaces promote


A Comparison of the Propertiesof Plasticized Acrylics versus

Silicone Rubber

Plasticized AcrylicsLess resilientHardens by time/loss of plasticizerGood durable bond with denture baseMore resistant to growth of Candida albicansAcceptable tear strengthBetter abrasion resistanceReasonable resistance to damage by denture

cleanser

Silicone RubberHighly resilientRetains softness and elasticityLow bond strength to acrylic base, particularly

RTV siliconesMore susceptible to growth of C. albicans/ other

microorganismsLow tear strengthLow abrasion resistanceLess resistant to damage by cleansers particu-

larly RTV silicones

RTV, Room temperature vulcanization.

Box 12-7

Requirements of an IdealDenture Cleanser

1. Nontoxic2. Easy to remove and harmless to the patient

(eyes-skin-clothes) if accidentally spilled orsplashed

3. Harmless to the denture base materials anddenture teeth as well as soft liners

4. Able to dissolve all the denture deposits suchas calculus

5. Exhibits a bacteriocidal and fungicidal effect6. Long shelf life and inexpensive

Box 12-8

accumulation of denture deposits, increase stainingand fouling with oral microorganisms, and theydramatically compromise denture esthetics. Pasteswith some gentle abrasives (sodium bicarbonate oracrylic resin) may be used. Similarly, patientsshould be strongly advised against using abrasivehousehold kitchen or bathroom cleansers, such asscouring powder, to clean their dentures.

Chemical Denture Cleansers

The most commonly used commercial chemicaldenture cleansers use immersion techniques; theseinclude alkaline peroxides and hypochlorites.Advantages of immersion cleansers include fullaccessibility of the solutions to all areas of thedenture, minimum damage from mishandling den-tures, minimum abrasion of denture bases andteeth, and use simplicity of the technique.

Oxygenating Cleansers Alkaline peroxides areprovided in powder and tablet forms. The materialcontains alkaline compounds, detergents, sodiumperborate, and flavoring agents. When mixed withwater, sodium perborate decomposes releasing per-oxides, which in turn decomposes releasing oxygen.Cleansing is a result of the oxidizing ability of theperoxide decomposition and from the effervescentaction of the evolved oxygen. This effectivelybreaks down, dissolves, and floats away organicdeposits and kills microorganisms. Peroxides arenot as effective, though, in removing heavy calcu-lus deposits. Some are not compatible with softdenture liners. Overnight immersion of dentures inan alkaline peroxide solution is a safe, effectivemethod of denture cleaning and sterilization, par-ticularly among geriatric or disabled patients,whose limited manual dexterity may deter themfrom using mechanical brushing techniques.

Hypochlorite Solutions Diluted householdbleaches (sodium hypochlorites) are commonlyused as denture cleansers, for removing plaque andlight stains, and are capable of killing dentureadherent organisms. One technique involves theimmersion of the dentures in a solution of one partof 5% sodium hypochlorite in three parts of water(1:3 water) followed by light brushing. Alternatively,the denture is immersed in a solution containing

1 teaspoon of hypochlorite (Clorox) and 2 teaspoonsof a glassy phosphate (Calgon) in half a glass ofwater, to help control calculus and heavy stains.

Alkaline hypochlorites are not recommendedfor dentures fabricated from cast base metal alloys.The chlorine ions can result in corrosion and dark-ening of these metals. Concentrated hypochloritesolutions should also not be used because pro-longed use may alter the color of the denture baseresins. Bleaches may eventually discolor softdenture liners, particularly silicones. The impor-tance of avoiding soaking dentures in hot watershould be stressed to the patient to avoid distortionof the denture bases.

Other Techniques/Materials● Ultrasonic units provide vibrations that can

be used to clean dentures. When this tech-nique is used, the denture is placed into acleaning unit, which is filled with a soakingchemical agent supplied by the manufac-turer. The cleansing action of the soakingagent is supplemented by the mechanicaldebriding action of the ultrasonic vibrations.This in turn creates areas of vacuum next tothe denture surface and thus dislodges anddispenses debris. Despite its effectiveness,this technique may not adequately removeplaque on the denture surface. It is mostlyavailable for use in institutions such asnursing homes and hospitals.

● Dilute acids (citric acid, isopropyl alcohol,hydrochloric acid, or plain householdvinegar) are available to remove obstinatedeposits. The brush-on cleanser is swabbedonto the denture surfaces with a brush. Thematerials attack the inorganic phosphateportion of denture deposits, thus reducingcalculus accumulations. Vinegar can also killmicroorganisms but less effectively thanbleaching solutions. Brush-on materialsmust be used cautiously, and the denturemust be rinsed thoroughly to avoid contactof the material with the skin and mucosa.Diluted acids may also cause corrosion ofsome alloys.

● Denture cleansers containing enzymes(mutanese and protease) have been shown to


reduce denture plaque significantly, with adaily 15-minute soak, particularly whencombined with mechanical brushing of thedentures.

● Other materials and techniques include theuse of silicone polymers. These cleansersprovide a protective coating, which inter-feres with bacterial adherence to the denturesurface until their next application.Overnight air-drying and microwave radia-tion have been also used to disinfect andclean resin bases, mostly in conjunction withmechanical brushing.

Table 12-3 describes disadvantages of the varioustypes of denture cleansers.

CAST METAL ALLOYS AS DENTURES,BASESDespite the popularity of PMMA as a denture basematerial, its inherent weaknesses in mechanicalproperties increases its susceptibility to impact andfatigue failure. Both are considered to be the twomain causes of denture fractures. The reinforcementof conventional PMMA resins through the incorpo-ration of rubber inclusions and fibers has signifi-cantly enhanced the impact and flexural strengths ofthe material as well as its fatigue resistance.However, there are various clinical situations wherea dentist may select an alternative material. Onesuch situation is where a single maxillary completedenture opposes a full or partial complement of

natural mandibular teeth. An unfavorable/irregularocclusal plane, heavy anterior occlusal contacts,and heavy masticatory forces directed onto a virtu-ally thin palatal resin plate may collectively con-tribute to denture fracture. In such a situation, thechoice of a cast metal base has been recommendedas an effective alternative to resin bases.

A variety of metals and metal alloys have beenused as complete denture bases. Currently, the mate-rials of choice include cast base metal alloys: cobalt-chromium, nickel-chromium, cobalt chromiumnickel, and more recently titanium alloys.

In this technique a relatively thin metal base iscast to contact the denture-bearing mucosa surface,covering the whole palate, providing superior fitand comfort to the patient. Acrylic resin is used toretain the denture teeth and provide buccal/labialflanges that enhance the esthetic quality of thedenture. The processed acrylic resin is attached tothe cast metal base by a retentive meshwork. Theacrylic resin and metal meet at a definite finish lineto ensure a strong butt junction. Care must be takento avoid inadequate shaping of the palatal contoursat the finish line or placing the acrylic resin–metaljunction too far laterally or medially, which couldresult in crowding or inadequate contact with thelateral border of the tongue, causing discomfort oraltering the patient’s phonetics (Figure 12-2).

Cobalt-chromium alloys, often referred to asstellite alloys, consist of about 60% cobalt and 25%to 30% chromium, together with minor alloyingelements such as manganese and silicone toenhance its fluidity for casting. Other components


Table 12-3Disadvantages of the Various Types of Denture Cleansers

Cleanser Main Constituent Disadvantages

Oxygenating cleansers Alkaline perborate Ineffective for removal of heavy calculus deposits; harmful to soft liners

Hypochlorite solutions Dilute sodium hypochlorite May bleach denture base resins May discolor soft liners Corrosion of base-metal alloys Unpleasant odor

Dilute acids Hydrochloric acid Corrosion of some alloys Citric acid/isopropyl alcohol Unpleasant odor

Denture cleansing powder/paste Abrasive agents Abrasion of denture polymeric bases and teeth

included are aluminum, gallium, copper, iron, andplatinum. Molybdenum, tungsten, and carbon arealso added as hardening and strengthening ele-ments. The resulting alloys display high strength,hardness, high modulus of elasticity (stiffness),low density, and high corrosion resistance, andthey have a substantially lower cost than goldalloys.

Nickel-chromium alloys contain about 70%nickel and a lower content of chromium (16%). Theinclusion of beryllium (0.5%) in minor quantitieslowers the melting range and enhances fluidity ofthe alloy. The inclusion of aluminum (2%) leads tothe formation of an intermediate (Ni3-Al) com-pound that increases the strength and hardness ofthe alloy. Box 12-9 lists the advantages and disad-vantages of base metal alloys, as compared to allresin complete denture bases as listed in Table 12-1.

The controversy surrounding the biocompati-bility of cobalt- and nickel-containing alloys aspotential allergenics and the biological risks ofmetal ions released in the mouth during corrosion(such as beryllium, a carcinogenic hazard) suggeststhe merits of another cast base metal, titanium, asan alternative. Superiority of titanium stems fromits remarkable biocompatibility and high corrosionresistance. In addition, it exhibits high dimensionalstability, low density, and mechanical propertiesthat are comparable to those of cobalt-chromiumalloys. The main drawback of titanium as a denture


Advantages and Disadvantagesof Base Metal Alloys

AdvantagesHigh thermal conductivityIncreased tissue toleranceReduced bulk across the palate creates more

tongue space/increased comfort to patientDimensional stability/increased accuracy of fit

of the denture baseSuperior biocompatibility of titanium basesStronger bases that withstand high masticatory

stressesIncreased weight, enhances stability of a

mandibular denture

DisadvantagesGreater technical costsDifficulty of rebasing and relining metal/cur-

rently facilitated with adhesivesLess margin of error permissible in the poste-

rior palate seal areaIncreased weight for a maxillary denture

Box 12-9

A

BFigure 12-2 Metal bases for complete dentures. A, Gold, stellite (cobalt/chromium), or titanium alloycovers the palate and residual ridges with the bordersformed in acrylic resin. It should be noted that manydentists prefer to not cover the residual ridges withmetal so as to facilitate relieving and reliningprocedures for acrylic resin covered sites in the future.B, Also note that the posterior palatal seal area neednot be made of metal. Many dentists prefer a “mesh”area here to provide excellent retention for an acrylicposterior palatal seal. The tuberosity regions may needto be entirely covered in metal or a mesh plus acrylicas dictated by the interarch space.

base alloy relates to difficulties in its casting tech-nique. Casting problems of titanium are a result ofits relatively low density, high melting point (about1700˚ C), high chemical affinity to gases (oxygen,hydrogen, nitrogen), and its reactivity with compo-nents of most investment materials. This has led toa variety of problems such as low casting effi-ciency, casting porosities, difficulty in finishing,soldering, and welding of the metal. Casting tita-nium is a relatively expensive laboratory techniquethat requires high-cost equipment.

Recent advances in casting technology andmelting techniques, such as electric arc melting andlaser welding; in investment materials; and inalloying titanium with other metals to attain lowermelting and casting temperatures have greatlyfacilitated the casting of titanium-based metals andits use in dental laboratories.

SUMMARYThe premise in preparing this review chapter is thatdentists should possess sufficient knowledge of theproperties of the different prosthodontic materialsthey deal with so that they can exercise prudentjudgment in their selection. This knowledge shouldbe preferably based on evidence-based informationplus large scale, long-term clinical trials to ensuretreatment efficacy and effectiveness.

BibliographyAu AR, Lechner SK, Thomas CJ et al: Titanium for removable

partial dentures (III): 2-year clinical follow-up in an under-graduate program, J Oral Rehabil 27:979-985, 2000.

Blagojevic V, Murphy VM: Microwave polymerization ofdenture base materials: a comparative study, J Oral Rehabil26:804-808, 1999.

Clarke RL: Glassy polymers. In Braden M, Clarke RL,Nicholson J, Parker S, editors: Polymeric dental materials,Verlag Berlin, 1997, Springer.

Combe EC, Burke FJT, Douglas WH: Dental biomaterials,Boston, 1999, Kluwer Academic.

Cunningham JL: Shear bond strength of resin teeth to heat-cured and light-cured denture base resins, J Oral Rehabil27:312-316, 2000.

Cunningham JL, Benington IC: An investigation of the variableswhich may affect the bond between plastic teeth and denturebase resins, J Dent 27:129-135, 1999.

Da Silva L, Martinez A, Rilo B et al: Titanium for removabledenture bases, J Oral Rehabil 27:131-135, 2000.

Jagger DC, Harrison A, Jandt KD: The reinforcement of den-tures, J Oral Rehabil 26:185-194, 1999.

John J, Gangadhar SA, Shah I: Flexural strength of heat-poly-merized polymethylmethacrylate denture resin reinforcedwith glass, aramid or nylon fibres, J Prosthet Dent 86: 424-427, 2001.

Kawano F, Ohguri T, Koran A III et al: Influence of lining designof three processed soft denture liners on cushioning effect, JOral Rehabil 26:962-968, 1999.

Koran A III: Prosthetic applications of Polymers. In Craig RG,Powers JM, editors: Restorative dental materials, ed 11, StLouis, 2002, Mosby Inc.

Malmström HS, Mehta N, Sanchez R et al: The effect of two dif-ferent coatings on the surface integrity and softness of atissue conditioner, J Prosthet Dent 87:153-157, 2002.

McCabe JF, Carrick TE, Kamohara H: Adhesive bond strengthand compliance for denture soft lining materials,Biomaterials 23:1347-1352, 2002.

Murata H, Kawamura M, Hamada T et al: Dimensional stabilityand weight changes of tissue conditioners, J Oral Rehabil28:918-923, 2001.

O’Brien WJ: Dental materials and their selection, ed 3,Chicago, 2002, Quintessence Publishing Co, Inc.

Ödman PA: The effectiveness of an enzyme-containing denturecleanser, Quintessence Int 23:187-190, 1992.

Parker S: Soft prosthesis materials. In Braden M, Clarke RL,Nicholson J, Parker S, editors: Polymeric dental materials,Verlag Berlin, 1997, Springer.

Phoenix RD: Denture base resins, technical considerations andprocessing technique. In Anusavice KJ, editor: Phillips’science of dental materials, ed 10, Philadelphia, 1996,WB Saunders.

Qudah S, Harrison A, Huggett R: Soft lining materials in pros-thetic dentistry: a review, Int J Prothodont 3:477-483, 1990.

Shay K: Denture hygiene: a review and update, J Contemp DentPract 1:28-41, 2000.

Taguchi N, Murata H, Hamada T et al: Effect of viscoelasticproperties of resilient denture liners on pressures under den-tures, J Oral Rehabil 28:1003-1008, 2001.

Takahashi Y, Chai T, Takahashi T et al: The bond strength ofdenture teeth to denture base resins, Int J Prosthodont13:59-65, 2000.

Takamata T, Setcos JC: Resin denture bases: review of accuracyand methods of polymerization, Int J Prosthodont 2:555-560, 1989.

Tan HK, Woo A, Kim S et al: Effect of denture cleansers, surfacefinish and temperature on Molloplast B resilient liner, color,hardness and texture, J Prosthodont 9:148-155, 2000.


211

If dentures and their supporting tissues are to coex-ist for a reasonable length of time, the dentist mustfully understand the anatomy of the supporting andlimiting structures involved, for these are the foun-dation of the denture-bearing area. The denturebase must extend as far as possible without inter-fering in the health or function of the tissues. It isconvenient to regard the impression surface of adenture as comprising two areas: a stress-bearingor supporting area and a peripheral or limiting area.Each of these is discussed separately, but like thesides of a coin they are inseparable.

ANATOMY OF SUPPORTING STRUCTURESThe foundation for dentures is made up of bone ofthe hard palate and residual ridge, covered bymucous membrane. The denture base rests on themucous membrane, which serves as a cushionbetween the base and the supporting bone.

Mucous Membrane

The mucous membrane is composed of mucosaand submucosa. The submucosa is formed by con-nective tissue that varies in character from dense toloose areolar tissue and also varies considerably inthickness. The submucosa may contain glandular,fat, or muscle cells and transmits the blood andnerve supply to the mucosa. Where the mucousmembrane is attached to bone, the attachmentoccurs between the submucosa and the periostealcovering of the bone.

The mucosa is formed by stratified squamousepithelium, which often is keratinized, and a subja-cent narrow layer of connective tissue known as thelamina propria. In the edentulous person, themucosa covering the hard palate and the crest ofthe residual ridge, including the residual attachedgingiva, is classified as masticatory mucosa. It ischaracterized by a well-defined keratinized layer onits outermost surface that is subject to changes inthickness depending on whether dentures are wornand on the clinical acceptability of the dentures.

Although the importance of the mucosa from ahealth standpoint cannot be neglected, the thick-ness and consistency of the submucosa are largelyresponsible for the support that the mucous mem-brane affords a denture because in most instances,the submucosa makes up the bulk of the mucousmembrane. In a healthy mouth, the submucosa isfirmly attached to the periosteum of the underlyingsupporting bone and will usually withstand suc-cessfully the pressures of the dentures. Whenthe submucosal layer is thin, the soft tissues willbe nonresilient, and the mucous membrane will beeasily traumatized. When the submucosal layer isloosely attached to the periosteum or it is inflamedor edematous, the tissue is easily displaceable, andthe stability and support of the dentures areadversely affected.

Hard Palate

The ultimate support for a maxillary denture is thebone of the two maxillae and the palatine bone. Thepalatine processes of the maxillae are joinedtogether at the medial suture (Figure 13-1). The

C H A P T E R 13Developing an Analogue/Substitute forthe Maxillary Denture-Bearing AreaDavid M. Davis

palatine processes of the maxillae and the palatinebone form the foundation for the hard palate andprovide considerable support for the denture. Moreimportant, they support soft tissues that increasethe surface areas of the basal seat.

A cross section of the hard palate shows that thepalate is covered by soft tissue of varying thickness,even though the epithelium is keratinized through-out. In the region of the medial palatal suture, thesubmucosa is extremely thin, with the result thatthe mucosal layer is practically in contact with theunderlying bone. For this reason, the soft tissuecovering the medial palatal suture is nonresilientand may need to be relieved to avoid trauma fromthe denture base. Anterolaterally, the submucosacontains adipose tissue, and posterolaterally it con-tains glandular tissue. This tissue is displaceable,

and although it contributes to the support of thedenture, the horizontal portion of the hard palatelateral to the midline provides the primary supportarea for the denture. In the area of the rugae, thepalate is set at an angle to the residual ridge and israther thinly covered by soft tissue. This area con-tributes to the stress-bearing role, though in a sec-ondary capacity. The submucosa covering theincisive papilla and the nasopalatine canal containsthe nasopalatine vessels and nerves.

Residual Ridge

The shape and size of the alveolar ridges changewhen the natural teeth are removed. The resorptionfollowing extraction of the teeth is rapid at first, butit continues at a reduced rate throughout life. If the

212 Part Three Rehabilitation of the Edentulous Patient: Fabrication of Complete Dentures

D

CB

A

Figure 13-1 Both the maxillae and the palatine bone provide support for an upper den-ture. Individual differences in form determine how forces should be directed to these bonesduring function. A, Spiny projections that would irritate tissues under a denture. B, Roughand irregular bone of the maxillary ridges. C, Incisive foramen, which comes to lie closer tothe crest of the ridge as resorption takes place. Thus the location of the incisive papilla,which covers the incisive foramen, in relation to the crest of the ridge is a guide to theamount of resorption that has occurred. D, Greater palatine foramen, which often has a spinyoverhanging edge to it.

teeth have been out for many years, the residualridge may become small, and the crest of the ridgemay lack a smooth, cortical bony surface under themucosa. There may be large, nutrient canals andsharp bony spicules (see Figure 13-1).

The mucous membrane covering the crest ofthe ridge in a healthy mouth is firmly attached tothe periosteum of the bone by the connective tissueof the submucosa. The stratified squamous epithe-lium is thickly keratinized. The submucosa isdevoid of fat or glandular cells and is characterizedby dense collagenous fibers that are contiguouswith the lamina propria. The submucosal layer,though relatively thin in comparison with otherparts of the mouth, is still sufficiently thick to pro-vide adequate resiliency to support the denture.

The crest of the edentulous ridge is an impor-tant area of support. However, the bone is subject toresorption, which limits its potential for support,unlike the palate, which is resistant to resorption.Because of this, the ridge crest should be looked onas a secondary supporting area, rather than a pri-mary supporting area. The inclined facial surfaceof the maxillary ridge provides little support,

although the peripheral tissues should be contactedto provide a border seal.

As the mucous membrane extends fromthe crest along the slope of the residual ridge tothe reflection, it loses its firm attachment to theunderlying bone (Figure 13-2). The more looselyattached mucous membrane in this region has anonkeratinized or slightly keratinized epithelium,and the submucosa contains loose connective tissueand elastic fibers. This loosely attached tissue willnot withstand the forces of mastication transmittedthrough the denture base as well as the mucousmembrane covering the crest of the ridge and thepalate.

Histological studies of the effect of wearingdentures on the keratinization of the mucosa of thecrest of the residual ridges and the palate have pro-duced conflicting results. However, most studiesindicate that wearing dentures does not seem tobe harmful to the epithelium, even though in den-ture wearers the keratinization is of reduced thick-ness. Cytological studies indicate that increasedamounts of keratinized material are present inedentulous ridges when the clinical quality of the

Chapter 13 Developing an Analogue/Substitute for the Maxillary Denture-Bearing Area 213

Figure 13-2 Arrows denote the line of demarcation between the attached and unat-tached mucous membrane. Attached mucous membrane is desirable for support. However, itis the peripheral area that contributes to the border seal. Notice the prominent incisivepapilla lying anteriorly on the center of the residual ridge.

dentures is good, an indication that well-fitting den-tures may be important in maintaining the normalhistological condition of the mouth. Stimulation ofthe mucosa of the residual ridge through tooth-brush physiotherapy also increases the presence ofkeratinized material. Histologically, removing thedentures from the mouth for 6 to 8 hours a day,preferably during periods of sleep, allows kera-tinization to increase and the signs of inflamma-tion, often found in the submucosa when denturesare worn, to be dramatically reduced.

Shape of the Supporting Structure

The configuration of the bone that provides thesupport for the maxillary denture varies consider-ably with each patient. Factors that influence theform and size of the supporting bone include (1) itsoriginal size and consistency; (2) the person’s gen-eral health; (3) forces developed by the surround-ing musculature; (4) the severity and location ofperiodontal disease (a frequent cause of tooth loss);(5) forces accruing from the wearing of dentalprostheses; (6) surgery at the time of removal of theteeth; and (7) the relative length of time differentparts of the jaws have been edentulous. In addition,a number of anatomical features influence theshape of the hard palate and residual ridge. Theseare described in the following material.

Incisive Foramen This is located beneath theincisive papilla, which is situated on a line imme-diately behind and between the central incisors. Itlies nearer to the crest of the ridge as resorptionprogresses (see Figure 13-2). Thus the location ofthe incisive papilla gives an indication as to theamount of resorption that has taken place. Thenasopalatine nerves and blood vessels pass throughthe foramen, and care should be taken that the den-ture base does not impinge on them.

Maxillary Tuberosity The tuberosity region canhang down abnormally low because when the max-illary posterior teeth are retained after themandibular molars have been extracted and notreplaced, the maxillary teeth overerupt, bringingthe process with them (Figure 13-3). Theseenlargements often are fibrous but can be bony.This excess tissue can prevent proper location of

the occlusal plane and may interfere with the lowerdenture, if it is not surgically removed.

Sharp, Spiny Processes Frequently, there aresharp, spiny processes on the maxillary and pala-tine bones (see Figure 13-1). These usually causeno problems because they are covered deeply bysoft tissue. However, in individuals with consider-able resorption of the residual ridge, these sharpspines can irritate the soft tissue left between themand the denture base. The posterior palatine foram-ina often have a sharp, spiny overhanging edge thatmay irritate the covering soft tissues as a result ofpressure from the denture.

Torus Palatinus The torus palatinus is a hardbony enlargement that occurs in the midline of theroof of the mouth and is found in about 20% of thepopulation (Figure 13-4). It is covered by a thinlayer of mucous membrane that is easily trauma-tized by the denture base unless a relief is provided.This relief should conform accurately to the shapeof the torus because an extensive arbitrary reliefrobs the denture of part of its support area.

ANATOMY OF PERIPHERAL OR LIMITING STRUCTURESThe limiting structures of the upper denture can bedivided into three areas: (1) the labial vestibule,


Figure 13-3 The enlarged tuberosities limit thespace available and will compromise the occlusal planeand distal extension of the mandibular denture.

which runs from one buccal frenum to the other onthe labial side of the ridge; (2) the right and leftbuccal vestibule, which extends from the buccalfrenum to the hamular notch; and (3) the vibratingline, which extends from one hamular notch to theother across the palate (Figure 13-5).

Labial Vestibule

The labial vestibule is divided into a left and rightlabial vestibule by the labial frenum, which is afold of mucous membrane at the median line. Itcontains no muscle and has no action of its own.It starts superiorly in a fan shape and converges asit descends to its terminal attachment on the labialside of the ridge. The labial notch in thelabial flange of the denture must be just wideenough and just deep enough to allow the frenumto pass through it without manipulation of the lip(Figure 13-6).

The mucous membrane lining the labialvestibule has a relatively thin mucosa. The submu-cosal layer is thick and contains large amounts ofloose areolar tissue and elastic fibers. The mucosaof the vestibular spaces is classified as liningmucosa. It is normally devoid of a keratinized layerand is freely movable with the tissues to which it isattached because of the elastic nature of the laminapropria. Lining mucosa also forms the covering ofthe lips and cheeks, the alveololingual sulcus, the


Figure 13-4 A torus palatinus is covered by a thinlayer of mucous membrane, which is easily trauma-tized by the denture base unless a relief is provided.

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8 9

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Figure 13-5 Correlation of anatomical landmarks. A, Intraoral drawing of the maxillaryarch; 1, labial frenum; 2, labial vestibule; 3, buccal frenum; 4, buccal vestibule; 5, coronoidbulge; 6, residual alveolar ridge; 7, maxillary tuberosity; 8, hamular notch; 9, posteriorpalatal seal region; 10, foveae palatinae; 11, median palatine raphe; 12, incisive papilla; 13,rugae. B, Maxillary final impression shows the corresponding denture landmarks: 1, labialnotch; 2, labial flange; 3, buccal notch; 4, buccal flange; 5, coronoid contour; 6, alveolargroove; 7, area of tuberosity; 8, pterygomaxillary seal in area of hamular notch; 9, area ofposterior palatal seal; 10, foveae palatinae; 11, median palatine groove; 12, incisive fossa;13, rugae.

A B

soft palate, the ventral surface of the tongue, andthe unattached gingiva found on the slopes of theresidual ridges.

The main muscle of the lip, which forms theouter surface of the labial vestibule, is the orbic-ularis oris. Its tone depends on the support itreceives from the labial flange and the positionof the teeth. The fibers of the orbicularis orispass horizontally through the lips and anasto-mose with the fibers of the buccinator muscle.Because the fibers run in a horizontal direction,the orbicularis oris has only an indirect effect on

the extent of an impression and hence on thedenture base.

The buccal frenum forms the dividing linebetween the labial and buccal vestibules. It issometimes a single fold of mucous membrane,sometimes double, and, in some mouths, broad andfan shaped. The levator anguli oris muscle attachesbeneath the frenum and consequently affects theposition of the frenum. The orbicularis oris pullsthe frenum forward, and the buccinator pulls itbackward. Thus it requires more clearance for itsaction than the labial frenum does (Figure 13-7).


A

BFigure 13-6 A, A broad maxillary labial frenum. B, The labial flange must fit snuglyaround the frenum.

Buccal Vestibule

The buccal vestibule lies opposite the tuberosityand extends from the buccal frenum to the hamularnotch. The size of the buccal vestibule varies withthe contraction of the buccinator muscle, the posi-tion of the mandible, and the amount of bone lostfrom the maxilla. The size and shape of the distalend of the buccal flange of the denture must beadjusted to the ramus and the coronoid process ofthe mandible and to the masseter muscle. When themandible opens or moves to the opposite side, thewidth of the buccal vestibule is reduced. Whenthe masseter muscle contracts under heavy closingpressures, it reduces the size of the spaceavailable for the distal end of the buccal flange. Theextent of the buccal vestibule can be deceivingbecause the coronoid process obscures it when themouth is opened wide. Therefore it should beexamined with the mouth as nearly closed as possi-ble. This space usually is higher than any other partof the border. The mucous membrane lining thebuccal vestibule is similar to that lining the labialvestibule.

Distal to the buccal frenum lies the root of thezygoma, which is located opposite the first molarregion (Figure 13-8). With increasing resorption ofthe ridge, it becomes more noticeable, and a den-ture may require relief over this area to preventsoreness of the underlying tissue.

The hamular notch, which forms the distal limitof the buccal vestibule, is situated between the

tuberosity and the hamulus of the medial pterygoidplate (see Figure 13-8). The mucous membraneof the hamular notch consists of a thick submu-cosa made up of loose areolar tissue. This tissue, inthe center of the deep part of the hamular notch,can be safely displaced by the posterior palatalborder of the denture to help achieve a posteriorpalatal seal.

Vibrating Line

The vibrating line is an imaginary line drawnacross the palate that marks the beginning ofmotion in the soft palate when an individual says“ah.” It extends from one hamular notch to theother (Figure 13-9). At the midline, it usuallypasses about 2 mm in front of the fovea palatinae.These are indentations near the midline of thepalate formed by a coalescence of several mucousgland ducts. They are always in soft tissue, whichmakes them an ideal guide for the location of theposterior border of the denture.

The vibrating line is not to be confused withthe junction of the hard and soft palate because thevibrating line is always on the soft palate. It is nota well-defined line and should be described as anarea rather than a line. The distal end of the den-ture should extend at least to the vibrating line. Inmost instances it should end 1 to 2 mm posterior tothe vibrating line. The submucosa in the region ofthe vibrating line contains glandular tissue similarto that in the submucosa in the posterolateral partof the hard palate. However, because the soft palatedoes not rest directly on bone, the tissue for a fewmillimeters on either side of the vibrating line canbe repositioned in the impression to improve theposterior palatal seal.

In addition, the distal end of the denture mustcover the tuberosities and extend into the hamularnotches. Overextension at the hamular notches willnot be tolerated because of pressure on the pterygoidhamulus and interference with the pterygo-mandibular raphe, which extends from the hamulusto the top inside back corner of the retromolar padin the mandible. When the mouth is opened wide,the pterygomandibular raphe is pulled forward(Figure 13-10). If the denture extends too far intothe hamular notch, the mucous membrane coveringthe raphe will be traumatized.


Figure 13-7 An upper denture with a properlyformed notch for the buccal frenum. The buccalfrenum requires more clearance than the labial frenumbecause it will move posteriorly as a result of theaction of the buccinator muscle and anteriorly as aresult of the action of the orbicularis oris.

PRINCIPLES AND OBJECTIVESOF IMPRESSION MAKINGThe objectives of an impression are to provide sup-port, retention, and stability for the denture. Animpression also will act as a foundation forimproved appearance of the lips and, at the sametime, should maintain the health of the oral tissues.The impression should record all the potential den-ture-bearing surfaces available. To a large extent,this surface is readily identified if the biologicalconsiderations of impression making are under-stood correctly. However, the denture’s retention isenhanced considerably if the denture extendsperipherally to harness the resiliency of most of thesurrounding limiting structures. An impression thatrecords the depth of the sulcus, but not its width,will result in a denture that lacks adequate reten-tion. Although impression techniques, methods,

and materials vary, they should be selected on thebasis of biological factors. Too often techniquesfollow shortcuts without a consideration of thefuture damage that such procedures may induce.

For a successful impression to be achieved, thefollowing concepts should be adhered to, irrespec-tive of the selected technique:

1. The tissues of the mouth must be healthy.2. The impression should extend to include all of

the basal seat within the limits of the functionsof the supporting and limiting tissues.

3. The border must be in harmony with theanatomical and physiological limitations ofthe oral structures.

4. A physiological type of border-moldingprocedure should be performed by the den-tist or by the patient under the guidance ofthe dentist.


A A

C

B

Figure 13-8 A, The root of the zygoma is close to the crest of the residual alveolar ridgebecause of the amount of resorption of the alveolar ridge. The bone is thinly covered bymucous membrane and may require relief of the denture border to prevent soreness. B,Hamular notch. C, Hamular process of the medial pterygoid plate.

5. Proper space for the selected impressionmaterial should be provided within theimpression tray.

6. The impression must be removed from themouth without damage to the mucous mem-brane of the residual ridges.

7. A guiding mechanism should be providedfor correct positioning of the impressiontray in the mouth.

8. The tray and the impression material shouldbe made of dimensionally stable materials.

9. The external shape of the impression mustbe similar to the external form of the com-plete denture.

All of these factors will contribute to a successfulimpression, but probably the two most importantfactors in making satisfactory impressions are aproperly formed and accurately fitting impressiontray and proper positioning of the tray within themouth.

PREPARATION OF THE MOUTHIt is essential that the oral tissues be healthy beforeimpressions are made. There should be no distortion

or inflammation of the denture foundation tissues.These must be eliminated before the impressions aremade; otherwise, the new dentures will not fit the tis-sues once they are no longer distorted by theswelling. The patient will then complain that the den-tures, although fitting well initially, became looseafter a few days. The most effective way of resolvingthe inflammation is to ensure that patients leave theirdentures out of the mouth for at least 24 hours beforethe impressions are made, although a longer periodoften is required to resolve the problem completely.Many patients understandably object to leaving theirdentures out because it is extremely disfiguring. Theuse of tissue conditioners is a very effective alterna-tive, although patients should still be encouraged toleave their old dentures out as much as possi-ble before the impressions are made. Preparation ofthe mouth before construction of the new dentures isdiscussed in detail in Chapters 7 and 8.

MAXILLARY IMPRESSION PROCEDURESImpressions are made with a variety of materialsand techniques. Some materials are more fluid thanothers before they harden or set. The softer materi-als displace soft tissue to a lesser extent and require


X

Figure 13-9 The vibrating line marked by an indelible pencil. Notice the two foveapalatinae (X) in the middle of the soft palate.

less force in their molding than do more viscousmaterials. These variations in the working proper-ties of materials make it possible to devise differenttechniques for controlling the position and shapeof the oral tissues. Some techniques are intended torecord the shape of the tissues with a minimum ofdisplacement; others are intended to displace theborder tissues to a predetermined extent. Still oth-ers are devised to obtain controlled displacement ofthe tissues under the denture. Impressions thatrecord the tissues with minimum displacement aredescribed as mucostatic, whereas those that dis-place the tissues are classified as mucodisplacing.There is, however, no evidence to indicate that onetechnique produces better long-term results thananother. The choice is made by the dentist on thebasis of the oral conditions, concept of the functionof the tissues surrounding the denture, and abilityto handle the available impression materials.

Regardless of the type of impression beingmade, the tray is the most important part of the

impression-making procedure. If the tray is toolarge, it will distort the tissues around the bordersof the impression and will pull the soft tissuesunder the impression away from the bone, distort-ing the dimensions of the sulcus in the process. If itis too small, the border tissue will collapse inwardonto the residual ridge. This too will distort theaccurate recording of the border extension of thedenture and prevent the proper support of the lipsby the denture flange. A properly formed trayenables the dentist to carry the impression materialto the mouth and control it without distorting thesoft tissues that surround it.

Individual or custom trays have borders thatcan be adjusted so they control the movable soft tis-sues around the impression but do not distort them.At the same time, space is provided inside the trayso that the shape of the tissues covering the den-ture-bearing area may be recorded with minimal orselective displacement. Because each mouth is dif-ferent, these requirements cannot be achieved suc-


A

B

C

Figure 13-10 A, The maxillary tuberosity. B, The pterygomandibular raphe, which ispulled forward when the mouth is opened wide. C, The retromolar pad of the mandible. Thecheek lies to the right in this picture and the palate to the left.

cessfully with stock trays. Therefore most impres-sion procedures involve making a preliminaryimpression only in a stock tray. This is then pouredin artificial stone and the resulting cast used to con-struct a custom tray. The final impression is thenmade with the custom tray.

PRELIMINARY IMPRESSIONSStock trays are constructed in either metal or plasticand may be perforated or unperforated. Althoughthey are available in a range of shapes and sizes,they cannot fit the upper jaw of each individualwithout distorting the soft tissues. It is, however,important that the preliminary impression is asaccurate as possible. An unsatisfactory preliminaryimpression will result in an unsatisfactory customtray. This will in turn require considerable effort andtime-consuming modifications before it can be usedto make the final impression. Even a correctlyselected stock tray will not fit the denture-bearingarea perfectly. Therefore when the impression ismade, it is advisable to select an impression mate-rial that has a relatively high viscosity, therebyallowing the material to compensate more easily forthe deficiencies of the tray. The most suitable mate-rials are alginate (irreversible hydrocolloid),silicone putty, or impression compound.

Silicone putty impression material has a highviscosity. It will flow beyond the tray to compen-sate for underextension of the stock tray, and onceset, it will support itself in this position. It exhibitssome degree of elasticity and so will record under-cuts with reasonable accuracy. Its high viscositymeans that it records surface detail poorly, andin addition, it cannot be added to if part of theimpression is deficient.

The irreversible hydrocolloids record detailaccurately if they are properly controlled. Becausethey do not absorb the mucous secretions from thepalate, they can exhibit defects in the palatal part ofthe impression. Furthermore, the irreversiblehydrocolloids lose moisture rapidly and can conse-quently change their size. The casts must thereforebe poured soon after the impressions are removedfrom the mouth. The weight of the artificial stoneof the cast may be sufficient to distort the bor-ders of the impression, particularly if they are notsupported by the borders of the tray.

Impression compound is a thermoplasticmaterial with a high viscosity. Like silicone putty,the material will flow beyond the tray to compen-sate for underextension and will support itself inthis position once it is chilled. Therefore it is notnecessary to correct any underextension of thestock tray before using this material. Also, addi-tions can be made to it if part of the impressionis deficient. Its high viscosity means that it recordssurface detail poorly. In addition, it is nonelasticand so will not record undercuts accurately. In pre-vious editions of this text, a technique is describedwhereby a preliminary compound impression iscarefully and diligently “converted” into a superbcustom tray. The technique has, however, beeneclipsed by the one described in this chapter and inthe next one on mandibular impression making.The current technique reflects a synthesis of threeconsiderations: developments in biomaterials,a better understanding of the macroscopic andmicroscopic anatomy plus physiology of the eden-tulous milieu, and compelling clinical experiencesunderscoring its applied merits. The material ofchoice for most dentists is now a high-viscosityalginate impression material.

Tray Selection

The space available in the mouth for the upperimpression is studied carefully by observation ofthe width and height of the vestibular spaces withthe mouth partway open and the upper lip heldslightly outward and downward. An edentulousstock tray that is approximately 5 mm larger thanthe outside surface of the residual ridge is selected.The dentist places the tray in the mouth and ini-tially positions it by centering the labial notch ofthe tray over the labial frenum. The posterior extentof the tray relative to the posterior palatal sealarea is maintained, and then the handle isdropped downward to permit visual inspection(Figure 13-11). Posteriorly, the tray must includeboth the hamular notches and vibrating line.

Alginate impression material will not supportitself away from the confines of the tray, so anyareas of underextension need to be corrected withsoft boxing wax before the impression is made.A common site for a stock tray to be underextendedis around the tuberosities and into the buccal


vestibules. In addition, soft boxing wax can be usedto line the entire border of the stock tray to createa rim that helps adapt the borders of the tray to thelimiting tissues. Such a wax periphery also pro-tects fragile border tissues from the risk of theimpinging tray’s hard material (e.g., metal). Acrossthe posterior border of the tray, wax is adapted tothe tissue of the posterior palatal seal area by care-ful elevation of the tray in this region, with theanterior part of the tray in the proper position.Again, the borders of the tray are observed visuallyrelative to the limiting anatomical structure (Figure13-12). The objective is to obtain a preliminaryimpression that is slightly overextended around theborders.

Impression Making

Before making the preliminary impression, it isadvisable to practice placing the tray in position.The patient is asked to open the mouth halfway, andthe tray is first centered below the upper residualridge. The upper lip is elevated, and the tray is car-ried upward anteriorly into position, with the labialfrenum used as a centering guide. When the tray islocated properly anteriorly, the index fingers areplaced in the first molar region on each side of thetray, and with alternating pressure they seat the trayupward until the wax across the posterior part ofthe tray comes into contact with the tissue in theposterior palatal seal area. The fingers of one hand


Figure 13-11 The stock tray must be of proper size and must be correctly positioned inthe mouth. A, The patient is asked to open the mouth halfway, and the tray is rotated intothe mouth in the horizontal plane using the handle. B, The tray is centered by positioningthe labial notch over the labial frenum. C, The handle of the tray is dropped downward topermit visual inspection of the posterior extension across the palate and hamular notches.

A B

C

are shifted into the middle of the tray, and bordermolding is carried out.

The labial and buccal vestibules can be moldedby asking the patient to “suck down” onto the tray.In addition, the patient should be asked to move themandible from side to side and then open wide.These movements will record the influence of thecoronoid processes on the shape of the buccalvestibules.

The tissue surface and borders of the tray,including the rim of wax, are painted with an adhe-sive material to ensure that the alginate impressionmaterial adheres to the tray. The irreversible hydro-colloid is mixed according to the manufacturer’sinstruction and is placed in the tray and evenly dis-tributed to fill the tray to the level of its borders.A small amount of impression material is placed inthe anterior part of the palate and in the sulci oppo-site the tuberosities to help prevent air from beingtrapped in these parts of the preliminary impres-sion (Figure 13-13, A). The loaded tray is then posi-tioned in the mouth in a manner similar to thatduring the practice sessions (Figure 13-13, B, C, andD). Once the material has set, the cheeks and upperlip are lifted away from the borders of the impres-sion to introduce air between the soft tissue at thereflection and the border of the impression. Whilethe lip is elevated, the tray is removed from themouth in one motion and inspected to ensure that allthe basal seat has been recorded (Figure 13-13, E).

If impression compound or silicone putty isused for making the preliminary impression, the

technique is the same except that the borders of thestock tray are not modified with wax. There is noneed to use a tray adhesive for impression com-pound, although one is necessary for silicone putty.Preloading of the palate and around the tuberositiesis not undertaken. The tray is loaded with theimpression material and seated in the mouth inexactly the same manner as for alginate impressionmaterial.

The borders of the custom tray should now bedetermined. Two choices are available. Eitherthe periphery is outlined with a disposable indeli-ble marker on the impression at the chairside (thepreferred option), or the outline is somewhat arbi-trarily marked on the poured cast in the laboratory.The completed impression should be observed nextto the patient’s mouth and the junction of theattached and unattached mucosal tissue visuallyidentified on the border of the impression (Figure13-14). The impression is poured in artificial stone,and the custom tray outline should now be evidenton the cast. If the outline has not been marked onthe impression, it can be drawn directly on the cast.However, with the patient not present for a correla-tion between anatomical features and the cast, thisbecomes an educated guess.

Clinical experience has shown that a largenumber of edentulous patients seeking treatmentfor new complete dentures are already wearingcomplete dentures. If these have been worn suc-cessfully for a number of years and if the extensionof the base is satisfactory, then logic suggests thatthese dentures can be used as a starting point fordeveloping an accurate impression of the denture-bearing surface.

As part of the protocol for restoring the healthof the supporting tissue, the denture will have beenrelined with a tissue conditioner. The result can beregarded as the preliminary impression and used toproduce the preliminary cast by pouring artificialstone into the fitting surface of the denture. Ifundercuts exist on the fitting surface of the denture(e.g., around the tuberosities), then artificial stoneshould not be used. It would be impossible toremove the denture from the cast without damagingeither the cast or, even worse, the denture.The undercuts can, of course, be removedbefore adding the tissue conditioner, but this meansthat the fitting surface of the denture has been


Figure 13-12 The modified stock tray is ready formaking the preliminary impression.


Figure 13-13 A, A small amount of irreversible hydrocolloid is placed into the palateand around the tuberosities. B, The upper lip is elevated and the tray carried upward anteri-orly. The labial notch is lined up with the labial frenum. C, The tray is seated posteriorly bythe index fingers in the region of the first molars. D, The tray is held in place with a fingerplaced into the center of the palate. E, The completed impression.

A B

C D

E

irretrievably altered. This is of no consequence ifthe replacement denture is successful. However, ifthe new denture does not meet the patient’sapproval, then a very awkward situation candevelop. If undercuts exist, the cast should be pro-duced preferably in silicone putty, which exhibitssufficient elasticity to permit the denture to beremoved but is rigid enough to allow the fabrica-tion of a custom tray.

FINAL IMPRESSIONSA number of materials are available for making thefinal impression. Plaster of Paris was once widelyused as a final impression material, but it is not“user friendly” and has been superseded by othermaterials. These include metallic oxide impressionpaste, polyether and silicone impression materials,and irreversible hydrocolloids.

Metallic oxide impression pastes are rigid whenset and can be used only where there are no bonyundercuts. They are used in a close-fitting tray, andso the overall bulk of the impression is kept to aminimum. This is particularly useful where thedenture-bearing area is considerably reduced. Inthese circumstances, a close-fitting tray is easier tolocate correctly in the mouth compared with aspaced tray. In addition, it is easier to avoid dis-placing the limiting structures with a close-fittingtray. Metallic oxide impression pastes should notbe used in patients with dry mouths because thepaste tends to adhere to the mucous membrane.

The elastomeric impression materials and irre-versible hydrocolloids are all used in spaced cus-tom trays. To avoid displacing the border tissues, aless viscous irreversible hydrocolloid is used formaking the final impression compared with thatused for the preliminary impression. Irrespective ofwhich material is selected, the optimum result willbe achieved only if the custom tray has been con-structed and refined correctly.

Construction of the Custom Tray

Baseplate wax, approximately 1 mm thick, isplaced on the cast within the outlined border toprovide space in the tray for the final impressionmaterial. The posterior palatal seal area on the castis not covered with the wax spacer. Therefore thecompleted custom tray will contact the mucousmembrane across the posterior palatal border, andadditional stress placed here during the making ofthe final impression will help achieve a posteriorborder seal. In addition, this part of the tray will actas a guiding stop to help position the tray properlyduring the impression procedure (Figure 13-15, A).A wax spacer will not be used if a metallic oxideimpression paste has been selected for making thefinal impression.

The custom tray should be 2 to 3 mm thick,with a stepped handle in the anterior region of thetray to facilitate removal from the mouth. The stepshould be of sufficient height to avoid distortion ofthe upper lip when the tray is in the mouth (Figure13-15, B). The premise in prescribing a custom trayis that the proposed denture-bearing area of thedenture will be reflected in the tray’s extension.

Refining the Custom Tray

When the custom tray is removed from the prelim-inary cast, the wax spacer is left inside the tray(Figure 13-16). The spacer allows the tray to beproperly positioned in the mouth during bordermolding procedures.

Border molding is the process by which theshape of the border of the tray is made to conformaccurately to the contours of the buccal and labialvestibules. This essential requirement of the tray’sfit ensures an optimal peripheral seal. It beginswith manipulation of the border tissue against a


Figure 13-14 The clinically determined proposeddenture base outline is drawn on with a disposableindelible marker.

moldable impression material that is properlysupported and controlled by the tray. The amount ofsupport supplied by the tray and the amount of forceexerted through the tissues vary according to theresistance or viscosity of the impression material.

For border molding to be carried out success-fully, space must be created for the border moldingmaterial. Therefore the flanges of the custom trayshould be reduced until they are 2 mm short of thereflections. Once the buccal and labial flanges ofthe custom tray have been adjusted, the posteriorpalatal border is checked. The tray must containboth hamular notches and extend approximately2 mm posterior to the vibrating line. The vibrating

line is observed in the mouth as the patient says aseries of short “ahs.” The posterior border of theimpression tray is marked with a disposable indeli-ble marker, the palatal tissues are dried quickly, thetray is placed in the mouth, and the patient is askedto say “ah.” The tray is removed from the mouth,and the mark that has been transferred from the trayto the mouth is compared with the vibrating lineand the hamular notches. If it is underextended, thelength is corrected by the addition of modelingcompound.

The tray is now ready for border molding, dur-ing which the borders of the tray are molded to aform that will be in harmony with the physiologi-cal action of the limiting anatomical structures.This may be carried out in sections either recordingone part of the border at a time or recording allparts of the border simultaneously.

Recording all of the border simultaneously hastwo general advantages: first, the number of inser-tions of the tray is reduced to one, and second,developing all borders simultaneously avoids prop-agation of errors caused by a mistake in one sectionaffecting the border contours in another.

The requirements of a material to be used forsimultaneous molding of all borders are that itshould (1) have sufficient body to allow it toremain in position on the borders during loading ofthe tray, (2) allow some preshaping of the formof the borders without adhering to the fingers,(3) have a setting time of 3 to 5 minutes, (4) retainadequate flow while the tray is seated in the mouth,


Figure 13-15 A, Relief wax covers the basal seat area except for the posterior palatalseal area and the labial and buccal reflections. B, The custom tray should be 2 to 3 mm thickand the handle shaped so that it does not interfere with the position of the upper lip.

A B

Figure 13-16 The custom tray covers the entirebasal seat area. The wax spacer has been left inside thetray to allow the tray to be properly positioned in themouth during border molding.

(5) allow finger placement of the material intodeficient parts after the tray is seated, (6) not causeexcessive displacement of the tissues of thevestibules, and (7) be readily trimmed and shapedso excess material can be removed and the bordersshaped before the final impression is made.

Stick impression compound is ideally suited forcarrying out border molding in sections. However,it is unsuitable for recording all parts of the bordersimultaneously because it is impossible to get thematerial softened over the full length of the border.Polyether impression materials are well suited forborder molding as they meet all of the requirementslisted previously.

When border molding with polyether impres-sion material, the following procedure should befollowed:

1. An adhesive for polyether impressions isplaced on the border of the tray, coveringboth the inside and outside of the border.The wax spacer is left inside the tray butshould be cut away from the border to allowspace for the impression material.

2. The polyether material is mixed and intro-duced into a plastic “impression” syringe.Slightly less catalyst should be used thanrecommended by the manufacturers to pro-vide sufficient working time to complete theborder molding.

3. The polyether material is syringed aroundthe border and across the posterior palatalseal area (Figure 13-17). The material isquickly preshaped to proper contours withfingers moistened in cold water.

4. The tray is placed in the mouth, making cer-tain that the lips are retracted sufficiently toavoid scraping the material from the border.

5. The border is inspected to ensure that impres-sion material is present in the vestibule. Ifinsufficient material is present, excess mate-rial from an adjacent site should be transferredwith a finger moistened in the patient’s saliva.

6. Border molding is carried out. This isaccomplished in the anterior region whenthe lip is elevated and extended out, down-ward, and inward (Figure 13-18, A). In theregion of the buccal frenum, the cheek iselevated and then pulled outward, down-

ward, and inward and moved backwardand forward to simulate movement of thefrenum (Figure 13-18, B). Posteriorly,the buccal flange is border molded by extend-ing the cheek outward, downward, andinward. The patient is asked to open wide andmove the mandible from side to side.

7. When the impression material is set, the trayis removed from the mouth.

8. The border molding is examined to deter-mine that it is adequate (Figure 13-19). Thecontour of the border should be rounded.Any deficient sites can be corrected with asmall mix of polyether material added tothe appropriate area. Overextensions arereadily detected because the tray will pro-trude through the polyether material and beadjusted as necessary.

The technique is basically the same if stick impres-sion compound is used except that the border ismolded in sections. The labial vestibule is moldedinitially, then each buccal vestibule and finally theposterior palatal area. The tray with the addition ofsoftened compound is placed in the mouth, with thewax spacer still inside the tray, and the appropriatearea is molded. The tray is carefully removed fromthe mouth, and the impression compound is chilledin cold water. There is no need to use an adhesiveto attach the impression compound to the tray.

If the custom tray is constructed on a casttaken from the optimized previous denture, it can


Figure 13-17 The polyether material is placedacross the posterior palatal seal area and continuedaround the entire border of the tray.

be presumed that the tray already reflects the bor-der molding developed with the tissue conditionerthat has been used to reline the denture. Thus fur-ther border molding is very likely unnecessary.This is assuming that the previous denture baseis correctly extended and that care has beentaken with the tissue conditioner to obtain the cor-rect border shape. A careful scrutiny of the tray’speriphery in the mouth while moving the peripheral

tissues will help the dentist determine whetheradditional segmental border molding is required.Patients are able to wear complete dentures withapparent success even though the bases are notextended correctly. Accepting an incorrectlyextended base just because the denture has beenworn previously is not good practice and excludesthe possibility of providing something better.

Preparing the Tray to Secure theFinal Impression

Space must now be created for the final impressionmaterial; otherwise, the borders will be overex-tended and the mucous membrane displacedunnecessarily.

The spacer wax is removed from inside the trayalong with any border molding material thathas flowed over it. Any excess material on the out-side of the tray also is removed. The thickness ofthe border will vary from individual to individual,but a thick border in the anterior region results in apoor appearance. If necessary, the thickness of thelabial flange should be adjusted to approximately2.5 to 3 mm in thickness from one buccal frenumto the other. Material that extends into an undercutis reduced because this allows the tray to be seatedmore easily. Finally, a small amount of material isremoved from those parts of the border that have


Figure 13-18 A, Border molding in the anterior region is achieved by moving the lipoutward, downward, and inward. B, The left buccal flange is molded by moving thecheek outward, downward, inward, and then backward and forward to simulate movementof the frenum.

A B

Figure 13-19 Border molding has been com-pleted, including the posterior palatal seal area. Therelief wax is still in the impression tray.

not already been adjusted. Approximately 0.5 mmis removed from the inner, outer, and top surface ofthe border.

Stick impression compound is adjusted witha scalpel; the polyether is adjusted with either ascalpel or a bur. The material over the posteriorarea is not adjusted. This serves three functions.First, it slightly displaces the soft tissues at the dis-tal end of the denture to enhance posterior border(palatal) seal. Second, it serves as a guide for posi-tioning the tray properly for the final impression.Third, it helps prevent excess impression materialfrom running down the patient’s throat.

Finally, holes can be placed in the palate of theimpression tray with a medium-sized round bur toprovide escape ways for the final impression mate-rial, and the adhesive material is applied. The holesfurnish relief during the making of the finalimpression so that the mucous membrane over themedial palatal raphe and in the anterolateral andposterolateral regions of the hard palate is not dis-placed excessively. Holes are also preferablyplaced over residual ridge sites where the soft tis-sues are mobile and displaceable. The objective isto avoid recording denture-bearing tissues in a dis-placed or distorted position.

Making the Final Impression

As with any impression, the correct positioning ofthe tray in the patient’s mouth is essential if the finalimpression is to be achieved successfully. The pro-cedure for placing the tray is the same as that usedwhen making preliminary impressions. The tray iscentered as it is carried to position on the upperridge. This is most easily achieved by observing theposition of the labial frenum relative to the labialnotch in the tray. When the frenum is positionedwithin the notch, the index fingers of each hand areshifted to the first molar region, and with alternat-ing pressure the tray is carried upward, without dis-placement of the front end of the tray downward,until the posterior palatal seal of the tray fits prop-erly in the hamular notches and across the palate.The tray is held in position with a finger placed inthe palate immediately anterior to the posteriorpalatal seal. This procedure should be practicedwith the empty tray until the dentist feels confidentof the proper position of the tray in the mouth.

The final impression material of choice ismixed according to the manufacturer’s instructionsand uniformly distributed within the tray. All bor-ders must be covered. The tray is then positioned inthe mouth, as described previously, and bordermolding is performed.

When the final impression material has set, thetray is removed from the mouth and inspected foracceptability. If it needs to be remade, the impres-sion material is removed with particular care topreserve the border molding. Assuming the traywas formed properly, faulty positioning is the mostfrequent reason that a final impression must beremade. A number of reasons for remaking finalimpressions are described in the next chapter.

Boxing Impressions and Making the Casts

Great care is taken when making the final impres-sion to record the functional width and depth of thesulcus. It is essential that this be preserved in thefinal cast. The procedure for preserving this form iscalled boxing.

A strip of boxing wax is attached all the wayaround the outside of the impression approximately2 to 3 mm below the border and sealed to it with aspatula (Figure 13-20, A). The strip must be main-tained at its full width, particularly at the distal endof the impression, to hold the vertical walls of theboxing away from the impressions and providespace for adequate thickness of the cast in thisregion. A thin sheet of modeling wax is thenattached to the outside of the boxing strip to formthe vertical wall of the boxing (Figure 13-20, B).The vertical wall should extend 10 to 15 mm abovethe impression so that the base of the cast at its nar-rowest point will be of this thickness. The sheet ofwax should extend completely around the impres-sion and be sealed to the boxing wax strip to pre-vent the escape of artificial stone when this ispoured into the impression. Also, the impressionshould be supported in a level position by the box-ing. Boxing procedures cannot be used on impres-sions made in hydrocolloid materials because thewax will not adhere to the impression.

Artificial stone is mixed according to the man-ufacturer’s instructions. The stone is poured intothe boxed impression level with the top of the ver-tical wall of the boxing and allowed to set. After


the final impression is separated from the cast, thecast must be shaped to maintain the form of theborders of the impression and yet be easily accessi-ble for adaptation of the materials used in makingthe occlusion rims (Figure 13-20, C).

SUMMARY1. Ensure the tissues of the mouth are healthy.

a. Optimize the present dentures with tissueconditioners and occlusal adjustments.

b. Encourage the patient to leave the denturesout as much as possible.

c. Instruct the patient in oral and denturehygiene and to massage the denture-bearingtissues.

d. Prescribe any necessary preprosthetic surgery.

2. Make preliminary impressions.a. Use a stock tray, modified with wax around

the border, and irreversible hydrocolloidimpression material.

b. Use a stock tray with impression com-pound material or silicone putty impressionmaterial.

c. On the impression’s border, identify theperipheral outline of the proposed customtray. This will conform to a line between theattached and unattached mucous membrane.Make a laboratory stone cast.

d. If the denture has been optimized, that is,functionally border molded with a tissue con-ditioner, regard it as the preliminary impres-sion. Make a laboratory cast in stone orsilicone putty.


Figure 13-20 A, Boxing wax has been attached just below the borders of the finalimpression. B, The vertical wall of the boxing is securely attached to the boxing strip. Theheight of the wall will allow the base of the cast to be from 10 to 15 mm thick. C, The castprovides an accurate positive record of the basal seat and reflections. The thickness and formof the cast permit easy adaptation of the materials used in making the occlusion rims.

A B

C

3. Fabricate a custom tray.a. Cover the basal seat area with wax except for

the posterior palated seal area and the labialand buccal reflections

b. Construct a custom tray that extends just pastthe identified junction of the attached andunattached mucosa.

4. Refine the custom tray.a. Try the tray in the mouth and adjust the bor-

ders as necessary. The flanges should be 2mm short of the reflection and extendapproximately 2 mm beyond the vibratingline.

b. Develop the borders of the tray with either anincremental technique with stick tracingcompound or a one-step technique with apolyether impression material.

c. If the tray has been constructed on a casttaken from the optimized previous denture,then border molding may not be necessary.

d. Place relief holes in the tray as required.

5. Make final impression with preferred impres-sion material.

6. Master cast preparation.a. Box and pour the final impression.b. Trim the cast.

BibliographyJani RM, Bhargave K: A histologic comparison of palatal

mucosa before and after wearing complete dentures,J Prosthet Dent 36:254–260, 1976.

Laney WR, Gonzalez JB: The maxillary denture: its palatalrelief and posterior palatal seal, J Am Dent Assoc75:1182–1187, 1967.

Lye TL: The significance of the fovae palatini in complete den-ture prosthodontics, J Prosthet Dent 33:504–507, 1975.

Martone AL: Clinical applications of concepts of functionalanatomy and speech science to complete denture prostho-dontics, J Prosthet Dent 13:4–33, 1963.

Watson IB, MacDonald DG: Oral mucosa and complete den-tures, J Prosthet Dent 47:133–140, 1982.

Watson IB, MacDonald DG: Regional variations in thepalatal mucosa of the edentulous mouth, J Prosthet Dent50:853–859, 1983.


C H A P T E R 14Developing an Analogue/Substitute forthe Mandibular Denture-Bearing AreaDavid M. Davis

232

THE MANDIBLEThe mandibular denture poses a great technical chal-lenge for the dentist and often a significant manage-ment challenge for the patient. Nonetheless, thefundamental principles for mandibular impressionsare similar to those for maxillary impressions. Boththe support or stress-bearing area and the peripheralor limiting area will be in contact with the denture’sfitting or impression surface. The denture base mustextend as far as possible without interfering withthe health or function of the tissues. The supportfor a mandibular denture comes from the body ofthe mandible. The peripheral seal is provided by theform of the denture’s border as determined by themacroscopic and microscopic anatomy of the limit-ing structures. However, the presence of the tongueand its individual size, form, and activity complicatethe impression procedure for the lower denture andalso the patient’s ability to manage the denture.Consequently, the retention of a mandibular dentureis constantly threatened by tongue movements.

ANATOMY OF SUPPORTINGSTRUCTURESSupport for the lower denture is provided by themandible and the soft tissues overlying it. The totalarea of support from the mandible is significantlyless than from the maxillae. The average availabledenture-bearing area for an edentulous mandible is14 cm2, whereas for edentulous maxillae it is 24cm2. This means that the mandible is less capable

of resisting occlusal forces than the maxillae are,and extra care must be taken if the availablesupport is to be used to advantage.

Crest of the Residual Ridge

The crest of the residual alveolar ridge is coveredby fibrous connective tissue, but in many mouthsthe underlying bone is cancellous and without agood cortical bony plate covering it (Figure 14-1).

The mucous membrane covering the crest ofthe residual ridge is similar to that of the upperridge insofar as in the healthy mouth, it is coveredby a keratinized layer and is attached by its submu-cosa to the periosteum of the mandible. The extentof this attachment varies considerably. In somepeople, the submucosa is loosely attached to thebone over the entire crest of the residual ridge, andthe soft tissue is quite movable. In others, the sub-mucosa is firmly attached to the bone on both thecrest and the slopes of the lower residual ridge.

The mucous membrane of the crest of the lowerresidual ridge, when securely attached to the under-lying bone, is capable of providing good soft tissuesupport for the denture. However, because underly-ing bone is often cancellous, the crest of the resid-ual ridge may not be favorable as the primarystress-bearing area for a lower denture.

The Buccal Shelf

The area between the mandibular buccal frenumand the anterior edge of the masseter muscle is

known as the buccal shelf (Figure 14-2). It is boundmedially by the crest of the residual ridge, laterallyby the external oblique ridge, and distally by theretromolar pad. The total width of the bony founda-tion in this region becomes greater as alveolarresorption continues. The reason is that the width ofthe inferior border of the mandible is greater thanthe width at the alveolar process (see Figure 14-1).

The mucous membrane covering the buccal shelfis more loosely attached and less keratinized than themucous membrane covering the crest of the lowerresidual ridge and contains a thicker submucosallayer. The inferior part of the buccinator muscle isattached to the buccal shelf, and its fibers are foundin the submucosa immediately overlying the bone.

The mucous membrane overlying the buccalshelf may not be as suitable histologically to provideprimary support for the denture as the mucous mem-

brane overlying the crest of the residual ridge.However, the bone of the buccal shelf is covered bya layer of cortical bone. This, plus the fact that theshelf lies at right angles to the vertical occlusalforces, makes it the most suitable primary stress-bearing area for a lower denture (Figure 14-3).

Shape of the Supporting Structure

The configuration of the bone that forms thesupport for a mandibular denture varies consider-ably among individuals. Factors that influence thisform are listed in the previous chapter. Many eden-tulous mandibles are extremely flat, and indeed, thebearing surface can become concave, allowing theattaching structures, especially on the lingual sideof the ridge, to fall over onto the ridge surface.Such conditions require displacement of these

Chapter 14 Developing an Analogue/Substitute for the Mandibular Denture-Bearing Area 233

E

A

F

D

C

B

Figure 14-1 A, The crest of the residual ridge is often composed of cancellous bone.B, The buccal shelf consists of cortical bone. C, The mental foramen. D, The genial tubercles.E, The coronoid process. F, When the alveolar ridge resorbs, it results in a basal seal thatbecomes wider and larger. This change occurs because as resorption moves the crest of theridge inferiorly, the width of the mandible becomes greater than that of the alveolar processat the time the teeth were removed.

tissues by the impression and make the lingualflange of the denture more difficult to adapt.

The maxillae resorb upward and inward tobecome progressively smaller because of the direc-tion and inclination of the roots of the teeth and thealveolar process. The longer the maxillae have beenedentulous, the smaller their bearing area is likelyto be. The opposite is true of the mandible, whichinclines outward and becomes progressively wideraccording to its edentulous age. This progressivechange of the edentulous mandible and maxillaemakes many patients appear prognathic (Figure14-4).

In addition, there are a number of anatomicalfeatures that influence the shape of the supportingstructure.

Mylohyoid Ridge Soft tissue usually hides thesharpness of the mylohyoid ridge. The shape andinclination of the ridge vary greatly among edentu-

lous patients. Anteriorly, the mylohyoid ridge, withits attached mylohyoid muscle, lies close to the infe-rior border of the mandible. Posteriorly, after resorp-tion, it often lies flush with the superior surface ofthe residual ridge (Figure 14-5). The mucous mem-brane over a sharp or irregular mylohyoid ridge willbe easily traumatized by the denture base, unlessrelief is provided in the denture base. The area underthe mylohyoid ridge is undercut.

Mental Foramen As resorption takes place, themental foramina will come to lie closer to the crestof the residual ridge (see Figure 14-1). In these cir-cumstances, the mental nerves and blood vesselsmay be compressed by the denture base unlessrelief is provided. Pressure on the mental nerve cancause numbness of the lower lip.

Genial Tubercles Like the mental foramina, thegenial tubercles usually lie well away from the crest


B

A

C

Figure 14-2 The buccal shelf is shown by the dotted line. It extends from the buccalfrenum (A) to the retromolar pad (B) and from the external oblique ridge of the mandible tothe crest of the residual alveolar ridge (C).


B

A

Figure 14-3 The crest of the residual alveolar ridge consists of cancellous bone (A). Itsporosity and roughness make it unsuitable as the primary stress-bearing area. Therefore thebuccal shelf (B) is selected as the primary support area.

A BA AB B

Figure14-4 Progressive resorption of the maxillary and mandibular ridges makes themaxillae narrower and the mandible wider. The lines A and B represent the centers of theridges. Notice how the distance between them becomes greater as the mandible andmaxillae resorb.

of the ridge. However, with resorption, the genialtubercles become increasingly prominent (seeFigure 14-5).

Torus Mandibularis The torus mandibularis is abony prominence usually found bilaterally and lin-gually near the first and second premolars midwaybetween the soft tissues of the floor of the mouthand the crest of the alveolar process. In edentulousmouths, where considerable resorption has takenplace, the superior border of the torus may be flushwith the crest of the residual ridge (Figure 14-6).The torus mandibularis is covered by an extremelythin layer of mucous membrane. It often needs tobe removed surgically because it can be difficult toprovide relief within the denture for the toruswithout breaking the border seal.

ANATOMY OF PERIPHERAL ORLIMITING STRUCTURESThe influence of the limiting structures in themandible is more difficult to record than in the max-illae. The reason is that the structures on the lingual

side must be considered, as well as those around thelabial and buccal surfaces of the denture. The struc-tures on the lingual side of the mandible are morecomplicated to control than those on the buccal andlabial sides. The problem is the greater range of theirmovement and the speed of their actions.

Labial Vestibule

The labial vestibule runs from the labial frenum tothe buccal frenum (Figures 14-7 and 14-8). Thelength and thickness of the labial flange vary withthe amount of tissue that has been lost. The extentof the denture flange in this area often is limitedbecause of the muscles that are inserted close to thecrest of the ridge. The mentalis muscle is a partic-ularly active muscle in this region. The depth of theflange will be determined by the turn of the muco-labial fold, which is the line of flexure of themucous membrane as it passes from the mandibleto the lip.

The mandibular labial frenum contains a bandof fibrous connective tissue that helps attach theorbicularis oris muscle. Therefore the frenum is


B

AA

Figure 14-5 An edentulous ridge with a flat residual alveolar ridge. A, The mylohyoidridges lie flush posteriorly with the crest of the alveolar ridge. The mylohyoid ridges aresharp and the area beneath them is undercut. B, The genial tubercles that come to lie closerto the crest of the alveolar ridge as resorption occurs.


X

X

A B

B

Figure 14-6 Tori mandibulari (X). Surgical reduction of these will be necessary before asatisfactory seal can be developed.

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11 2

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88

6

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10 9

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Figure 14-7 Correlation of anatomical landmarks. A, Intraoral drawing of themandibular arch: 1, labial frenum; 2, labial vestibule; 3, buccal frenum; 4, buccal vestibule;5, residual alveolar ridge; 6, buccal shelf; 7, retromolar pad; 8, pterygomandibular raphe;9, retromylohyoid fossa; 10, tongue; 11, alveololingual sulcus; 12, lingual frenum; 13, regionand premylohyoid eminence. B, Mandibular final impression showing the correspondingdenture landmarks: 1, labial notch; 2, labial flange; 3, buccal notch; 4, buccal flange;5, alveolar groove; 6, buccal flange, which covers the buccal shelf; 7, retromolar pad;8, pterygomandibular notch; 9, lingual flange with extension into retromylohyoid fossa; 10,inclined plane for the tongue; 11, lingual flange; 12, lingual notch; 13, premylohyoideminence. (Adapted from Martone AL: J Prosthet Dent 13: 4-33, 1963.)

A

quite sensitive and active, and the denture must befitted carefully around it to maintain a seal withoutcausing soreness.

The muscles of the lower lip pull activelyacross the denture border, polished surfaces, andteeth. When the patient’s mouth opens wide, theorbicularis oris muscle becomes stretched, narrow-ing the sulcus. This would displace the mandibulardenture if the flange was unnecessarily thick.Mandibular dentures and, hence, impressions willalways be narrowest in the anterior labial region(see Figures 14-7 and 14-8).

The mucous membrane lining the labialvestibule and all limiting structures in the mandibleis similar to that lining the vestibule in the upper

jaw. The epithelium is thin and nonkeratinized, andthe submucosa is formed of loosely arranged con-nective tissue fibers mixed with elastic fibers andmuscle fibers, depending on the site of histologicalexamination.

Buccal Vestibule

The buccal vestibule extends posteriorly fromthe buccal frenum to the outside back corner of theretromolar pad. The buccal flange, which startsimmediately posterior to the buccal frenum, swingswide into the cheek and is nearly at right angles tothe biting force. The impression is always widest inthis region (see Figures 14-7 and 14-8).


A

G

B

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D

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Figure 14-8 A completed final impression with border outline landmarks. A, Mandibularlabial notch. B, Mandibular labial flange. C, Mandibular buccal notch. D, Buccal flange. E,Area influenced by the masseter. F, Retromolar pad area. G, Lingual notch. H, Premylohyoideminence. I, Retromylohyoid fossa. Notice the S curve of the lingual flanges and also that inthe molar region, the flanges slope toward the tongue and extend below the attachment ofthe mylohyoid muscles on the mylohyoid ridges. The slope of the lingual flanges allows themylohyoid muscles to contract and raise the floor of the mouth without displacing the lowerdenture. The length of the lingual flange in the molar region allows it to reach themucolingual fold of tissue in the floor of the mouth to maintain the seal of the lowerdenture. The posterior end of the lingual flange bends laterally toward the mandible to fitinto the retromylohyoid fossa. This part of the denture guides the tongue onto the top of thelingual flange.

The extent of the buccal vestibule is influencedby the buccinator muscle, which extends from themodiolus anteriorly to the pterygomandibularraphe posteriorly and has its lower fibers attachedto the buccal shelf and the external oblique ridge.The external oblique ridge does not govern theextension of the buccal flange because the resist-ance, or lack of resistance, encountered in thisregion varies widely. The buccal flange may extendto the external oblique ridge, up onto it, or evenover it, depending on the location of the mucobuc-cal fold. However, palpation of the external obliqueridge is a valuable landmark in helping to ascertainthe relative amount of resistance, or lack of resist-ance, of the border tissues in this region.

The denture should cover completely thebuccal shelf, despite the fact that it will rest directlyon fibers of the buccinator muscle. The bearing ofthe denture on muscle fibers would not be possibleexcept for the fact that the fibers of the buccinatormuscle run parallel to the base and, hence, its pull,when in function, is parallel to the border and notat right angles to it. Thus its displacing action isslight. More resistance is encountered in this regionwhen the denture is first inserted than is manifesteda few weeks after the denture has been worn. Thusit is possible to stretch and displace these tissuesand so increase the area available for support andstability.

The distobuccal border, at the end of the buccalvestibule, must converge rapidly to avoid displace-ment by the contracting masseter muscle, whoseanterior fibers run outside and behind the buccina-tor muscle in this region (see Figure 14-8). Whenthe masseter muscle contracts, it pushes inwardagainst the buccinator muscle and produces a bulgeinto the mouth. The extent to which the massetermuscle influences the distobuccal edge of themandibular impression and, hence the denture,varies from individual to individual. If the ramus ofthe mandible has a perpendicular surface and theorigin of the muscle on the zygomatic arch is situ-ated medially, the muscle pulls more directly acrossthe distobuccal denture border. This forces the buc-cinator muscle inward, reducing the space in thisarea. If the opposite is true, greater extension isallowed on the distobuccal portion of the mandibu-lar impression. The extent of its effect will berecorded only when the masseter muscle contracts.

Distal Extension

The distal extension of the mandibular denture islimited by the ramus of the mandible, by the bucci-nator muscle fibers that cross from the buccal to thelingual side as they attach to the pterygomandibularraphe and the superior constrictor muscle, and by thesharpness of the lateral bony boundaries of theretromolar fossa, which is formed by a continuationof the internal and external oblique ridges ascendingthe ramus. If the impression extends onto the ramus,the buccinator muscle and adjacent tissues will becompressed between the hard denture border and thesharp oblique ridges. This will not only cause sore-ness but also limit the function of the buccinatormuscle. The desirable distal extension is slightly tothe lingual of these bony prominences and includesthe pear-shaped retromolar pad, which provides asoft tissue border seal (Figure 14-9).

The retromolar pad is a triangular soft pad oftissue at the distal end of the lower ridge. Its mucosais composed of a thin, nonkeratinized epithelium,and in addition to loose alveolar tissue, its submucosacontains glandular tissue, fibers of the buccina-tor and superior constrictor muscles, the pterygo-mandibular raphe, and the terminal part of thetendon of the temporalis muscle. The action ofthese muscles limits the extent of the denture andprevents placement of extra pressure on the distalpart of the retromolar pad during impression pro-cedures. Because of this, the denture base shouldextend approximately one half to two thirds overthe retromolar pad.

Lingual Border

The lingual tissues under the tongue exhibit lessdirect resistance than the labial and buccal bordersdo and are distorted easily when the impression isbeing made. Such extension will cause tissue sore-ness and dislodgement of the denture by tonguemovements. For success to be achieved with alower impression, it is important to understand theaction of the mylohyoid muscle.

Mylohyoid Muscle The floor of the mouth isformed by the mylohyoid muscle, which arisesfrom the whole length of the mylohyoid ridge. Thisridge is sharp and distinct in the molar region andbecomes almost indiscernible anteriorly. Medially,


the fibers join those from the mylohyoid muscle ofthe opposite side, and posteriorly they continue tothe hyoid base (Figure 14-10). The muscle lies deepto the sublingual gland and other structures in the

anterior region and so does not affect the border ofthe denture in this region except indirectly.

However, the posterior part of the mylohyoidmuscle in the molar region affects the lingual impres-


X

Figure 14-9 The retromolar pad (X) is the posterior landmark for a mandibular denture.

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Figure 14-10 Relationships of the mylohyoid muscle in various regions. The letters withprime signs denote cross sections of the designated areas. A, Canine region. B, Premolarregion. C, First molar. D, Third molar. At point D, notice that the mylohyoid ridge approachesthe level of the alveolar crest. The angle of the posterior lingual flange in the molar region isaffected by this muscle; anteriorly, only the length of the flange is affected.

sion border in swallowing and in moving the tongue.During swallowing, the mylohyoid muscles contract,raising the floor of the mouth. During impressiontaking, it is very easy to carry the impression mate-rial into the undercut below the mylohyoid ridgebecause the mylohyoid muscle is a thin sheet offibers that, in a relaxed state, will not resist the impres-sion material. Extension of the lingual flange underthe mylohyoid ridge cannot be tolerated in functionbecause it will interfere with the action of the mylo-hyoid muscle when it contracts, and this will displacethe denture, causing soreness. For the denture tobe successful, the flange must be made parallel to themylohyoid muscle when it is contracted.

Fortunately, in this posterior region, the lingualflange can go beyond the mylohyoid muscle’sattachment to the mandible because the mucolin-gual fold is not in this area. Thus the impressionmay depart from the stress-bearing area of thelingual surface of the ridge, moving away from thebody of the mandible to be suspended underthe tongue in soft tissue on both sides of the mouth,thereby reaching the mucolingual fold of soft tissuefor a border seal (see Figures 14-7 and 14-8). Thedistance that these lingual borders can be awayfrom the bony areas will depend on the functionalmovements of the floor of the mouth and by theamount that the residual ridge has resorbed.

An extension of the lingual flange well beyondthe palpable position of the mylohyoid ridge, butnot into the undercut, has other advantages. Thelack of direct pressure on the sharp edge of theridge will eliminate a possible source of discom-fort. If the impression is made with pressure on orslightly over this ridge, displacement of the dentureand soreness are sure to result from lateral and ver-tical stresses. On the other hand, if the border stopsabove the mylohyoid ridge, vertical forces willcause soreness, and the border seal will be easilybroken. If the flange is properly shaped andextended, it will provide border seal and guide thetongue to rest on top of the flange.

Retromylohyoid Fossa

The retromylohyoid fossa, as its name implies, isthe area posterior to the mylohyoid muscle. As thelingual flange moves into this fossa, it ceases to beinfluenced by the action of the mylohyoid muscle

and so can move back toward the body of themandible producing the typical S curve of the lingualflange (see Figures 14-7 and 14-8).

The retromylohyoid fossa is bounded by theretromylohyoid curtain. The posterolateral portionof the retromylohyoid curtain overlies the superiorconstrictor muscle, and the posteromedial portioncovers the palatoglossal muscle plus the lateralsurface of the tongue. The inferior wall overlies thesubmandibular gland, which fills the gap betweenthe superior constrictor muscle and the most distalattachment of the mylohyoid muscle. The dentureborder should extend posteriorly to contact theretromylohyoid curtain when the tip of the tongueis placed against the front part of the upper residualridge. Protrusion of the tongue causes the retromy-lohyoid curtain to move forward.

The medial pterygoid muscle lies behind thesuperior constrictor muscle (Figure 14-11). Contrac-tion of the medial pterygoid muscle can cause abulge in the wall of the retromylohyoid curtainin the same way that contraction of the massetermuscle can cause a bulge in the buccinator muscle.

Sublingual Gland Region

In the premolar region, the sublingual gland restsabove the mylohyoid muscle. When the floor of themouth is raised, this gland comes quite close to thecrest of the ridge and reduces the vertical space avail-able for the extension of the flange in the anterior partof the mouth (Figure 14-12). The sublingual glandmay be pushed down and laterally out of position byresistant impression material. This can be avoided byshaping this part of the flange of the tray to slopeinward toward the tongue and making the finalimpression with a low-viscosity impression material.

The lingual frenum area is also rather shallow.It should be registered in function because at restthe height of its attachment is deceptive. In func-tion, it often comes quite close to the crest of theridge, even though when at rest it is much lower.

Alveololingual Sulcus

The alveololingual sulcus, which is the spacebetween the residual ridge and the tongue, extendsfrom the lingual frenum to the retromylohyoidcurtain. Part of it is available for the lingual flange



PR

B

M

RM

MP

RMC

SC

Figure 14-11 Diagram shows the relationship of the medial pterygoid muscle to thesuperior constrictor muscle. B, Buccinator muscle; M, masseter muscle; MP, medial pterygoidmuscle; PR, pterygomandibular raphe; RM, ramus of the mandible; RMC, posterolateralportion of the retromylohyoid curtain formed by the mucous membrane covering thesuperior constrictor muscle (SC).

A

B

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Figure 14-12 The lingual side of the mandible shows the positions of the sublingualgland relative to the mylohyoid muscle, at rest (A) and when contracted (B). The mylohoidridge is denoted by C.

of the denture. From the preceding discussion onthe functional anatomy of the floor of the mouth,the shape of the lingual border of the dentureshould now be clear.

The border can be considered in the followingthree regions:

1. The anterior region. This extends from thelingual frenum back to where the mylohyoidridge curves above the level of the sulcus.Here a depression, the premylohyoid fossa,can be palpated and a corresponding promi-nence, the premylohyoid eminence, seen onimpressions (see Figures 14-7 and 14-8).The lingual border of the impression in thisanterior region should extend down to makecontact with the mucous membrane floor ofthe mouth when the tip of the tongue touchesthe upper incisors. The lingual flange will beshorter anteriorly than posteriorly. At thepremylohyoid fossa, the flange becomeslarger as it extends below the level of themylohyoid ridge.

2. The middle region. This part extends fromthe premylohyoid fossa to the distal end ofthe mylohyoid ridge, curving medially fromthe body of the mandible. This curvature iscaused by the prominence of the mylohyoidridge and the action of the mylohyoidmuscle (see Figures 14-7 and 14-8).

When the middle of the lingual flange ismade to slope toward the tongue, it can extendbelow the level of the mylohyoid ridge. In thisway, the tongue rests on top of the flange andaids in stabilizing the lower denture on theresidual ridge. In addition, this slope of thelingual flange provides space for the floorof the mouth to be raised during functionwithout displacing the lower denture. The sealof the lower denture is maintained duringthese movements because the lingual flangeremains in contact with the mucolingual foldin the alveololingual sulcus. Therefore in thisarea, the flange rests not on mucous mem-brane in contact with bone but on soft tissue.When the mylohyoid muscle is relaxed, thereis a space between the flange and the floor ofthe mouth, but contact is reestablished whenthe floor of the mouth is raised.

3. The posterior region. Here the flange passesinto the retromylohyoid fossa. As it does, itis no longer influenced by the action of themylohyoid muscle, and so the flange canturn laterally toward the ramus to fill thefossa and complete the typical S form of thecorrectly shaped lingual flange (see Figures14-7 and 14-8).

MANDIBULAR IMPRESSIONPROCEDURESThe same principles of impression making are usedfor lower impressions as for upper impressions (seeChapter 13). As for the upper jaw, it is essential thatthe oral tissues are healthy before impressions aremade.

Making the Preliminary Impression

The space available in the mouth for the lowerimpression is studied to determine the general formand size of the basal seat. An edentulous stock trayis selected that will provide for approximately5 mm of bulk of impression material over the entirebasal seat area. Posteriorly, the retromolar padsshould be covered by the tray. The tray is raisedanteriorly for observation of the relation betweenthe lingual flanges and the lingual slope of thelower residual ridge (Figure 14-13). If the stocktray is made from metal, the lingual flanges can bereshaped, if necessary, by bending to allow for theaction of the mylohyoid muscle (Figure 14-14).Any areas of underextension need to be correctedwith soft boxing wax before the impression ismade. A common site for stock trays to be under-extended is over the retromolar pads and down intothe retromylohyoid fossae. In addition, soft boxingwax can be used to line the entire border of thestock tray to create a rim, which helps adapt theborders of the tray to the limiting tissues (seeFigure 14-14).

Before the preliminary impression is made, it isadvisable to practice placing the tray in positionand to rehearse with the patient. The patient isasked to open the mouth halfway, and the tray isrotated into the mouth in the horizontal plane withthe handle (see Figure 14-13) until it is centered overthe residual ridge, with the tongue raised slightly so



Figure 14-13 Preliminary impression making. A, A lower stock tray is placed in themouth by extension of one corner of the mouth with the index finger. The side of the tray isplaced in the opposite corner and the tray is rotated into position. B, The tray is raisedanteriorly for observation of whether there is adequate space between the lingual flanges(arrows) and the lingual slope of the residual ridge to accommodate sufficient bulk ofimpression material.

A B

Figure 14-14 A rim of wax helps conform the borders of the tray to the mouth andconfines the impression material in the tray. Note the lingual shape of the tray toaccommodate the action of the mylohyoid muscles and to fit into the retromylohyoid fossae.

that it is positioned in the tongue space of the tray.As the tray is seated gently by alternating pressurefrom an index finger on either side of the tray in thefirst molar region, the patient is asked to let thetongue relax. Once the tray is seated, the borders ofthe impression are molded. A description of themovements necessary for molding the borders ofthe impression is given in the section on refiningthe custom tray.

The tissue surface and borders of the tray, includ-ing the rim of wax, are painted with an adhesivematerial to ensure that the irreversible hydrocolloidadheres to the tray. The irreversible hydrocolloid ismixed according to the manufacturer’s instructionsand evenly distributed to fill the tray to the level ofthe border. The loaded tray is then positioned inthe mouth in a manner similar to that during thepractice session and held in position while theimpression material sets (Figure 14-15, A). Oncethe material has set, the cheeks and lower lip arelifted away from the borders of the impression,and the tray is removed from the mouth in onemotion.

If impression compound is used for making thepreliminary impression, the technique is the sameexcept that the borders of the stock tray are notmodified with wax, and there is no need to use atray adhesive. Impression compound has a highviscosity, and unless care is taken, it is very easy to

displace the mylohyoid muscle while making theimpression. Silicone putty can be used as an alter-native to impression compound.

Once the preliminary impression has beenremoved from the mouth, the borders of the customtray should be identified. As with the upper pre-liminary impression, this is best done at the chair-side with a disposable indelible marker to outlinethe periphery on the impression before it is pouredin artificial stone (Figure 14-15, B).

A preliminary cast also can be obtained fromthe fitting surface of the patient’s existing lowerdenture, provided the extension is satisfactory.

Constructing the Custom Tray

A wax spacer, approximately 1 mm thick, is placedover the crest and slopes of the residual ridge,leaving the borders uncovered. The buccal shelf oneach side also may be left uncovered so that thecompleted custom tray contacts the mucous mem-brane in the region of the buccal shelves. This helpsto position the tray correctly in the mouth and toplace additional pressure on this primary stress-bearing area when the final impression is made.Extra wax can be placed over the lingual slopes ofthe cast below the level of the mylohyoid ridge toprovide additional space for the action of the mylo-hyoid muscle.


Figure 14-15 A, The stock tray is held in the mouth by an index finger from either handplaced on top of the tray in the region of the first molar. The tongue should be raised andprotruded by the patient. B, The outline for the custom tray should be marked on theimpression at the chairside with a disposable indelible marker.

A B

The custom tray should be 2 to 3 mm thick,with an anterior handle centered over the labialflange in the approximate position of the anteriorteeth, and shaped so as not to interfere with theposition of the lip. This may be achieved witheither a stepped handle of sufficient height to avoiddistortion of the lower lip or a straight handle,approximately 20 mm in height, which runs verti-cally and parallel to the lip. Two additional handles,one on each side, are placed in the first molarregion. These are centered over the crest of theresidual ridge and are approximately 20 mm inheight (Figure 14-16).

The anterior handle is used to carry the trayinto the mouth and position it over the residualridge. The posterior handles are used as finger reststo complete the placement of the tray and to stabi-lize the tray in the correct position, with minimaldistortion of the soft tissues by the fingers as theyhold the tray in position. The flanges of the trayshould be contoured like the flanges of the com-plete denture. Thus while the impression is made,the limiting border tissues will be in a positionsimilar to the one they will be in when the dentureis in the mouth.

Refining the Custom Tray

When the custom tray is removed from the pre-liminary cast, the wax spacer is left inside the tray.This allows the tray to be positioned correctly onthe residual ridge for border molding procedures.

For border molding to be carried out success-fully, space must be created for the border moldingmaterial. The flanges of the custom tray should bereduced until they are approximately 2 mm short ofthe limiting structures. This is easier to achieve andcheck for the labial and buccal flanges than thelingual flange, where direct observation of the rela-tionship is difficult to observe.

Border molding can be achieved with either anincremental technique with stick tracing com-pound or a one-step technique with a rubber mate-rial such as polyether impression material. Whenan incremental technique is used, stick tracingcompound is added and molded initially along theborder of the labial flange, followed in turn byeach buccal flange. Lingually, the same sequenceis followed. The anterior lingual border is moldedfirst, followed by the left and right posteriorlingual extension, including the retromolar pads.

The one-step technique for border molding thelower custom tray is similar to that used for theupper tray. See Chapter 13 for a description (Figure14-17).

Irrespective of which method is used, the sameborder molding movements are carried out by thedentist and the patient. These are the following:

1. The labial flange is molded by lifting thelower lip outward, upward, and inward.

2. In the region of the buccal frenum, thecheek is lifted outward, upward, inward,backward, and forward to simulate move-ment of the frenum.

3. Posteriorly, the cheek is pulled buccally toensure that it is not trapped under the tray,and then the cheek is moved upward andinward. The effect of the masseter muscle onthe border of the impression is recorded byasking the patient to exert a closing forcewhile the dentist exerts a downward pres-sure on the tray.

4. The anterior lingual flange is molded byasking the patient to protrude the tongue andthen to push the tongue against the front partof the palate. Protruding the tongue deter-mines the length of the lingual flange of thetray in this region, whereas pushing thetongue against the anterior part of the palatecauses the base of the tongue to spread out


Figure 14-16 The completed tray shows theanterior handle shaped to avoid interfering with thelower lip and the two finger rests in the molar region.

and develop the thickness of the anteriorpart of the flange.

5. Protruding the tongue activates the mylohy-oid muscle, which raises the floor of themouth. This helps the dentist determinethe length and slope of the lingual flange inthe molar region. The lingual flange mustslope toward the tongue more or less paral-lel to the direction of the fibers of the mylo-hyoid muscles. It is important to ensure thatthe tongue moves bodily forward when it isprotruded. Apparent protrusion of thetongue can be achieved by contraction of theintrinsic muscles of the tongue, but this doesnot raise the floor of the mouth. Because of

this, some clinicians get the patient to makea “k” sound because this activates the mylo-hyoid muscle.

If border molding material builds up on theinside of the lingual flange in this region, itmust be removed; otherwise, it will interferewith the action of the mylohyoid muscle. Itis better to have the tray contoured with toomuch slope toward the tongue in the molarregion than with too little because thefinal impression material will fill the excessspace.

6. The distal end of the lingual flange ismolded by again asking the patient to pro-trude the tongue. This action activates the


Figure 14-17 A, The borders of the custom tray have been reduced, but the relief waxremains in place. B, The polyether impression material is syringed around the borders of thetray until they are all covered. C, The completed border molding with the relief waxremoved.

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C

B

superior constrictor muscle, which supportsthe retromylohyoid curtain. The patient isthen asked to close the mouth as the dentistapplies downward force on the impressiontray. This records any effect that the contrac-tion of the medial pterygoid muscle has onthe retromolar curtain.

7. Finally, the patient is asked to open wide. Ifthe tray is too long, a notch will be formedat the posteromedial border of the retromo-lar pad, indicating encroachment of the trayon the pterygomandibular raphe, and thetray must be adjusted accordingly.

The final border molded tray should be so formedthat it supports the cheeks and lip in the samemanner as the finished denture will do. The lingualsurface of the tray should be shaped so that itguides the tongue into the same position it willoccupy in relation to the finished denture. It shouldbe possible for the patient to wipe the top of thetongue across the vermilion border of the upper lip,with the tray in place in the mouth, without notice-able displacement of the tray.

If the custom tray is constructed on a cast takenfrom the optimized previous denture, it can be pre-sumed that the tray already reflects the bordermolding developed with the tissue conditioner and,thus, further border molding is unnecessary.

Preparing the Tray to Secure the FinalImpression

Space must now be provided for the final impres-sion material; otherwise, the borders will beoverextended and the mucous membrane displacedunnecessarily. The wax spacer is removed frominside the tray along with any border moldingmaterial that has flowed over it. Any excess mate-rial on the outside of the tray is removed, andapproximately 0.5 mm of border molding materialis removed from around the border.

Finally, small holes can be drilled through thetray, approximately 10 mm apart, in the center ofthe alveolar groove and over the retromolar pads.These will provide escapeways for the finalimpression material and relieve pressure over thecrest of the residual ridge and the retromolar padswhen the final impression is made.

Making the Final Impression

A good final impression cannot be made unless aproperly fitting tray is in the correct position on theresidual ridge. Therefore this procedure should bepracticed before making the final impression. Theprocedure is the same as that used when makingpreliminary impressions. The tray is rotated intothe mouth in the horizontal plane with the anteriorhandle until it is over the residual ridge. At thistime, the patient is asked to raise the tongueslightly, and the tray is moved downward toward itsfinal position. The dentist’s index fingers of eachhand are placed on top of the posterior handles,and, with alternating gentle pressure, the tray isseated until the buccal flanges come into contactwith the mucosa covering the buccal shelf. With thetray held steadily and not moving on the residualridge, the borders of the impression are formed inthe manner already described.

Once the patient and dentist are familiar withthe procedure, the final impression material ofchoice is mixed according to the manufacturer’sinstructions and evenly distributed within the tray.All borders must be covered. Before the custom trayis placed into the mouth, any gauze that has beenplaced under the tongue to help dry the mouth mustbe removed. The tongue must be kept forward,touching the upper lip, while the impressionmaterial sets.

When the final impression material has set, thetray is removed from the mouth and inspected foracceptability (Figure 14-18). If it needs to beremade, the impression material is removed withparticular care to preserve the border molding.


Figure 14-18 The completed final impression.


A B

C DFigure 14-19 Boxing the impression. A, Boxing wax has been attached just below theborders of the impression. It extends for the full width at the posterior ends of theimpression (arrows) to hold the vertical walls of the boxing in the proper position. B, Thetongue space is filled with wax. C, The wall of the boxing is securely attached to the strip ofboxing wax and to the posterior extent of the tongue space filler. D, The final cast is formedso that posterior ends of the residual ridges are well supported, with artificial stoneproviding the needed strength in these regions.

Boxing Impressions and Making the Casts

A wax form is developed around the border of thefinal impression to preserve the shape of theperiphery and to simplify making casts. This pro-cedure is called boxing and has already beendescribed for the upper impression. The techniqueis the same for the lower impression, with the addi-tion that the tongue space is filled with a sheet ofwax that is attached to the superior surface of theboxing wax (Figure 14-19).

REMAKING THE FINAL IMPRESSIONImpression making is not easy. It requires greatattention to details and a thorough understanding of

the anatomy and physiology of oral tissues. Theextra time that may be spent in making impressionsnot only means the difference between success andfailure, but also means less time spent in makingadjustments to the finished dentures.

Patients should be told that often it is necessary tomake more than one impression before a final impres-sion is acceptable. If the tray is correctly positioned inthe mouth, errors in the impression indicate that thetray needs to be modified before another impressionis made. The tray should not be modified unless it waspositioned correctly when the impression was made.

The most common reason for having to repeatan impression is due to incorrect positioning of thetray. The following are some possible errors:

1. A thick buccal border on one side with athin buccal border on the opposite side. Thisindicates that the tray was out of position inthe direction of the thick border.

2. A thin labial border with the tray showingon the inside surface of the labial flange.This indicates that the tray was placed toofar posteriorly and not centered correctlyover the anterior ridge.

3. A thick lingual border on one side with athin lingual border on the opposite side. Thisindicates that the lower tray was out of posi-tion in the direction of the thin border.

4. A thin anterior lingual border with the trayshowing on the inside surface of the lingualflange. This suggests that the lower tray wastoo far forward in relation to the residualridge. It will be accompanied by a thick labialborder. In a similar manner thick labial borderin the upper arch with the tray showingthrough over the anterior slope of the palateindicates that the tray was too far forward inrelation to the residual ridge.

5. Excess thickness of impression materialover the fitting surface of the tray and mate-rial unsupported by the borders of the tray.This indicates that the tray was not seateddown sufficiently on the residual ridge. Thecorrect thickness of material over the fittingsurface of the tray, but with material extend-ing beyond the border of the tray so that it isunsupported by the tray, suggests that thetray is underextended in that area.

6. The tray showing through the impressionmaterial over the fitting surface of the trayand the borders showing through the finalimpression material. This indicates that thetray has been seated on the residual ridgewith too much pressure. The correct thick-ness of material over the fitting surface of thetray, but with the border showing through thefinal impression material, suggests that thetray is overextended in that area.

Other reasons for having to repeat an impressioninclude the following:

1. Voids or discrepancies that are too large tobe corrected accurately

2. Incorrect consistency of the final impres-sion material when the tray was positionedin the mouth

3. Movement of the tray while the finalimpression material was setting

4. Incorrect border molding procedures (e.g.,an excess bulk of impression material in theanterior lingual region and impression mate-rial unsupported by the tray at the distal endof the lingual flange indicates that thetongue was allowed to drop back from itsanterior position and so did not correctlymold the lingual border)

5. The use of either too much or too littleimpression material

SUMMARY1. Ensure that the tissues of the mouth are healthy.

a. Optimize the present denture with tissue con-ditioners and occlusal adjustments.

b. Encourage the patient to leave the dentureout as much as possible and to massage theproposed supporting tissues.

c. Ensure that oral and denture hygiene proto-cols are observed.

d. Prescribe any necessary preprosthetic surgery.2. Make the preliminary impression.

a. Use a stock tray, modified with wax aroundthe border, and irreversible hydrocolloidimpression material, or

b. Use a stock tray and either impression com-pound or silicone putty.

c. Identify the peripheral outline of the customtray. Mark the junction of the attached andunattached mucous membrane on the prelimi-nary impression. Make a laboratory stone cast.

d. If the denture has been optimized, that is,functionally border molded with a tissue con-ditioner, regard it as the preliminary impres-sion. Make a laboratory cast in stone orsilicone putty.

3. Make a custom tray.a. Outline the stress-bearing surface for the

denture and lay down a wax spacer as appro-priate.

b. Construct a custom tray that extends just pastthe identified junction of the attached andunattached mucous membrane.


4. Refine the custom tray.a. Try the tray in the mouth and adjust the

borders as necessary. The flanges should be 2mm short of the reflection and should allowfor the action of the mylohyoid muscleswhen the floor of the mouth is raised.

b. Develop the borders of the tray with either anincremental technique with stick tracingcompound or a one-step technique with arubber material.

c. If the tray has been constructed on a casttaken from the optimized previous denture,then border molding may not be necessary orelse required at an individual site or sites.

5. Make the final impression with the preferredimpression material.

6. Master cast preparation.a. Box and pour the final impression.b. Trim the cast.

BibliographyBarrett SG, Wheeler HR: Structure of the mouth in the

mandibular molar region and its relation to the denture,J Prosthet Dent 12:835-847, 1962.

Martone AL: Clinical applications of concepts of functionalanatomy and speech science to complete denture prostho-dontics, J Prosthet Dent 13:4-33, 1963.

Pietrokovski J, Massler M: Alveolar ridge resorption followingtooth extraction, J Prosthet Dent 17:21-27, 1967.

Schwarz WD: The lingual crescent region of the complete lowerdenture, Br Dent J 144:312-314, 1978.

Shannon JL: The mentalis muscle in relation to edentulousmandibles, J Prosthet Dent 27:477-484, 1972.


C h a p t e r 15Identification of Shape and Location ofArch Form: The Occlusion Rim andRecording of Trial Denture BaseGeorge A. Zarb, Yoav Finer

252

Many years ago, the distinguished British scholarSir Wilfred Fish described a denture as havingthree surfaces: an impression, an occlusal, and apolished surface. Each surface (Figure 15-1) isdeveloped separately in complete denture prostho-dontics, but the dentist integrates all three to createa stable, functional, and esthetic result. Theimpression surface rests on the residual ridges andtransmits forces directly to the denture-bearingtissues. The occlusal surface consists of the articu-lating surfaces of the prosthetic teeth that makecontact during most functional and parafunctionalactivity. The polished surface comprises the nonar-ticulating parts of the teeth (buccal and lingual sur-faces) along with the labial, buccal, lingual, andpalatal parts of the denture base material. Bothdesign and orientation of the polished surface aredetermined by its relationship to the functional roleof the tongue, lips, and cheeks (Figure 15-2, A toC). The polished surface occupies a position ofequilibrium among these groups of muscles and isfrequently referred to as the neutral zone (Figure15-2, D). The dentist determines the neutral zone’slocation by reconciling intraoral anatomical land-marks with a clinical assessment of lingual and cir-cumoral activity. This three-dimensional plannedlocation of a planned denture’s polished surface isfirst established in the occlusion rims.

Occlusion rims are used as provisional substi-tutes for the planned complete dentures or implant-supported prostheses and are used to record firstthe neutral zone and then the maxillomandibularrelations. They are made on the stone cast that rep-resents the denture-supporting tissues and consist

of a trial denture base (TDB), which is a provi-sional substitute for the eventual denture base, anda wax rim.

The TDB must be rigid, accurate, and stable.It is made of hard baseplate wax or, preferably,autopolymerizing (cold-curing) or light-curedacrylic resin. Such a TDB will be used at both themaxillomandibular registration and the try-inappointments. Infrequently, the TDB is made ofprocessed acrylic resin, after final impressions aremade, and eventually the selected teeth are alsoprocessed onto it. The rim itself is made preferablyof baseplate wax because it is a convenient andeasy material to manage.

TDBs made in wax (Figures 15-3 and 15-4) areusually reinforced with wire. These bases are occa-sionally bulky and brittle, but dentists and techni-cians frequently find them easier to work withwhen setting up teeth, especially when a restrictedinterarch distance exists. Autopolymerizing orlight-cured resin TDBs also are extensively used.Undercuts are first blocked out on the cast to avoidpossible cast surface damage, and the resin in itsdoughlike state is molded onto the cast. Alternatively,a wax template is lined with autopolymerizing resin(Figure 15-5), though this is slightly more time-consuming. An autopolymerizing resin base alsocan be made by the “sprinkle-on” method (Figure15-6). In both cases, the monomer and polymer areapplied alternately until a relatively even thicknessof resin base is achieved, and in both cases the castsare placed in hot water in a pressure cookerfor 10 minutes under 30 lb of pressure. This pro-duces rapid polymerization, and excess monomer

Chapter 15 Identification of Shape and Location of Arch Form 253

Figure 15-1 Complete dentures have three surfaces that must harmonize with the oralbiological environment. A, The dentures’ polished surfaces are so contoured as to support andcontact the cheeks, lips, and tongue. B and C, The impression or basal surfaces are fitted to thebasal seats. D and E, The occlusal surfaces of one denture must fit those of the opposing denture.

A B

C D

E

is eliminated. Both methods produce a base that isrigid, stable, and easily contoured and polished.Acrylic resin bases are excellent for making maxil-lomandibular relation records. They fit accuratelyand are not easily distorted. Their only disadvan-tage is that they may take up space needed forsetting the teeth, necessitating some grinding of theacrylic resin base in required areas. They may alsobe loose because of the necessary blockout ofundercuts in the cast. A TDB and occlusion rimmade of extra-hard baseplate wax are easiest forsubsequent teeth arrangement (see Figures 15-3and 15-4). The wax can be softened all the waythrough to the cast, so the teeth can be set directlyagainst the cast if necessary. For many patients,

“hard” baseplate materials must be cut away toallow the teeth to be set in their proper places whenrestricted interarch space is present.

OCCLUSION RIMSThe occlusion rims are used to establish (1) thelevel of the occlusal plane, (2) the neutral zone orarch form (which is related to the activity of thelips, cheeks, and tongue and includes preliminarycircumoral and facial support), and (3) the prelim-inary maxillomandibular relation records, whichinclude the vertical and horizontal jaw relation-ships and an estimate of the interocclusal distance.Unfortunately, none of these determinations can


Cheek

TongueCheek

Figure15-2 The design and orientation of the denture’s polished surface are influencedby functional activities of the tongue, cheeks, and lips. A to C, Relative positions of thegroups of muscles making up the tongue, cheeks, and lips simulated by the fingers. D,Arrows indicate the direction of muscular activity in a coronal plane through the molarregion of the two occlusion rims. Shaded areas denote the neutral zone.

A B

C D

A

B C

D EFigure 15-3 Construction of an extra-hard wax occlusion rim. A, The maxillary cast isdusted with talcum powder as a separating medium. B, Ten-gauge reinforcement wire isadapted to the posterior palatal area to extend through the hamular notches, 2 mm in frontof the vibrating line. C and D, A sheet of softened baseplate wax is pressed firmly against thecast to form the recording base. E, The roll of softened wax is sealed to this base andcontoured to the desired arch form. The rim is built to a height slightly greater than the totallength of the teeth and the amount of residual alveolar ridge shrinkage.

Figure 15-4 This mandibular cast (A) has a reinforcing wire adapted on the lingual ofthe residual ridge (B to D). A sheet of softened baseplate wax is closely adapted to thepotential denture-bearing area of the cast to form the recording base. E, The roll of softenedwax is sealed to the base and contoured to the desired form.

A B

C D

E


A B

C D

EFigure 15-5 Wax template technique for making a trial denture base (TDB). A, Mastercasts prepared by waxing out the undercuts and applying a separating medium. B, Waxtemplates are formed and lined with autopolymerizing acrylic resin (C and D). E, Thecompleted (well-fitting and stable) trial base is ready for the addition of occlusion rims.

be made in a precise scientific way, and most ofthe knowledge concerning them is theoretical.However, clinical experience has provided success-ful directions or protocols, which are used to helpachieve the clinical objectives. The preferred

clinical sequence to follow is (1) design the archform on each wax occlusion rim, (2) establish thelevel/height of the occlusal plane on the mandibularocclusion rim, (3) modify the maxillary rim to meetthe mandibular rim evenly at the desired vertical

dimension of occlusion (VDO), and (4) make apreliminary centric relation (CR) record.

Arch Form

Both the width of the occluding surfaces and thecontour of the arch form of the occlusion rimsshould be individually established for each patient

to simulate the desired arch form of the artificialteeth. This is an integral part of the neutral zonedetermination objective. Such an analogue of themissing teeth and their supporting tissues willenable the dentist or technician to accurately followinstructions for arranging the artificial teeth. Thiscan serve to reduce the amount of time spent withthe patient by the dentist at the try-in appointment


A B

C

D

EFigure 15-6 “Sprinkle-on” method of making a resin denture base. A and B, Monomerand polymer are applied alternately until an evenly thick base is developed. The base (C) andcast (D) are placed in a pressure cooker to complete polymerization. E, The denture base istrimmed and polished, and a wax rim is sealed onto it.

and allow more time for perfecting the arrange-ment of the teeth.

Fish drew the profession’s attention to theconcept of a neutral zone in complete denture con-struction. He argued that the natural teeth occupy azone of equilibrium, with each tooth assuming aposition that is the resultant of all the various forcesacting on it. This is usually a stable position unlessactual changes in the dentition have occurred.When natural teeth are replaced by artificial teeth,it is logical to set the artificial teeth in a position asclose as possible to the one the natural teeth occu-pied. The same forces that stabilized the naturalteeth can then be used to stabilize the dentures. Inthe treatment of partially edentulous patients, it iscommon to find that sufficient natural teeth remainto provide a guide for the positions of the artificialteeth. When the patient is edentulous, it is notalways easy to determine where the natural teethwere in relation to the partially or totally resorbedalveolar ridges. Clinical judgment must be broughtto bear in such situations, and this may be quitechallenging.

Certain types of dentitions are accompanied byspecific patterns of soft tissue behavior. Clinicalobservation of patients with dentures suggests thatthese characteristic types of soft tissue movementspersist into old age and offer a clue to the locationof the preexisting natural teeth. The best guide fordetermining and designing the arch form is to con-sider the pattern of bone resorption where the teethare lost and the use of anatomical landmarks thatare relatively stable in position. Furthermore, doc-umented clinical experience confirms that thedenture space or neutral zone can be reproducedwith minor variations that lie within the range ofclinical acceptability.

Mandibular Arch The occlusion rim is designedto conform to the arch form that, in the dentist’sjudgment, the patient had before the natural teethand alveolar bone were lost. In the lower jaw, alarger proportion of bone loss occurs on the labialside of the anterior residual ridge. The loss occursequally on the buccal and lingual sides of the resid-ual ridge in the premolar region, but in the molarregion the loss appears to be primarily from thelingual side of the ridge because of the cross-sectional shape of the mandible (which is wider at

its inferior border than at the ridge crest). Thus theresidual ridge almost invariably becomes more lin-gually placed in the anterior region and more buc-cally placed in the posterior region. Most often, theocclusion rim is contoured as a guide for placingartificial teeth labial to the ridge in the anteriorregion, over the ridge in the premolar region, andslightly lingual to the ridge in the molar region. Thecurvatures of the occlusion rims, which simulatethe arch form of the posterior teeth, follow the cur-vature of the mandible itself when seen from above.Lines are drawn on the cast to provide a tangibleguide for shaping/designing the arch form. Oneline is drawn from the lingual side of the retromo-lar pad and extended anteriorly to a point justlingual to the crest of the ridge in the premolarregion. This line aids in positioning the lingual sur-faces of the posterior teeth, and it establishes thelingual extent of the occlusion rim (Figure 15-7).This lingual line can be curved similar to the cur-vature of the body of the mandible.

The anterior part of the occlusion rim is con-toured to compensate for the estimated bone loss inthis region, and the corners of the mouth are usedas guides for determining an approximate locationfor the canines and first premolars. The experi-enced dentist learns to visualize the artificial teeth(represented at this state by the contoured rim) asgrowing out of the alveolar bone and following thecurvature of the bone. The end result is an archform that is frequently not on the residual ridge butanterior or labial to it. Several techniques employsoft waxes, impression materials, and tissue condi-tioners as adjunctive efforts to functionally estab-lish a correct neutral zone for the arch form. Whenadvanced anterior ridge reduction has been accom-panied by an upward migration of the mentalismuscle attachment to the crest of the ridge, acertain amount of compromise is essential, and therim is trimmed very thin and placed on, or lingualto, the ridge crest (note the risk of the denture’sencroachment on the tongue space). If this sort ofcompromise creates an intolerable situation for thepatient, surgical labial sulcus deepening in this areaor the provision of implants may be considered toprovide adequate support for the anterior segmentof the denture. Some dentists and technicians havesubscribed to a tooth-on-the-ridge philosophy,which has seriously undermined efforts for denture


stability and esthetics. The concept of a neutralzone in the context of a keen understanding of pat-terns of alveolar ridge resorption enables thedentist to determine the arch form for the patientreceiving treatment.

Maxillary Arch The tongue’s size and positionsduring function do not appear to have as profoundan impact on the stability of the maxillary dentureas on the mandibular one. However, optimal neutral

zone determination is still mandatory for speechand esthetic purposes, with a little more leewayavailable for the latter consideration. Bone reduc-tion usually occurs on the labial and buccal areas ofthe maxillary residual ridge. Consequently, theresidual edentulous ridge is usually palatal to theoriginal location of the natural teeth. The maxillaryteeth should be labial and buccal to the residualedentulous ridge if they are to be placed in theneutral zone and occupy the position of their pred-ecessors. If this pattern of bony reduction isignored, the dentist ends up with a contracted max-illary arch form within the confines of the mandibu-lar arch form. This oversight guarantees inadequatelabial support.

The incisive papilla appears to occupy a stablelocale on the palate, unless it is modified surgi-cally. Clinical experience and anthropometricmeasurements indicate that the incisal edges of themaxillary central incisors are usually 8 to 10 mmanterior to the center of the incisive papilla. Thetips of the canines are also related to the center ofthe papilla, and a high percentage of canines are 61mm in front of the papilla (Figure 15-8, A). Thepapilla is circled and used as a rough guide in locat-ing the anteroposterior position of the maxillaryanterior teeth (Figure 15-8, B). Also, after thenatural teeth are lost the canines should be locatedin a coronal plane passing through the posteriorborder of the papilla. A patient’s old dentures, pre-extraction photographs, or diagnostic casts andphotographs made before the dentition deterioratedshould be used to assist both selection of artificialteeth and establishment of the optimal labialsupport for the patient. The simulated position ofthe posterior teeth is really a clinical judgment call.An assessment of the amount of resorption that hasoccurred, coupled with realization that the poste-rior teeth’s inclinations are buccal to the ridgeshape, is the guide to be followed. Furthermore, theposition of the posterior maxillary teeth will, to avarying extent, also be influenced by the size of apatient’s smile, as well as the position of themandibular teeth. The latter’s positions tend to bemore rigidly determined.

If the patient has been wearing inadequate den-tures, tooth loss will have a pronounced effect onthe appearance of the lips and adjacent tissues. Asa result of the loss of substance and the reduction


A

BFigure 15-7 A, A straight line drawn from lingualof the retromolar pad to a point just lingual to thecrest of the ridge in the premolar region can act as aguide for positioning artificial posterior teeth. B, Apartially edentulous cast with a straight line on theright and a curved line on the left, showing thecurvature of the body of the mandible.

in elastic properties, the connective tissue willnot provide sufficient resistance to the activitiesof the orbicularis oris and associated muscles. Con-sequently, the effect of the degenerative changes inthe skin becomes exaggerated, and the lips appear tohave aged to a much greater extent than the sur-rounding parts. The skin becomes roughened, anddeep vertical lines appear in the body and marginsof the lips. There is a noticeable shortening/thin-ning of the lips because of a tendency for the lipmargins to roll inward. The nasolabial fold changesdirection to become almost continuous with the

groove at the corner of the mouth, and the lips andcheeks are no longer distinctly separated (Figure15-9). Such a loss of well-defined demarcationtends to produce a generally disordered appearanceof the lower half of the face. At this stage, it may bedifficult to visualize proper lip support in anattempt to counter the changes just described.However, the dentist can and should use the occlu-sion rim to achieve the best balance betweenneutral zone determination and harmonious labialsupport.

Altering labial support probably does not affectcheek support as much as it affects lip supportbecause the buccinator muscle is stretched betweenthe pterygomandibular raphe and the modiolusmuscles. It must be remembered that the longer theperiod of edentulism, the greater will be the loss ofthe muscle tone. Consequently, the relearning ofthe original muscle patterns and recovery of tone islikely to be insufficient even if the best dentures areprovided. The more accurate the position of teethreplacement and the sooner it occurs, the easier willbe the task of relearning and reacquiring optimalcheek and lip support.

Another useful average value is an approximatemeasurement between the peripheries of the dentureflanges in the regions of the maxillary and mandibu-lar canines. A 40-mm figure is a good place to start,with an average measurement of 20 mm for eachocclusion rim. These values are not fixed, and theyare modified depending on clinical assessment ofthe particular patient being treated (Figure 15–10).


A

BFigure 15-8 A, In the natural dentition, the tips ofthe maxillary canines are frequently 61 mm anterior tothe center of the incisive papilla (dotted circle). B, Onan edentulous cast, the papilla is circled because itprovides a rough guide to positioning the maxillarycanines.

Figure 15-9 Degenerative skin changes createvirtual continuity between the nasolabial fold and thecorner of the mouth.

Level of the Occlusal Plane

Many dentists use a technique whereby the startingpoint for establishing the occlusal plane is the max-illary occlusion rim. The procedure entails shapingthe occlusion rim so the incisal plane is parallel tothe interpupillary line and is at a height that allowsfor the length of the natural tooth plus the amountof tissue resorption that has occurred. The upper lipcan also be a guide if it is of average length. Theocclusal plane, posteriorly, is made to parallel theala-tragus line on the basis of the position of mostnatural occlusal planes (Figure 15-11). Then thelower occlusion rim is adjusted to meet evenly withthe upper rim and reduced until sufficient interoc-clusal distance has been obtained. This procedureis adequate for many patients and usually results insatisfactory dentures. It certainly cannot beregarded as applicable to all patients, however.

There are other approaches to occlusal planedetermination. The preferred method is to first seekto reconcile tongue function and its relation to the

occlusal plane and mandibular denture stability.When this approach is related to Fish’s descriptionof the neutral zone and the activity of the modiolusmuscles as described below, a rational and clearguide for occlusal plane determination evolves.The food bolus is triturated while resting on themandibular occlusal surfaces (occlusal table). Thistable is an area bounded by the cheek tissues buc-cally, the tongue lingually, the pterygomandibularraphe and its overlying tissues distally, and the con-traction of the corner of the mouth mesially. Themesial boundary is a point where eight musclesmeet at the corner of the mouth. The meeting place,called the modiolus (“hub of a wheel” in Latin),forms a distinct conical prominence at the corner ofthe mouth (Figure 15-12). If the thumb is placedinside the corner of the mouth and the fingeroutside on the prominence, and then the lip andcheek are contracted, the modiolus feels like a


Figure 15-10 Two occlusion rims have beencontoured and adjusted and are now ready to be usedfor making the preliminary centric relation record. Thetrimmed and contoured wax rims serve as an analoguefor the mouth’s neutral zone. They can be used toindicate position of the prosthetic teeth.

Figure 15-11 For demonstration purposes, theala-tragus line on this patient has been bilaterallytaped on. The occlusal plane is established when thewax occlusion rim is made parallel to this line. A Foxplane-guide or similar device may be used for theparalleling.

knot. The modiolus becomes fixed every time thebuccinator muscle contracts, which is a naturalaccompaniment of all chewing efforts. The con-traction of the modiolus presses the corner of themouth against the premolars so the occlusal table isclosed in front. Food is crushed by the premolarsand molars and does not escape at the corner of themouth unless seventh nerve damage has occurred(as in Bell’s palsy). A good reminder of the signif-icance of this observation is the drooling that fre-quently occurs when a patient with an inferioralveolar local anesthesia block attempts to drink.

The practical application of this approach liesin establishing the height of the occlusal plane anddeveloping the polished surface of the denture inthe occlusion rims. The corners of the mouth aremarked on the occlusion rims to provide the dentistand technician with anterior landmarks for theheight of the first premolars (Figure 15-13, A to C).The retromolar pads are relatively stable posteriorlandmarks, even in patients with advanced ridgereduction. The mandibular first molar is usually ata level corresponding to two thirds of the way upthe retromolar pad (Fig. 15-13, D). The retromolarpads are circled on the final casts, and the land of

the cast (edge) is marked at points one half to twothirds of the height of the pad. These points will aidin determining the height of the distal end of theocclusal plane. The anterior and posterior land-marks are joined when the wax is melted to thislevel with a hot spatula. The resultant occlusal planeis almost invariably parallel to the residual alveolarridges and to the interpupillary line. Its height willconform to activities of the tongue, cheek, andcorner of the mouth (Figure 15-13, E), which tendto enhance mandibular denture stability.

Tests to Determine Vertical Dimension ofOcclusion

The maxillary occlusion rim is next adjusted tomeet evenly with the mandibular rim, and they areaugmented or reduced until an adequate function-ally determined interocclusal distance is obtained.

The anterior position of the maxillary occlusionrim is so modified that the lower lip gently caressesthe rim during pronunciation of the letter F. The rimis usually parallel to the interpupillary line and is ata height that accommodates the length of the naturaltooth plus the amount of assessed bone reductionthat has occurred. It is possible to simulate (thoughrather difficult to visualize) proper length and lipsupport by contouring the labial aspect of the max-illary occlusion rim. It would be preferable, and infact easier, for the dentist to select the anterior teethfor the patient’s denture at the examination appoint-ment and set them for proper length and lip supportin the occlusion rims. Further characterization ofthe anterior arrangement could then be done at thepatient’s next appointment.

The tests that aid the dentist in establishing thecorrect VDO by means of occlusion rims arereviewed in Chapter 16, and the following are thetests most frequently used:

1. Judgment of the overall facial support2. Visual observation of the space between the

rims when the jaws are at rest3. Measurements between dots on the face

when the jaws are at rest and when theocclusion rims are in contact

4. Observations when the “s” sound is enunci-ated accurately and repeatedly—the averagespeaking space


Zygomaticusmajor

Risorius

Buccinator

Triangularis

Orbicularisoris

Modiolus

Figure 15-12 The modiolus.


A B

C D

EFigure 15-13 A mandibular occlusion rim (A) is trimmed to conform to two pairs oflandmarks: the right and left corners of the mouth (B and C) and a point two thirds of theway up the retromolar pads (D). The wax rim is melted with a hot spatula to the levelindicated by the arrows in A. Mandibular teeth set to this level (E) will conform to the tongueand cheeks and to activities of the corners of the mouth (arrowheads).

The last test ensures that the occlusion rimscome close together but do not contact. It must beemphasized that the interocclusal (interim) orspeaking space that exists between the posteriorteeth when the patient is enunciating “s” sounds isunrelated to the interocclusal space of rest position.Clinical experience suggests that this space isabout 1.5 to 3 mm for most patients. However,patients with a Class II occlusion tend to have alarger speaking space, and patients with a Class IIIocclusion have a smaller space.

Both tests 1 and 2 are particularly effective ifthe patient’s old dentures are used for comparison.Old dentures can be valuable for prognostic pur-poses, especially if they are used with treatmentliners to recover an optimal VDO. Old dentures canalso have their facial surfaces selectively aug-mented with a soft wax to assist the dentist inassessing the required cosmetic support from thedentures’ polished surfaces. This is a useful stepwhen the shape of the dental arch form is deter-mined, as it should be, by the dentist.

The next clinical step is creating a preliminaryCR record, which is made after the height of themandibular occlusal plane has been determinedand the occlusion rims have been contoured to sim-ulate the position that will be occupied by the arti-ficial teeth and tissues of the complete dentures(see Figure 15-10) and the preferred interocclusalspace established. The occlusion rims are used toestablish a preliminary CR record and to transfer itby means of a face bow, or an arbitrary mounting,to a semiadjustable articulator.

The vertical and horizontal relations of the jawsare integral components of the CR position inedentulous patients. The provisional VDO is firstestablished (as already described). The horizontaljaw relation record is then made at this level, andthe occlusion rims are transferred to an articulator.

An articulator is used in complete denture con-struction to simulate very simple jaw movements,for convenience and to provide a solid base in thepatient’s mouth. The use of a semiadjustable artic-ulator permits three jaw relations be transferredfrom the patient to the instrument: (1) the relationof the jaws to the opening axis (face bow transfer);(2) the vertical separation of the jaws (VDO deter-mination) and the horizontal relation of the lower tothe upper jaw in CR; and (3) the relation of the

lower jaw to the upper jaw when the mandible isprotruded so the incisor teeth will be edge to edge.Obviously, the dentist makes all these records.However, many dentists prefer to use an articulatorwith average setting of the condylar guidance (seeChapter 16) and use a CR record exclusively.

Interocclusal Centric Relation Records

Most clinical educators agree that the actual methodof transferring a centric jaw relation record to thedentist’s articulator of choice is arguably irrelevant.Several excellent methods or techniques are avail-able, but what counts is that the record is correctlymounted on the articulator before proceeding withthe setting up of the prosthetic tooth. Therefore thisnext clinical step, making an interocclusal CR record,is a crucial one. It must be carried out impeccably iftime-consuming clinical repeat activities are to beavoided. Interocclusal records are described as static,graphic, or functional. Static records are made with asoft material interposed between the two rims. Thematerial used (e.g., wax) hardens to provide a“checkbite” record, which is stable and very easyto use. Graphic recordings are done with intraoralor extraoral tracing devices, with a central bearingpoint secured to the trial denture or record bases.Functional records are made with pantographictracing devices. All these methods are very useful.However, the graphic and functional records areinfrequently used. The preferred method is the statictechnique because of its ease of reproducibility andrepeatability. The technique is carried out as follows:

1. Prepare small (3 to 4 mm deep) V-shapedgrooves in the maxillary occlusion rim. Thereare usually two grooves that are placed bilat-erally in the first molar–second premolarregion, in areas touched by the opposing waxrim. These areas are lubricated with a petro-leum jelly, and the maxillary occlusion rim isplaced in the mouth. If the anterior rims arealso in contact, it is possible to prepare asimilar groove in the region of the maxillarycentral incisor.

2. Prepare box-shaped areas (2 to 3 mm deep)in the corresponding opposing areas of themandibular occlusion rim. Fill these areaswith the chosen registration material (e.g.,


softened beeswax), and place the mandibu-lar occlusion rim in the mouth.

3. The comfortably seated and upright patienthas his or her head supported by a suitableheadrest. The dentist guides the patient’smandible into a CR position. Stabilize themandibular trial base with the forefingerand thumb of one hand and use the thumband fingers of the other hand to guide themandible. The fingers stabilizing the basealso can be moved upward to stabilize themaxillary base, if required. In this manner,the bases’ stability is ensured, and themandible can be guided while visibility isretained. Alternative hand positions areadvocated by different clinicians.

4. The patient and bases must be kept immo-bile while the material is setting. This maysimply not be possible for some patients,especially where mandibular residual ridgeresorption is extensive or neuromuscularcontrol is compromised. Clearly, implant-stabilized occlusion rims solve this problemquite easily. The advantage of a wax record-ing medium lies in its allowing the operatorto guide mandibular opening and closure intothe soft wax to verify the record’s accuracy.

It is prudent to rehearse the previously describedmaneuvers before the recording medium is actuallyintroduced. The trial bases should be taken out ofthe mouth, excess recording material removed, andthe distal areas of the bases checked to ensure thatthey do not contact distally. This is a frequent sitefor recording errors. The accuracy of this recordshould be checked and rechecked before proceed-ing to an articulator mounting. The use of frequenttrial closures, plus a practical and meticulouslyapplied technique, will yield accurate results. Anyadditional checks or tests that ensure an accurateCR record are strongly endorsed. An ingenioustechnique for this purpose is the use of centriccheckpoints.

Infrequently, the preliminary CR record is anincorrect one and undiagnosed at this appointment.It will, however, become apparent at the try-inappointment when a new record and remount willhave to be made. This is a time-consuming step andshould hopefully not be required. However, it must

be recalled that clinical determination of occlusaldiscrepancies is more discernible with prostheticteeth in place than with wax occlusion rims. Theproblem can be rectified, although additional chair-side and laboratory time is required.

SUMMARY1. Ensure well-fitting, retained, and stable TDBs.

The retention may have to be aided with adenture adhesive. The stability will be enhancedafter design of the arch form, or neutral zone.

2. Establish the neutral zone by considering thefollowing:a. Arch forms’ location in previous dentures (if

present)b. An assessment of the amount and pattern of

bone lossc. Use of anatomical landmarksd. Preliminary esthetic evaluation

3. Determine the height of the occlusal plane inthe mandibular occlusion rima. Use corners of the mouth as the anterior

landmarksb. Use the retromolar pads (two thirds up) as

the posterior landmarksc. Join all four points with a hot, broad wax

spatula4. Establish the VDO by modifying the height of

the occlusion rim while ensuring the following:a. An even meeting of both rims in CR positionb. An interocclusal distance that the dentist

judges as being functionally adequate for thepatient in question

5. Prepare rims for a CR registration with groovesin the maxillary wax and opposing box-shapedareas in the mandibular wax

6. Return the occlusion rims to the mouth forrepeated trial closures. The CR record is madewith the dentist’s selected medium. The CRrecord is confirmed and remade, if requested,until a repeatable CR record is established.

BibliographyBarrenäs L, Ödman P: Myodynamic and conventional construc-

tion of complete dentures: a comparative study of comfortand function, J Oral Rehabil 16:457-465, 1989.

Beresin VE, Schiesser FJ: The neutral zone in complete andpartial dentures, ed 2, St Louis, 1978, Mosby.


Berry DC, Wilkie JK: An approach to dental prosthetics, vol 2,Pergamon series on dentistry, London, 1964, PergamonPress.

Fish EW: An analysis of the stabilizing factors in full dentureconstruction, Br Dent J 52:559-570, 1931.

Fish EW: Principles of full denture prosthesis, ed 4, London,1948, Staples Press Ltd.

Karlsson S, Hedegård B: Study of the reproducibility of thefunctional denture space with a dynamic impression tech-nique, J Prosthet Dent 41:21-25, 1979.

Lee JH: Dental esthetics, Bristol, 1962, John Wright & SonsLtd.

Lott F, Levin B: Flange technique: an anatomic and physiologicapproach to increased retention, function, comfort, andappearance of denture, J Prosthet Dent 16:394-413, 1966.

Nairn RI: The circumoral musculature: structure and function,Br Dent J 138:49-56, 1975.

Neill DJ, Glaysher JKL: Identifying the denture space, J OralRehabil 9:259-277, 1982.

Pound E: Controlling anomalies of vertical dimension andspeech, J Prosthet Dent 36:124-135, 1976.

Tallgren R: The continuing reduction of the residual alveolarridges in complete denture wearers: a mixed longitudinalstudy, J Prosthet Dent 27:120-132, 1972.

Watt DM, Likeman PR: Morphological changes in the denturebearing area following the extraction of maxillary teeth, BrDent J 136:225-235, 1974.

Wright CR: Evaluation of the factors necessary to develop sta-bility in mandibular dentures, J Prosthet Dent 16:414-430,1966.

Wright SM: The polished surface contour: a new approach, IntJ Prosthodont 4:159-163, 1991.


C H A P T E R 16Biological and Clinical Considerations inMaking Jaw Relation Records andTransferring Records from thePatient to the ArticulatorJames D. Anderson

268

The different components of the masticatory systemare closely related and can be regarded as a func-tional unit. They are composed of the jaws and teeth;the temporomandibular joints (TMJs) and associ-ated ligaments; the muscles of mastication; thetongue, cheeks, and lips; and the sensory and motorinnervation (and vasculature) to these structures. Inthe edentulous patient, the teeth and their associ-ated periodontal ligament nerves are lost. It is theaim of prosthodontic treatment to provide (completedenture) replacement function for the lost teeth. Forthese rather unnatural acrylic (denture) replacementsto function successfully in the physiological envi-ronment to which they are so intimately related,knowledge is needed of the functional anatomy; thecontrol and limits of jaw and joint motion; and therelationships and control of the lips, tongue andother structures. This includes some understandingof the neurophysiological, behavioral, and psycho-logical mechanisms involved.

In the identification of the elements of jaw rela-tions for the treatment of edentulous patients, the aimis to facilitate adaptation of the complete dentures tothe rest of the masticatory system. For this goal to beachieved, it is necessary to find a vertical dimensionof occlusion that is appropriate, stable occlusal con-tacts that are harmonious with the existing TMJs andmasticatory muscles, and contours that are consistentwith the surrounding facial soft tissues and muscula-ture. All of these features can, in theory, be simulatedin properly trimmed occlusion rims.

If it were practical, virtually all the steps to createthese features could be done by the dentist at thechairside with the patient. Not only could the dentureteeth be arranged to be esthetically pleasing and bio-logically compatible, but they could also be arrangedso that the occlusal surfaces contact and glide overone another smoothly, without dislodging the denturebases. However, it is extremely inconvenient toperform intraorally the procedures involved in theconstruction of complete dentures. The difficultiesposed by the presence of saliva, movement of thedenture bases, the surrounding soft tissues, and thepatient’s ability to cooperate all make it impracticalto do many of the steps intraorally. Instead, the occlu-sion rims are used to transfer the jaw relation infor-mation to an articulator so that trial tooth arrangementscan be set up in the laboratory where working condi-tions are much more easily controlled.

This chapter discusses the biological consider-ations in identifying the important aspects of jawrelations and details methods of transferring thatinformation to the articulator.

REGULATION OF MANDIBULARMOVEMENTBefore the identification of vertical and horizontaljaw relations, a short description of mandibularmovements of relevance for jaw recordings ispresented. Mandibular movements are complex innature and vary greatly among persons and within

each person. Many different mandibular move-ments occur during mastication, speech, swallow-ing, respiration, and facial expression. Whenparafunctional movements (bruxism and clench-ing) are also added, the complexity of mandibularmovements is obvious. It is essential that thedentist be knowledgeable of mandibular move-ments to understand various aspects of occlusion,to arrange artificial teeth, and to select and adjustrecording devices and articulators. Ideally, thearticulator should exactly reproduce jaw move-ments within the range of contacts between oppos-ing teeth so that the planned occlusion on theinstrument will function properly in the patient’smouth. However, no such perfect articulator isavailable. Therefore regardless of the methods andinstruments chosen, the dentist needs to knowabout their inherent inaccuracies to inform the clin-ical adjustments needed after their use.

Factors That Regulate Jaw Motion

When opposing teeth are in contact and mandibu-lar movements are made, the direction of the move-ment is controlled by the neuromuscular systemand limited by the movement of the two condylesand the guiding influences of the contacting teeth.When the opposing teeth are not in contact andmandibular movements occur, the direction ofmovement is controlled by the mandibular muscu-lature and limited by condylar movements alone.The condyles and teeth modify mandibular move-ments initiated by the neuromuscular system.

Influence of Opposing Tooth Contacts

An important aspect of many jaw movementsincludes the contacts of opposing teeth. The mannerin which the teeth occlude is related not only to theocclusal surfaces of the teeth themselves but alsoto the muscles, TMJs, and neurophysiological com-ponents including the patient’s mental well-being.When patients wearing complete dentures bring theirteeth together in centric or eccentric positions withinthe functional range of mandibular movements, theocclusal surfaces of the teeth should meet evenly onboth sides. In this manner, the mandible is notdeflected from its normal path of closure, nor arethe dentures displaced from the residual ridges. In

addition, when mandibular movements are madewith the opposing teeth of complete dentures incontact, the inclined planes of the teeth should passover one another smoothly and not disrupt the influ-ences of the condylar guidance posteriorly and theincisal guidance anteriorly.

Research has shown that condylar movement islimited not solely by the anatomy of the TMJs butalso by the contacts of opposing teeth. Variationsin condylar movement have been observed con-comitantly as deflective occlusal contacts or steepincisal guidance from opposing canines changethe pathway of mandibular movement. Thus theinclined planes of artificial teeth must be so posi-tioned that they will be in harmony with the otherfactors that regulate jaw motion. A failure todevelop this kind of occlusion can disturb the sta-bility of complete dentures and cause denture basesto move on the soft tissues of the residual ridges.

Several dentists have observed that patientsadapt to complete dentures by avoiding eccentrictooth contacts during mastication and by chewingon both sides at the same time. Such a chewingpattern will presumably reduce the risk of denturedislodgment. It may also explain why patientsappear to function well with dentures even in theabsence of a balanced occlusion. Such an occlusalchange, loss of balancing contacts in lateral excur-sion, has been reported to occur in patients alreadywithin a year or two after denture insertion.

Influence of Temporomandibular Joints

All mandibular motion is either rotation or transla-tion (or more commonly a combination of these,Figure 16-1). A rotational movement is one in whichall points within a body describe concentric circlesaround a common axis. A translatory movement isone in which all points within a body are moving atthe same velocity and in the same direction.Rotational movements of the mandible take place inthe lower compartment of the TMJ between thesuperior surface of the condyle and the inferiorsurface of the articular disk. Translatory, or gliding,movements of the mandible take place in the uppercompartment of the TMJ between the superiorsurface of the articular disk as it moves with thecondyle and the inferior surface of the glenoid fossa.Mandibular movements, except opening and closing

Chapter 16 Biological and Clinical Considerations in Making Jaw Relation Records 269

when the mandible held by the patient or dentist inits most posterior position (posterior terminal hingemovement), are combinations of rotation and trans-lation. This terminal hinge movement is of specificinterest in complete denture construction because itis the basis for recording centric relation.

Muscular Involvement in Jaw Motion

The muscles responsible for mandibular movementgenerally show increased activity during any jawmovement. This increase in activity may be associ-ated with movement of the mandible, fixation on agiven position, or stabilization so movement willbe smooth and coordinated from one position to

another. The activity and interaction of the musclesfor a series of jaw movements have been studiedextensively by researchers with electromyography(EMG). In clinical practice, however, muscle pal-pation and observation of the movement patternusually are enough for evaluation of the muscularinvolvement in jaw motion.

Neuromuscular Regulation of MandibularMotion

Mastication is a programmed event residing in a“chewing center” located within the brain stem(probably in the reticular formation of the pons)(Figure 16-2). The cyclic nature of mastication


ECO

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Figure 16-1 Mandibular border movements in the sagittal plane. The mandibularposition in centric occlusion (CO) is depicted in 1, and centric relation or the most retrudedposition (B) in 2. Rotation, the terminal hinge movement (3) takes place between B and C,from which the translation phase of the posterior opening occurs to D, the maximumopening position (4). The most protrusive closure from D ends in E, maximum protrusionwith tooth contacts, 5. The postural rest position (PR) and the habitual closure (H) are locatedwell inside the borders. (Redrawn from Mohl ND, Zarb GA, Carlsson GE et al. editors: Atextbook of occlusion, Carol Stream, IL, 1988, Quintessence Publishing.)

(jaw opening and closure) is the result of the actionof this central pattern generator. Conscious effortmay either induce or terminate chewing, but it isnot required for the continuation of chewing. In asimilar manner, sensory impulses from the orofa-cial region may modify the basic cyclic pattern ofthe chewing center to achieve optimal function (seeFigure 16-2). The alteration of chewing character-istics (rate, force, duration) as related to the consis-tency of a bolus of food is an example of this typeof influence. Finally, central influences from areasof the brain associated with other patterned or“learned” behavior, emotion, and stress may inhibitor excite the chewing center.

The muscles that move, hold, or stabilize themandible do so because they receive impulses fromthe central nervous system. The impulses that reg-ulate mandibular motion may arise at the consciouslevel and result in voluntary mandibular activity.They also may arise from subconscious levels as aresult of the stimulation of oral or muscle receptorsor of activity in other parts of the central nervous

system. The impulses initiated at the subconsciouslevel can produce involuntary movements ormodify voluntary movements. At any one time thecell body of the motor nerve may be influenced bythese various sources to inhibition or excitation(Figure 16-3). Impulses from the subconsciouslevel, including the reticular activation system, alsoregulate muscle tone, which plays a primary role inthe physiological rest position of the mandible.

The Envelope of Motion

In an explanation of the clinical implications ofmandibular movements, it is helpful to define thelimits of possible motion and certain mandibularreference positions. Figure 16-3 shows one methodthat may be used to record and study mandibularmovements. Tests indicate that edentulous patientscan make reproducible lateral border movements


Higher Centers(e.g., cerebral cortex)

Masticatory MuscleMotoneuronsJaw

Reflexes

PeripheralInfluences

Masticatory Muscles

Central Neural PatternGenerator

(Pontine Reticular Formation)

Figure 16-2 The masticatory muscle motoneuronsare primarily influenced by the central neural patterngenerator but may be initiated or modified by thehigher centers in the cerebral cortex. All threestructures are influenced by impulses received from theperipheral nerves. (From Orchardson R, Cadden SW:Mastication. In Linden RWA, editor: The scientific basisof eating: Taste and smell, salivation, mastication, andswallowing and their dysfunctions [Frontiers of oralbiology, vol. 9] Basel, Switzerland, 1998, S. Karger AG.)

Figure 16-3 Tracing of mandibular movements inthe saggital plane. For further explanation see Figure 16-1.

when stabilized baseplates are used to supportthe pantographic recording device. Envelopes ofmotion (maximum border movements) in thesagittal and frontal planes as scribed by a dentatesubject are shown in Figures 16-4 and 16-5. Thedotted line represents the masticatory cycle. Thisfunctional movement takes up only a small part ofthe maximum movement area. Mastication is very

seldom a pure hinge movement but involves simul-taneous translatory and rotary movements.

Rest Position

The rest position (or physiological rest, or the verti-cal dimension, or postural position of the mandible)is established by muscles and gravity. There have


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Figure 16-4 Envelope of motion (mandibular border movement area) in the sagittalplane. CO, Centric occlusion; CR, centric relation; MHO, maximum hinge-opening position;MO, point of maximum opening of the jaws; P, most protruded position of the mandiblewith the teeth in contact; Rest, postural rest position.

been two main hypotheses about the postural restposition of the mandible. One involves an activemechanism and the other a passive mechanism.According to the first hypothesis, this position isassumed only when the muscles that close the jawsand those that open the jaws are in a state ofminimal contraction to maintain the posture of themandible. The second hypothesis holds that theelastic elements of the jaw musculature, and notany muscle activity, balance the influence ofgravity. However, numerous studies have shownevidence of EMG activity in patients at posturalrest position. It also is well known that the jaw

drops when one falls asleep, and muscle tension isreduced further. The current consensus is that thephysiological rest position is actively determined.The clinically recorded rest position, usually 2 to4 mm below the maximum intercuspation position,does not correspond to recorded minimal EMGactivity. The mandible in the EMG rest position isusually several millimeters lower than in the clini-cal rest position. A range of reduced muscletension, up to an interocclusal distance of about10 mm, has been reported (Figure 16-6). It is there-fore more accurate to refer to a “range of posture”rather than to a single rest position.


MO

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2 cm

3 cm

1 cmLeft lateral border movem

ent

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ovement

Superior border movement

Figure 16-5 Envelope of motion (mandibular border movements) in the frontal plane.CO, Centric occlusion; MO, point of maximum opening of the jaws; Rest, postural restposition.

Study results of growth and development haveshown that the rest position of the mandible tendsto remain relatively stable for reasonable lengths oftime. However, short- and long-term intraoral andgeneral factors can influence the postural rest posi-tion, such as wear and loss of teeth, aging, andgeneral health factors. The physiological rest posi-tion also is influenced by the position of the head.This position can be verified by reclining and inclin-ing the head. When the patient’s head is reclined,the distance between the teeth is less than whenthe head is held in a normal alert position. When thehead is inclined, the distance is greater. Thereforethe patient’s head should be upright and unsup-ported when observations of physiological restposition are being made.

IDENTIFYING THEMAXILLOMANDIBULAR RELATIONSFOR COMPLETE DENTURESDetermining the Vertical Dimension

The vertical jaw relations are expressed in theamount of separation of the maxillae and mandibleunder specified conditions. They are classified asthe vertical dimensions of occlusion and rest. Thevertical dimension of occlusion is established by thenatural teeth when they are present and in occlu-sion. In patients who have lost their natural teethand must wear dentures, the vertical dimension ofocclusion is established by the vertical height of the

two dentures when the teeth are in contact. Thus thevertical dimension of occlusion must be establishedfor edentulous patients so their denture teeth willcome into contact at the appropriate height.

The natural teeth establish the occlusal verticaldimension during jaw development and in place. Inthe course of a person’s lifetime, many thingshappen to the natural teeth. Some are lost, some areso worn that they lose their clinical crown length,some are attacked by dental caries, and in somea restoration fails to maintain their full clinicalcrown length. Consequently, even patients who haveretained their natural teeth may have a reducedocclusal vertical dimension. The preextraction verti-cal measurement may not reliably indicate thedimension to be incorporated in complete dentures.Information about occlusal vertical dimension withnatural teeth, or with previous dentures, should notbe ignored, however, because it is probably betterthan not having any values or record at all as in atotally edentulous subject. Modifications from pre-extraction values or previous dentures should bemade as indicated when the information is available.

The methods for determining vertical maxillo-mandibular relations can be grouped roughly intotwo categories. The mechanical methods include useof preextraction records and measurements, ridgeparallelism, and others. The physiological methodsinclude the use of physiological rest position, theswallowing phenomenon, and phonetics as a meansfor determining the facial dimension at which occlu-sion should be established. The use of esthetics and


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Figure 16-6 Nonspecific electromyographic (EMG) activity in the masseter and anteriortemporalis areas at different vertical dimensions with an interpolated best fit parabola. Thelowest point on the parabola indicates an “EMG rest position” of 5.2 mm of jaw opening.(From Michelotti A, Faralle M, Vollaro S et al.: Mandibular rest position and electrical activityof the masticatory muscles, J Prosthet Dent 78:48-53, 1997.)

patient-reported comfort adds to the mechanical andphysiological approaches to the problem.

All estimates of the vertical dimension must beconsidered tentative until the teeth are arranged ontheir trial bases, and observations of phonetics andesthetics can be used as a check against the verticalrelations established by mechanical or physiologi-cal means.

Mechanical Methods

Preextraction RecordsProfile Radiographs Profile radiographs of

the face have been much used in research of verti-

cal dimension of occlusion (Figure 16-7), butbecause of radiation risks they cannot be consideredadequate today for routine clinical use in prostho-dontic treatment for edentulous patients.

Casts of Teeth in Occlusion A simple methodof recording the vertical overlap relation and thesize and shape of the teeth is to use diagnostic castsmounted on an articulator (Figure 16-8). The castsgive an indication of the amount of space requiredbetween the ridges for teeth of this size.

Facial Measurements Various devices formaking facial measurement have been used inmany different forms. Devices have been made torecord the relation of the head to the central incisors


Figure 16-7 Cephalometric radiograph that could be used to help determine verticaldimension of occlusion.

vertically and anteroposteriorly by placement of aface bow with auditory meatus plugs and withspectacle suspension. Another method is to recordthe distance from the chin to the base of the nose bymeans of a pair of calipers or dividers before theteeth are extracted (Figure 16-9).

Ridge RelationsIncisive Papilla to Mandibular Incisors The

incisive papilla is a stable landmark that changescomparatively little with resorption of the alveolarridge. The distance of the papilla from the incisaledges of the mandibular anterior teeth on diagnos-tic casts averages approximately 4 mm in thenatural dentition. The incisal edges of the maxillarycentral incisors are an average of 6 mm belowthe incisive papilla. Therefore the mean verticaloverlap of the opposing central incisors is about2 mm (Figure 16-10). It is important to remem-ber that these are average measurements aroundwhich there is considerable individual variation.They should be used with caution, and they donot appear to be relevant in patients with severeresorption.

Parallelism of the Ridges Parallelism of themaxillary and mandibular ridges, plus a 5-degreeopening in the posterior region, often gives a clueas to the appropriate amount of jaw separation.


Figure 16-8 Preextraction study models mounted to measure estimates of size, shape,arrangement, and overlap of teeth.

Figure 16-9 A measurement is made between twopoints on the face when the mandible is inphysiological rest position.

Because the clinical crowns of the anterior andposterior teeth have nearly the same length, theirremoval tends to leave the residual alveolar ridgesnearly parallel to each other. This parallelism isnatural, provided there has been no abnormalchange in the alveolar process such as previousadvanced periodontal disease or gross overerup-tions (Figure 16-11).

This parallelism of the ridges is favorable froma mechanical point of view because occlusalloading on the dentures is less likely to cause themto slide anteriorly or posteriorly. However, in mostpeople, the teeth are lost at different times, andwhen a person finally becomes edentulous, it oftenis observed that the residual ridges are no longerparallel. In addition, the edentulous ridges of themandible and maxillae will become progressivelymore discrepant from the standpoint of width(Figure 16-12).

Measurement of the Former DenturesDentures that the patient has been wearing can bemeasured, and the measurements can be correlatedwith observations of the patient’s face to determinethe amount of change required. These measure-ments are made between the ridge crests in themaxillary and mandibular dentures with a Boleygauge (Figure 16-13). Then, if the observations ofthe patient’s face indicate that this distance is too

short or too long, a corresponding change can bemade in the new dentures.

Physiological Methods

Physiological Rest Position Registration of thejaw in physiological rest position gives an indica-tion of the appropriate vertical dimension of occlu-sion. This is possible because the differencebetween the occlusal vertical dimension and therest vertical dimension is the interocclusal distance(formerly referred to as the “freeway space”). Theinterocclusal distance is the distance or gap exist-ing between the upper and lower teeth when themandible is in the physiological rest position. Itusually is 2 to 4 mm when observed at the positionof the first premolars. This may not be an exactguide; however, when used with other methods, itwill aid in determining the vertical relation of themandible to the maxillae. One method is to havethe patient relaxed, with the trunk upright and thehead unsupported. After insertion of the wax occlu-sion rims, the patient swallows and lets the jawrelax. When relaxation is obvious, the lips are partedto reveal how much space is present between theocclusion rims. The patient must allow the dentist toseparate the lips without moving the jaws or lips ortrying to help the dentist. The interocclusal distance


Figure 16-10 Sectioned casts, posterior view. A, When the teeth are in centric occlusion,the incisal edges of the mandibular central incisors are on average 4 mm from the incisivepapilla. B, Sagittal view of the central incisors; the vertical overlap is about 2 mm.

at the rest position should be between 2 and 4 mmwhen viewed at the premolar region. The interarchspace and rest position can be measured by meansof indelible dots or adhesive tape on the face. If thedifference is greater than 4 mm, the occlusal verti-cal dimension may be considered too small; if lessthan 2 mm, the dimension is probably too great.The occlusion rims are adjusted until the dentist issatisfied with the amount of interarch space anduntil other requirements of an acceptable verticaldimension have been obtained, such as patientcomfort and phonetic and esthetic considerations(Figure 16-14). It is worth noting that the presenceor absence of dentures or occlusion rims and thevertical dimension of these can affect the physio-logical rest position. The method used for deter-mining the position (e.g., relaxation, swallowing,or phonetics) also may modify its vertical level(see Figure 16-14). Dentists must keep this in mindwhen using the rest position as a guide for estab-lishing vertical maxillomandibular relations.

It is essential that an adequate interocclusal dis-tance exist when the mandible is in its physiologi-cal rest position. However, results of experimentalresearch have shown that a rapid adaptation takesplace after changes of the vertical dimension,leading to another rest position and creation of anew interocclusal distance. This has been found tooccur even after an increase that was greater thanthe original interocclusal distance. Such findingsindicate that the rest position alone is not a reliablebasis for the determination of maxillomandibularrelations and that small variations of the verticaldimension are not so critical because the adaptivecapacity of the masticatory system usually is great.It should be combined with other evaluations, suchas patient comfort, phonetics, and esthetics.

Phonetics Phonetic tests of the vertical dimen-sion include listening to speech sound productionand observing the relationships of teeth duringspeech. The production of ch, s, and j sounds brings


Figure 16-11 The crest of the lower residual ridge will be approximately parallel to thecrest of the upper ridge when the jaws are positioned at the vertical dimension of occlusion.This relationship is regarded as ideal for the stability of dentures.

the anterior teeth close together. When correctlyplaced, the lower incisors should move forward toa position nearly directly under and almost touch-ing the upper incisors. If the distance is too large, itmeans that too small a vertical dimension of occlu-sion may have been established. If the anteriorteeth touch when these sounds are made, the verti-cal dimension is probably too great. Likewise, ifthe teeth click together during speech, the verticaldimension is probably too great.

Esthetics The vertical relation of the mandible tothe maxillae also affects esthetics. A study of theskin of the lips compared with the skin over otherparts of the face can be used as a guide. Normallythe tone of the facial skin should be the samethroughout. However, it must be realized that therelative anteroposterior positions of the teeth are atleast equally as involved in the vertical relations ofthe jaws as in the restoration of skin tone. The

contour of the lips depends on their intrinsic struc-ture and the support behind them. Therefore thedentist must initially contour the labial surfaces ofthe occlusion rims so they closely simulate theanteroposterior tooth positions and the contour ofthe base of the denture. This contoured surfacemust replace or restore the tissue support providedby the natural structures (Figure 16-15). If the lipsare not properly supported anteriorly, they will bemore nearly vertical than when supported by thenatural tissues. In such a situation, the tendency isto increase the vertical dimension of occlusionto provide support for the lips, and this can lead toexcessive lower face height. The esthetic guide toan appropriate vertical maxillomandibular relationis, first, to select teeth that are the same size as thenatural teeth and, second, to estimate the amountof tissue lost from the alveolar ridges. However,recent evidence suggests that this method ofestimating the appropriate vertical dimension is a


Figure 16-12 It is a common finding in edentulous patients that the mandibular ridgebecomes progressively wider, and the maxillary ridge narrower, as bone resorption continues.This is exemplified in this edentulous skull.

relatively unreliable one. In a study of young dentateindividuals (where the issue of lip support is elim-inated), dentists gave relatively poor estimates of theeffects of changes in vertical dimension from facialphotos when the vertical dimension was artificiallyopened between 2 and 6 mm. This method shouldtherefore be used with caution or in combinationwith other methods.

Swallowing Threshold The position of themandible at the beginning of the swallowing acthas been used as a guide to the vertical dimensionof occlusion. The theory is that the teeth cometogether with a very light contact at the beginning

of the swallowing cycle. If denture occlusion iscontinually missing during swallowing, the dimen-sion of occlusion may be insufficient (too farclosed). On this basis, a record of the relation of thetwo jaws at this point in the swallowing cycle isused as an indicator of the vertical dimension ofocclusion. The technique involves building conesof wax on the lower denture base in such a way thatthey contact the upper occlusion rim when the jawsare open too wide (Figure 16-16). Then the flow ofsaliva is stimulated by food, such as a piece ofcandy. The repeated action of swallowing thesaliva will gradually reduce the height of the waxcones to allow the mandible to reach the level of


Figure 16-13 Boley gauge measuring the distance between the ridge crests as indicatedby the previous dentures.

the vertical dimension of occlusion. The lengthof the time to complete this action and the rela-tive softness of the wax cones will affect theresults. No consistency in the final vertical posi-tioning of the mandible has been found with thismethod.

Tactile Sense and Patient-Perceived ComfortThe patient’s tactile sense can be used as a guide forthe determination of the occlusal vertical dimen-sion. With this method, an adjustable centralbearing screw is attached to one of the occlusionrims, and a central bearing plate is attached to the


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Upper andLower(c/c)

Figure 16-14 Change in postural face height with insertion (or removal) of dentures.

Figure 16-15 The maxillary occlusion rim is contoured so its labial surface will besimilar to that of the finished denture base and the artificial teeth. Lateral (A) and occlusal(B) views show the contour and dimensions of the neutral zone, which have beenapproximated in this occlusion rim. Identical principles are used in contouring mandibularocclusion rims. (From Heath MR, Boutros MM: The influence of prosthesis on mandibularposture in edentulous patients, J Prosthet Dent 51: 602-604, 1984.)

other one (Figure 16-17). The central bearing screwis adjusted first, so it is obviously too long. Then, inprogressive steps, the screw is adjusted downwarduntil the patient indicates that the jaws are closingtoo far. The procedure is repeated in the oppositedirection until the patient indicates that the teethfeel too long. The screw then is adjusted downwardagain until the patient indicates that the length isabout right. The adjustments are reversed alter-nately until the height of the contact feels comfort-able to the patient. The problem with this methodrelates to the presence of foreign objects in thepalate and the tongue space. There are also someconflicting results on the precision of this method.Patient participation in the decision to establish avertical dimension record should be considered,however, because there are both physiological andpsychological advantages to this approach.

Testing the Vertical Jaw Relations with theOcclusion Rims None of the methods just listed,used alone, will yield an appropriate vertical


Figure 16-16 Cones of soft wax attached to themandibular base form an interocclusal record as theyare forced against the maxillary occlusion rim when thepatient swallows. Swallowing should establish theproper horizontal and vertical relations of themandible to the maxillae.

Figure 16-17 A to C, An intraoral tracing instrument (the Coble device) that can be usedboth for recording of the vertical dimension by means of the adjustable central bearingpoint and for horizontal jaw relation by tracing mandibular movements from side to side.The apex of the tracing should indicate the position of centric relation.

A

C

B

dimension of occlusion reliably in all patients. It isappropriate therefore to use one or more of themethods to approximate the relationship and thento use other methods to independently test theappropriateness of the relationship initially esti-mated, before the record is sent for the set-up ofteeth.

When multiple independent methods used fordetermining the vertical dimension appear to yieldsimilar results, this (still preliminary) estimate can betaken as the vertical height at which teeth should beset. When the horizontal jaw relations have beenestablished, the centric relation record will be taken atthis vertical dimension for transfer to the articulator.

Of course a further review of this tentativedetermination will occur later at the try-in appoint-ment, when teeth are set in the wax trial denturesand the vertical dimension is verified in the mouth.At that time these methods will be used again col-lectively to confirm the vertical dimension beforecompletion of the dentures.

DETERMINING HORIZONTAL JAWRELATIONSThe principles of good occlusion apply to bothdentate and edentulous patients. The problem is,however, that there is no consensus on the defini-tion of good occlusion. It also is most probable thatthe requirements of the occlusion for completedentures differ from those of a natural dentition.For stability of complete dentures to be maintained,the opposing teeth must meet evenly on both sidesof the dental arch when the teeth contact anywherewithin the normal functional range of mandibularmovement. Dentists usually agree that such a bal-anced occlusion is preferable for complete den-tures. (In the natural dentition, a mutuallyprotected occlusion is frequently observed, withthe modifications canine protected occlusion andgroup function occlusion as equally acceptablevariations.)

The basic horizontal relationship is centric rela-tion. It is a reference relationship that must be rec-ognized in any prosthodontic treatment. Otherhorizontal jaw relations are at points of movementaway from centric relation in the horizontal plane.Collectively they are referred to as eccentric rela-tions and include protrusive positions, right and leftlateral excursions, and all intermediate positions.

Confusion in Terms and Concepts

The term centric relation is given a number of dif-ferent meanings in its application to the develop-ment of dental restorations. In the dental literature,centric relation has been associated with, amongother things, the neuromuscular reflex learnedwhen the primary teeth are in occlusion, the poste-rior terminal hinge position, the physiological restposition, and the position of the mandible duringswallowing.

The “Glossary of Prosthodontic Terms” (1999)lists no less than seven different definitions of centricrelation. Although these definitions are somewhatdifferent, all of them indicate that centric relationis determined by the TMJ structures and not by thedentition. Most of them relate to the terminal hingeaxis, some of them mention the retruded or poste-rior position, and others emphasize the uppermostposition of the condyles. The condylar position(an anatomical relationship) cannot be determinedwith certainty at clinical examination, but the ter-minal hinge axis (a relationship defined by jawmovement) can be demonstrated. The physiologicaltransverse hinge axis is located by a series of con-trolled opening and closing movements of the jawswhen the mandible is held in its most retrudedposition relative to the maxillae. These mandibularmovements are called terminal hinge movementsand are part of the posterior border movement thatoccurs without translation (see Figure 16-1).

Several studies have shown that the terminalhinge axis and a mandibular position on that axiscan be recorded with good precision. The small dif-ferences found with various techniques for record-ing centric relation do not seem to be of clinicalsignificance, especially not for complete dentureswith their tendency to move on the soft tissues ofthe residual ridges.

The confusion in terminology has been aggra-vated by controversy over the connection betweencentric relation and centric occlusion. The currentdefinition of centric occlusion is the occlusion ofopposing teeth when the mandible is in centricrelation. This may or may not coincide with themaximum intercuspation position. The mostcommon concept in construction of complete den-tures is to have the maximum intercuspation posi-tion coinciding with centric relation. Anotherconcept maintains that in many patients a broaderarea of stable contacts near centric relation is


necessary, the so-called freedom in centric or longcentric.

Some authors have argued in favor of the “mus-cular position” on the grounds that it is the mostfrequently used in function. It has been defined asthe position reached after a relaxed mandibularclosure from the rest position, and it usually coin-cides with the maximum intercuspation or inter-cuspal position in a healthy natural dentition.Research has shown that the muscular position ismore variable than a retruded position and cannotbe recorded with the same predictability as centricrelation is. It is true, however, that most patients’teeth occlude in a position that is slightly anterior,0.5 to 1.0 mm, to the centric relation. This factwould speak in favor of a limited range of continu-ous tooth contact in occlusion anterior and lateralto centric relation, even when that position is usedfor the recording of the horizontal jaw relation.Another argument for this concept concerns therepeated findings in clinical studies that the dis-tance between the maximum intercuspation posi-tion and centric relation is increased in long-termcomplete denture wearers, even if the relationshipscoincided when constructed. This increase is mostprobably caused by movements of the denturesover time as a consequence of changes in thedenture-supporting tissues.

Significance of Centric Relation

There is extensive dental literature in which con-cepts, definitions, and methods for recording thehorizontal jaw records are discussed. Even if thereare many varying opinions on details, there seems tobe a consensus that a correct registration of centricrelation is essential in the construction of completedentures. Many dentures fail because the occlusionis not planned or developed to include this position.Centric relation is the horizontal reference positionof the mandible that can be routinely assumed byedentulous patients under the direction of thedentist. It is possible for dentists to verify the rela-tionship of casts on the articulator when they aremounted in centric relation. If the hinge axis recordhas been properly transferred, an accurate centricrelation record will orient the lower cast to theopening axis of the articulator in the same relation-ship as the patient’s mandible relates to his/her

opening axis. Clinical experience, however, sug-gests that good function is possible when an arbi-trary face bow or even no face bow is used duringdenture construction. It appears that the most criti-cal factor is an appropriate centric relation record,whereas the face bow is of minor importance.Therefore it is recommended that when an arbitraryface bow, or no face bow is used, the centric relationrecord should be made at or very close to theselected vertical dimension of occlusion. In thisway, the potential errors of not having recorded thetrue hinge axis will be greatly reduced.

Eccentric Relation Records

As the mandible moves forward in protrusive excur-sion, the condyles move downward and forward.Similarly, as the mandible moves laterally to oneside, the condyle on the opposite side moves down-ward, forward, and inward. These downward move-ments of the posterior part of the mandible have theeffect of moving the mandibular posterior teethdownward, creating space between them and themaxillary posterior teeth or occlusion rims. Thiseffect is known as the Christensen phenomenon.Because dentists seek to provide the patient withsmooth, continuous contact of the denture teeththroughout the functional range of jaw motion, theChristensen phenomenon should be included inthe development of the occlusion, particularly in theposterior segments of the dentition. A registration ofthe condyle paths can be performed by means ofa variety of intraoral and extraoral methods andthe articulator adjusted accordingly. However, suchrecordings are associated with extremely great varia-tions, and the clinical value of them is not supportedby convincing documentation. Therefore they are notregarded as necessary for achieving clinically accept-able results.

TRANSFERRING RECORDS FROM THEPATIENT TO THE ARTICULATORFor the articulator to provide accurate interocclusalrelationships, the casts on the articulator must relateto the hinge axis of the instrument in as nearly aspossible the same way as the jaws relate to thepatient’s arc of closure. The dentist must record therelationship between the upper jaw and arbitrary


points near the condyles and then transfer that rela-tionship to the instrument. As noted earlier, theselocations near the condyles are serving as an approx-imation of the hinge axis of mandibular motion.Relating the maxillary and mandibular casts just asthe jaws relate puts the mandibular cast in the correctposition on the articulator so that it will moveappropriately. The mandibular cast is thus relatedindirectly to the hinge axis only through the maxil-lary cast, which in turn relates directly to the guid-ances. The articulator can then be programmedwith the eccentric records if needed to yield areasonable estimate of jaw motion and resultingocclusal relationships.

TYPES OF PATIENT RECORDSBoth the vertical and horizontal relationships of themandible to the maxillae can be transferred fromthe patient to the articulator with three generalclasses of records: hinge axis records; interocclusalrecords, such as the centric relation and eccentricrecords; and graphic records. The simplest articulatorsare designed to accept only interocclusal records,whereas the more sophisticated instruments arecapable of providing adjustments in response to allthree types of records.

Hinge Axis Records

As the patient’s jaw opens and closes, the posteriorborder of its movement, at least in the earliest phases,is the arc of a circle in the sagittal plane around animaginary transverse axis passing through or nearthe condyles. The same is true of the articulator.Similarly, other movements of the jaws occur in arcs.For an accurate reproduction of those movements,the axes of those arcs should be coincident betweenpatient and instrument, particularly where thepatient’s vertical dimension is to be changed. Theaxis of the arcs can be located when the mandible isin its most posterior position by means of a kinematicface bow or hinge bow, or it can be approximated byuse of an arbitrary type of face bow. There is evi-dence that the kinematic record cannot be transferredto the articulator reliably, even in dentate patients. Itis even more difficult in the edentulous patient.Consequently, the kinematic record of the hinge axisis usually ignored in complete denture construction,

in favor of an arbitrary location with facial land-marks. This method provides a substantially lessaccurate estimate of the location of the true hingeaxis, but evidence suggests that there is no clinicalimpact from this loss accuracy.

The Face Bow

The face bow is a calliper-like device that is used torecord the relationship of the jaws to the openingaxis of the jaws and to orient the casts in this samerelationship to the opening axis of the articulator. Itis important to note that this is a relationshipbetween the jaws and the axis of movement, not ananatomical relationship between the jaws and theTMJs, except to the extent that the axis of move-ment might happen to be near the TMJs. (Somedentists and dental technicians also consider theface bow a convenient instrument for supportingthe casts while they are being attached to the artic-ulator.) The instrument consists of a U-shapedframe or assembly that is large enough to extendfrom the region of one TMJ around the front of theface (5 to 7.5 cm in front of it) to the other TMJ andwide enough to avoid contact with the sides of theface. The parts that contact the skin near the TMJsare the condyle rods, and the part that attaches tothe occlusion rim is the fork. The fork attachesto the face bow by means of a locking device(which also serves to support the face bow, themaxillary occlusion rim, and the maxillary castwhile the casts are being attached to the articulator)(Figure 16-18). The fork of the arbitrary face bowis attached to the maxillary occlusion rim, so therecord is a simple relationship between the upperjaw and the approximate axis of the jaw opening.

Some face bows are designed to fit directly intothe external auditory meatus. This type of design iseasier to manipulate clinically than holding thecondylar rods over the hinge axis markings whilethe bite fork is tightened in position (Figure 16-19).An average distance from the external auditorymeatus to an arbitrary hinge axis is built into theface bow design. This distance is compensated forin the articulator by offsetting the mounting pointsan equivalent amount (Figure 16-20).

There is much in the prosthodontic literature thatmaintains that a face bow transfer is essential foravoiding errors in the occlusion of finished dentures.


Indeed it is easy to acknowledge the theoreticaladvantages of using a face bow to orient the casts tothe hinge axis of the articulator (Figure 16-21). Itshould be remembered, however, that these theoreti-cal advantages to the use of a face bow might notnecessarily produce a better clinical end result.Results of one of the few systematic studies made tocompare patient response to variations in denturestechnique failed to show any significant differencesbetween a “complex” technique involving hinge-axislocation for a face bow transfer to the articulator anda “standard” technique without face bow and with anarbitrary mounting. Similar clinical results with den-tures constructed by the two techniques were found atboth short- and long-term recall assessments. Theinvestigation included dentists’ evaluation of occlu-sion, denture stability, retention, and condition of the

denture-bearing tissues, with patients’ satisfactionand adaptation. The results indicated that the successof denture treatment involves many factors, and theuse of a face bow is not an essential one. Theseresults have been supported by similar findings in thecontext of constructing stabilization appliances. Suchdocumentation and extensive clinical experience


Figure 16-18 Patient with upper occlusion rimand bite fork held in place with the lower occlusionrim. The ear rods are over the markings on the side ofthe face.

Figure 16-19 A face bow related to a patient’sexternal auditory meatus and nasion.

Figure 16-20 The ear rod of an articulator fittingto a point on the condylar housing that compensatesfor the use of the external auditory meatus.

Figure 16-21 The theoretical advantages of usinga face bow include the anatomical similarity of theresulting relationship between the teeth and thecondyles. However, this relationship does not ensurethat the movements of the articulator will result in abetter clinical result for the patient with dentures.

have caused many practicing dentists to stop using aface bow. It is also clear that imperfections may existwith both complex and standard techniques. Anytype of face bow and all articulators suffer fromerrors and can only approximate conditions in thepatient’s masticatory system. This is, of course,no excuse for abandoning impeccable techniqueand sound principles of denture construction.Consequently, scrupulous clinical control and theacceptance of a need for adjustments are necessarywith any method.

The argument that a face bow is helpful in sup-porting the maxillary cast while it is being mountedon the articulator may be true. However, an arbi-trary mounting of the maxillary cast can be accom-plished on any articulator with any convenientsupport material by aligning the occlusal plane ofthe wax occlusion rim horizontally and parallel tothe arms of the articulator.

Interocclusal Records

Virtually all articulators will accept at least someinterocclusal records. An interocclusal recordsimply provides a measure of one single positionalrelationship of the lower jaw to the upper jaw. Thatposition might be centric relation, maximum inter-cuspation position, or any eccentric point in lateralor protrusive excursions. Although the centric rela-tion position establishes a “static” relationship ofthe jaws, the protrusive and lateral records permitadjustment of the articulator components toperform variations in the movement pattern of thecasts over one another. The instrument then inter-polates between records (with varying degrees ofaccuracy) to provide a representation of the fullrange of jaw movement. As noted earlier, theseeccentric records are highly variable, to the extentthat their clinical value has not been demonstrated,and they are therefore regarded as unnecessary forclinically acceptable results.

Graphic Records

A shortcoming of the interocclusal records is thatthey provide accurate relations between the castsonly at the jaw positions where they were taken.The articulator must interpolate the movementsbetween the record points. Because the border

movements of the jaw are typically curved, anarticulator programmed with only interocclusalrecords is likely to be inaccurate. Graphic recordscapture these curved limits, and an articulatorcapable of curved movements can be programmedto accept these records, thus yielding a more accu-rate reproduction of the jaw movements.

However, obtaining accurate records from thepatient requires that the graphic writing apparatusbe firmly fixed to the jaws. This is not difficultwhere teeth are present but is very problematicwhen the patient is edentulous and the attachmentcan only be made through occlusion rims. Thegraphic records are inaccurate as a result and there-fore offer no advantage over the more arbitraryinterocclusal records. The extra capability of anarticulator that will reproduce curved movements istherefore of no use.

Clinical Steps

Maxilla The face bow is the instrument thatcarries the relationship between the maxillae andthe condyles from the patient to the articulator. Thearbitrary face bow is placed on the face, with thecondyle rods located approximately in the region ofthe hinge axis, which will be near the condyles.

The first step in this process is to mark theapproximate location of the hinge axis on the skinon each side of the patient’s face. One frequentlyrecommended method is to position the condylerods on a line extending from the outer canthus ofthe eye to the top of the tragus of the ear andapproximately 13 mm in front of the external audi-tory meatus. This placement generally locates therods within 5 mm of the true center of the openingaxis of the jaws. The imaginary line joining the twopoints is an approximate hinge axis.

The occlusion rim is trimmed to the positionthat will be occupied by the teeth as described inthe previous chapter. The second step is to ensurethat the occlusion rim (with bite fork attached) isstable and tightly adapted to the maxillary ridge.The patient can help hold the occlusion rim firmlyseated by biting against it using the mandibularocclusion rim. This biting or closed position is onlyused for the practical purpose of holding the max-illary rim firmly seated. This is not a record of inte-rocclusal relationships.


In the final clinical step, the condylar rodsof the face bow are positioned over the condylarmarkings, thus recording the approximate hingeaxis (see Figure 16-18). The patient can help byholding the condylar rods in place while the clini-cian locks the bite fork to the face bow. This locksthe relationship between the maxillae and theapproximate hinge axis through the occlusion rim,the bite fork, and the face bow. This relationship cannow be carried to the articulator (Figure 16-22).

Mandible The relationship of the mandible to thearticulator hinge axis is achieved indirectly byrelating the mandible to the maxilla. In the edentu-lous patient, this relationship is recorded by meansof a centric relation record taken between theocclusion rims.

Recording Centric Relation

The registration of centric relation is considereddifficult, and it is true that it requires training andexperience to achieve reliable results. There arebiological difficulties that arise from a lack of coor-dination of mandibular musculature, psychologicaldifficulties that are due to a patient or dentist whois uncertain or tense because of the importance ofthe recording, and mechanical difficulties that aredue to unstable and sometimes poorly fitting base-plates and varying tissue resiliency. As a result,even consistently repeatable centric relation recordscan, in fact, be in error.

The following instructions can assist the patientin retruding the mandible:

1. Instruct the patient by saying, “Let your jawrelax, pull it back, and close slowly andeasily on your back teeth.”

2. Instruct the patient by saying, “Get thefeeling of pushing your upper jaw out andclosing your back teeth together.”

3. Instruct the patient to protrude and retrudethe mandible repeatedly while holding his orher fingers lightly against the chin.

4. Instruct the patient to turn the tongue back-ward toward the posterior border of theupper denture.

5. Instruct the patient to tap the occlusion rimsor back teeth together repeatedly.

6. Tilt the patient’s head back while the variousexercises just listed are carried out.

7. Palpate the temporal and masseter musclesto relax them.

The instructions should be given in a calm and con-fident manner. When the patient is respondingproperly, the dentist should say so. When thepatient is not responding properly, there should beno criticism. In this manner, the patient’s aware-ness of the desired position is reinforced whileavoiding tension.

Such recommendations have a long traditionin clinical practice. However, their effectivenessis not supported by documented evidence.Patient-governed activity to close in centric rela-tion has proven to yield extremely variableresults. On the other hand, research has shownthat the most reproducible recording of a retrudedmandibular position in dentate subjects isachieved by gently guiding the mandible back-ward with the subject relaxing the jaws. This alsocan be effective in helping record centric relationin edentulous patients. Many clinicians haveobtained good results by training the patients toperform a hinge-axis rotation before the actualregistration, by having the patient as relaxedand passive as possible, and by actively guiding themandible in small movements up and down. Bymaintaining finger contact with the mandible, thedentist can usually feel when the hinge movementis performed.


Figure 16-22 The completed face bow recordready to be matched to the articulator.

There is probably no best method for recordingcentric relation. A method favored by one dentistwill fail for another. Both accurate and erroneousrecords of centric relation have been made by thesemethods. Therefore it cannot be overemphasizedthat, irrespective of the method used, subsequentclinical checking and rechecking must be donethroughout the denture construction phases.

The consistency of the recording material is ofsignificance: it must not offer resistance duringmandibular closure, or it will inadvertently guidethe path of the mandible as it approaches the pointof the static record. On the other hand, once set, therecording material must have sufficient strengthand rigidity to retain the relationship between theocclusion rims and support the models during themounting process. Silicone bite registration materi-als are acceptable.

Recording Eccentric Records

The methods for recording eccentric records areanalogous to the methods for recording centric rela-tion. Similarly, the instructions to the patient areanalogous. However, given the enormous variationin the accuracy of these records and the absence ofevidence for their usefulness in the clinical result,little can be gained by taking such records.

Laboratory Steps

Maxilla The first step in relating the maxilla tothe articulator is to ensure that the articulator islocked in the centric relation position. The condy-lar balls are thus immobilized in their housingsduring the steps that follow.

The next step is to attach the face bow ear rodsto the instrument with special connections thatmatch one to the other (see Figure 16-20). Thisusually is done either by altering the distancebetween the ear rods until they fit the width of thearticulator hinge pin, or the reverse, by altering thewidth between the articulator condylar housingsuntil they fit the distance between the ear rods(Figure 16-23). The latter arrangement is theoreti-cally advantageous because altering the widthbetween the condylar balls will change the arc ofrotation of the nonworking side condyle. This maybe significant in fixed prosthodontics, but probablyirrelevant for complete denture construction.

The ear rods on the hinge axis represent twopoints of attachment between the face bow and thearticulator. To hold the maxillary occlusion rim andcast firmly in three dimensions, a third point of ref-erence must be set. Some face bows use an infraor-bital pointer, set to approximate the infraorbitalforamen on the patient, with a matching indicatoron the articulator. Others use a nasion relater for


Figure 16-23 The width between the articulator condylar elements can be adjusted tofit the intercondylar width recorded on the face bow.

the same purpose. The intent of these “third point”recording devices is to position the occlusal planeon the articulator so that the arms of the instrumentare approximately parallel to the patient’s Frankfortplane (see Figure 16-21). However, because thearticulator is designed to reproduce the movementof the mandible and not the anatomy of the maxil-lomandibular relations, the need for the third pointbecomes moot. The articulator will be programmedto move relative to the occlusal plane at any angu-lation within the mechanical limits of the instru-ment. As a practical matter, it is easiest to workwith the instrument if the occlusal plane is posi-tioned about halfway between the upper and lowermembers, with the midline of the models in linewith the incisal pin. The face bow can be supportedon the lab bench at this level while the plaster is

poured on the maxillary cast to join it to the uppermember of the articulator (Figure 16-24).

Given that the use of a face bow has been foundnot to be essential for successful denture construc-tion and that the articulator reproduces the move-ment of the mandible, not the anatomical facialrelationships, the cast of the maxilla can be mountedby any convenient arbitrary method that is within theworking limits of the articulator. The maxillaryocclusion rim supporting the maxillary cast could beheld in place by an easily moulded ball of clay, whilethe plaster is added to the upper member to lock thecast in place. As just noted, it is usually easiest towork with the articulator if the occlusal plane isroughly parallel to the upper and lower members andabout halfway between them, and the midline isapproximately coincident with the incisal pin.


Figure 16-24 A, Face bow, occlusion rim, and cast, and upper member of the Whip Mixarticulator, supported by the lower member to facilitate mounting of the upper cast. Thelower member is used in this procedure for convenience only. B, With the upper memberraised, plaster is distributed over the top of the upper cast. C, The upper member of thearticulator has been closed back into position, bringing the mounting plate into the plaster.D, Mounting of the upper cast on the articulator completed. Notice the neat appearance ofthe plaster that attaches the upper cast to the mounting ring.

A B

C D

Mandible As noted earlier, the relationship of themandibular cast to the lower member of the articu-lator is established indirectly by the relationshipbetween the mandible and the maxilla—the centricrelation record. This relationship is achieved verysimply by inverting the articulator and relating themandibular occlusion rim to the maxillary with theCR record (Figure 16-25). This provides supportfor the mandibular cast while plaster is placed tojoin it to the lower member.

ARTICULATORSArticulators are instruments that attempt to repro-duce the range of movement of the jaws. Maxillary

and mandibular casts are attached to the articulatorso that the functional and parafunctional contactrelations between the teeth can be studied.Diagnosis, the arrangement of artificial teeth, andthe development of the occlusal surfaces of castfixed restorations are common uses.

Some articulators are very simple, consisting ofnothing more than a simple hinge (Figure 16-26).These articulators do little more than simulate thehinge motion of the mandible and hold the casts incentric relation. At the other extreme, complicatedarticulators, which require very complex recordingapparatus, aim to simulate all the nuances of jawmovement. No articulator exactly reproduces thefull range of jaw movement, nor is the reproduction


A B

C DFigure 16-25 A, The occlusion rims and lower cast are placed in position on the uppercast, which is attached to the upper member of the articulator. B, The lower member of thearticulator is positioned on the inverted upper member, leaving adequate space between themounting ring on the lower member and the lower cast. C, With the lower member of thearticulator removed, plaster is distributed over the surface of the lower cast. D, The lowermember is placed on the upper member. The condylar spheres must be firmly seated in thecondylar housings, and the incisal guide pin must be firmly seated in the incisal table. The lowercast is attached to the mounting ring on the lower member of the articulator by the plaster.

of such a range required for fabricating any kind ofprosthesis. In between is a series of several instru-ments that provide a more or less accurate repro-duction of movement (Figure 16-27). The challengefor the dentist is to choose an articulator that issuitable for the purpose at hand, neither more norless complicated than necessary. This requires anunderstanding of what the instrument will and willnot do, as well as a grasp of the treatment objec-tives for the given patient.

Early articulators were based on individual theo-ries of occlusion. However, the normal variation inmandibular movement between patients, and eventhe variable movement of the joints within onepatient, soon made it necessary to design adjustablearticulators. An emerging understanding of the neu-rophysiology of mandibular movement and the influ-ence of several morphological and behavioralconsiderations led to the notion that each patientis his or her own best articulator. Therefore thediverse, and frequently subtle, variations required foreach individual occlusion could be more easilyachieved with an adjustable articulator that accepteda variety of records. The final “individualization” ofan occlusion can then be done intraorally as required.

Most articulators in common use today areadjustable and attempt to reproduce jaw movement ofeach patient’s jaw by trying to reproduce the anatomyof the jaw joints and related structures. Although thisapproach has the benefit of being intuitive, it ignorescertain realities of the biological system. Forexample, the great variation in movements at theTMJs within the envelope of motion is virtuallyimpossible to reproduce mechanically. Furthermore,the movement of the occlusion rims on the underly-ing ridges is not reflected on the instrument. It isimportant then to recognize that the adjustmentsmade on an articulator are not attempts to make theinstrument more anatomically correct, but ratherthey are attempts to more closely simulate the motionof the mandible regardless of the settings that result.

Selecting the Articulator for FabricatingComplete Dentures

The large number and great range in complexity ofmodern articulators can mislead the dentist intothinking that the choice of a suitable instrument isa potentially difficult one. However, the choice isgreatly simplified if one considers what records


Figure 16-26 A simple hinge articulator.

can be obtained accurately, what the instrumentwill be required to do, and the fact that articulatortechnology is not a substitute for a biological under-standing of the masticatory system.

As noted earlier, it would be extremely difficultto obtain accurate graphic records, so sophisticated,fully adjustable articulators that reproduce thecurves of the border movements are unnecessarily


A

Figure 16-27 Examples of two semiadjustable arcon articulators. A, Hanau Model 130-28. B, Whip Mix.

B

complex. Similarly, instruments that require a kine-matic face bow transfer to locate the hinge axisoffer no advantage.

At the other extreme, the simple hinge articula-tor can be relied on to preserve the centric relationposition precisely, provided the original interoc-clusal record is accurate and the instrument itself isrigid. Occlusal contacts in centric relation can thusbe perfected with confidence. However, this instru-ment cannot be used to relate the occlusal surfaces inexcursive movements because it cannot accept evensimple eccentric interocclusal records. Refiningnonworking side contacts for balanced occlusion isthus not possible on this type of instrument.

Between the extremes is the semiadjustablearticulator, which will accept an arbitrary face bowrecord, and interocclusal records. This instrumenthas individually adjustable condylar guidances bothhorizontally and vertically. The majority of suchinstruments in use today are arcon* instruments,meaning that the condylar guidance is located in theupper (cranial) member on the articulator and theball (condylar analogue) is located in the lower(mandibular) member (see Figure 16-21).

Programming the Articulator

The centric relation record is the first essentialrecord that is used to mount the casts on the articu-lator. The instrument is thus programmed alreadyin two significant respects: the casts are relatedtogether in centric relation and at the selected ver-tical dimension of occlusion (provided by thetrimmed occlusion rims). It remains then, toprogram the posterior (condylar) and anterior(incisal) elements of the articulator.

Whether or how the articulator is programmedbeyond these basic parameters will depend on theclinical records that are taken, their demonstratedvalue, and the ability of the articulator to acceptthese records. It will also depend on the plans ofthe clinician, particularly the choice of posteriortooth mould and the overbite-overjet relations.Because both graphic records and eccentric recordsare of limited value, as noted earlier, there is littlereason to program an articulator beyond the centric

relation record and the vertical dimension. On theassumption that there is an intention to program thearticulator to more than the first two basic parame-ters, two elements need to be considered.

Condylar Elements As the mandible movesforward in protrusive excursions, the condyles typ-ically move downward, separating the posteriorteeth. Therefore the amount by which the posteriorteeth are separated is a measure of the amount thecondyles move downward as they move forward(ignoring for the moment the effect of the incisalguidance). As noted earlier, interocclusal recordsthat attempt to capture that downward and forwardmovement are highly variable and therefore oflimited value. An arbitrary setting of the condylarelements will therefore provide an entirely satisfac-tory representation of the condylar movement.Average settings of the condylar inclination on thearticulator can be used. (The average values givenin early studies were 33 degrees for sagittal and 15degrees for lateral condyle path inclination.)

With the adjustment of these two settings, thecondylar elements of semiadjustable articulatorswill be programmed. The instrument interpolatesthe movements among the centric, protrusive, andlateral positions with limited precision to provide arepresentation of the range of mandibular move-ment. As noted earlier, although the accuracy maybe limited, clinical experience suggests that suchaccuracy is not needed for the patient needingcomplete dentures.

Incisal Elements The overbite-overjet relationsof the anterior teeth are determined primarily byesthetics and phonetics. However, the resultingincisal guidance also influences the separation of theposterior teeth during excursions. Therefore thefunctional consequences of the incisal guidance rela-tionship must be considered. These factors deter-mine how the incisal elements of the articulator willbe programmed.

Where no overbite is planned between the ante-rior teeth, the incisal guide table will be left per-fectly flat (Figure 16-28). When the table is set thisway, the anterior teeth will have to be arranged sothat they contact only on the incisal edges (or not atall). Any posterior disclusion will be the result ofthe descending condyles.


*Arcon is a contraction of the words ARticulator and CONdyle.

Whereas esthetics or phonetics require overlap-ping incisors, an incisal guidance will likely becreated (which will have an impact on the posteriordisclusion). The dentist has control over the steep-ness of that guidance by setting the incisal table:where an incisal guidance is needed in protrusion, thetable is rotated to an elevated position. As the incisalpin travels along the table, the models are separatedanteriorly. Tooth contact then can only be maintainedin protrusion by arranging the teeth in an overlappedposition. Where a lateral guidance is sought (morecommon in fixed than complete denture prosthodon-tics), the lateral plates of the tables can be elevated ina similar way. The result is an overlapping of lateralcusps and tooth guidance that was intended by theclinician when the tables were set (Figure 16-29). Analternative approach is to set the preferred estheticallyinfluenced anterior teeth set-up to create a cus-tomized incisal guidance in acrylic resin on theincisal guide table. This technique is very usefullyemployed in fixed prosthodontics, but rarely so whenrehabilitating edentulous patients.

Arbitrary Settings All articulators suffer fromerrors and can only approximate conditions in thepatient’s masticatory system. Consequently, carefuladjustments must be performed at insertion of mostprostheses, especially dentures, regardless of theocclusal system or articulator used. Many dentistshave recognized this fact and have abandoned theuse of a face bow, adopting instead a technique ofmounting casts arbitrarily. (Some dentists mayeven have developed a troubled conscience as aresult.)

Recognizing that the denture bases move onthe tissues under load, the dentist can make anarbitrary setting of the condylar elements at zerodegrees. This will yield an artificially diminishedseparation of the posterior teeth. However, whencombined with a neutral (zero) incisal guidanceand cuspless teeth, with or without a compensat-ing curve or a second molar ramp, the tootharrangement becomes perfectly flat with bilateralnonworking contact (Figure 16-30). When the


Figure 16-28 The incisal guide table and lateralplates set perfectly flat. Figure 16-29 The incisal guide table and lateral

plates raised.

dentures are inserted in the mouth, the naturalseparation of the posterior teeth is largely com-pensated for by the compression of the tissuesunder the denture bases, the compensating curve,or the molar ramp, if necessary. The articulator isthus reduced to a simple hinge, and the arrangingof the teeth is greatly simplified. The appropriate-ness of this tooth arrangement (and thus the choiceof the articulator used) is a clinical judgment thatshould be made in advance. A more complexinstrument is thus not necessarily a better choice.

BibliographyAnonymous: The glossary of prosthodontic terms, J Prosthet

Dent 81:39-110, 1999.Bakke M: Mandibular elevator muscles: physiology, action, and

effect of dental occlusion, Scand J Dent Res 101:314-331,1993.

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Bowley JF, Bowman HC: Evaluation of variables associatedwith the transverse horizontal axis, J Prosthet Dent 68:537-541, 1992.

Bowley JF, Michaels GC, Lai TW et al: Reliability of a facebowtransfer procedure, J Prosthet Dent 67:491-498, 1992.

Bowley JF, Pierce CJ: Reliability and validity of a transversehorizontal axis location instrument, J Prosthet Dent 64:646-650, 1990.

Brill N, Fujii H, Stoltze K et al: Dynamic and static recordingsof the comfortable zone, J Oral Rehabil 5:145-150, 1978.

Broekhuijsen ML, van Willigen JD, Wright SM: Relationship ofthe preferred vertical dimension of occlusion to the height ofthe complete dentures in use, J Oral Rehabil 11:129-138,1984.

Carlsson GE, Ericson S: Postural face height in full denturewearers: a longitudinal x-ray cephalometric study, ActaOdontol Scand 25:145-162, 1967.

Ellinger CW, Somes GW, Nicol BR et al: Patient response tovariations in denture technique, part III: five-year subjectiveevaluation, J Prosthet Dent 42:127-130, 1979.

Goldberg LJ, Chandler SH: Central mechanisms of rhythmicaltrigeminal activity. In Taylor A, editor: Neurophysiology ofthe jaws and teeth, Basingstoke, 1990, MacMillan Press.

Gross M, Nissan J, Ormianer Z et al: The effect of increasingocclusal vertical dimension on face height, Int J Prosthodont15:353-357, 2002.

Hiiemae KM, Heath MR, Heath G et al: Natural bites, food con-sistency and feeding behaviour in man, Arch Oral Biol41:175-189, 1996.

Keshvad A, Winstanley RB: An appraisal of the literature oncentric relation, part III, J Oral Rehabil 28:55-63, 2001.

Lavigne G, Kim JS, Valiquette C et al: Evidence that periodontalpressoreceptors provide positive feedback to jaw closingmuscles during mastication, J Neurophysiol 58:342-358, 1987.

Manns A, Miralles R, Guerrero F: The changes in electricalactivity of the postural muscles of the mandible upon varyingthe vertical dimension, J Prosthet Dent 45:438-445, 1981.

Mohl ND, Zarb GA, Carlsson GE et al, editors: A textbook ofocclusion, Chicago, 1988, Quintessence Publishing.

Morneburg TR, Pröschel PA: Predicted incidence of occlusalerrors in centric closing around arbitrary axes, Int JProsthodont 15:358-364, 2002.

Muller F, Heath MR, Kazazoglu E et al: Contribution of peri-odontal receptors and food qualities to masseter muscleinhibition in man, J Oral Rehabil 20:281-290, 1993.

Olsson KA, Westberg KG: Interneurons in the trigeminal motorsystem. In van Steenberghe D, De Laat A, editors:Electromyography of jaw reflexes in man, Leuven, 1989,Leuven University Press.

Palla S: Occlusal considerations in complete dentures. In:McNeill C, editor: Science and practice of occlusion,Chicago, 1997, Quintessence Publishing Co. Inc.

Rugh JD, Drago CJ: Vertical dimension: a study of clinical restposition and jaw muscle activity, J Prosthet Dent 45:670-675, 1981.

Schwartz G, Enomoto S, Valiquette C et al: Mastication in therabbit: a description of movement and muscle activity,J Neurophysiol 62:273-287, 1989.

Sessle BJ: Mastication, swallowing and related activities. InRoth GI, Calmes R, editors: Oral biology, St Louis, 1981,Mosby.

Shodadai SP, Turp JC, Gerds T et al: Is there a benefit of usingan arbitrary facebow for the fabrication of a stabilizationappliance? Int J Prosthodont 14:517-522, 2001.

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Thexton AJ, Hiiemae KM: The effect of food consistency uponjaw movement in the macaque: a cineradiographic study,J Dent Res 76:552-560, 1997.

Toolson LB, Smith DE: Clinical measurement and evaluation ofvertical dimension, J Prosthet Dent 47:236-241, 1982.

Walker PM: Discrepancies between arbitrary and true hingeaxes, J Prosthet Dent 43:279-285, 1980.


Figure 16-30 The condylar guide inclination andincisal guide table set at zero degrees, with the cusplessteeth set on a flat plane.

Wiskott HW, Belser UC: A rationale for a simplified occlusaldesign in restorative dentistry: historical review and clinicalguidelines, J Prosthet Dent 73:169-183, 1995.

Wood DP, Korne PH: Estimated and true hinge axis: a compar-ison of condylar displacements, Angle Orthod 62:167-175;discussion 176, 1992.

Zarb GA: Oral motor patterns and their relation to oral prosthe-ses, J Prosthet Dent 47:472-478, 1982.

Zarb GA, Carlsson GE, Sessle BJ et al, editors: Temporo-mandibular joint and masticatory muscle disorders,Copenhagen, 1994, Munksgaard.


C H A P T E R 17Selecting and Arranging ProstheticTeeth and Occlusion for the EdentulousPatientAaron H. Fenton

298

A knowledge and understanding of a number of phys-ical and biological factors directly related to thepatient are required to appropriately select artificialteeth to rehabilitate the occlusion. The goals for thisphase of therapy are to construct complete denturesthat (1) function well, (2) allow the patient to speaknormally, (3) are esthetically pleasing, and (4) will notabuse the tissues over residual ridges. The dentist isthe best person to accumulate, correlate, and evaluatethe biomechanical information so that the artificialteeth selected will meet the individual needs of thepatient. The selection of artificial teeth is a rela-tively simple non–time-consuming procedure, but itrequires the development of experience and confi-dence. The setting of the selected teeth in wax accord-ing to a concept of occlusion is a laboratory procedurethat requires the use of accurate record bases andarticulator mountings of models. These record basespermit the dentist to transfer the tooth arrangement orocclusal scheme back from the articulator to thepatient’s mouth for a final examination of the maxil-lomandibular jaw relationships, an evaluation of theocclusal concept, and the philosophy of occlusion tobe fulfilled. These activities are performed duringwhat is termed the try-in appointment.

ANTERIOR TOOTH SELECTIONA smile is the most visible record of a dentist’s careof an edentulous patient. It is present for all to see.Anterior tooth selection (ATS) has been based ontheories that tooth shape relates to head shape, andtooth appearance is influenced by a patient’s age, sex,

and personality. If no other information about ATS isavailable, these systems can be used to select teeth.

The dentist’s professional obligation is to givethe patient adequate information, guidance, andopportunity to choose their teeth. ATS is the area ofprosthodontic care in which the patient should begiven a primary responsibility to determine theesthetic outcome.

ATS for dental prostheses has both psychologi-cal and dental considerations that are influenced bythe societal values for youth and health. Patientsmay wish to have teeth that look whiter and lessrestored than what would normally be expected inpersons their age. The dentist’s task is to assist apatient in making the best decision.

Tooth manufacturers provide a variety of shadeguides, mold guides, and measurement charts toassist dentists in the selection of anterior teeth(Figure 17-1). Because each system can produce sat-isfactory results, select a manufacturer based on localavailability and reliable delivery. Future tooth repairsare easier if the prosthetic teeth are readily matched.

Although the dental profession seeks to realis-tically replace the missing dentition, prostheticteeth are often smaller in size and lighter in colorthan the range of the natural dentition. This doesnot seem to be a problem because patients mostoften object to teeth being too large or too dark.They often prefer teeth that are lighter. Ask yourlocal laboratory which tooth sizes and colors areselected most often. Find out if the laboratory hasproblems with a manufacturer’s tooth color andsize matching or if frequent repairs are needed.

Psychology of Acceptance: Give PatientsWhat They Want

The United States is a consumer-oriented society,yet patients leave many dental decisions to thedentist, such as the posterior palatal seal or theretromylohyoid extension. Dentists have knowl-edge of oral anatomy and esthetics and the physiol-ogy of speech and mastication. Teeth can beselected without the patient’s input. This is dentallyfeasible, but therapeutically dangerous.

Everyone sees the anterior teeth, and everyonehas an opinion. Patients should be given enoughinformation and assistance and should be guidedtoward a limited selection of anatomically possibletooth selections so that they can choose the teeth thatmake them happy. Let the patient decide; then boththe patient and dentist will get what each wants.

Patients, and perhaps their close personalfriends, know what they think teeth should looklike, so get them involved in the decision making.Psychologically, this is effective therapy. Patientsmore readily accept prosthetic care if they have hadsome input. Satisfied patients tell their friends whotreated them; dissatisfied patients tell everyone.

The first step in ATS is to listen to the patient.What the patient wants is the reason that she or hecame to your office. Do not miss it. Too often, den-tists are so keen to make impressions and all thosedental things that they alone know about that theyunderestimate the value of hearing what the patientwants.

At the first appointment, ask your patient forhis or her opinion about the existing teeth. Write itdown in the patient’s own words (e.g., “My teethdon’t show anymore.”) Then restate it in yourwords to clarify what the patient expects (e.g., “Ifwe make teeth of the same size, but lighter in color,and a little longer at the front, would that makethem show the way you want?”) Listen much andtalk little. We cannot hear when we are talking.

Let the decision maker choose the teeth.A patient may have another person such as a spouse,relative, or friend whose opinion is valued. Askthem. That person may be more the reason why thepatient is seeking treatment than the patient. It takesonly a few seconds to find out if there is someoneelse with whom the patient would like to checkregarding tooth color and size. You may devote hoursof laboratory and chairtime only to find out that thesetup that you and the patient agree on in the officeis not liked by their spouse, and they demand thatyou change the teeth or set-up. This will have tohappen only once for you to remember it.

People vary in how much they value theappearance of their teeth. The importance of ATSto patients can range from the indifferent “itdoesn’t matter” to unrealistic expectations thatcannot be satisfied. Fortunately, almost all patientsare well between these two extremes. Your mostimportant task is to quickly find out where yourpatients are on this spectrum of interest in theappearance of their smiles. Their responses willindicate how interested they are in change and howmuch time you will devote to tooth appearance.This affects your cost of providing the service ofcomplete denture treatment.

Second, get records of existing and previousteeth and find out the patient’s opinion of them.Ask patients what their teeth looked like before theexisting dentures. Explain that to get the best resultfor them, you need to know what their teeth werelike before. Their mouth has probably changed,and present appearances can be misleading. Askthe patient to bring any models, old dentures, andphotographs that show them happy and smiling, tothe next appointment. The patient will give youcredit for trying to provide the best personalservice, and you will get some indication of whatthe teeth were like. Make alginate impressions andplaster models of the dentures that best satisfy the

Chapter 17 Selecting and Arranging Prosthetic Teeth and Occlusion for the Edentulous Patient 299

Figure 17-1 Shade and mold guides assist in toothselection.

patient, and with the patient’s permission, make aphotocopy of any relevant pictures (Figure 17-2).You may make good dentures, but patients willnever forget if a favorite wedding picture gets tooclose to a Bunsen burner.

If your patients are happy with the appearanceof their teeth, use these records to provide a dentureservice that has similar teeth, but a better verticaldimension of occlusion and adaptation to thetissues. This has been identified as a “conformativeapproach” to prosthodontic care. The message thatyou are interested in making their teeth as naturalas possible can be personalized further by askingif their teeth were like their direct descendents:their children. Photographs or dental models of adultchildren are sometimes the best way to create asmile that your patient appreciates. At least ask.The patient can always decline (Figure 17-3).


Figure 17-2 Photocopy a patient’s photograph tohelp in selecting tooth size and positioning.

Figure 17-3 A, This patient’s childhood photograph provided assistance in selectingdenture teeth for her at age 54. B and C, Diagnostic casts made of her 30-year-old daughterfurnished additional assistance. The daughter’s tooth shade (Vita A1 for the centrals andlaterals, A2 for the canines) also substantiated her mother’s request for a light tooth shade.

A

B

C

On the other hand, your patients may not liketheir present teeth. Often the most important thingto find out is how not to make teeth because of thepatients’ dislike of their own teeth or previous den-tures. If the teeth are the wrong color, size, shape,or position, plan on improvements. Also, the teethmay be excessively worn, or tissue changes may beso advanced that making teeth similar to what thepatient has would be of little benefit. In these situ-ations, consider a reorganized approach where youplan to change the prostheses to improve them.Even though you are planning improvements,improvements are a change. Assess the toleranceand motivation of your patients for change andwork within the range that they can accept. Thepleasure of prosthodontics is blending the interper-sonal aspects of patient care with the biology of themouth and the science of dental materials.

Third, arrange your practice for ATS. Make iteasy for you and your patients to view their faces ingood light. Your patient should be able to standbefore a north-facing window, and you should haveadequate color-corrected lighting. Tall or shortpatients should stand so that you can see their faceand smile as others see them. Position yourself sothat the window light comes over your shoulderand onto your patient’s face. Make sure yourpatients put their glasses on if they need them. Giveyour patients a hand mirror of about 6 inches (or 15cm) in diameter so that they can see how their facelooks. A smaller mirror does not give an adequateimage to the patient; a larger mirror makes it diffi-cult for you to see around it.

Fourth, allow your patients to select the colorof teeth they prefer. Dentists are familiar with anarray of tooth shades and mold guides and charts,but these can be too confusing for patients todecide. They beg off making a decision and tell thedentist to decide what is best for them. Then youare responsible. If your patients like your decision,that is fine. If they, or anyone else, are at all skep-tical, suddenly it is your teeth that are the problem,not theirs. Avoid this roadblock by tactfully insist-ing that your patients decide which teeth are bestfor them. This is easily done in a nonthreateningmanner by giving the patients a simple choice withtwo options (i.e., a Method of Pair Comparison).

Tell your patients that you need their help to getthe best results. Explain that you have many colors

and sizes of teeth to best treat your patients, butonly a few are appropriate for them. A display of allof your shade and mold guides at this point isimpressive but confusing to a patient untrained indental anatomy. Reassure your patients that anyrequired decisions will be simple. They will onlyhave to tell which one of two things they prefer; inother words, make a simple choice.

Color is the easiest thing for a patient to decideabout teeth. Show the patient a complete shadeguide and select the two tabs that are lightest anddarkest (Figure 17-4). Point out how different thesetwo are and satisfy yourself that the patient can seethe difference and agree. Hold them against thepatients’ lips and ask them to note how differentthey are. Then ask them to point to the one that theyprefer. Delete the rejected color. On the basis of thedecision, select another shade in the preferred halfof the shade guide and repeat the pair comparison.After two selections by the patient, you will proba-bly have a pair of shades that are very close to whatthe patient wants. To confirm the patient’s decision,reverse the sides of the pair so that the preferredshade is presented on the opposite side. Try anothershade that is close to the preferred shade. By nowthe psychology of decision making is as importantas the physiology of color perception. Usuallypatients can still select the same shade even whenyou move it from side to side in the pair, but some-times they are unwilling to state a preference.


Figure 17-4 A pair of tooth shades to compare.Ask your patient to point to the one that he or sheprefers.

If patients are unable or unwilling to decide ona shade, their powers of perception can still help toselect a tooth color. Ask them to point out whichone of the pair of tabs they notice. By default, thetab that they do not notice is less conspicuous andtherefore a better color.

In the rare situations in which patients stillcannot decide, advise them that they are correct.Both shades are appropriate, and a pleasing appear-ance could be made with either one of them.However, you would still like them to be happy, sothey should choose between the two shades whenyou have the actual teeth. Order two sets of teeth sothat the patient can compare them side by side andselect the best before they are needed for setup.

Fifth, choose a size of tooth that is appropriate.Existing dentures, models of previous teeth, andphotographs all give valuable input for selection ofthe size and shape of teeth. Teeth can be measuredin millimeters and teeth of similar size selected(Figure 17-5). Even so, patients may have a clearperception of how large a tooth they prefer.Coupled with actual measurement, again use theMethod of Pair Comparison to assist patients todecide what size of tooth they prefer. Set two dif-ferent sizes of teeth on a piece of wax rope or onthe tooth selector rim that some companiesprovide. Place this under the upper lip and find outwhich one the patient prefers. The decision is oftennot one of preference, but rejection. People noteand reject the teeth that are, for example, too large,

small, long, or short. By default they prefer theother set of teeth.

Sixth, select the mold of the teeth. Teeth of asimilar size can have a different appearancebecause of differences in the crown taper and labialcurvature. This is the least obvious of the threejudgments to be made, yet it can provide the “fin-ishing touch” to replicate a realistic appearance foryour patient. Mold determination requires previousmodels or photographs for guidance. If the patientis to receive immediate insertion complete den-tures, the actual teeth are the best indicator ofmold. If teeth are unavailable, allow the patient toselect between molds of the same size but differentshapes. Set two different molds on the right and leftsides of a piece of wax rope and ask patients whichthey prefer (Figure 17-6).

Anterior tooth selection should be completedearly in treatment, preferably before final impres-sions are made. This gives ATS appropriate signif-icance and allows time for judgment of the resultbefore the teeth are needed. Order all of the teeth(1 × 28) because the premolars are part of thesmile. Their color, size, and shape should comple-ment the anterior teeth. Show patients the actualteeth at the impression appointment and securetheir agreement (Figure 17-7). If the teeth are notwhat patients think they will be, based on the shadeand mold guide estimations, they can be reorderedand exchanged before they are needed for setup in


Figure 17-5 Use a Boley gauge to determine thesize of teeth in millimeters. A similar-sized tooth canbe selected based on this evidence.

Figure 17-6 Pair comparison to identify the bestmold of teeth. The two teeth on the left and the twoteeth on the right are from different molds. The patientcan see them in the mirror, and he is pointing to theones that he prefers.

wax. Otherwise, it is expensive for your laboratoryfees and office chairtime to exchange and reset asecond set of teeth.

Additional Clinical and TechnicalConsiderations in Anterior Tooth Selection

Patient preferences, local anatomy, and the opposingdentition can affect the ATS of materials or mold.

Patient Preference Patients may want teeth to beporcelain or acrylic, depending on various reasonsthat they have heard: “Acrylic teeth stain,”“Porcelain teeth are real,” “Porcelain teeth arenoisy for chewing,” or “Porcelain teeth are heavy.”There are a variety of opinions. Listen and respondwith your knowledge of dental materials, but do notbe disheartened if the patient is skeptical. Facts arenot always as accepted as opinions. If the denture isnot compromised by patients’ requests, you canperhaps accede to their wishes. Make patientsaware that you are modifying your therapy person-ally for them and make a note in the chart. Again,this is an opportunity for patients to accept respon-sibility for their decisions.

Highly Visible Gingiva Select squarer teeth witha long contact point rather than highly taperedteeth. This will minimize the interproximal display

of pink gingival acrylic. It is harder to make reali-stic-appearing gingival acrylic compared withteeth. Therefore make a smile with slightly moredental and less gingival display.

Limited Interocclusal Space Use acrylic teeth.They can be ground thin, yet they will still chemi-cally bond to the underlying denture base acrylic.Porcelain teeth lose their mechanical retention ifthe palatal pins are ground off.

Opposing Natural Teeth Porcelain can be veryabrasive. Use acrylic teeth for dentures that opposenatural teeth to minimize their wear. The acrylicteeth will wear, but they can be replaced. This ispreferable to the porcelain destruction of enamel.Also, acrylic teeth are less brittle than porcelainwhen additional adjustment is required to matchnatural occlusion.

Overdentures The tooth positioned just over aretained tooth root or implant abutment has to be“hollow-ground,” and a little extra tooth volume isneeded for strength. Use a square flat mold in astandard nonlaminated acrylic. Tapered or curvedteeth get too thin and weak in the gingival areas.Highly characterized or laminated teeth maybecome translucent or separate their veneers whenground thin over tooth roots or implants.

The Personal Touch: Characterization ofSelected Teeth

Explain to patients that smiles are more realistic withsubtle chips, wear, or restorations. These hint at thepresence of a dentition for many years, as opposedto looking “brand new.” Although this service isoffered to all patients, lately, more patients seem toprefer an undamaged appearance of light-coloredteeth. Fewer patients opt for too-visible characteriza-tion. Nevertheless, anterior tooth characterizationcan produce strikingly realistic effects that make thepatient’s smile look as if it is enamel, dentin, andgingiva. Teeth can be modified to create a personalsmile in a number of ways and combinations, such aschanges in color and position (Figure 17-8), individualgrinding and placement (Figure 17-9), placement ofrestorations and worn appearance (Figure 17-10),and natural proportion and subtle variations inposition (Figure 17-11).


Figure 17-7 Order the selected teeth early so thatthe patient can see them at the impressionappointment. Confirm their acceptability before theyare needed for setup.


Figure 17-8 Characterization with colors: use different tooth colors to create the besteffect. A, The prominent position and color of this patient’s maxillary right central wereidentified from a photograph. B, The maxillary central incisors were Dentsply shade 102; therest of the smile was Dentsply shade 114. This emphasized the tapered arch form andcreated the illusion of more prominence for the upper right central incisor than wasprosthetically possible. The smile appears real to this patient.

A B

Figure 17-9 Characterization by grinding: immediate dentures allow for realistic toothselection and shaping. A, A previous photograph hints at the prominence of the maxillarycentral incisors, their overlap of the lateral incisors, and the Angle Class II relationship. B, Astudy model allows selection of the best available mold.

A B

Continued


Figure 17-9 cont’d C, The acrylic teeth are trimmed to recreate the actual tooth shape.It could not be found in any mold guide. D, The completed prosthesis faithfully replicates theirregularity of tooth color, size, mold, and Angle Class II position. This patient’s smile looksreal.

C D

Figure 17-10 Characterization with restorations and wear. A gold inlay is in the mesialof the upper right canine, the upper left lateral incisor is rotated prominently, and the incisalis chipped, with an Angle Class II Division 2 tooth arrangement. The teeth are a singleuncharacterized shade, but all the other natural effects make them appear real.

POSTERIOR TOOTH SELECTIONUntil the middle 1920s, most posterior dentureteeth were anatomical in design and represented theforms of natural teeth. In the mid 1920s, dentistsbegan to experiment with tooth forms that, weredesigned for a specific functional purpose rather

than merely reproducing natural forms. Thusemerged a number of nonanatomical denture teeth.The occlusal surfaces of these teeth are not copiesfrom the natural form but are given forms that, inthe opinion of the tooth carver, were designed tomeet specific patient needs, such as denture basestability and improvements in mastication. Some


Figure 17-11 Characterization by natural arrangement: a standard anterior tooth shadeand mold is made to look real by the subtle natural irregularity of tooth positioning. A, Thepatient’s presenting smile with teeth that are too small and hardly visible. B, The maxillaryteeth are a single uncharacterized color, too small, out of proportion to the lower teeth, andtoo uniform in position. C, The new smile has better lip support and visibility at rest. Themidline of the teeth is different from the lip at rest because it is set for the more visibleasymmetrical smile. D, The patient’s smile is in proportion to the surrounding tissues. Eachtooth has an individual identity because of subtle variations in angle and rotation. Thecentral incisors are at the midline of the smile, but they are not a mirror image of eachother. The patient’s left lateral incisor is rotated out at the mesial. The canines and visiblepremolars vary in gingival prominence and angulation. The gingiva is inconspicuous. Thissmile is perceived to be real and gives the patient self-confidence.

C D

A B

nonanatomical posterior denture teeth were designedcompletely without cusps, whereas others weremechanical in design, possessing metal cutters toincrease masticatory efficiency. The maintenance ofhard and soft tissues of the dental arches has beendifficult to relate to tooth forms and occlusalschemes. Other factors, such as (1) properly fittedbases; (2) correct jaw relation records that aretransferred to an instrument capable of acceptingwhat is recorded; and (3) the arrangement of teethfor the best stability and other functional and non-functional activities, are considered to have aninfluence on the maintenance of these tissues.

Posterior teeth are selected for color, buccolin-gual width, total mesiodistal width, cusp tip to cer-vical collar height, material, and the cuspalinclination needed for the concept of occlusion tobe used in restoring the patient.

Buccolingual Width of Posterior Teeth

The buccolingual widths of artificial teeth should beless than the widths of the natural teeth they replace.Artificial posterior teeth that are narrow enhance thedevelopment of the correct form of the polishedsurfaces of the denture by allowing the buccal andlingual denture flanges to slope away from theirocclusal surfaces. These narrower forms, especiallyin the lower denture, assist the cheeks and tongue inmaintaining the dentures on the residual ridge.

Mesiodistal Length of Posterior Teeth

The length of the mandibular residual ridge fromthe distal of the canine to the retromolar pad willdictate the dimensions of the posterior teethselected. Artificial posterior teeth are manufac-tured with varying widths and lengths that easilyaccommodate the needs of the patient.

After the six anterior mandibular teeth have beenplaced in their final position, a point is marked onthe cast landing area at the distal of the canine. Asecond mark is placed on the landing area of the castat the point where the mean residual ridge begins toascend to the retromolar pad. Posterior teeth are notpositioned on this inclined plane. The availablespace will dictate whether three or four posteriorteeth are used. The arrangement of only three poste-rior teeth is more often the norm and will reduce the

potential for placement of the second molar too farposterior. Maxillary posterior teeth that extend tooclose to the posterior border of the maxillary denturemay cause the patient to bite the cheek.

Vertical Height of the Facial Surfaces ofPosterior Teeth

It is best to select posterior teeth corresponding tothe interarch space and to the height of the anteriorteeth. Artificial posterior teeth are manufactured invarying occlusal-cervical heights. The height of themaxillary first premolar should be comparable withthat of the maxillary canines to have the properesthetic effect. Without this relationship, the denturebase material will appear unnatural distal to thecanines. Ridge lapping the posterior teeth can bedone without sacrificing leverage or esthetics. Theform of the dental arch should copy, as nearly as pos-sible, the arch form of the natural teeth they replace.

Types of Posterior Teeth According toMaterials

For many years, porcelain was the favorite toothmaterial because of the rapid wear of acrylic resin.However, with the tendency for porcelain to chip andfracture, acrylic resin teeth have gained in popularity.Improved acrylic resin teeth and newer compositeresin teeth are more wear resistant, and they havesupplanted porcelain during the past two decades.

Acrylic resin or composite resin posterior teethare specifically called for when they oppose naturalteeth or teeth whose occlusal surfaces have beenrestored with gold. These resin teeth reduce thepossibility that the artificial teeth will cause unnec-essary abrasion and destruction of the natural ormetallic occlusal surfaces of the opposing teeth.Acrylic resin teeth also are desirable when the toothmust be excessively reduced in height because of asmall interarch distance. The chemical bonding ofthe resin teeth with the denture base prevents theseteeth from breaking away from the denture base.

Types of Posterior Teeth According to CuspInclines

The cuspal inclines for posterior teeth weredescribed earlier in great detail. Posterior artificial


teeth are manufactured with cusp inclines thatvary from steep to flat. Selecting the tooth to beused is based on the concept of occlusion tobe developed, the philosophy of occlusion to befulfilled, and the accomplishment of both ofthese goals with the least complicated approach(Table 17-1).

ARRANGING TEETH FOR COMPLETEDENTURE OCCLUSIONOnce the master casts have been mounted on thearticulator, the teeth are set in the occlusion rimsso a more accurate observation of the jaw rela-tionship can be recorded, and eventually the


Table 17-1Comparison of Denture Tooth Molds and Occlusal Concepts

Tooth Mold Occlusal Concept Advantage Disadvantage

20- or 30-degree ● Centric jaw record, face ● Reported slightly more ● Most time and cusped teeth bow, protrusive records to efficient in chewing tests complexity of records

semiadjustable articulator ● Posteriors appear more ● Limitations of anterior ● Set upper anterior and natural tooth positions

posterior teeth, then ● Restriction of posterior lowers to cross-arch contact tooth positions to that or “balanced occlusion” allowed by cuspal anatomy

Monoplane ● Centric relation jaw ● Simplest of all ● Flat premolars may 0-degree teeth record only recordings appear less esthetic

● Simple articulator ● Simplest articulator ● Reported as less efficient ● Set 12 anterior teeth with ● Quick arrangement of teeth in chewing tests

overjet but no overbite ● Wide range of posterior ● Anterior esthetics need ● Set lower teeth in flat plane tooth positions possible more overjet and no

to middle of retromolar pad ● No lateral stresses on overbite● Set upper to match; no mucosa with parafunction

attempt on contact on ● Easier for patients with excursions uncoordinated closures

(e.g., patients with dyskinesias, Parkinson’s disease, or stroke)

Flat teeth with ● Centric relation jaw record ● Simple to set up; allows ● Slightly more laboratorycompensating ● Semiadjustable articulator for more esthetic overlap setup time than flat teethcurve or ● Anterior teeth with overjet of anterior teeth ● Premolars appear flat ifsecond and slight overbite ● The posterior point contact visiblemolar ramp ● Posteriors set to contact maintains denture base

on at least 1 point on stability on excursions or nonworking or balancing parafunctioncontact

Combinations or ● Centric jaw record ● Upper premolars appear ● Some grinding needed to “lingualized” ● Monoplane lower natural create upper cusp occlusion posterior teeth set to ● Some range of posterior tip/lower fossa contacts

retromolar pad tooth position allowed (some manufacturers are ● Anatomical upper ● Reported slightly better now producing molds for

posterior teeth set with chewing than monoplane this occlusal concept)only lingual, not buccal teethcusps touching

occlusion established. Most dentists carve thewax occlusion rims as accurately as they can fordetermining the desired amount of lip support andhave their technician make the preliminaryarrangement of teeth. The carved occlusion rimsprovide the technician with reliable guides forplacement of the anterior teeth in the wax occlu-sion rims. Subsequently, these dentists make cor-rections in the tooth positions when the wax trialdentures are observed in the mouth at the try-inappointment.

The incisive papilla is a valuable guide to ante-rior tooth placement because it has a constant rela-tionship to the natural central incisors (see Figure17-3, Figure 17-12). The incisive papilla is found inthe lingual embrasure between these incisors.Naturally, it should serve to position the midline ofthe upper denture or, more specifically, the centralincisors in the dental arch. However, the mesial sur-faces of the central incisors of some people are notexactly in the center of their face or mouth.Therefore information on the center of the upper


Figure 17-12 Indications of correct anteroposterior positioning of artificial anteriorteeth. A, By measurement from the middle of the incisive fossa on the trial denture base tothe labial surfaces of the central incisors. B, By visualization of the imaginary roots ofartificial anterior teeth. The imaginary roots will be further in front of the residual ridgewhen a great amount of resorption has occurred. C, By determining the relationship of atransverse line extending between the middle of the upper canines and the incisive fossa.

A

B C

lip or face should be recorded on the carved waxocclusal rim.

A line marking the center of the incisive papillaon the wax rim can be extended forward onto thelanding area of the cast (Figure 17-13). The centralincisors set on either side of this line will havepositions similar to those of the natural teethinsofar as right and left orientations are concerned.The incisive papilla is also a good guide for theanteroposterior positioning of the teeth (see Figure17-13). The labial surfaces of the central incisorsare usually 8 to 10 mm in front of the papillae. Thisdistance, for obvious reasons, will vary with thesize of the teeth and the labiolingual thickness of

the alveolar process carrying the natural teeth, so itis not an absolute relationship. Furthermore, assevere resorption of the residual ridge in a verticaldirection occurs, the incisive papilla may belocated more posteriorly to the position of thereplacement teeth. Thus the distance from thepapilla to the labial surface of the teeth maybecome greater for those patients with excessivebone loss in the maxillary anterior region.

Another guide to positioning the central inci-sors is their relationship to the reflection of softtissues under the lip or as recorded in the maxillaryimpression. The labial surfaces and incisal edges ofthe teeth are anterior to the tissues at the reflection,where the denture borders would be placed. Thisfact must be kept in mind when placing an artificialincisor in the wax occlusion rim. The root of thenatural tooth extends into the alveolar process, witha relatively thin layer of bone over it labially. Thismeans that in some situations the residual ridge canbe used as a guide to determine the proper inclina-tion of anterior teeth. However, the accuracy of thisguide decreases as resorption of the residual ridgeprogresses. Clinical judgment is essential in theevaluation and application of these guides.

The anteroposterior position of the dental archshould be governed chiefly by consideration of theorbicularis oris muscle and its attaching musclesand by the tone of the skin of the lips. Superficially,this means the position and expression of the lips.The orbicularis oris muscle affects, and is affectedby, the following seven muscles: the quadratuslabii superioris, caninus, zygomaticus, quadratus labiiinferioris, risorius, triangularis, and buccinator.These muscles control expression and reflect thepersonality and appearance of every person wear-ing complete dentures. The tone and action ofthese muscles depend on the anteroposteriorsupport provided by the teeth and the denture basematerial.

Setting teeth over the maxillary anterior ridgemay undermine the esthetic result. The greatestharm is done when the maxillary anterior teeth areset too far back on the ridge or under the ridge. Inother words, the tooth’s direction is upward andbackward. In the resorbed situation, the crest of theridge is considerably more posterior than it is in apatient with recent extractions. If the rule of settingteeth over the ridge is followed after the residual


Figure 17-13 The incisive papilla is used to helplocate the midline of the dental arch. A, A mark ismade on the cast through the center of the papilla.B, The mark is transferred to the occlusion rim as aguide to placement of the maxillary incisors.

A

B

ridge has resorbed, a prematurely aged appearancewill result.

If the wax occlusion rims have been accuratelycarved to support the lips and the maxillomandibu-lar jaw relationship, they will provide an excellentguide to correct anteroposterior tooth positioningin the dental arch. If they have not been accuratelycarved, the dentist must decide what alterationswill be necessary when the teeth are arranged. Forexample, if the lip needs more support when theocclusion rims are in the mouth, the incisors shouldbe set in front of the labial surface of the wax rim.If the lips are too full at that time, more of the labialsurface of the occlusion rims should be cut awaybefore the teeth are set.

Arranging the Maxillary Anterior Teeth

After selecting the anterior molds for the maxillaryand mandibular teeth, the arrangement is left to thediscretion of the individual dentist to achieve theesthetic needs of the patient. Remove the maxillarywax occlusal rim on one side from the midlinearound the arch for a distance of approximately 1inch (about 25 mm). For the maxillary anterior teethto be set with the appropriate labial orientation, itmay be necessary to grind the acrylic resin to reducethe thickness of the record base. This is a commonoccurrence in clinical practice and should always beperformed before grinding on the neck of the tooth.A longer tooth clinically will provide a betteresthetic result. Short, stubby teeth are not natural inappearance. Do not be concerned should you createa hole in the record base because it will be coveredwith wax in setting the anterior teeth. Often it ishelpful to set both central incisors and thus establishthe midline before setting the lateral and canine.

Maxillary Central Incisor Place a small portionof soft, pink wax on the neck of the maxillarycentral incisor and attach the tooth to the recordbase over the anterior region of the residual ridge.Make certain that the long axis of the tooth is per-pendicular to the horizontal, with the incisal edge0.5 mm below the wax occlusal rim. Seal the toothinto position with pink wax, using the no. 7 spatula.Try to use only the amount of wax needed forsecurely attaching the teeth to the record base.Excess wax should be removed from the teeth. The

maxillary central incisor is the most difficult toothto set because it establishes the midline and theesthetic support of the patient’s lip. The properarrangement of the maxillary and mandibular ante-rior and posterior teeth relies on the setting of themaxillary central incisors.

Maxillary Lateral Incisor Place the maxillarylateral incisor next to the central incisor, with theneck slightly depressed. Arrange the incisal edge insymmetry with the central incisor and with theremaining anterior occlusal rim. This incisal edgeis even with the remaining maxillary wax occlusalrim and is therefore slightly elevated from thecentral incisor. The incisal edge is parallel with themandibular wax occlusal rim. After this tooth isarranged in the normal position for a lateral incisor,it may be repositioned with spacing, lapping, orrotation to meet the individual esthetic require-ments for the patient.

Maxillary Canine Place the maxillary canine sothat the anterior one half of the incisal edge is insymmetry with the lateral and central incisors as itcurves around the labial contour of the waxocclusal rim. The neck of the tooth must be promi-nent and the tooth tilted slightly to the distal. Likethe central incisor, the incisal tip of the canine mustbe 0.5 mm below the maxillary wax occlusal rim.Again, after initially setting the tooth to theseguidelines, any individual changes necessary forthe creation of naturalness for the patient should beperformed.

Remaining Maxillary Anterior Teeth Arrangethe remaining maxillary anterior teeth on the othersides of the arch to complete the anterior setup. Thewax supporting the teeth must be heated and sealedboth to the teeth and to the record base to maintainthe set teeth in position.

Arranging the Mandibular Anterior Teeth

The wax occlusal rim is removed from the area ofthe lower midline around the arch for approxi-mately 1 inch (around 25 mm). This is similar tothe procedure you performed on the maxillary waxocclusal rim when the maxillary anterior teethwere set.


Mandibular Central Incisor Position the centralincisor next to the midline and tip it slightly to thelabial. Direct the long axis of the tooth toward theresidual ridge. Be certain that the necks of the teethare depressed so that they are in from the edge ofthe record base. The incisal edges of these teethmust be at the height of the mandibular waxocclusal rim. This will result in a 0.5-mm verticaloverlap with the maxillary central and canineteeth. A 1- to 2-mm horizontal overlap must existbetween the lingual surface of the maxillary ante-rior teeth and the labial surface of the mandibularanterior teeth. Such an arrangement will create a

low incisal guidance, which is exactly what oneshould achieve for the patient (Figure 17-14).

Mandibular Lateral Incisor Position the lateralincisor next to the central incisor, with the long axisof the tooth directed toward the residual ridge. Theincisal edge should be at the height of the waxocclusal rim. The 1 to 2 mm of horizontal overlapbetween the maxillary and mandibular anteriorteeth should be continued.

Mandibular Canine Place the mandibular caninewith the anterior one half of the incisal edge in


1-2 mm

0.5 mm

Figure 17-14 A, 0.5 mm of vertical overlap and 1 to 2 mm of horizontal overlap mustexist between the maxillary anterior teeth and their mandibular antagonists to achieve a lowincisal guidance, which is needed for the anterior teeth to function in harmony with mostposterior tooth forms. B, The low incisal guide angle is both esthetic and functional.

A B

symmetry with the lateral and central incisors.Place the incisal tip at the same level as the lateraland central incisors. The neck of the tooth isslightly prominent and tilted to the distal. Afterthese teeth are adjusted to this ideal arrange-ment, they may be altered by rotation, spacing, andtilting the teeth to achieve the naturalness require-ment of the patient.

Remaining Mandibular Anterior Teeth Arrangethe remaining anterior teeth on the other side of thearch to complete the anterior setup. Again, be sureto seal all the teeth to the record base with pinkbaseplate wax and the no. 7 spatula. It is at thispoint in the clinical management of a patient thatyou may wish to evaluate the esthetics of all ante-rior teeth by a try-in with the patient.

Anterior artificial teeth should be placed inessentially the same positions previously occupiedby the natural teeth, and the labial surface ofthe denture base material should duplicate, asnearly as possible, the contour and position of themucous membrane covering the alveolar ridge.Reducing the horizontal and vertical overlaps ofthe anterior teeth is necessary to reduce the incisalguide angle. It should be recognized that thisreduction may have an impact on esthetics. Thedangers from a high incisal guidance far exceedthe possible impact on esthetics that might be pro-duced when the teeth are set with less horizontaland vertical overlaps. It is not necessary for theanterior teeth to contact in maximum intercuspa-tion. In fact, it is better that they be set just out ofcontact.

If the mandibular ridge is forward of the maxil-lary ridge (as in a prognathic jaw relationship), theupper anterior teeth should be set end to end, withthe incisal edges in light contact with the mandibu-lar anterior teeth. When the prognathism is extreme,it may not be possible to have tooth contact in theincisor region because the maxillary incisors will beplaced too far anteriorly and will put the upperlip under too much tension. In such situations, ananterior crossbite is the only alternative.

Extremely high ridges may seem to create aproblem unless it is realized that natural teeth onceprojected from these ridges. Insufficient spacebetween the residual ridges is an indication thateither the artificial teeth selected are longer than the

natural teeth or the vertical dimension of the facemay be closed. However, if only parts of the ridgesare too close together, the cause may be an incom-plete alveolectomy during tooth extraction. Surgicalremoval of small bony projections may be indicated.

Arranging the Posterior Teeth

The preliminary arrangement of posterior teethinvolves the application of principles similar tothose applied in the arrangement of anterior teeth.The artificial posterior teeth should be placed nearto where the natural teeth were positioned. This iseasier said than done, however, because there areonly a few guides for posterior tooth position. Thefinal position of the occlusal plane, the occlusalcontacts, and even the number of posterior teethcannot be determined until the jaw relations areevaluated and found correct.

The orientation of the anterior occlusal plane isdetermined initially by the wax occlusal rim. Theanatomical guides most often used in developingthe anterior plane of occlusion are the corners ofthe mouth. In general, the plane should be locatedeither at or slightly below the corners of the mouth.During the arrangement of the mandibular anteriorteeth, the position of the incisal edges of themandibular anterior teeth eventually establishes thelevel of the anterior plane of occlusion. The poste-rior plane of occlusion is an extension of thisanterior plane level with the junction betweenthe middle and upper third of the retromolar padsbilaterally. These posterior references (retromolarpads) will place the overall plane at a level that isfamiliar to the tongue. If the plane is located higheror lower, for whatever reason, the dentures willinterfere with normal tongue action. This willadversely influence denture base stability (Figure17-15).

The inclination of the occlusal plane is impor-tant to the stability or instability of dentures. If theplane is too low in the anterior region or too high inthe posterior region, the maxillary denture will tendto slide forward. Ideally, the plane of occlusionshould parallel the mean mandibular residual ridge.

The height of the occlusal plane is not simply amatter of dividing the maxillomandibular denturespace equally. This space is governed by the rela-tive amount of bone lost from the two ridges. More


bone may have been lost from the maxillae thanfrom the mandible, and the occlusal plane shouldnot be placed an equal distance between the tworidges. It also should not be at a level that wouldfavor the weaker of the two ridges (basal seats).The most reliable guides are esthetics or anteriortooth placement and the retromolar pads.

The buccolingual position of the posterior teethand the posterior arch form are determined anteri-orly by the position of the canine and posteriorly bythe shape of the basal seat and the location of theretromolar pads. The curvature of the arch of ante-rior teeth should flow pleasingly toward the poste-rior teeth. The posterior teeth are positioned in sucha way that they are properly related to the bone thatsupports them and to the soft tissues that contacttheir facial and lingual surfaces. In the final tootharrangement, the posterior form of the arch will bedetermined largely by the “neutral zone” betweenthe cheeks and tongue. This is the space resultingfrom the removal of the posterior teeth and the lossof bone from the residual ridges. The pressure ofthe cheeks and tongue against the facial and lingualsurfaces of the erupting natural teeth was strongenough to influence their alignment in the dentalarch. These forces also are applied against den-tures. Therefore the final arrangement of the archmust be developed with respect for the tongue andcheek (see Figure 17-15).

The solution to the problem is to position theteeth along a line extending from the tip of the

canine to the middle of the retromolar pad. This arbi-trary line should pass through the central fossa of themandibular premolars and molars (Figure 17-16).

The basic principle for the buccolingual posi-tioning of posterior teeth is that they should bepositioned over the residual ridge. The canine andretromolar pad should provide guides for thisarrangement.

OCCLUSAL SCHEMES FOR COMPLETEDENTURE OCCLUSIONThe occlusal scheme or the tooth molds selected forocclusal rehabilitation will depend on the conceptof occlusion that has been selected to satisfy theneeds of the patient. The posterior teeth, arrangedaccording to the occlusal concept selected, shouldfulfill the dentist’s philosophy of occlusion as wellappear esthetically pleasing. Posterior tooth formshave aroused a great deal of controversy among cli-nicians and researchers. Chewing efficiency testshave shown a slight advantage to cusped teeth.Cuspal anatomy has not been shown to have anysignificant effect on the supporting tissues. Patientpreference surveys have been inconclusive.Prosthetic tooth anatomy seems to be more impor-tant to dentists than to the patients who use theteeth. In the absence of clear evidence of the bene-fits of one tooth anatomy compared with others,dentists should use the least complicated proce-dures and tooth forms that will satisfy their con-


Figure 17-15 A, Mandibular teeth positioned too far toward the buccal of the ridge (r)and too far toward the lingual (l). B, Positions of the mandibular teeth corrected from thoseshown in A.

A B

cepts of occlusion and articulation of a mucosalsupported dentition.

There are several schools of thought on thechoice of occlusal forms of posterior teeth for thethree concepts of occlusion most often selected,namely, (1) bilateral balance, (2) monoplane or

nonanatomical, and (3) lingualized articulations.Anatomical molds usually are selected for bilateralbalanced articulation; however, nonanatomicalteeth can be used in a balanced concept with the useof compensating curves. Nonanatomical or cusp-less teeth are generally the choice for monoplane


Figure 17-16 A, The mean residual ridge, as well as selected anatomical landmarks,provides the guidances used in the buccolingual and anteroposterior positioning of themandibular posterior teeth. B, Centering the wax occlusal rim on the mandibular record basewith the anatomical guides is essential to the appropriate placement of the artificial teeth.The basal seat, or mean residual ridge, and the retromolar pads bilaterally are used todevelop the positioning and height of the wax occlusal rim.

A

B

articulation, although teeth with cusps also can beused. For the lingualized occlusal concept, a com-bination of upper anatomical and lower non-anatomical molds has been introduced by severaltooth manufacturers.

Arranging Anatomical Teeth to a BalancedArticulation

The anterior teeth are set with a minimal verticaloverlap of 0.5 to 1 mm and 1 to 2 mm of horizon-tal overlap to establish a low incisal guidance (seeFigure 17-14). After these requirements are satis-fied, the teeth may be rotated, tipped, overlapped, orspaced to achieve naturalness. In the arrangementof the posterior teeth, most clinicians setthe mandibular teeth before the maxillary becausethis provides better control of the orientation ofthe plane of occlusion both mediolaterally andsuperoinferiorly.

Number of Posterior Teeth Set The decision onthe number of teeth to use will depend on the avail-able space for posterior teeth from the distal of thecanine to the retromolar pad. Placing teeth onthe residual ridge incline as it ascends to the padshould be avoided. If only three teeth are to bearranged, it is more convenient to drop the first pre-molar and place the second premolar and the firstand second molars into the available space.Eliminating the first premolar is a logical choicebecause this tooth has less occlusal surface for themastication of food.

Setting the Mandibular Teeth First The primaryconsideration in positioning the premolars is thatthey follow the form of the residual ridge. The facialsurface of the premolars should be perpendicular tothe occlusal rim, and yet slightly facial to the canine,but never farther facially than the buccal flange.

In the ideal situation, the mandibular first andsecond premolars, with their central grooves, arepositioned on a line from the canine tip to 1 to 2mm below the top of the retromolar pad (Figure 17-17). Before the first premolar is positioned, a smallsection of the mandibular wax occlusal rim isremoved to accommodate the first and second pre-molars. A small cone of soft pink baseplate wax isattached to the neck of the first premolar tooth, and

it is positioned in the arch in contact with thecanine and with its central grooves on the referenceline from the tip of the canine to the retromolarpad. The long axis of the tooth is positioned so thatthe cusp tips are level with the remaining mandibu-lar wax occlusal rim. The second premolar is set ina similar manner. When these lower teeth have beenarranged, a segment of the maxillary occlusal rimis removed to accommodate the first maxillary pre-molar, which is set into maximum intercuspationwith the two lower premolars. If a space developsbetween the maxillary canine and first premolar,the maxillary first premolar is aligned with thecanine, and the maxillary second premolar is posi-tioned in the upper arch. Then the two mandibularpremolars are repositioned to achieve maximumintercuspation with the maxillary premolars. Themandibular first premolar may need to be adjustedmesiodistally to fit into the available space.Reshaping of the tooth by grinding usually willsatisfy the space requirements. Maintenance of theocclusal plane by positioning the mandibular teethat the appropriate height is of paramount impor-tance as is the placement of their central grooves onthe reference line from the tip of the canine to theretromolar pad. The first three premolars set (twomandibular and one maxillary) are the key to therelative anteroposterior intercuspation of all theremaining posterior teeth. Once the premolars areset and properly related to each other, positioningof the remaining mandibular posterior teeth iseasily accomplished.

In the positioning of the mandibular first molar,the central groove is placed on the canine to retro-molar pad reference line. The vertical height of thetooth is adjusted by positioning the cusp tips on theocclusal plane. After these adjustments are com-pleted, the maxillary first molar is articulated withthe mandibular first molar. A small segment of thewax occlusal rim is removed, and the tooth isattached to the record base with a small cone of softbaseplate wax. After the tooth is positioned, it issealed to the record base with molten wax and thehot no. 7 spatula. After the maxillary first molar ispositioned, the articulator is closed so that themandibular tooth will assist in seating the maxil-lary tooth into maximum intercuspation. The indexfinger is used to hold the cervical neck of the max-illary tooth in place while the articulator is closed.


This will develop the desired lingual cusp contactof the maxillary molar in the central fossa of themandibular antagonist. The same procedure is usedfor setting the remaining maxillary teeth. The teethon the opposite side of the dental arches arearranged in a similar manner.

Setting the Maxillary Teeth First In arrangingthe maxillary posterior teeth first, start with themaxillary first premolar and continue the arrange-ment of the teeth through to the second molar.During the positioning of these teeth, the maxillarylingual cusps are aligned with the reference line that

has been scribed on the mandibular wax occlusalrim from the mandibular canine tip to the middle ofthe retromolar pad. Positioning the maxillary teethwith a slight opening of the contact points betweenthese teeth allows the mandibular teeth to betterassume their correct mesiodistal position as they areinterdigitated with the maxillary posterior teeth.Because this intercuspation is very exacting, it isbest done by placing the mandibular first molar inposition first. For the first molar to be placed andstill preserve the reference line on the wax occlusalrim, a block of wax approximately the size of themandibular molar tooth is all that is removed from


1-2 mm

Figure 17-17 A, A point 1 to 2 mm below the top of the retromolar pad and the tip ofthe positioned mandibular cuspid are guides used in the placement of the mandibularposterior teeth. B, The central grooves of the posterior teeth are positioned on a linebetween the cuspid tip and the middle of the retromolar pad. When only three posteriorteeth are arranged, it is essential that the central grooves of the molars be positioned slightlyto the buccal to avoid crowding the tongue.

A B

the mandibular wax occlusal rim. When themandibular first molar is placed in position withoutadjoining teeth, it is possible to determine itscorrect anteroposterior position more easily. If themandibular first premolar is positioned first, theinconstant vertical overlap might crowd the toothinto difficult intercuspation with the maxillaryteeth, and this would be continued throughout allthe mandibular posterior teeth. Therefore placementof the mandibular first premolar is left until last totake up all the variation in vertical and horizontaloverlap of the anterior teeth. The first premolar isthen ground to fit the remaining space.

The second mandibular molar is placed afterthe positioning of the first molar, thereby assuringits anteroposterior correctness. The mandibularsecond premolar is next placed, after another blockof wax has been cut away from the occlusal rim.The mandibular first premolar is the last tooth to beplaced. It frequently needs to be ground because ofthe minimal space remaining between the secondpremolar and the canine after these teeth have beenarranged in maximum intercuspation. For thisreason, the tooth must be ground and shaped to fitthe space available. The teeth on both sides of thedental arches are arranged in a similar manner.

Evaluating Bilateral Balanced Articulation Thepresence of a balanced articulation can be inspectedafter all the maxillary and mandibular teeth havebeen arranged. However, it must be rememberedthat unless the teeth are positioned in exactly thesame location in the articulator as they were whentheir primordial forms were carved in the cuttinginstrument, they will not balance. Furthermore, ifthe end-controlling factors recorded from thepatient and transferred to the instrument are also notthe same as those used in developing the toothmolds, one should not expect a perfect bilateralbalance to be present. With luck, what one will seeduring this exercise is that some minor deflectionsare observed and that some tooth material is avail-able for selective reshaping after processing toachieve the required balanced articulation duringthe various movements. The amount of movementof the articulator in a lateral direction during thisevaluation process should be minimal, usuallybringing the maxillary and mandibular canines intoan end-to-end relation to each other will suffice.

Arranging Nonanatomical MandibularPosterior Teeth to Balanced Articulation

The arrangement of nonanatomical posterior teethwith both anteroposterior and mediolateral com-pensating curves permits the establishment of abalanced articulation. In such arrangements, themandibular teeth usually are arranged first fol-lowed by the maxillary teeth. The contours estab-lished in the wax occlusal rim and the use of theseveral reference lines and guides developed for theanatomical arrangement also are used with thenonanatomical teeth. The major difference is in thepositioning of the mandibular posterior teeth todevelop the compensating curves.

Number of Posterior Teeth Set Most often, thenumber of posterior teeth used in balanced articu-lation with nonanatomical teeth will be limited tothree. It is more convenient to drop the first pre-molar and place the second premolar and the firstand second molars into the available space.Eliminating the first premolar is a logical choicebecause this tooth has less occlusal surface for themastication of food. With the elimination of thefirst premolar and with the use of only three poste-rior teeth, it often is necessary to position the twomolars slightly to the facial.

Anteroposterior Compensating Curve Theanteroposterior compensating curve begins at thedistal marginal ridge of the first posterior replace-ment tooth (which is usually the second premolar)and continues through the second molar (Figure17-18). The amount of curvature developed isdependent on the steepness of the condylar guid-ance, but it rarely requires more than a combined20-degree elevation of the occlusal surfaces of theposterior teeth from the horizontal plane of orien-tation established by the anterior and posteriorreference points. The anteroposterior curve isdeveloped to provide the needed tooth structure forbalancing contacts in the protrusive movement.

Mediolateral Compensating Curve A mediolat-eral compensating curve also is needed to providethe needed tooth structure to achieve balancedarticulation during lateral movements. This curvealso is initiated with the first replacement tooth and


continues through the second molar. The degree towhich the facial cusps are elevated in relation to thelingual cusps to establish this curve will vary withthe condylar and incisal guidances. The curveusually does not exceed 5 to 10 degrees from thehorizontal plane of orientation when viewed in thefrontal plane (Figure 17-19).

First Premolar The position of the first mandibu-lar replacement tooth (second premolar) will be dic-tated by the position of the lower anterior teeth. Thesecond premolar should be positioned immedi-ately next to the canine, with no space allowed todetract from pleasing esthetics. The central fossa ofthe mandibular premolar tooth is aligned with the


Figure 17-18 The anteroposterior compensating curve involves the cuspid tips and theretromolar pads as the anatomical guides. The curve begins with the mesial of the molarpositioned level with the plane of occlusion and the distal surface slightly elevated. Thecurve continues with the placement of the second molar with the distal surface located at orabove the top of the retromolar pad. The extent of the curve rarely exceeds 20 degrees.

Figure 17-19 The mediolateral curve is formed by slightly elevating the buccal cusps ofthe posterior teeth above the lingual cusps. The curve usually does not exceed 10 degreesfrom the horizontal plane.

reference line from the tip of the canine to themiddle of the retromolar pad. The long axis of thetooth is perpendicular to the occlusal plane, and thefacial cusp is slightly elevated above the lingualcusp.

First Molar Position the mandibular first molarnext to the premolar with the mesial marginal ridgeat the same level as the distal marginal ridge of thepremolar and its distal marginal ridge slightly ele-vated. This will position the tooth with its long axisdirected anteriorly. The anteroposterior compensat-ing curve begins with this tooth. The distal of thefirst molar should be elevated approximately 1 mmabove the occlusal plane that was established by theanterior and posterior reference points. The amountof elevation may need to be increased or decreased,depending on the mechanical equivalent recordedfor the horizontal condylar guidance. A high,condylar guidance will require a greater compen-sating curve. The central fossa of the first molarshould be slightly to the facial in relation to the ref-erence line from the canine to the retromolar pad.This will avoid possible crowding of the tongue.When viewed in the frontal plane, the mediolateralcompensating curve, initiated with the setting ofthe premolar, should be maintained by a slight ele-vation of the facial cusp above the lingual cusp.The tooth is sealed with the hot no. 7 spatula andpink wax when its arrangement has been achieved.

Second Molar The mandibular second molar ispositioned with the mesial marginal ridge at thesame level as the distal marginal ridge of the firstmolar. The anteroposterior compensating curve iscontinued posteriorly by elevating the distal of thissecond molar tooth approximately 2 mm above theocclusal plane established by the reference points.The long axis of this tooth also will be anteriorlydirected. The central fossa of the second molaralso will be positioned slightly to the facial of thereference line. The facial cusps of both the first andsecond molars should be in a straight line whenviewed from the occlusal surface. The teeth shouldnot be positioned “around” the remaining residualridge. The mediolateral compensating curve shouldbe continued as viewed in the frontal plane. Whenthe arrangement is completed, the tooth is sealed tothe record base with the hot no. 7 spatula.

Remaining Mandibular Posterior Teeth Themandibular posterior teeth are arranged for theother side of the arch with the same criteria andprocedures as just outlined. As the remaining teethare positioned, they should be evaluated in relationto the teeth on the opposite side of the arch. This isextremely important, especially in trying to main-tain (1) the appropriate level of the occlusal planeand (2) the same degree of anteroposterior andmediolateral compensating curves for both sides ofthe mandibular arch. When all teeth have beenproperly positioned, they are sealed to the recordbase with pink baseplate wax.

Arranging Nonanatomical Maxillary PosteriorTeeth to Balanced Articulation

First Premolar For most patients, only three max-illary posterior teeth will be used. In such instances,only one premolar and two molars are the custom-ary teeth selected. The premolar selected is usuallythe maxillary first premolar because of its longerocclusal cervical height, which provides a moreesthetic arrangement. After some of the waxocclusal rim distal to the canine is removed, thefirst premolar is set. Place a small portion of soft,pink wax on the neck of the maxillary premolar andattach the tooth to the record base. Carefully closethe articulator and establish contact between theocclusal surface of the maxillary tooth and thecentral fossa or marginal ridges of the mandibularantagonist. There should be approximately 1 to 2mm of horizontal overlap of the maxillary facialcusp in relation to the mandibular facial cusp. Thisrelationship will help prevent cheek biting and alsowill contribute to the attainment of a balancedarticulation.

First Molar Position the maxillary first molartooth alongside the premolar, aligning their mar-ginal ridges and facial surfaces. Carefully close thearticulator and establish contact between the max-illary occlusal surface and the central fossa or mar-ginal ridges of the mandibular antagonist. Maintainmaximum contact between the maxillary occlusalsurface with the central fossa of the lower tooth andthe 1 to 2 mm of horizontal overlap of the maxil-lary facial cusp in relation to the mandibular facialcusps. View the tooth-to-tooth relationships from


the lingual by turning the instrument around andlooking through the tongue space. Seal the toothwith pink wax.

Second Molar Position the maxillary secondmolar tooth with a small cone of pink wax. Again,carefully close the articulator and establish thetooth contacts as you did with the first molar. Sealthe tooth to the record base.

Remaining Maxillary Posterior Teeth The max-illary posterior teeth are arranged for the other sideof the arch with the same criteria and procedures aspreviously outlined for maxillary posterior teeth.As the remaining teeth are positioned, they shouldbe evaluated for the required contacts between themaxillary occlusal surfaces and the central fossaeand marginal ridges of the mandibular antagonists.When all teeth have been properly positioned, theyare sealed to the record base with pink wax andevaluated. Bilateral balanced articulation betweenthe maxillary and mandibular teeth will be devel-oped and refined after the dentures are processedwith the selective occlusal reshaping procedures.

Arranging Nonanatomical Teeth toMonoplane Articulation

The technique for arranging cuspless teeth in a flatplane or monoplane occlusal concept is a distinctdeparture from what has been previously described.With this concept of occlusion, there is no attemptto eliminate deflective occlusal contacts in lateralor protrusive excursions. The dentist’s desire toachieve an optimal esthetic result will require somevertical overlap of the anterior teeth. However, thiscan generally be accommodated for with sufficienthorizontal overlap to permit a range of anterior andlateral movements without anterior tooth contacts.Basically, the patient can clench and grind in andaround maximum intercuspation during both func-tional and nonfunctional activities. However, somedeflective occlusal contacts of the posterior teethwill be experienced.

When the nonanatomical teeth are arranged tosatisfy the monoplane occlusal concept, the condy-lar inclinations on the articulator are set at 0degrees. The articulator is reduced to a simplehinge articulator. With the mandibular wax occlu-

sion rim positioned on its cast on the articulator, asmall segment of the rim is removed from the pos-terior tooth area. The maxillary posterior teeth arepositioned one at a time with the mandibular waxocclusal rim and its references and guides for toothplacement. The maxillary teeth are positioned toocclude with the flat surface of the mandibular waxocclusion rim and to approximate the position ofthe maxillary occlusion rim contour that was previ-ously determined. There should be approximately 1to 2 mm of horizontal overlap of the maxillaryfacial cusp in relation to the mandibular waxocclusal rim. When completed, the occlusal sur-faces of the maxillary posterior teeth should be flatagainst the mandibular wax occlusal rim.

The mandibular teeth are arranged so they willmaximally contact the upper teeth. A segment ofthe mandibular wax occlusal rim is removed toaccommodate each tooth. Each tooth, in turn, isplaced with a small cone of wax, and the articula-tor is closed while the wax is still warm. The toothis arranged in maximum contact with the flatlingual cusp of the maxillary tooth contacting thecentral groove area of the flat mandibular posteriortooth. The anteroposterior relation of the upper andlower teeth is not critical because of the absence ofcusps. Any combination of premolars or molars canbe used to fill the available space. The posteriorlimit of the extent of these teeth is the point atwhich the mandibular ridge begins to curve upwardtoward the retromolar pad.

Arranging Mandibular Posterior Teeth toLingualized Articulation

Lingualized articulation has been advocated bymany practitioners over the past 70 years, and inmost instances these clinicians have done so witha variety of tooth molds. However, what has beenlacking for the practitioner are tooth molds designedspecifically for this concept. Myerson LingualizedIntegration (MLI) molds represent an occlusalscheme designed for this concept. It has been sug-gested that these molds will provide maximumintercuspation, an absence of deflective occlusalcontacts, adequate cusp height for selective occlu-sal reshaping, and a natural and pleasing appearance.

The MLI teeth are available in two poste-rior tooth molds: (1) controlled contact (CC) and


(2) maximum contact (MC) molds. The primarydifference in the two molds is the maxillary poste-rior teeth. The mandibular teeth are the same forboth molds. The mandibular teeth were designedwith lower cusp heights and multiple occlusal spill-ways to assist in mastication. The selection of oneor the other mold (CC or MC) is dependent on thepatient’s ability to consistently reproduce theircentric jaw relation position. Judgments regardingthis capability are generally made during severalappointments before and after the maxillomandibu-lar record appointment. For those patients in whomuncertainty exists in the registration and repro-ducibility of the centric jaw relation position, theCC mold is suggested because it provides forgreater freedom of movement around maximumintercuspation. For those patients in whom musclecontrol is not a problem and jaw relation recordsare easily repeated, the MC mold may be the toothselection of choice.

In the MC mold, the maxillary teeth are moreanatomical in appearance with greater cusp heights.This form demands some minor reshaping andrefinement of the occlusal fossae and marginalridges of the mandibular teeth during the arrange-ment of the teeth to accept the lingual cusps of themaxillary teeth. With the MC mold, a more exactingocclusion can be attained in maximum intercuspa-tion, and bilateral balanced articulation can bedeveloped over a greater range of movement bothanteroposteriorly and mediolaterally. Lingualizedintegration is based on the maxillary lingual cuspfunctioning as the main supporting cusp in harmonywith the occlusal surfaces of the lower teeth. Fromthe position of maximum intercuspation, the maxil-lary lingual cusps glide over the opposing teeth withan absence of deflection during nonrestrictivelateral and protrusive movements.

The maxillary cusp heights in the CC moldare lower and permit greater flexibility aroundmaximum intercuspation. The tooth contacts ineccentric positions remain as bilateral balancedarticulation, even though the range of contact isless because of the reduced height to the maxillarylingual cusps. However, a greater range of contactis probably not necessary for most edentulouspatients, and the bilateral balanced articulationachieved with the CC mold is very acceptable.

A natural appearance to the “buccal corridor” isprovided by both MLI molds. The facial surfacesand cusps for the maxillary tooth forms provide theillusion of naturalness because of their anatomicalform.

In the arrangement of the teeth for lingualizedarticulation, the mandibular teeth are set first toestablish the occlusal plane. The MLI tooth schemecalls for anteroposterior and mediolateral compen-sating curves arranged in the mandibular arch,thereby permitting balanced articulation betweenthe maxillary lingual cusps and the mandibularteeth during various jaw movements. The supero-inferior position of the mandibular teeth in rela-tion to the tongue and the medial roll of thebuccinator muscle is again an important considera-tion during the arrangement of the teeth. The medi-olateral positioning of the mandibular teeth inrelation to the tongue and cheek interactions also isconsidered.

Number of Posterior Teeth Set The decision onthe number of teeth to use with lingualized articu-lation will depend on the available space for poste-rior teeth. Most often, the number of posterior teethwill be limited to three. The second premolar, withits wider occlusal surface, and the first and secondmolars are the teeth most often selected for thearrangement.

Anterior and Posterior Reference Points Theanterior references that assist in tooth positioningare the same as those described earlier. A line drawnbetween the anterior and posterior reference pointswill establish the plane of occlusion and serve as thestarting point for the setting of the teeth.

Buccolingual Positioning of the Teeth A linethat extends from the tip of the canine to the middleof the retromolar pad will help in determining thebuccolingual positioning of the teeth. Eliminating apremolar in the tooth arrangement places the firstmolar in a more anterior position. The wider firstmolar in the anterior position will crowd the tongueif it is not positioned properly. Both the first andsecond molars should be positioned slightly to thefacial of the reference line to increase the spaceavailable to the tongue.


Anteroposterior Compensating Curve Theanteroposterior compensating curve begins withthe distal marginal ridge of the first premolar toothand continues through the last replacement tooth orthe second molar. The amount of curvature isdependent on the condylar guidance mechanicalequivalent established by the protrusive interoc-clusal record. Only rarely will the condylar guid-ance be more than 30 degrees if the maxillary casthas been mounted with a face bow. Obviously, thethird point of reference used with the face bow willinfluence the mounting. It is recommended that thebite fork, positioned parallel to the mean residualridge of the maxillary arch, be used as the thirdpoint of reference. The anteroposterior curve isestablished to permit a balanced articulation alongthe protrusive pathway.

Mediolateral Compensating Curve A mediolat-eral compensating curve is established to providebalanced articulation during lateral movements.The curve is initiated with the first replacementtooth (second premolar) in the mandibular arch andcontinues through the second molar. This curve iscreated by positioning the facial cusp slightlyabove the lingual cusp. A mediolateral compensat-ing curve usually will not exceed 5 to 10 degreesfrom the horizontal plane of occlusion as viewed inthe frontal plane.

Premolar The first premolar tooth is positionedin contact with the canine and with its long axisperpendicular to the occlusal plane. The occlusalsurface is positioned on the occlusal plane;however, the facial cusp is elevated slightly abovethe lingual cusp to establish the mediolateral com-pensating curve. The second premolar is eliminatedfrom the arrangement.

First Molar The mesial marginal ridge of the firstmolar is placed in contact with the distal margin ofthe premolar. The distal marginal ridge of this toothis elevated slightly above the mesial marginal ridgeto create the anteroposterior compensating curve.The mediolateral compensating curve is main-tained by elevating the facial cusp of the molarslightly above the lingual cusp. The central fossa ofthe first molar is positioned slightly to the facial of

the reference line connecting the canine with themiddle of the retromolar pad.

Second Molar The mesial marginal ridge of thesecond molar is placed level with the distal ofthe first molar, and the anteroposterior compensat-ing curve is continued by elevating the distal mar-ginal ridge of this tooth. In general, the distal of thesecond molar will be at the height of the top ofthe retromolar pad. The central fossa of the secondmolar is positioned to the facial of the buccolingualreference line and in a straight line with the firstmolar. The mediolateral compensating curve iscontinued by elevating the facial cusps above thelingual cusps.

Remaining Mandibular Posterior Teeth Themandibular posterior teeth are arranged for theother side of the arch with the same criteria andprocedures, as previously outlined. As the remain-ing teeth are positioned, it is extremely important tomaintain (1) the appropriate level of the occlusalplane and (2) the same degree of anteroposteriorand mediolateral compensating curves for bothsides of the mandibular arch.

Arranging Maxillary Posterior Teeth toLingualized Articulation

Premolar The first tooth arranged in the maxil-lary arch is the first premolar. This tooth is selectedbecause of its cusp tip to cervical margin height.A longer tooth will provide a more esthetic expres-sion of naturalness along the buccal corridor. Thetooth is positioned in contact with the canine andwith its long axis perpendicular to the occlusalplane. The lingual cusp is positioned to contact themarginal ridge or occlusal fossa of its mandibularantagonist. No attempt is made at this time tobalance the facial or lingual cusps in lateral or pro-trusive movements. Maximum interdigitation ofthe lingual cusp against the occlusal surface of themandibular tooth is the primary consideration.

First Molar The mesial marginal ridge of the firstmolar is placed in contact with the distal margin ofthe premolar. The lingual cusp is positioned in thecentral fossa of the mandibular tooth, and


maximum interdigitation is assured. Often, a ClassI molar relationship will not be present. Such arelationship is not necessary, and positioning of theteeth to establish such a relationship is discour-aged. Integration of the lingual cusps with the mar-ginal ridge or fossa of the mandibular antagonist isthe primary consideration. Position of the toothemphasizing maximum intercuspation will con-tinue the mediolateral compensating curve estab-lished in the arrangement of the mandibular teeth.

Second Molar The mesial marginal ridge of thesecond molar is placed level with the distal ofthe first molar. The anteroposterior compensatingcurve is continued when the tooth is closed intocontact with the mandibular tooth. Again,maximum intercuspation is essential, as is the main-tenance of the mediolateral compensating curve.

Arranging the Maximum Contact Mold In thearrangement of the MC mold, the maxillary teeth arepositioned with the incisal pin slightly open whenthe lingual cusps are in contact with their mandibu-lar antagonists. The prominence of the maxillarylingual cusps will require some occlusal reshapingof the central fossae and marginal ridges of the lowerteeth to establish maximum intercuspation. Aftereach maxillary tooth is positioned, a thin sheet ofarticulating paper is interposed between the toothand its mandibular antagonist. The articulator isclosed, marking the first contact point. The contactpoint on the occlusal surface of the mandibular toothis enlarged by grinding with a round bur to permitthe lingual cusp to obtain positive seating with thelower tooth. This process is continued until maxi-mum interdigitation is achieved and the incisal pin isin contact with the incisal table.

Remaining Maxillary Posterior Teeth Theremaining maxillary posterior teeth are arrangedfor the other side of the arch with the same criteriaand procedures, as previously outlined.

OCCLUSAL MODIFICATIONS AND THESELECTIVE RESHAPING PROCESS

Processing changes, coupled with the lack ofocclusal balance before processing, requires a

remount procedure to correct occlusal discrepan-cies and to obtain a balanced articulation. Theocclusal reshaping procedures usually are per-formed at the denture delivery appointment.

Establishing Maximum Intercuspation

It is much easier to develop maximum intercuspa-tion at the centric jaw relation position when theprostheses are on the articulator. Once maximumintercuspation is achieved, balanced articulation inthe several eccentric movements may be attained inthe mouth.

After the clinical remount of the maxillary andmandibular complete dentures, small strips ofarticulating paper are placed on the occlusal sur-faces of the mandibular teeth. With the articulatorlocked in the hinged position, all occlusal prematu-rities are marked. Using a Brasseler carbide trim-ming and finishing bur no. 7010, remove toothstructure in all areas of contact except the maxil-lary lingual cusps. Premature contacts most oftenare at the central fossae or marginal ridges of thelower teeth and on the lingual inclines of the max-illary facial cusps. Continue marking the contactsand reshaping the teeth until all lingual cusps in themaxillary posterior teeth demonstrate maximumintercuspation with their mandibular antagonists(Figure 17-20). Remember this procedure is onethat establishes the maxillary lingual cusp as themain supporting cusp in the occlusal contactpattern. The dentures are returned to the oral envi-ronment after the occlusal reshaping procedures toverify that maximum intercuspation has beenachieved at centric jaw relation position (Figure17-21).

Adjusting the Working and BalancingContacts

Working side interferences will result from contactbetween the lingual inclines of the maxillary facialcusps and the facial inclines of the facial cusp of themandibular tooth in lateral excursions. Balancingside interferences will occur between the lingualcusps of the maxillary teeth as they move across thelingual inclines of the facial cusps of the mandibu-lar teeth in lateral excursions. Balancing contactsare the direct result of the compensating curves


being out of harmony with the lingual cusps, andthe refinement of the occlusal contacts between themaxillary lingual cusp and the occlusal surface ofthe mandibular teeth is required.

The development of a harmonious working andbalancing occlusion will require the judicious

reduction of heavy working side contacts. Theseheavy working contacts are created during the adjust-ment of maximum intercuspation when the prema-ture contacts were eliminated. After the workingand balancing contacts are marked, careful selec-tive grinding procedures are performed. Adjusting


Figure 17-20 The lingual cusps of the maxillary posterior teeth are the main supportingcusps that interdigitate with the central fossae and marginal ridges of the mandibularposterior teeth.

Figure 17-21 Maximum intercuspation as viewed from the buccal.

the working and balancing contacts is a clinicalprocedure to be completed after the complete den-tures are positioned over their residual ridges. Witharticulating paper positioned between the posteriorteeth bilaterally, carefully guide the patient into alateral movement. The extent of the movement willbe approximately 2 to 3 mm in the molar region.Working interferences will appear as markings onthe lingual inclines of the facial cusps of the max-illary teeth as they pass over the facial inclines ofthe mandibular facial cusps. Occlusal reshapingprocedures with the use of the Brasseler carbidetrimming and finishing bur no. 7010 are completedby gently grinding the lingual inclines of the max-illary facial cusp that demonstrate interferences.

Balancing interferences and maximum inter-cuspation contacts may occur very near to eachother on the occlusal surfaces of the mandibularteeth. The maximum intercuspation stop is gener-ally in the central portion of the tooth, whereas bal-ancing contacts begin in the same area and move ina distal facial direction onto the lingual inclines ofthe mandibular facial cusps. The width of the bal-ancing contact markings may be very small, andcare must be used in reducing balancing interfer-ences. If the balancing contact must be reduced, itwill be only the facial portion of the mandibular

marking that is altered. Selective grinding of theentire contact area will result in the loss ofmaximum intercuspation. The selective occlusalreshaping procedures should be continued until asmooth, free-gliding movement is observed(Figures 17-22 and 17-23).

Adjusting the Protrusive Contacts

Protrusive contacts result from the maxillarylingual cusps gliding over the distal lingual “cusp”of the mandibular tooth in a straight protru-sive movement (Figure 17-24). Should deflectiveprotrusive contacts be observed, as evidencedby heavy occlusal markings, their refinement willbe necessary. Position articulating paper between theposterior teeth bilaterally and guide the mandibleinto a protrusive movement from maximum inter-cuspation. Premature protrusive contacts also mayappear between the lingual inclines of the maxil-lary facial cusps and the facial inclines of themandibular facial cusps during this movement.Such contacts may be eliminated by grinding onthe mandibular facial cusp with the Brasseler bur.When heavy maxillary facial cusp contacts occur,their removal or the modification of the opposingdeflective contacts on the mandibular teeth must be


Figure 17-22 Right working movement demonstrates the occlusal contacts between themaxillary buccal cusps and the mandibular posterior teeth during this lateral movement.

accomplished without disturbing any of the con-tacts required in the other movements.

When the anterior teeth are brought intocontact in a protrusive movement, it is desirableto have the posterior teeth contact bilaterally to

prevent tilting and dislodgment of the dentures. Ifthe anterior teeth contact prematurely in the protru-sive movement, the anterior mandibular teeth arethe teeth usually modified, keeping the esthetics ofthe dentures in mind.


Figure 17-23 During the right lateral movement, the maxillary lingual cusps contact thelingual inclines of the mandibular buccal cusps to create a balanced articulation.

Figure 17-24 During the protrusive movement, a balanced articulation is achieved bycontact between the maxillary buccal cusps of the posterior teeth and the buccal cusps oftheir mandibular antagonists.

With the occlusal reshaping procedures accom-plished for maximum intercuspation and working,balancing, and protrusive movements, the occlu-sion is examined for holding contacts in centric jawrelation position. The occlusion also is examinedfor an absence of deflective occlusal contactsduring all of these mandibular movements.

SUMMARY OF TOOTH SELECTION ANDARRANGEMENTTreatment of edentulous patients is enjoyable whenone has empathy, listening skills, and an apprecia-tion of dental esthetics. Impressions and recordingsof healthy tissues need to be made and accuratelytransferred to an articulator. Teeth should be posi-tioned in harmony with intraoral and circumoralmuscle activity and adjusted so that they occludeand articulate evenly. Several different prosthetictooth molds have been produced, and each hassome purported advantages. In the absence of aclear advantage, dentists should use tooth moldsthat are esthetically pleasing and have a simple pro-cedure for setup.

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C H A P T E R 18The Try-in AppointmentCharles L. Bolender

329

SECTION I: PERFECTION AND VERIFICATION OF JAW RELATION RECORDS

The vertical dimension and centric relation (CR) ofedentulous jaws are tentatively established with theocclusion rims, as described in Chapter 16. Afterthe preliminary arrangement of the artificial teethon the occlusion rims, it is essential that the accu-racy of the jaw relation records made with theocclusion rims be tested, perfected if incorrect, andthen verified to be correct. The dentist must assumethat the preliminary jaw relation records wereincorrect until they can be proven correct. Thismental attitude of the dentist—attempting to provethat the jaw relation records are wrong—is essen-tial in perfecting and verifying jaw relation records.

Patients should be advised to leave existingdentures out of the mouth for a minimum of 24hours before the jaw relation records are perfectedand verified at the time of the try-in appointment.Unfortunately, most patients will find this to be anunreasonable request. An acceptable alternative isto have the existing dentures relined with a softtemporary material. Whichever approach is taken,the soft tissues of the basal seat will be rested andin the same form as they were when the finalimpressions were made. If this procedure is not fol-lowed, the distorted condition of the soft tissue canprevent the registration of accurate interocclusalrecords.

It is almost impossible to overemphasize theimportance of perfection and verification of jawrelation records. The appearance and comfort ofthe patient, occlusion of the teeth, and health of thesupporting tissues are all directly related to theaccuracy of jaw relation records.

VERIFYING THE VERTICAL DIMENSIONThe maxillary and mandibular trial dentures areplaced in the patient’s mouth. The patient isinstructed to close lightly so the maxillary labialfrenum can be checked to see that it is absolutelyfree. This is necessary before the relation of the lipto the teeth can be observed. If the denture bordercauses binding of the frenum, the labial notchshould be deepened.

Next, a tentative observation of the centricocclusion (CO) is made. The mandible is guidedinto CR by a thumb placed directly on the anteroin-ferior portion of the chin with patient instructions to“open and close until you feel the first feather touchof your back teeth.” At first contact, the patientopens and repeats this closure, only this time stop-ping the instant a tooth touch is felt and then clos-ing tight. The procedure will reveal errors in CR bythe touch and slide of teeth on each other. Errors inCR can interfere with tests for vertical relations.

The vertical dimensions of occlusion and ofrest must now be given careful considerationbecause the final positions of the anterior and pos-terior teeth will depend to a great extent on theamount of space that is available vertically.Unfortunately, there is no precise scientific methodof determining the correct occlusal vertical dimen-sion. The acceptability of the dentures’ verticalrelations depends on the experience and judgmentof the dentist. Nevertheless, the factors that governfinal determination of this relation can be said tohang on careful consideration of the following:

1. Preextraction records2. The amount of interocclusal distance to which

the patient was accustomed, either before theloss of natural teeth or with old dentures

3. Phonetics and esthetics4. The amount of interocclusal distance

between the teeth when the mandible is in itsrest position

5. A study of facial dimensions and facialexpression

6. Lip length in relation to the teeth7. The interarch distance and parallelism of the

ridges as observed from the mounted casts8. The condition and amount of shrinkage of

the ridges

A combination of these factors and considera-tions may be used to aid in determining an accept-able vertical dimension.

VERIFYING CENTRIC RELATIONAfter the vertical dimension has been determined,CR is verified. This can be done by intraoral obser-vation of intercuspation or by an extraoral methodon the articulator.

Intraoral Observation of Intercuspation

The test for accuracy of the preliminary CR recordinvolves the observation of intercuspation when themandible is pulled back by the patient as far as itwill go and closure is stopped at the first tooth con-tact. The patient is guided into CR by a thumbplaced on the anteroinferior portion of the chin andthe index fingers bilaterally on the buccal flangesof the lower trial denture (Figure 18-1). With theindex fingers, the dentist checks that the lower trialdenture is seated in an inferoanterior direction. Thepatient pulls his lower jaw back as far as it will goand closes just until the back teeth make a “feathertouch.” As tooth contact approaches, the dentist’sindex fingers should rise off the buccal flanges.Pressure on the buccal flanges, or stretching the lipwith the index fingers, will create the risk of poste-riorly displacing the lower trial denture. Then thepatient closes tightly. Any error in CR will beapparent when the teeth slide over each other, espe-cially if anatomical teeth are used (Figure 18-2).A second closure made with the same instructions


Figure 18-1 A, Hand and finger positions for checking the accuracy of centric relationrecords. B, As tooth contact approaches, the index fingers are raised off the buccal flanges toavoid displacement of the lower denture.

A B

and a stop at first tooth contact will permit visualobservation of any error.

Errors in the mounting may prevent intercuspa-tion of some teeth when the first contact is made. Ifthe patient stops the closure at the instant the firstteeth touch, an error will be indicated by the spacebetween the lower tooth or teeth and the teeth theywere supposed to touch. The amount of errorobserved in this manner will be magnified by theeffect of the inclined plane contacts. All the teeththat occluded uniformly on the articulator musthave equally uniform contacts in the mouth; if theydo not, the touch and slide observation will provethe mounting incorrect.

Once it is determined that the mounting is incor-rect, a preliminary observation of esthetics is made.If the anterior teeth are not placed to support the lipproperly, their positions are corrected. Then verticaloverlap of the anterior teeth is carefully noted. Thisis important because the amount of vertical overlapwill be a guide to the amount of closure permittedwhen the next interocclusal record is made.

Because complete dentures rest on movablesoft tissues, it is difficult to detect anything otherthan gross occlusal errors by visual observation ofthe occlusion. As a result, one should not rely onvisualization for the final determination of castmounting accuracy.

The posterior teeth are removed from the lowerocclusion rim, and both occlusion rims are placedin the mouth. Impression plaster (or an interoc-clusal registration paste), is mixed, and with thehands in the same position as for testing the previ-

ous record, the selected recording medium is placedon both sides of the lower occlusion rim in themolar and premolar regions. This may be done witha narrow plaster or cement spatula. Then the patientis instructed to pull the lower jaw back and closeslowly until requested to stop and hold that position.The closure is stopped when the anterior teeth havethe same vertical overlap as they had before the pos-terior teeth were removed. Thus the vertical relationof the two jaws will not have changed. When theplaster or registration paste is set, the new record isremoved with the two occlusion rims, and the lowercast is remounted on the articulator.

In an alternate technique an abbreviatedbeeswax occlusion rim is used to replace theremoved posterior teeth. (The rim may replace allthe posterior teeth, or else a “tripod” of beeswaxstops can be used [Figure 18-3].) The patient is

Chapter 18 The Try-in Appointment 331

Figure 18-2 An error in centric occlusion (CO) thatis due to an error in centric relation mounting willproduce contact of the inclined planes of the cusps(B). Further closure will allow the teeth to slide into CO (A). The path of closure is an arc (C) about the posteriorterminal hinge axis.

Figure 18-3 A modified beeswax interocclusalrecord of centric relation (CR) is made to correct anerror in the preliminary mounting of casts. The lowerposterior teeth are removed so there will be no contactbetween upper and lower trial dentures. The verticaloverlap of anterior teeth is a guide to the verticaldimension at which CR will be recorded. Arrowsindicate the beeswax tripod of stops.

guided into the most retruded mandibular positionat the selected vertical dimension when the upperposterior teeth will indent the softened opposingwax rims. The lower cast is remounted on thearticulator, and the lower posterior teeth are resetin CO.

The occlusion rims, with the teeth in goodtight CO, are returned to the mouth, and the sametests are made as before. If the teeth occludeperfectly and uniformly when the lower jaw isdrawn back as far as it will go, the CR mountingmay be assumed to be correct. There should be uni-form simultaneous contact on both sides of themouth, in the front and back and without anydetectable touch and slide.

It is essential with this procedure that thedentist tries to find an error in the previousrecord. The record must be assumed to be incor-rect unless no touch and slide can be detected.The entire procedure is repeated until all doubt asto the correctness of the relationship of the casts isgone.

Extraoral Articulator Method

CR can be checked or verified by an extraoralmethod in which observations are made on thearticulator rather than in the mouth. The techniqueis easy and thus attractive, but its use depends ontaking one or two liberties. A CR registration insoft wax is placed between the opposing teeth.The teeth do not contact through the wax; thus therecord is made at a slightly increased verticaldimension. Although clinical experience endorsesthis technique, a purist might argue that such veri-fication is likely to work correctly only if a kine-matic hinge axis, rather than an arbitrary face bowrecording, is used originally. Because conclusiveresearch to support such an argument is absentand because extensive clinical application of thetechnique has led to predictable and reproducibleresults, it deserves description.

Remember: The purpose of the extraoralmethod is to determine whether the positionof the teeth on the articulator (Figure 18-4) isthe same as that in the patient’s mouth (Figure 18-5). As mentioned previously, it is difficultto detect occlusal errors by clinical observation,so wax, plaster, or a bite registration paste must


Figure 18-4 Artificial teeth positioned on aDentatus ARH articulator.

Figure 18-5 The same trial dentures as shown inFigure 18-4 being evaluated for proper occlusion.Clinical observation of tooth contacts is not as accurateas the extraoral method.

be used as the recording medium in thistechnique.

Impression material (e.g., two pieces ofAluwax) is placed over the posterior mandibularteeth (Figure 18-6). A thickness is chosen that willeliminate the danger of making contact with theopposing teeth when biting pressure is exerted. Nowax is placed on the anterior teeth because anteriortooth contact tends to cause the patient to protrudehis lower jaw. The teeth must be completely dryand the wax pressed firmly on the teeth to elimi-

nate voids between it and the teeth. The two thick-nesses of wax are sealed with a warm spatula(Figure 18-7). The chilled upper trial denture isplaced in the patient’s mouth. Next, just the waxportion is immersed in a water bath of 130° F(54° C) for 30 seconds (Figure 18-8). Both the tem-perature and the time are critical in achieving a uni-formly softened wax. (Aluwax retains heat longerthan baseplate wax, which provides more workingtime for the next step.)

The mandibular trial denture is seated with theindex fingers bilaterally positioned on the buccalflanges. The mandible is guided into CR by a thumbon the anteroinferior portion of the chin to directsome guidance toward the condyles. The thumbmust be on the point of the chin, not under it; thepatient is guided in a hinge movement, closinglightly into the wax (Figure 18-9). As contact withthe wax approaches, the index fingers are raisedfrom the buccal flanges. The patient then closesinto the wax until a good index is made (Figure18-10). Care must be taken that the patient does notpenetrate the wax and make tooth contact. If onemethod of suggested retrusion does not work,another may. In any case, a minimum amount ofocclusal pressure should be exerted on the wax.

The lower trial denture is then carefullyremoved from the mouth and placed in ice water tochill the wax thoroughly (Figure 18-11). Next, thetrial dentures are removed from the ice water and


Figure 18-6 A second layer of warmed Aluwax isapplied to the first layer, which has been carefullyadapted to the posterior teeth.

Figure 18-7 The two layers of Aluwax are sealedwith a warm spatula.

Figure 18-8 Only the Aluwax is immersed in 130° F(54° C) water for 30 seconds.

dried. It is important that the imprint of the oppos-ing teeth be crisp and about 1 mm deep, with nopenetration of the wax by a maxillary tooth (Figure18-12). If penetration occurs, it will likely deflectthe occlusal contact as well as shift the bases orchange the maxillomandibular relation horizontallyand vertically. The chilled dentures are returned tothe patient’s mouth, and the patient is guided intoCR. The record is acceptable if there is no tilting ortorquing of the trial dentures from initial contact to

complete closure (Figure 18-13). Underlying softtissue displacement may cause a slight movementof the bases and must be taken into account whenevaluating the contact. If the record is unaccept-able, the procedure must be repeated.

After the wax has been chilled, the trial den-tures are placed on their casts, and the locked artic-ulator is closed in CR; the opposing teeth should fitinto the indentations in every way (anteriorly, pos-teriorly, laterally, and vertically) (Figure 18-14).When the original CR interocclusal record and thecheck are both correct, these teeth will fit into theindentations surprisingly well.


Figure 18-11 The lower trial denture andattached Aluwax are chilled in ice water for severalminutes.

Figure 18-12 The occlusal record should beapproximately 1-mm deep and free of any penetrationby the underlying teeth.

Figure 18-10 The patient is instructed to closelightly into the softened wax. The index fingers shouldbe slightly raised from the buccal flanges at this point.

Figure 18-9 The mandible is guided into centricrelation with the thumb on the anteroinferior portionof the chin and the index fingers seating the lower trialdenture in a downward and forward direction.


Figure 18-13 Checking the accuracy of the interocclusal wax record clinically.

A B

C DFigure 18-14 With the condylar mechanisms locked in a centric position (A and B), theupper teeth should fit accurately into the wax index (C and D). When this occurs, it meansthat the original recording was correct.

If the opposing teeth do not fit exactly into theindentations in the new record, it means that theoriginal mounting was incorrect or that the patientdid not bite cleanly into the interocclusal wax. Toevaluate this, the dentist must return the chilledtrial dentures and wax record to the mouth andreevaluate their accuracy, as previously described.If the record still appears to be correct in thepatient’s mouth, then the original CR registration,mounting, or both were incorrect. In these cases,the mandibular cast must be separated from themounting ring and the cast remounted by means ofthe last interocclusal wax record. The new mount-ing is again checked to prove or disprove itscorrectness.

If the initial registration (preliminary CRrecord) was made in plaster or a bite registra-tion paste, the same recording medium shouldbe used to verify the accuracy of the mounting onthe articulator. Likewise, if wax was used, waxshould be the verifying medium. However, it iseasier to distort wax when the record is removedfrom the mouth and tested on the articulator(Figure 18-15).

SECTION II: ECCENTRIC JAW RELATION RECORDS, ARTICULATOR AND CAST ADJUSTMENT, ESTABLISHMENT OF THE POSTERIOR PALATAL SEAL

When the final occlusion is developed and cor-rected on the articulator, it is essential that themovements of the articulator simulate mandibularpositions or movements of the patient within therange of normal functional contacts of teeth. Thusthe condylar elements of the articulator must beadjusted so that they approximate the condylar-guiding factors within the temporomandibularjoints (TMJs). These adjustments of the condylarelements of the articulator are made by means ofinterocclusal eccentric records.

PROTRUSIVE AND LATERAL RELATIONSThere seems to be confusion in the minds of manydentists as to what a protrusive registration isintended to attain. The idea that the angle and lines


Figure 18-15 A plaster interocclusal centric relation (CR) record is used to test the accu-racy of preliminary mounting on the articulator. The location of the condylar sphere in con-tact with the posterior, lateral, and superior elements of the condylar housing indicates thatthe preliminary record and test record are clinically identical. Thus the casts on the articula-tor are assumed to be in CR.

of the bony fossa completely govern the path of thecondyle is erroneous. A study of the anatomy andfunction of the joint reveals that the condylar pathis governed partly in its shape and function by themeniscus. The meniscus is attached in part to thelateral pterygoid and moves forward during open-ing and lateral mandibular movements. The path iscontrolled further by the shape of the fossa, theattachments of the ligaments, the biting load duringmovement (muscular influence), and the amount ofprotrusion. Variation in registrations can be causedby several factors. The registration may varyaccording to the biting pressure exerted after themandible has been protruded. The condyle, notbeing locked on a path, is subject to change in itspath with a variation of pressure. Undoubtedly,there is some leeway for adaptability to conform tothe changing conditions of the teeth. Many parts ofthe body are phenomenal in their ability to adapt tounusual conditions, and the TMJ is one of them.Not many complete dentures could be worn if thiswere not true. However, registration of a normalcomfortable movement of the condyle in its path,with subsequent harmonious eccentric occlusionand CO to conform to this, greatly augments last-ing function of dentures. Therefore there does notseem to be much excuse for failure to register thispath because it is not difficult or time-consumingin proportion to the results obtained.

CONTROLLING FACTORS OF MOVEMENTEdentulous patients bring only one controlling fac-tor to the movement of the mandible, a fact thatseems to be misunderstood generally. The miscon-ception exists because many dentists think thecondyle paths control the movement of the mandibleentirely. In the laws of articulation, the incisal guid-ance provided by the anterior teeth is an importantpart of the control. This guidance is always decidedby the dentist, consciously or not. With semiad-justable articulators like the Dentatus, Hanau, andWhip Mix, incisal guidance is controlled by theinclination of the incisal guidance mechanism,which is determined by the horizontal and verticaloverlap of the anterior teeth. The incisal guidance ismore influential in controlling movements of themandible than the condylar paths are because the

condylar paths are farther away from the cuspinclines, which both the incisal angle and thecondyle angle influence.

ECCENTRIC RELATION RECORDSA previous chapter underscored the fact that eccen-tric relation records are rarely used in the fabrica-tion of complete dentures. They are referred to inthis chapter mainly for historical purposes. Theirconsideration also provides interesting insights intothe complexity of mechanical simulation of jawmovement. Skipping over this section is certainlyan option for the reader.

The path of the condyle in protrusive and lat-eral movements is not on a straight line. The shapeof the mandibular fossa is an ogee curve as viewedin the sagittal plane. This double curve will causethe apparent path of the condyle to be differentwith varying amounts of mandibular protrusion.The ideal amount of protrusion for making therecord is the exact equivalent of the amount of pro-trusion necessary to bring the anterior teeth end toend. However, the mechanical limitations of mostarticulators require a protrusive movement of atleast 6 mm so the condylar guidance mechanismscan be adjusted.

Methods of registering the condyle path may beclassified as intraoral and extraoral. Extraoralmethods are generally exemplified by the Gysi andMcCollum techniques. The intraoral methods maybe listed as (1) plaster and carborundum grind-in,(2) chew-in by teeth opposing wax, (3) chew-in mod-ified by a central bearing point, (4) Needles’s stylusescutting a compound rim, (5) Needles’s techniquemodified by a Messerman tracer, (6) protrusive reg-istration in softened compound, (7) protrusiveregistration in plaster, and (8) protrusive registra-tion in softened wax.

Lateral and protrusive condylar inclinationsmay be registered when straight protrusive move-ments are made. Many dentists consider these short-range lateral movements sufficiently indicative forpractical purposes. However, for a complete regis-tration, lateral records are necessary to indicate thelimit of the range of movement, as shown by theGothic arch (needle point) tracings.

Wax interocclusal records may be made on theocclusion rims before the teeth are set up or on


the posterior teeth at the try-in appointment.Records made on occlusion rims must be consid-ered tentative because the vertical and horizontaloverlaps of the anterior teeth have not as yet beendetermined and the exact amount of protrusion andthe level at which the anterior teeth are to contactare still unknown. These preliminary records per-mit tentative adjustment of the condylar guidanceson the articulator.

Plaster interocclusal records are made after theanterior teeth have been arranged for esthetics andafter both CR and the vertical dimension have beenverified. If the horizontal overlap is sufficient toobtain enough protrusive movement of the lowerjaw that the articulator can be adjusted, this recordwill be adequate. It also will be an accurate recordof the relation of the jaws during incision. If thehorizontal overlap of the incisors is too small topermit sufficient mandibular movement for adjust-ment of the condylar guidance, the patient must beinstructed to protrude the jaw farther when therecord is made. The minimum amount of protru-sion for condylar guidance adjustment is 6 mm.This limitation is necessary because of mechanicaldeficiencies of most articulating instruments.

Lateral interocclusal records can be made to setthe condylar inclination and the mandibular lateraltranslation on the articulator. However, with com-plete dentures, it is more difficult to secure accu-rate and reproducible lateral records thanprotrusive records, in part because of the displace-ability of the ridge mucosa. In addition, most semi-adjustable articulators are not able to accept manylateral eccentric records. It is therefore generallyaccepted that making lateral interocclusal recordsfor patients with complete dentures is not practicaland probably not warranted.

Eccentric interocclusal records may be madewith the guidance of extraoral tracings. While thetracing device is still attached to the occlusionrims, the amount of protrusive movement is deter-mined by observation of the distance between theapex of the tracing and the needle point. Theamount and direction of the lateral movement canbe determined by observing the distance of the nee-dle point from the apex of the tracing while theneedle is on one of the arcs of the tracing. Whenthe needle point is 6 mm from the apex, themandible in the first molar region will be approxi-

mately 3 mm lateral to its position in CR. Themolar tooth will have moved laterally 3 mmbecause it is approximately midway between thetracing and the working-side condyle.

Protrusive Interocclusal Records for the WhipMix Articulator (Arcon Type)

After try-in, the trial dentures are placed on thearticulator. The lateral condylar guidances are set at0 degrees so the articulator will be moved in astraight protrusive direction. The horizontal condy-lar guidances are set at 25 degrees to give an indi-cation of the space that will exist between theposterior teeth when the mandible is protruded.

The lower member of the articulator is movedforward approximately 6 mm, with the teeth out ofcontact and then closed, until the incisal edges ofthe lower anterior teeth reach the vertical levelof the incisal edges of the upper anterior teeth. The6 mm of forward movement that is necessary topermit proper adjustment of the horizontal condy-lar path of the articulator may bring the lower ante-rior teeth several millimeters in front of the upperanterior teeth.

The horizontal relation of the lower to the upperanterior teeth and the relationship of the midlinesof the upper and lower anterior teeth are observedcarefully because they will be the guides to thedentist that the patient has closed in approximatelythe proper position when the protrusive record ismade in the mouth (Figure 18-16, A). Interferingopposing posterior teeth that contact before thelower anterior teeth reach the desired vertical rela-tion should be removed from the wax occlusionrim.

When the dentist has become familiar with therelation of the lower to the upper anterior teeth inthe protrusive position, the trial dentures areremoved from the articulator and placed in thepatient’s mouth. The trial dentures are held in posi-tion by the dentist in the same way as for makingthe interocclusal CR record.

The patient is instructed to move his jawstraightforward and then to bite lightly on his frontteeth. The dentist determines the amount andnature of the forward protrusion by the previousobservation of the relationship of the anterior teethon the articulator. The patient practices closing in


the protrusive position under the guidance of thedentist until both become familiar with the proce-dure (Figure 18-16, B).

A small amount of recording material that doesnot distort easily when set (impression plaster) isplaced on the occlusal surfaces of the lower poste-rior teeth. Then, as in the practice sessions, thepatient protrudes his mandible and closes into therecording material. The patient is instructed to stopthe closure before the opposing teeth make contactand to hold the jaw lightly and steadily in thedesired position until the recording material sets.The relationship of the lower to the upper anteriorteeth in the patient’s mouth should closely approx-imate the relationship observed on the articulatorand during the rehearsal sessions.

The trial dentures and interocclusal record areremoved from the mouth. The lateral condylarguidances on the upper member of the articulatorare set at 20 degrees so they will not interfere if themandible has not moved forward in straight protru-sion and the horizontal condylar guidances are setat 0 degrees. Then the trial dentures and interoc-clusal protrusive record are returned to the articu-lator (Figure 18-17, A). The horizontal condylarhousings are rotated individually until the guidanceplates contact the condylar spheres (Figure 18-17,

B and C) and the angulation of the protrusivemovement for both sides is recorded.

The advantages of the protrusive registrationmade in plaster, or a recording material of similarconsistency, are that the resistance to the bitingforce is minimal and uniform and there is nothingthat guides the patient’s mandible except the mem-ory patterns of mandibular protrusion and theinstructions by the dentist. Also, the recordingmaterial will not be distorted during adjustment ofthe articulator. The disadvantage of plaster isrelated to the difficulty many patients experience inholding their mandibles in a steady protrusive posi-tion long enough for the material to set.

Protrusive Interocclusal Record for theDentatus Articulator (Non-Arcon Type)

Three thicknesses of Aluwax are placed over theocclusal surfaces of the mandibular posterior teeth,rather than the two described for CR verification. Theedges of the wax are sealed on both the buccal and thelingual sides with a warm spatula (Figure 18-18). Thechilled upper trial denture should be placed in posi-tion on the upper cast mounted in the articulator.

Next, only the Aluwax portion of the lower trialdenture is immersed in a water bath of 130° F (54°C)


Figure 18-16 A, The articulator (Whip Mix) in a protrusive position to show the amountof forward movement necessary to adjust the condylar elements. This relationship will guidethe dentist when a protrusive record is made in the patient’s mouth. B, The patient rehearsesclosing in protrusive position, and the dentist observes the anteroposterior relation of theopposing anterior teeth and their alignment (between the upper and lower central incisors);this will be used as a guide for the amount and direction of protrusive movement. Themovement should be similar to that observed on the articulator.

A B


Figure 18-17 Trial denture bases positioned by an interocclusal protrusive record(impression plaster) are returned to the Whip Mix articulator. A, The horizontal condylarguidance mechanism is not in contact with the condylar sphere (arrow). B, The condylarmechanism is rotated into contact with the condylar sphere (arrow), thus establishing hori-zontal condylar guidance on the articulator. C, An interocclusal protrusive record has beenmade in wax, with the articulator adjusted as in B.

A B

Figure 18-18 Three layers of Aluwax sealed with awarm spatula.

Figure 18-19 Only the Aluwax portion isimmersed in 130° F (54° C) water for 30 seconds.

C

for 30 seconds (Figure 18-19). The lower trial den-ture is placed on the lower cast, and the articulatoris set a quarter of an inch (6 mm) in protrusion withthe condyle paths, registering 25 degrees. At thisposition, the upper member of the articulator ispressed into the warm wax to approximately a thirdof its depth. The mandibular trial denture is removedfrom the cast, and the wax record is chilledthoroughly.

Both trial dentures are now placed in thepatient’s mouth, and the patient is taught how to pro-trude into these indentations. The patient rehearsesthis protrusive action to prepare for making sucha protrusive movement later when the wax issoftened.

The mandibular trial denture is now removedfrom the mouth and the wax record is resoftened inhot water. Care is taken not to destroy the indenta-tions.

The trial denture is reinserted into the mouth,and the patient is told to feel carefully and moveinto these markings in the manner rehearsed previ-ously (Figure 18-20). (Instructions have alreadybeen given not to exert occlusal pressure into theseindentations until told to do so.)

The position of the teeth relative to the inden-tations is carefully observed, and when the teethcoincide with these markings, the patient isinstructed to bite, but not to bite through the wax.

As an alternative the patient can be instructed torelax his jaw muscles while the dentist elevates themandible with the index finger placed beneath theinferior portion of the chin. With either approach,the anterior teeth should remain slightly out of con-tact to avoid any tooth interference.

The wax record is chilled in the mouth, removed,and examined for any contact between the teeth. Thetrial dentures are replaced on the articulator, and thearticulator is protruded so the maxillary teeth willfit partially into the indentations. The locknuts forthe condylar guidance slot adjustments are loosened.While pressure is exerted on the upper articulatormember with one hand and the condylar guidance slotis worked back and forth with the other hand, a condy-lar path inclination is found that permits the teethto stay in contact with the wax throughout (Figure18-21). This adjustment is repeated for the oppositeside. It will readily be seen that too steep a pathprevents contact in the posterior part of the arch,and too horizontal a path prevents contact in theanterior part of the arch. As stated earlier, the cor-rect degree of condylar path incline can be attainedby tooth contact of the wax throughout the arch; thecondylar guidance slot is locked in the positionthus obtained.

A protrusive record is first made on the articu-lator so the correct amount of protrusive distance(which is also centered) will guide the patient’s


Figure 18-20 The mandible is guided into theindex previously made on the articulator.

Figure 18-21 Pressure on the Dentatus articulatorwith one hand and back and forth movement of thecondylar guidance slot with the other permit a condy-lar path inclination to be found that gives uniform con-tact of the wax index and opposing teeth.

mandible to the desired protrusive position. Unlessthe patient has a guide and has rehearsed, it will beextremely difficult to keep the mandible from clos-ing too far or not far enough in protrusive occlu-sion, to the right or left in lateral occlusion, or in acombination of protrusion and lateral occlusion.Such a record will give an unsatisfactory setting tothe articulator. The record is made with a protrusivedistance a quarter of an inch (6 mm) because it isthought that with a shorter distance the condylewill not move down its path sufficiently to berecorded on the instrument. A protrusive move-ment of more than a quarter of an inch is usuallybeyond the range of the patient, and registration ofa greater distance is not necessary.

An alternative procedure involves the use ofimpression plaster for making the protrusive inter-occlusal record, as described for the Whip Mixarticulator.

ESTABLISHMENT OF THE POSTERIORPALATAL SEALThe posterior palatal seal is completed before thefinal arrangement of the posterior teeth becausethis final arrangement is a laboratory procedureand is done in the absence of the patient.

The posterior border of the denture is deter-mined in the mouth, and its location is transferredonto the cast. A T burnisher, or mouth mirror, ispressed along the posterior, angle of the tuberosityuntil it drops into the pterygomaxillary (hamular)notch (Figure 18-22). The locations of the right andleft pterygomaxillary notches are marked with anindelible pencil. On the median line of the anteriorpart of the soft palate are two indentations formedby the coalescence of ducts known as the foveaepalatinae. The shape of these depressions variesfrom round or oval to oblong. The dentist can makethem more readily discernible by having the patienthold his nose and attempt to blow through it (Valsalvamaneuver). This will accentuate the foveae palatinaeand vibrating line.

The vibrating line of the soft palate, normallyused as a guide to the ideal posterior border of thedenture, usually is located slightly anterior to thefoveae palatinae. However, it may be on or slightlyposterior to the foveae palatinae. The slight devia-

tion from these markings is estimated by having thepatient say “ah” and thus vibrate the soft palate. Thedentist observes closely and marks the vibratingline with an indelible pencil (Figures 18-23 and 18-24). The two pterygomaxillary notch markingsare joined to the median line mark. The trial denturebase is now inserted so the indelible pencil line will


x

Figure 18-22 The pterygomaxillary (hamular) notch(arrow) in the mouth often is deceiving. To be certain ofits location, the dentist can palpate it with a mouth mir-ror placed posterior to the tuberosity (arrow).

Figure 18-23 The vibrating line has been tracedon the palatal tissues with indelible pencil. The X witharrows marks where it passes through the hamularnotch on both sides slightly anterior to the foveaepalatinae.

be transferred from the soft palate to the trial den-ture base, and the excess baseplate is reduced to thisline (Figure 18-25). The trial denture base is placedon the cast, and a knife or pencil is used to mark aline following the posterior limits of the baseplate(Figure 18-26). This line should extend laterally 3mm beyond the crest of the hamular notch.

The anterior line that indicates the location ofthe posterior palatal seal is drawn on the cast in

front of the line indicating the end of the den-ture (Figure 18-27). The width of the posteriorpalatal seal itself is limited to a bead on the den-ture that is 1- to 1.5-mm high and 1.5-mm broadat its base (Figure 18-28). A greater width creates anarea of tissue placement that will have a tendency topush the denture downward gradually and to defeatthe purpose of the posterior palatal seal. In otherwords, the posterior palatal seal should not be made


Figure 18-24 The vibrating line and width of the posterior palatal seal depend on thesoft palate form (A, B, or C). Form C allows only a narrow posterior palatal seal; A allows thewidest seal.

A BFigure 18-25 A, The indelible pencil line across the palate in Figure 18-23 has beentransferred to the denture base and can be seen rather indistinctly (1), anterior to the solidline marking the end of the denture (2). B, The trial denture base is shortened posteriorlywith an acrylic bur as far as this line.

Continued

too wide. Placement of tissue should be such thatwhen the dentures move in function, as they alwaysdo, the placed tissue will move with the denturesand not break the seal.

A V-shaped groove 1- to 1.5-mm deep is carvedinto the cast at the location of the bead. A large,sharp scraper is used to carve it, passing throughthe hamular notches and across the palate of the

cast (Figures 18-29 and 18-30). The groove willform a bead on the denture that provides the poste-rior palatal seal (Figure 18-31). The bead will be 1-to 1.5-mm high, 1.5-mm wide at its base, and sharpat its apex. The depth of the groove in the cast willbe determined by the thickness of the soft tissue


Figure 18-26 Posterior extent of the trial denturebase traced on the cast.

Figure 18-27 The posterior line (A) indicates theend of the denture posteriorly across the palate. Theanterior line (B) marks the location of the posteriorpalatal seal that will be carved into the cast andtransferred as a bead onto the denture.

C

Figure 18-25 cont’d C, The trial denture base shows the anticipated length of the com-pleted denture. X denotes the location of the vibrating line that was transferred from thepatient’s mouth.

against which it is placed and will establish theheight of the bead.

The narrow and sharp bead will sink easily intothe soft tissue to provide a seal against air beingforced under the denture. If the bead has been madetoo high, the sharpness will make this apparentwithin 24 hours of the insertion of the dentures, andit can be easily relieved. The narrowness of thebead makes the seal with minimal downward pressureon the denture.


Figure 18-28 Sagittal diagrammatic view of denture in place in the mouth. A bead onthe posterior extent (A) is 1 to 1.5-mm high and 1.5-mm broad at the base, and 2-mm ante-rior to the end of the denture (B). C, Movable soft palate. D, Muscles of the soft palate.

Figure 18-29 A groove is carved into the cast(arrows) with a large, sharp scraper to form the poste-rior palatal seal.

Figure 18-30 The groove in the cast (arrows) formsa bead on the finished denture (Figure 18-28).

Figure 18-31 The denture ends on the cast at A.The bead (B), located 2 mm in front of the vibratingline, is extended laterally through the center of thehamular notches.

SECTION III: CREATING FACIAL AND FUNCTIONAL HARMONY WITH ANTERIOR TEETH

The anatomical structures that collectively formthe face normally develop concurrently and areinterdependent during function throughout life.Disruptive events in this homeostatic complex canrange from relatively minor changes, such as adeflective occlusal contact to major alterations inbodily form, such as removal of the natural teeth,which drastically affects the form and function ofthe remaining living parts.

In this context of homeostasis, creating facialand functional harmony with anterior teeth becomesa biological challenge of utmost significance. Not

only must the teeth be of proper form, size, and colorto harmonize with the face, but they also mustbecome a functioning component in a living envi-ronment that depends on their proper position for itsnormal physiological activity. This proper positionallows patients to preserve their facial identities asthey existed when natural teeth were present. Theability of patients to maintain their normal facialexpressions will likely be the most important psy-chological factor in acceptance of the dentures.

ANATOMY OF NATURAL APPEARANCEAND FACIAL EXPRESSIONThe dentist who is treating a patient with completedentures has as much to do with the beauty ofthe face as has any other medical specialist. The


Figure 18-32 A, The lower part of this face lacks proper contour because of inadequatesupport for the orbicularis oris muscle and muscles related to it. B, Facial contours havebeen properly restored. The improvement in appearance is directly related to the position ofthe artificial teeth and the form of the suporting base material of the complete dentures (C).

A C

B

appearance of the entire lower half of the facedepends on the dentures. It is usually not difficulton casual meeting to detect the person who is wear-ing poorly constructed dentures (Figure 18-32).The characteristic thin, drooping upper lip thatappears lengthened and has a reduced vermilionborder is typical of malpositioned anterior teethand probably a reduced vertical dimension of occlu-sion. Tense, wrinkled lips often reveal the patient’sefforts to hold the denture in place. The droopingcorners of the mouth tell the story of the misshapenand misplaced dental arch form of the anterior teeth,the thin denture borders, and often the reducedocclusal vertical dimension. The appearance of pre-mature aging may be caused not by age itself but bythe lack of support for the lips and cheeks due to theloss or improper replacement of teeth. The apparentextra fullness of the lower lip may be the resultof too broad a mandibular dental arch or the elimi-nation or reduction of the mentolabial sulcus.This may indicate that the lower anterior teeth havebeen placed too far lingually or that the labialflange of the lower denture base is overextended ortoo thick.

Normal Facial Landmarks

One must study normal facial landmarks beforeattempting to achieve the goal of a natural andpleasing facial expression with complete dentures.The facial landmarks of the lower third of the facehave a direct relationship to the presence of the nat-ural teeth (Figure 18-33). The contours of the lipsdepend on their intrinsic structure and the supportfor them provided by the teeth and the soft tissuesor denture bases behind them. When the naturalteeth are lost, these landmarks and surroundingfacial tissues become distorted. To reestablish nor-mal appearance and function, the dentist mustreplace the artificial teeth in the same position asthe natural teeth that were lost.

The lips vary in length, thickness, shape, andmobility in different patients. Such varianceaccounts for the degree of visibility of the upperand lower anterior teeth during speech and otherfacial expressions. When the mandible is in theresting position, the lips usually contact each otherand turn slightly outward, exposing the vermilionborder. The vertical groove in the middle of the


Figure 18-33 Facial landmarks. A, Nares; B, rima oris; C, lower lip; D, mentum; E, men-tolabial sulcus; F, angulus oris; G, upper lip; H, philtrum; I, nasolabial sulcus; J, ala nasi.

upper lip is called the philtrum, and the horizontaldepression midway between the lower vermilionborder and the bottom of the chin is called the men-tolabial sulcus, or groove (see Figure 18-33).Incorrect positioning of the anterior teeth or sup-porting base material of complete dentures willalter the normal appearance of the vermilion bor-der, the philtrum, and the mentolabial sulcus inedentulous patients.

The nasolabial sulcus, or groove, is a depres-sion in the skin on each side of the face, which runsangularly outward from the ala of the nose toapproximately just outside the corners of the mouth(anguli oris) (see Figure 18-33). The zygomaticusmuscle originates on the zygomatic bone andangles downward and forward to insert at the cor-ner of the mouth into the orbicularis oris muscle.The action of the two zygomatici muscles in ele-vating the corners of the mouth for smiling pro-duces the nasolabial sulcus (Figure 18-34). Manyolder patients want to have the nasolabial sulcusobliterated because it becomes a wrinkle as the skinloses resilience. Removal of the nasolabial fold hasbeen attempted by thickening the denture baseunder the fold, but the extra bulk in this locationcauses a very unnatural appearance. The sulcus isnormal and should not be eliminated. The propertreatment is to bring the entire upper dental archforward to its original position when the naturalteeth were present and to maintain the original archform of the natural teeth and their supporting struc-tures. Thus the prominence of the nasolabial sulcuswill be restored to its original contour. In manypatients, the corners of the lip line (rima oris) willbe as high as the center portion, but the lip line willnot necessarily be straight all the way across.

The upper lip rests on the labial surfaces of theupper anterior teeth, and the lower lip on the labialsurfaces of the lower anterior teeth and incisaledges of the upper teeth. For this reason, the edgeof the lower lip should extend outward and upwardfrom the mentolabial sulcus. A reproduction of thehorizontal overlap of the natural anterior teeth inthe denture is essential to maintaining proper con-tour of the lips (Figure 18-35).

A study of the inclination of the osseous struc-ture supporting the lower anterior teeth indicatesthat in most patients the clinical crowns of thelower teeth are labial to the bone that supports

them. Likewise, a study of the inclination ofosseous structure and the inclination of maxillaryanterior teeth reveals that the upper lip functions onan incline (Figure 18-36). Neglect of these factorsin the replacement of natural teeth often will causethe lip to be ill formed and, in time, lead to the for-mation of vertical lines in the lip.

Maintaining Facial Support andNeuromuscular Balance

The orbicularis oris muscle and its attaching mus-cles are important in denture construction inas-much as the various contributing muscles havebony origins and their insertions are into the modi-oli and orbicularis oris muscle at the corners of themouth (Figure 18-37). Thus the functioning lengthof all these muscles depends on the function of theorbicularis oris. The muscles that merge into theorbicularis oris are the zygomaticus, the quadratuslabii superioris, the caninus (levator anguli oris),the mentalis, the quadratus labii inferioris, the tri-angularis (depressor anguli oris), the buccinator,and the risorius.

The orbicularis oris is the muscle of the lips. Itis sphincterlike, attaching to the maxillae along amedian line under the nose by means of a band offibrous connective tissue known as the maxillarylabial frenum and to the mandible on a median lineby means of the mandibular labial frenum. Thebuccinator is a broad band of muscle formingthe entire wall of the cheek from the corner of themouth and passing along the outer surface ofthe maxilla and mandible until it reaches the ramus,where it passes to the lingual surface to join thesuperior constrictor of the pharynx at the pterygo-mandibular raphe (see Figure 18-37, B). The twobuccinators and the orbicularis form a functionalunit that depends on the position of the dentalarches and the labial contours of the mucosa or thedenture base for effective action. With the loss ofteeth, the function of the orbicularis, buccinator,and attaching muscles is impaired. Because thesemuscles of expression are no longer supported attheir physiological length, contraction of theunsupported fibers does not produce normal facialexpression because the lips and face no longermove naturally or maybe even at all. Contractionsimply takes up the droop in the fibers. However,



Figure 18-34 The polyfunctional pyramid. A, Underlying superficial musculature. Ah,Angular head; DN, dilator naris; DSN, depressor septi nasi; ih, infraorbital head; N, nasalis;OOC, orbicularis oculi; OOR, orbicularis oris; P, platysma; Pr, procerus; QLI, quadratus labiiinferioris; QLS, quadratus labii superioris; R, risorius; T, triangularis; Z, zygomaticus; ZH,zygomatic head. B, Surface anatomy. AN, Ala nasi; AO, angulus oris; ApN, apex nasi; BN, basisnasi; DoN, Dorsum nasi; Me, mentum; MnL, mandibular lip; MS, mentolabial sulcus; MxL,maxillary lip; NS, nasolabial sulcus; Ph, philtrum; RO, rima oris; RZ, red zone or vermilionborder; Tu, tubercle. (From Martone AL, Edwards : J Prosthet Dent 11:1009-1018, 1961.)

T

P

Muscles of Expression

Pr

N

DN

OOc

ah

ihQLS

DSNzh

Z

OOr

OOrR

QLI

Surface Markings

DoN

ApN

AN

BN

NS

PhMxL

Tu

Rz

MnL

MS

Me

RO

AO

A B

when these muscles are correctly supported bycomplete dentures, impulses coming to them fromthe central nervous system cause a shortening ofthe fibers that allows the face to move in a normal

manner. Thus the memory patterns of facial expres-sion developed within the neuromuscular systemwhen the patient had natural teeth are continued orreinforced so the patient’s original appearance ismaintained (Figure 18-38).

Three factors affect the face in repositioningthe orbicularis oris with complete dentures: (1) the


Figure 18-35 A, Reproduction of a patient’s for-mer horizontal overlap with the correct facial contour.B, Horizontal overlap changed so the maxillary anteriorteeth contact the mandibular teeth, with resultantdamage to the upper lip.

A

B

Figure 18-36 The incisal edges and labial surfacesof the lower anterior teeth are labial to the bonesupporting them. The inclination of the labial plate ofbone and the labial surfaces of the upper anteriorteeth causes the upper lip to function on an incline. Itis easy to observe the lack of support of the lip thatwill result when artificial anterior teeth are positionedover the crest of the residual ridge. Resorption of thealveolar process in the mandibular anterior region afterremoval of the anterior teeth will move the residualbony ridge lingually at first and then labially asresorption continues.

thickness of the labial flanges of both dentures,(2) the anteroposterior position of the anteriorteeth, and (3) the amount of separation between themandible and the maxillae (Figure 18-39). If thejaws are closed too far, and the dental arch islocated too far posteriorly, the upward and back-ward positioning of the orbicularis oris complexwill move the insertions of these muscles closer totheir origins. This will cause the muscles to sag

when at rest and to be less effective when contract-ing. Such positions automatically drop the cornersof the mouth, with a resultant senile edentulousexpression, and may lead to atrophy of the musclefibers.

The correct width of the maxillary dentureborders plays a great part in supporting these mus-cles and lengthening the distance that they mustextend to reach their insertion. If the mouth has


Zygomaticusmajor

Quadratuslabii

Caninus

Risorius

Platysma

Triangularis

Quadratuslabii

inferioris

Figure 18-37 A, Muscles that maintain facial support. When artificial teeth and the den-ture base material restore the lips to their correct contour, the facial muscles will be at theirphysiological length, and contraction will create the normal facial expression of the patient.

A

Continued

Figure 18-37 cont’d B, Functional unit of the buccinator. This muscle (1) and the orbic-ularis oris muscle (2) depend on the position of the upper denture for their proper action.(3) is the pterygomandibular raphe, and (4) is the superior constrictor of the pharynx.

B

Figure 18-38 A, These lips are incorrectly contoured and are not moving naturally dur-ing speech. The lack of facial expression results from inadequate support of the lips by theanterior teeth, improper thickness of the labial flanges, and an inadequate vertical dimen-sion of occlusion. B, The lips have been restored to correct contour with new dentures.

A B


been edentulous a long time, with considerableresorption of the residual ridges, the borders needto be thick to restore the position of the muscles(Figure 18-40).

Repositioning anterior teeth that are protrud-ing or slightly protruding to reduce their horizon-tal overlap and improve the appearance of the

patient is a serious mistake. The muscles, teeth,and all associated structures grew simultane-ously; therefore the physiological length of themuscles was determined early. In fact, the mus-cles of the face, cheeks, tongue, and lips helpedalign the natural teeth in the dental arches. Tomove teeth back in dentures is to invite a loss of

Figure 18-39 Notice the activity of the lips during speech when they are properly supportedby new dentures. Compare this with the lack of activity in the same patient (Figure 18-38, A).

Figure 18-40 A and B, The labial flange is thick at the borders. This thickness harmo-nizes with the available space in the patient’s mouth because of resorption of the upperresidual ridge.

A B

Continued

facial expression that may be more damaging tothe appearance of the patient than the slightlyprotruding teeth. Individual pronounced irregu-larities may be improved, as long as the positionof the dental arch in its support of the orbicularisoris muscle and attaching muscles is not percep-tibly altered.

Thus normal facial expression and proper toneof the skin of the face depend on the positionand function of the facial muscles. These musclescan function physiologically only when the dentisthas positioned and shaped the dental arches cor-rectly and has given the mandible a favorable verti-cal position. In addition, the dentures themselvesmust have a pleasing and natural appearance inthe patient’s mouth, a condition that is dependent onarranging the artificial teeth in a plan that simulatesnature. This, then, is the challenge of creating facialand functional harmony with anterior teeth.

BASIC GUIDES TO DEVELOPING FACIALAND FUNCTIONAL HARMONYAfter an acceptable vertical dimension of occlusionhas been determined and the horizontal relation ofthe casts on the articulator has been verified for CR,the appearance of the patient is studied and modifi-cations are made in the arrangement of the teeth toobtain a harmonious effect with the patient’s face.

The guides that are considered in developing facialand functional harmony include the following:

1. The preliminary selection of artificial teeth2. The horizontal orientation of anterior teeth3. The vertical orientation of anterior teeth.4. The inclination of anterior teeth5. Harmony in the general composition of

anterior teeth6. Refinement of individual tooth positions7. The concept of harmony with sex, personality,

and age of the patient8. The correlation of esthetics and incisal

guidance

Although these factors are discussed individu-ally, for simplicity they are interrelated in theactual clinical situation.

Preliminary Selection of the Artificial Teeth

The preliminary selection of teeth must be criticallyevaluated for size, form, and color as they have beenarranged in the trial denture. The six upper anteriorteeth, when properly supporting the upper lip,should be of sufficient overall width to extend in thedental arch to approximately the position of the cor-ners of the mouth and still allow for individualirregularities of rotation, overlapping, and spacing.The canines should extend distally so they can bethe turning point in the dental arch. The form of theteeth should be harmonious with the face but notnecessarily identical with the outline form of theface. The color of the teeth should blend withthe face so the teeth do not become the main focalpoint of the face. The anterior teeth are the principalones to be considered in esthetics, although the pos-terior teeth, involving height of plane and width ofarch, play their part also. Any records used in theinitial selection of teeth should be consulted at thistime to ensure that the desired result has beenachieved (Plate 18-1). The dentist must makechanges in the selection of teeth if such changeswill improve the appearance of the dentures.

Horizontal Orientation of the Anterior Teeth

The position and expression of the lips and thelower part of the face are the best guides for deter-


Figure 18-40 cont’d C, The bulk is needed forcorrect support of the upper lip.

C

mining the proper anteroposterior orientation ofanterior teeth. The other guides or measurementsare secondary and must be ultimately related to theappearance of the patient.

The greatest harm done in esthetics issetting the maxillary anterior teeth back to orunder the ridge, regardless of the amount ofresorption that has taken place. A study of theanterior alveolar process will disclose that itsdirection is upward and backward from thelabial surface of the maxillary incisors (seeFigure 18-36). Therefore the crest of the upperridge is considerably more posterior in a resorbed

ridge than it was when the teeth were recentlyremoved (Figure 18-41).

Insufficient support of the lips resulting fromanterior teeth that are located too far posteriorly ischaracterized by a drooping or turning down of thecorners of the mouth, a reduction in the visible partof the vermilion border, a drooping and deepening ofthe nasolabial grooves, small vertical lines or wrin-kles above the vermilion border, a deepening ofthe sulci, and a reduction in the prominence of thephiltrum (Figure 18-42, A).

A striking difference occurs when the anteriorteeth are in proper position (Figure 18-42, B). The


Figure 18-41 A, Correct positioning of an artificial central incisor to restore the physio-logical length of muscles for proper functioning. Dotted outline shows the tooth incorrectlypositioned to follow the residual ridge. B, Position of the original natural central incisor.

A B

Figure 18-42 A, Artificial anterior teeth positioned too far posteriorly. Notice the lack oftone in the skin of the upper lip. B, Artificial anterior teeth positioned correctly in ananteroposterior direction. Notice the improved skin tone.

A B

vermilion borders become visible, the cornersof the mouth assume a normal contour, many ofthe small vertical lines above the vermilion of theupper lip are reduced or eliminated, and the tone ofthe skin surrounding the dentures takes on a char-acter similar to that of the skin in other parts ofthe face not affected by the position of theteeth. Although the nasolabial groove will stillbe present, the drooping appearance often can beconsiderably reduced. Nasolabial grooves shouldnot be eliminated, and the dentist must be carefulabout the information the patient receives in thisregard. However, patients should be informed asto the other improvements that can be made bythe dentures that will produce a more youthfulappearance.

Excessive lip support resulting from anteriorteeth located too far anteriorly is characterized by astretched tight appearance of the lips, a tendencyfor the lips to dislodge the dentures during func-tion, elimination of the normal contours of thelips, and distortion of the philtrum and sulci(Figure 18-43). A photograph of the patient withnatural teeth can be most helpful in the placing ofartificial teeth. The teeth can be so arranged thatthe appearance and contours of the lips and lowerpart of the face resemble those seen in the picture(see Plate 18-1, C).

The relation of the maxillary and mandibularanterior ridges to each other has an influence on theanteroposterior position of both the maxillary andthe mandibular anterior teeth. A common error is toattempt to establish a standard vertical and horizontaloverlap without regard to the ridge relation. Thisshould not be done because the anteroposteriorposition of the teeth must correspond to the posi-tions of the ridges. If the mandibular ridge is for-ward of the maxillary ridge, as in prognathism, theupper anterior teeth should be placed lingual to themandibular teeth. The anterior teeth can then be setend to end, with the incisal edges at an angle thatproduces a seating action on the maxillary denture(Figure 18-44).

A study of the position of natural teeth ondiagnostic casts will provide information that canbe transferred to the arrangement of artificialanterior teeth. As mentioned previously, theupper lip functions on an incline produced bythe labial plate of the alveolar process and thecrowns of the upper anterior teeth. The positionof the natural anterior teeth makes their labialsurfaces at least as far forward as the labial mostpart of the reflection (Figure 18-45, A). Thisinformation can be transferred to the position ofthe artificial anterior teeth on the trial denturebase. Such a guide also will be helpful in con-


Figure 18-44 Correct inclination of the teeth andincisal edges in a moderate prognathic relation.

Figure 18-43 A stretched appearance of the lipsand philtrum indicates that artificial anterior teeth arepositioned too far anteriorly.

touring the occlusion rims (Figure 18-45, B) andin developing the preliminary arrangement ofanterior teeth.

Observing the position of the anterior teethwhen the trial denture base is out of the mouth canbe helpful. The labial surfaces of many naturalupper central incisors are approximately 8 to 10mm in front of the middle of the incisive papilla.Measurements with a Boley gauge from the middleof the incisive fossa on the trial denture base to thelabial surfaces of the artificial central incisors willshow the relationship of these teeth to the incisivepapilla (Figure 18-46, A).

When the trial denture bases are viewed from thetissue-contacting surface, the labial portions of the

anterior teeth should be apparent, and a visualizationof their imaginary roots can be helpful. If the imag-inary roots appear to be on the labial side of theresidual ridge (with allowance made for bone lossfrom that part of the ridge), the anterior teeth will bevery near to their correct labiolingual positions.If the imaginary roots appear to extend into the crestof the residual ridge, the artificial teeth are posi-tioned too far posteriorly on the trial denture base(Figure 18-46, B). The location of the incisive fossain relation to the crest of the ridge gives an indica-tion of the amount of resorption of the upper resid-ual ridge: the greater the resorption, the fartherin front of the crest the imaginary roots shouldappear.

An imaginary transverse line between theupper canines, as viewed from the tissue-contact-ing surface of the upper trial denture base, shouldcross near the middle of the incisive fossa whenanterior teeth of the proper size are located cor-rectly in the anteroposterior position (Figure 18-46, C). If the line falls anterior to the incisivefossa, the overall width of the anterior teeth maybe too small or the teeth may be positioned toofar forward. If the line falls posterior to thepapilla, the overall width of the anterior teethmay be too large or the teeth positioned too farback.

Vertical Orientation of the Anterior Teeth

The amount of the upper anterior teeth seen duringspeech and facial expression depends on the lengthand movement of the upper lip in relation to thevertical length of the dental arch. If the upper lip isrelatively long, the natural teeth may not be visiblewhen the lip is relaxed or even during speech(Figure 18-47, A); however, in this situation someteeth may be exposed when the person smiles. Inother patients, with a relatively short upper lip, thefull crowns may be visible below the upper lip(Figure 18-47, B). In some of these patients, a largeamount of the mucous membrane (or denture base),in addition to the teeth, may be exposed when theysmile.

Furthermore, the movement of the lips duringfunction varies considerably among patients.Therefore when artificial teeth are placed in thesame position as the natural teeth, the amount of


Figure 18-45 A, Relation of the labial surface ofthe natural central incisor to the reflection in asectioned cast. B, The inclination of the labial surfacesof wax occlusion rims should simulate the inclinationobserved in the natural situation. When the occlusionrims slope lingually toward the occlusal surface in theanterior region, they will rarely if ever provide propersupport for the lips.

A

B

upper teeth visible will vary for each patient.During a normal smile, the incisal and middle thirdsof the maxillary anterior teeth are visible in almostall patients and the cervical third in approximatelyhalf the patients. The incisal third of the mandibularanterior teeth will be visible in most patients.Mandibular anterior teeth are seen to a greaterextent than maxillary anterior teeth in about halfthe patients during speaking. In addition, mandibu-lar anterior teeth become more visible in persons

40 years of age and older and are seen to a greaterextent in men than in women.

A simple test can be used to estimate the lengthof the upper lip in relation to the residual ridges.The index finger is placed on the incisive papillawith the relaxed upper lip extending down over thefinger (Figure 18-47, C). The amount of the fingercovered by the upper lip gives an indication of thelength of the lip relative to the residual ridge andthe extent to which it will cover the upper ante-


A

Figure 18-46 Indications of correct anteroposterior positioning of artificial anteriorteeth. A, By measurement from the middle of the incisive fossa on the trial denture base tothe labial surfaces of the central incisors. B, By visualization of the imaginary roots of artifi-cial anterior teeth—the imaginary roots will be farther in front of the residual ridge when agreat amount of resorption has occurred. C, By determining the relationship of a transverseline extending between the middle of the upper canines and the incisive fossa.

B C

rior teeth (Figure 18-47, D). An estimation of theamount of residual ridge resorption must beincluded in the calculation. Knowing the length oftime the natural teeth have been out will help makethis estimate.

However, the lower lip is a better guide for thevertical orientation of anterior teeth than the upperlip is. In most patients, the incisal edges of the nat-ural lower canines and the cusp tips of the lowerfirst premolars are even with the lower lip at thecorners of the mouth when the mouth is slightlyopen (Figure 18-48, A). If artificial lower anteriorteeth are located above or below this level, theirvertical positioning will probably be incorrect

(Figure 18-48, B). In addition to any changes inposition of the lower teeth, the position of the upperteeth and the vertical dimension of occlusion mustbe considered because these are all closely interre-lated. When the lower teeth are above the lip at thecorners of the mouth, any one or a combination ofthe following may exist: (1) the plane of occlusionmay be too high; (2) the vertical overlap of theanterior teeth may be too much; and (3) the verticalspace between the jaws may be excessive. Whenthe lower teeth are below the lip at the corners ofthe mouth, the opposite situations may exist. Theuse of other observations and guides will help indeciding what corrections should be made.


Figure 18-47 A, This long upper lip obscures the natural upper anterior teeth even dur-ing speech. B, A relatively short upper lip exposes almost all the crowns of the upper centraland lateral incisors. C, The upper lip is allowed to drape over the index finger, which hasbeen placed on the incisive papilla. The thumb is in contact with the vermilion border. D,The amount of index finger that has been covered by the upper lip is an indication of thelength of the upper lip relative to the upper residual ridge.

A B

C D

Observing the size of the trial denture bases cangive clues to the vertical orientation of the anteriorteeth. In most patients, the lower and upper naturalteeth occupy approximately the same amount ofinterarch space. If the dimensions of the lower trialdenture, from the border of the base to the incisaledges of the teeth, appear to be significantly differ-ent from the same measurements on the upper trialdenture, then the plane of occlusion may need to beraised or lowered to make the trial dentures moresimilar in height (Figure 18-49). These measure-ments are made from the incisal edges to the den-ture borders. The vertical space between the jaws(vertical dimension of occlusion) must also be con-sidered because of its close interrelationship withthe plane of occlusion. If there has been moreshrinkage from one jaw than from the other, theamounts of base material between the incisal endsof the teeth and the basal surface of the denturemay be different, even though the overall dimen-sions are similar.

A study of the location of artificial anteriorteeth and their imaginary roots, in relation to theresidual ridges on the trial denture bases, can helpdetermine the position of the teeth. The artificialanterior teeth should be located vertically in thesame positions as were previously occupied by the

natural teeth. When it appears as though there isinsufficient interarch space to accommodate theupper and lower anterior teeth without significantlyreducing their size by grinding, it is good toremember that at one time there was space for thenatural teeth, with an adequate interocclusal dis-tance in the patient’s mouth. Insufficient spacebetween the residual ridges is an indication thateither the artificial teeth are longer than the naturalteeth or the vertical dimension of the face is tooshort.

Inclination of the Anterior Teeth

In some patients, the upper anterior teeth areinclined labially relative to the frontal plane whenthe head is erect (Frankfort plane parallel to thefloor). In others, they are inclined more lingually(Figure 18-50, A). Diagnostic casts, photographs,and the patient’s memories about the “slant of theupper front teeth” can help solve the problem con-cerning the inclination of the natural teeth.

A study of teeth in human skulls indicates thatthe roots of the anterior teeth are parallel to andvery close to the labial surface of the bone. Usually,there is an obtuse angle between the bone and thelabial surfaces of the teeth. In some skulls, the labial


A BFigure 18-48 A, Incisal edge of the natural lower canine at the level of the lower lip.B, Relationship of artificial lower teeth to the lower lip. Left, correct height; middle, too high;right, too low.

surfaces of the teeth are parallel to the bone but alsoslope labially. When the labial surfaces are curvedfrom cervical to incisal, the cervical third mayappear to be continuous with the inclination of thelabial plate of bone (Figure 18-50, B). Diagnosticcasts support this premise. When the natural teethare removed with no unnecessary surgery, the orig-inal inclination of the labial plate of bone is pre-served and will remain until considerable resorptionhas occurred, thus providing a guide to the inclina-tion of the anterior teeth (Figure 18-50, C). Theinclination of the labial surface of the residualridges as seen on edentulous casts can supply thisinformation.

The profile form of the patient’s face often isrepresentative of the natural anterior tooth inclina-tion within the oral cavity. The lips supply the pres-sures from the outside that help determine theanteroposterior position and inclination of the ante-rior teeth. Therefore it is logical to assume that theinclination of the anterior teeth parallels the profileline of the face (Figure 18-51). Suggestions for indi-

vidual tooth position to provide harmony betweenthe inclination of the teeth and the profile line ofthe face are described later.

Harmony in the General Composition ofAnterior Teeth

A number of factors are interrelated in the generalcomposition of the anterior teeth for a normaland pleasing appearance. Although these factorsvary among patients, there is sufficient con-stancy to warrant individual attention. The topicsto be discussed in providing harmony within thegeneral composition of the anterior teeth include(1) harmony of the dental arch form and the formof the residual ridge, (2) harmony of the longaxes of the central incisors and the face, (3) har-mony of the teeth with the smiling line of the lowerlip, (4) harmony of the opposing lines of thelabial and buccal surfaces, (5) harmony of theteeth and profile line, and (6) harmony of incisalwear and age.


Figure 18-49 A, Upper and lower dentures of approximately the same height. B, Upperdenture considerably larger than the lower. Often this discrepancy in size indicates an incor-rect vertical positioning of the artificial teeth.

A B

Harmony of the Dental Arch Form and Form ofthe Residual Ridge The anterior arches may beclassified in a general way as square, tapering, andovoid, to follow the form of the dental arch whenthe teeth are present (Figure 18-52). However, theycannot be closely classified as such because of thefrequent intermingling of the characteristics of oneform with those of another.

The central incisors in the square archassume a position more nearly on a line withthe canines than in any other setup. The fourincisors have little rotation because thesquare arch is wider than the tapering arch.This gives a broader effect to the teeth andshould harmonize with a broad, square face(Figure 18-53, A).


Figure 18-50 Labial and lingual inclination of the anterior teeth. A, The natural teethhave varying degrees of inclination. B, Notice the inclination and position of the anteriorteeth in relation to the inclination of the labial plate of bone. C, The inclination of this lowerresidual ridge provides the information that the lower anterior teeth, which it oncesupported, had a labial inclination.

A

CB


Figure 18-52 Varying shapes of the natural dental arch. A, Square. B, Tapering. C,Ovoid.

A

C

B

Figure 18-51 The inclination of anterior teeth often parallels the profile line of thelower third of the face.

The central incisors in the tapering arch are agreater distance forward from the canines than inany other arch. There usually is considerable rotatingand lapping of the teeth in the tapering arch becauseof less space. Therefore crowding results. Therotated positions reduce the amount of tooth surfaceshowing, and the teeth do not appear as wide as inother setups. This narrowed effect is usually in har-mony with a narrower tapering face (Figure 18-53,B). In fact, the very narrowness of the tapered archcontributes to the narrowness and taper of the face.Natural teeth move in function, and this frictionalmovement wears the contact areas. Artificial teethneed to be ground on these corresponding contactareas to allow the necessary rotational positions andgive the desired effect of a tapering setup.

The central incisors in the ovoid arch are for-ward of the canines in a position between that ofthe square and that of the tapering arch. The teethin this form of arch are seldom rotated, and theytherefore show a greater amount of labial surfacethan in the tapering setup and, as a result, have abroader effect that should harmonize with an ovoidface (Figure 18-53, C).

The form of the palatal vault gives an indica-tion as to the original form of the dental arch beforeremoval of the natural teeth and resorption ofthe residual ridge. A broad and shallow edentulouspalatal vault indicates that the dental arch formoriginally may have been square; a high, V-shapededentulous vault probably indicates a tapering den-tal arch, and a rounded vault of average height mayindicate an ovoid dental arch. Most patients exhibitsome combination of these classifications.

The arch form of the artificial anterior teethshould be similar in shape to the arch form of theresidual ridge, if one assumes there was no unneces-sary surgery when the anterior teeth were removed(Figure 18-54). This simple anatomical fact often isneglected, but it should be observed carefully. Whenthe anterior teeth are arranged in an arch form thatcorresponds to the form of the residual ridge, natu-ral-appearing irregularities that may have been pres-ent in the patient’s mouth will often be reproduced.

Changing the shape and position of the artificialdental arch away from the form of the natural archcauses a highly unsatisfactory loss of face form andexpression. A square arch form where the naturalarch was more tapering will cause a stretching of

the lips, with elimination of the natural philtrum.A tapering arch form where the natural dental archwas square will not adequately support the cornersof the mouth for proper facial expressions.


Figure 18-54 Dotted lines indicate that the archform of artificial anterior teeth on the trial denturebase is basically similar to that of the anterior part ofthe residual ridge.

A

B

CFigure 18-53 Anterior arch forms. A, Square. B,Tapering. C, Ovoid.

The shape and position of the dental arch deter-mine the size of the buccal corridor. The buccalcorridor is the space between the buccal surfacesof the upper teeth and the corners of the mouthvisible when the patient smiles. It varies consid-erably among patients, and its size is not criti-cal. However, the presence of the buccal corridorhelps eliminate an appearance of too many teethin the front of the mouth. When the arch form ofthe posterior teeth is too wide or the lips do notmove to their full extent during smiling becauseof improper support, the size of the buccal corri-dor will be reduced or perhaps eliminated (Figure18-55).

Patients may request a change in the position orform of their dental arch, but the dentist should notcompromise on this point because the unfavorableconsequences can be laid to no one else.

Harmony of the Long Axes of the Central Incisorsand Face One of the early observations that

should be made in developing the arrangementof anterior teeth for the patient is the relationship ofthe long axes of the central incisors to the long axisof the face. When the long axes of these teeth are notin harmony with the long axis of the face, thearrangement will not blend with the face because theincisal plane of the anterior teeth will not be parallelto the interpupillary line (Figure 18-56, A). This willcause an unpleasant disharmony of lines. It is a sim-ple task to reset the central incisors to make theirlong axes harmonize with the long axis of the face(Figure 18-56, B). If the central incisors must bedivergent at their incisal edges, the midline of thedental arch should be at the center of the face. Thenthe lateral incisors and canines will almost automat-ically fall into their proper alignment, and the incisalplane will be in balance with the interpupillary line.

The long axes of the central incisors should beparallel to the long axis of the face, and the midlineof the dental arch (the contact area betweenthe central incisors) should be located near themiddle of the face. This is determined by droppingan imaginary perpendicular line from the midpointon the interpupillary line. The midline position ofthe natural central incisors can be estimated also byobserving the position of the incisive papilla on thecast and the corresponding fossa in the upper trialdenture base because the incisive papilla waslocated lingually and between the natural uppercentral incisors before their extraction.

The midline of the mandibular dental arch isbetween the central incisors and usually is alignedwith the midline of the maxillary central incisors.When the lower anterior teeth are correctly locatedanatomically in the lower dental arch, an imaginaryline drawn anteroposteriorly through the middle ofthe lower denture should pass between the lowercentral incisors (Figure 18-57). The maxillary andmandibular midlines fail to coincide in most adultswith natural teeth, however, so the prosthodontistmust attempt to set the artificial teeth to coincidewith this imaginary midline.

The application of these principles regardingthe placement of central incisors and their inclina-tions may be modified to meet individual needs asindicated by preextraction records.

Harmony of the Teeth with the Smiling Line ofthe Lower Lip When a person smiles, the lower


Figure 18-55 A, Buccal corridor inadequatebecause of improper placement of the upper teeth.B, Anterior teeth in proper position to support theupper lip. Notice the adequate buccal corridor.

A

B

lip forms a pleasant curvature known as the smilingline. This can be used as a guide in arranging theupper anterior teeth.

When the line formed by the incisal edges ofthe upper anterior teeth follows the curved line ofthe lower lip during smiling, the two lines will beharmonious and will create a pleasing appearance.When the incisal edges of the upper anterior teeth

form a curved line that is not in harmony with, oris opposite in contour to, the line formed by thelower lip during a smile, the contrast of the lines isdisharmonious and will be displeasing in appear-ance (Figure 18-58, A).

The vertical position of the upper canines is pri-marily responsible for the shape of the smiling line.When the canines are so arranged that their incisal


A

BFigure 18-56 The long axes of the central incisors should be parallel to the long axis ofthe face. A, The middle drawing shows that such parallelism provides a necessary harmonyof lines. Notice the disharmony of the left and right. B, The long axes of the artificial centralincisors have been correctly aligned.

edges are slightly shorter than the incisal edges ofthe lateral incisors, the smiling line will tend to par-allel the lower lip as the patient smiles (Figure 18-58, B). A reverse smiling line is one of the mostfrequent causes of artificial-appearing dentures.

Harmony of the Opposing Lines of Labial andBuccal Surfaces Setting teeth with their longaxes parallel to each other is what causes people todread complete dentures because the appearance isartificial. Many patients are subconsciously irri-tated by this artificial appearance of dentures and

tend to find other faults with them that would oth-erwise be overlooked.

A well-balanced painting or drawing must havelines at opposing angles as well as some parallel lines.The same principle applies to having a pleasing pic-ture of the teeth. For example, if the teeth on bothsides of the arch were inclined to be parallel to eachother, they would make a most unsatisfactory-appear-ing denture. There should be asymmetrical symmetryin the arrangement of the teeth (Figure 18-59).

The labial and buccal lines must have opposingequivalent angles, or nearly so, for a harmoniouseffect. If the maxillary right lateral incisor is set atan angle of 5 degrees to the perpendicular, the lat-eral incisor on the left side should be set 5 degreesto the perpendicular in the opposite direction. Thescheme of opposing angles can be carried to themaxillary canines and the mandibular opposingcanines (see Figure 18-59). Deviation in angulationmay also be arranged in different teeth on the twosides. Extra inclination of a lateral incisor on oneside may be balanced by inclination of the oppositecanine; asymmetrical symmetry is the objective.

There should be harmony between the labialand buccal lines of the teeth and the lines of theface. Square and ovoid faces should have teeth withlines that are more nearly perpendicular, whereastapering faces should have teeth with lines that aremore divergent from the perpendicular.

An optical illusion may be created for patientswho have a nasal deflection. Four of the maxillary


Figure 18-57 Lower anterior teeth correctly posi-tioned, as shown by the imaginary line passing throughthe middle of this lower denture between the lowercentral incisors.

A BFigure 18-58 Harmony of the line formed by the incisal edges of the upper anterior teethwith that formed by the curvature of the lower lip. A, Lines in harmony (left) and not in harmony(right). Results are a pleasing and a displeasing appearance. B, Notice the harmony in this face.

teeth can be set at an opposite angle to the devia-tion, making it less apparent.

Harmony of the Teeth and Profile Line of theFace As a general rule, the labial surfaces of themaxillary central incisors are parallel to the profileline of the face. In prognathic patients with pro-truding mandibular incisors, the incisal edges ofthe maxillary teeth are out farther than the cervicalends of the teeth. In the opposite condition (inwhich the mandibular incisors are retruded to someextent), the incisal edges of the maxillary teeth areinclined lingually more than the cervical ends ofthe teeth (Figure 18-60).

When the labial of the maxillary central inci-sors is parallel to the profile line of the face, the lat-

eral incisors should be set at an opposite angle toprevent parallelism from being predominant. Forexample, in a patient with retrognathic jaw rela-tions whose maxillary central incisors are out at thecervical ends, the lateral incisors could then bedepressed at their cervical ends to oppose the linemade by the labial surfaces of the central incisors.For the prognathic patient, the incisal edges of themaxillary central incisors often are set labially.The maxillary lateral incisors could then be placedslightly out at the cervical ends to oppose the labialface line of the central incisors.

Most faces are a blend of two or three types ofprofiles. Arrangement of teeth for a harmoniousappearance must be modified accordingly. The pre-dominating facial form can be helpful as a guidefor positioning the teeth.

Harmony of Incisal Wear and Age The incisaledges and proximal surfaces of anterior teeth wearconcomitantly with age. This is another character-istic of natural teeth that must be incorporated inartificial teeth if they are to appear in harmonywith the age of the patient. The incisal edges ofdenture teeth should always be ground to simulatethe wear surfaces that would have developed by thetime the patient reached his current age. Thereforea young patient would likely exhibit less incisalwear (Figure 18-61, A), and an older one more wear(Figure 18-61, B).

A sketch of the anticipated pattern of wear to beplaced on the incisal edges of anterior teeth can be


Figure 18-59 Balanced opposing lines.Dissimilarities in the inclination, rotation, and positionof the teeth on each side of the midline provide whatis called asymmetrical symmetry, which is essential fornatural-appearing teeth.

Figure 18-60 The labial face of the central incisor parallels the profile line of the face.Notice how the incisal third of the tooth breaks lingually from the profile line.

beneficial. The outline form of the artificial teeth issketched on a piece of paper, and the anticipatedchanges that are to be created to simulate wear onthe incisal edges are depicted on the drawing(Figure 18-62). In general, more lingually placedupper teeth or parts of teeth will wear increasingly,whereas more labially placed upper teeth will wearsomewhat less. The greatest amount of wear on thelower anterior teeth or parts of teeth will occur inthe more anteriorly placed lower teeth. The simula-tion of wear on anterior teeth should be logically inharmony with the way it occurs when the upper andlower teeth pass over each other.

Developing incisal wear on artificial teeth duringbalancing and correcting of the occlusion is a logicalapproach to this phase of esthetics. Thus wear isplaced on the teeth where it would have occurred dur-ing function and also where it assists in the mechan-ics of balancing the occlusion (Figure 18-63).

The effect that the form of the tooth creates canbe dramatically altered by reshaping the tooth tosimulate wear. The same mold of anterior teeth canbe altered to help create a young, soft, feminineappearance for one patient or an older, vigorous,masculine appearance for another (Figure 18-64, A).

Most patients who need dentures are at an agewhen the contact areas of their natural teeth havebeen worn, whether or not the teeth overlap eachother. Therefore the artificial teeth should be soaltered that they do not have the appearance of ballcontact points with large interproximal spaces. If theteeth selected have contact points that resemble thoseof a young person’s teeth, they should be ground toprovide a more natural appearance (Figure 18-64, B).

Refinement of Individual Tooth Positions

One of the essential factors in satisfying patientswith complete dentures is that the dentures bepleasing and natural in appearance. Dentures arenot pleasing unless the teeth are arranged in a planthat nature developed. If patients have some ante-rior teeth remaining, diagnostic casts should bemade as preextraction records to be used in select-ing and arranging the individual teeth. If dentistsuse preextraction records in construction of manydentures, they soon will learn nature’s scheme inarranging teeth for patients who have lost all teethbefore a record was made. With patients for whomno preextraction records are available, dentists canselect another cast of natural teeth and follow thisarrangement as a guide.


Figure 18-61 The amount of wear on the incisal edges of anterior teeth should concurwith the patient’s age. A, Lack of wear is compatible with youth. B, Extreme wear indicates amuch older person.

Figure 18-62 A simple sketch by the dentist of theoutline form of artificial teeth will be helpful in plan-ning the incisal wear to be incorporated for a particularpatient. Dotted line shows the original appearance ofthe incisal edges of artificial teeth; solid line shows theincisal wear anticipated.

A B

Figure 18-63 A, Incisal wear on artificial teeth. B, The pattern of wear in A has beendeveloped to improve the appearance of the denture and assist in balancing the occlusion.Wear on the upper canine is placed to correspond with wear on the lower canine in abalanced occlusion.

A B

Figure 18-64 A, One mold of teeth has been modified so the three teeth on the leftdepict youth and femininity, whereas the three on the right are suitable for an older mascu-line individual. B, The contact areas and incisal edges of artificial teeth must be modified toprovide a natural appearance.

A

The selection and placing of artificial teeth willnot appear natural unless the teeth are set with typ-ical inclinations and rotations that the eye has beenaccustomed to seeing. These inclinations and rota-tions can cause the same teeth to appear as over-sized or normal. For example, if the canine isrotated so the eye sees only its mesial half, thetooth will look only half as large as it would if itsentire labial surface were visible to the eye. Lateraland central incisors, especially in a tapering setup,do not show the entire labial surface when seenfrom directly in front. This reduction in the amountof surface showing harmonizes with a taperingface.

A beginning point for studying the labiolingualinclination of the maxillary anterior teeth in rela-tion to the perpendicular is shown in Figure 18-65.The labial surface of the maxillary central incisor isparallel to the profile line of the face, which isalmost perpendicular. The labial surface of the lat-eral incisor is angled in at the cervical end morethan that of the adjacent tooth. The labial sur-face of the canine is angled out at the cervical endmore than that of any other maxillary anteriortooth. The degree to which the cervical end of thecanine extends outward usually harmonizes withthe lateral lines of the face. The labial surface of themandibular central incisor is in at the cervical endmore than the labial of the lateral incisor or canineis. The mandibular lateral incisor is out at its cervi-cal end more than the central incisor, so as to bealmost perpendicular. The mandibular canine is outat its cervical end to the same degree as the maxil-

lary canine, except at an opposite angle. The labi-olingual inclinations of maxillary anterior teeth areintended to serve only as guidelines from whichvariations must be made if the individual patient’steeth are to appear natural.

A beginning point for studying the anteriorteeth from the labial aspect in their mesiodistalinclination is shown in Figure 18-66. The maxillaryand mandibular central incisors are almost perpen-dicular, whereas the laterals are inclined distally attheir cervical ends more than any other anteriortooth. The canines are inclined toward the distal attheir cervical ends more than the central and lessthan the lateral incisors are.

A beginning point for studying the rotationalpositions of the anterior teeth from an incisalaspect is shown in Figure 18-67. The maxillarycentral incisor is slightly rotated from parallelismwith the line of arch contour. The lateral incisor isrotated so its distal surface is turned lingually aconsiderable angle from the line of arch contour.The canine is rotated so the distal half of its labialsurface points in the direction of the posterior arch.The mandibular incisors have a rotational positionthat generally parallels the arch contour.

A beginning point for studying the superoinfe-rior position of the six anterior teeth in relation tothe incisal plane is shown in Figure 18-68. Themaxillary lateral incisor and canine are slightlyabove the level of the incisal plane.

All these positions of anterior teeth from the var-ious aspects serve only as beginning points and mustbe varied into harmonious irregularities that are not


Figure 18-65 Normal labiolingual inclinations of anterior teeth relative to theperpendicular. A, Maxillary central incisor. B, Maxillary lateral incisor. C, Maxillary canine.D, Mandibular central incisor. E, Mandibular lateral incisor. F, Mandibular canine.

A B C D E F

foreign to any that nature has established. For exam-ple, a maxillary canine is seldom in at the cervicalend and will appear completely artificial if this irreg-ularity is attempted. The patient cannot point outthe exact cause of the unnaturalness but will be

aware that something is wrong. Although these arethe beginning positions for studying teeth in idealalignment, dentures with teeth set precisely in thesepositions also will look artificial. Irregularities areessential to esthetics.

A number of irregularities are found so fre-quently that they appear natural when reproduced.To reduce the artificiality of dentures, the dentistshould make the teeth somewhat irregular. Whenthis is done, a study of the common irregularities ofmaxillary anterior teeth will show (1) a slight lap-ping of the mesial surfaces of lateral incisors overthe central incisors; (2) a depressing of the lateralincisors lingually so the distal surface of the centraland the mesial surface of the canine are labial tothe mesial and distal surfaces of the lateral; (3) arotating of the mesial incisal corner of each lateralincisor lingual to the distal surface of the centralwhile the distal surface of the lateral remains flushwith the mesial surface of the canine; and(4) placement of the incisal edge of each lateralhigher than that of the central incisor and canine.

Irregularities of the central incisors may bedeveloped by overlapping of the labial incisal angleof one central incisor on the adjacent central inci-sor, by placing one central incisor slightly lingualto the other central incisor without rotation, and byplacing one central slightly labial to and longerthan the other.


Figure 18-67 Incisal views of anterior teeth showingtheir angle of rotation. Maxillary (A) and mandibular (B).

Figure 18-66 Mesiodistal inclination of anteriorteeth relative to the perpendicular.

A

B

Figure 18-68 Superoinferior positions of anteriorteeth relative to the incisal plane.

The maxillary canine may be placed labially inthe dental arch, giving this tooth considerableprominence. However, the canine must maintain arotational position that does not expose the distalhalf of its labial surface to the eye when viewedfrom immediately in front. The canine must neverbe depressed at its cervical end. Rather, its labialsurface should be more or less parallel to the sideof the face when viewed from the front.

The mandibular anterior teeth can be madeslightly irregular, with much effectiveness, if theirregularities are harmonious with nature’s frequentirregularities. A setup that decreases the artificialappearance is one in which both central incisors areforward and rotated mesially, one or both lateralincisors are lingual to the arch curve and slightlylonger than the adjacent teeth, and the mesial sur-faces of the canines overlap the distal surfaces ofthe lateral incisors (Figure 18-69).

To overlap teeth in rotational positions and at thesame time avoid excessive labiolingual irregularities,the dentist must grind the lingual side of the proximalsurface of the overlapping tooth. The overlappingcontacts in natural teeth have been worn by the move-ment of the teeth on their contact points in function.Therefore to simulate worn natural overlapping, thedentist must grind the more labially placed of twooverlapped teeth on its lingual contact area.

Harmony of Spaces and Individual ToothPosition The use of spaces between teeth can beeffective for emphasizing individual tooth posi-

tions and creating a natural-appearing arrangementof teeth. A space usually is not desirable betweenthe upper central incisors unless one existedbetween the natural teeth. Even then, if the spacewas large, a smaller space in the denture can createa similar effect and be more pleasing (Figure 18-70, A). Spaces between central and lateral inci-sors, between lateral incisors and canines, andbetween canines and premolars are effective irreg-ularities that are visible, particularly when seenfrom the side (Figure 18-70, B and C). The locationof spaces should be chosen carefully to maintainproper balance in the overall composition. Spacesmust be designed so they can be self-cleansing.

Concept of Harmony with Sex, Personality,and Age of the Patient

Frush and Fisher presented the concept that creat-ing the illusion of natural teeth in artificial denturesis based on the elementary factors suggested by thesex, personality, and age of the patient. Femininityis characterized by curved surfaces, roundness andsoftness in the form of the dentition, and a promi-nent smiling-line alignment of the anterior teeth.Masculinity is characterized by boldness, vigor,and squareness in the dentition and a straightnessof the incisal line of teeth. The personality spec-trum is divided into delicate, medium, and vigor-ous, with connotations of personality variations inthe masculine or feminine classifications. It isrelated to the molds, colors, position of teeth, and


Figure 18-69 A, Notice the mesial rotation of the central incisors, the rotation and posi-tion of the lateral incisors, and the mesial aspect of the canines overlapping the distal of thelateral incisors. B, These mandibular anterior teeth appear natural in the patient’s mouth.

A B


A B

CFigure 18-70 A, Space between the upper central incisors can be effective in maintain-ing the identity of a patient if it was present between the natural central incisors. B, Spacebetween the central and lateral incisors helps create a natural appearance in the arrange-ment of artificial anterior teeth. C, Space between the lateral incisor and canine provides agood esthetic effect when seen from the side. However, it is not visible when seen from thefront. (Compare with Figure 18-56, B.)

form of the supporting matrix for the teeth. Age isdepicted in dentures by worn incisal edges, erosion,spaces between teeth, and variations in the form ofthe matrix around the cervical end of a tooth.

Individual tooth form and position also arerelated to these concepts. The size and position ofthe central incisors dominate the arrangement of thesix upper anterior teeth. Rotation of the distal sur-faces anteriorly and placement of one central inci-sor bodily ahead of the other make the appearanceof these teeth more vigorous (Figure 18-71, A).Smaller lateral incisors with rounded incisalangles appear more feminine than larger ones(Figure 18-71, B). Rotation of the lateral incisorswill harden or soften the composition. Canines arepositioned to complete the smiling line, rotated sotheir mesial surface faces anteriorly, abradedaccording to physiological age, set with the cervi-cal end out, and aligned with the long axis in a

vertical direction when viewed from the side(Figure 18-71, C).

The concept of the influence of sex, personal-ity, and age provides additional information fordeveloping harmony between the composition oftooth arrangement and the patient. Dentists musttake full advantage of all concepts to create den-tures that restore the natural appearance of theirpatients (Figure 18-72).

Correlating Esthetics and Incisal Guidance

The best plan of occlusion to enhance stability ofcomplete dentures is one with a shallow incisalguidance inclination. The reduction in verticaloverlap of the anterior teeth may detract fromthe appearance of dentures because it is likelyto place the maxillary anterior teeth too high orthe mandibular anterior teeth too low in the oral


Figure 18-71 A, The central incisors dominate this arrangement of artificial anteriorteeth. B, The rounded incisal edges and relative sizes of the upper lateral incisors provide acomposition that is feminine in appearance. C, Notice the location of the upper left caninerelative to the smiling line. Wear on this tooth is compatible with the patient’s age. Noticealso the anteriorly facing mesial surface and the vertical long axis of this tooth.

A

B C

orifice. The simplest way to overcome this diffi-culty and still maintain a pleasing esthetic appear-ance would be to increase the horizontal overlap(Figure 18-73). However, if this is done, the lipsupport or the occlusal vertical dimension will bechanged. These procedures may not be feasible ifthe esthetics and mechanics are to be protected.

The dentist can reduce the vertical overlap ofanterior teeth by increasing the interridge distance.However, this must not be done to the extent that itwould encroach on the interocclusal distance.

A compromise involves slightly shortening theupper and lower canines while maintaining the fulllength of the incisors. In this situation, occlusalbalance in the protrusive position may not be pos-sible, although it can be achieved in the lateralocclusions. Protrusive balance is less importantthan lateral balance because incision is performedconsciously. The patient can control the amountand direction of force applied when biting intofood. On the other hand, chewing is done at a sub-conscious level. Patients do not think of the


A B

Figure 18-72 A, Total lack of support of a patient’s face. Notice the prominent chin. B,The lips have been restored to a natural position, accompanied by an improved appearanceof the chin and restoration of the mentolabial sulcus. C, The upper anterior teeth arearranged on an incline relative to the upper lip. Notice their distance in front of the residualalveolar ridge. D, The lips move naturally because the muscles that control facial expressionhave been restored to their proper physiological length. The teeth also appear naturalbecause of their correct size, form, color, and arrangement.

C D


amount and direction of the force they apply.Consequently, they cannot protect themselvesfrom forces that would dislodge their dentures.The angle of incisal guidance for lateral occlusionmust be adjusted so the posterior teeth contact atthe same time that the upper and lower canines areend to end.

Even when the vertical overlap of the anteriorteeth must be severe for proper esthetics, theopposing anterior teeth should not be in contactwhen the posterior teeth are in CO (Figure 18-74).Such contact will eventually cause excess pressuresfrom occlusion of the anterior teeth when the resid-ual ridges resorb and the vertical dimension ofocclusion is decreased. Excessive force usuallycannot be tolerated by the anterior part of the resid-

ual ridges and will likely cause increased resorp-tion of bone and development of hyperplastic tissuein this region.

PATIENT ACCEPTANCE OF THEARRANGEMENT OF ANTERIOR TEETHPatients must be given the opportunity to observeand approve the final arrangement of the anteriorteeth at the try-in appointment. The denturesshould not be completed until approval is obtained.Even when patients indicate that they “do not carehow their teeth look,” they must be given fullopportunity to inspect and approve the arrange-ment. These patients often become extremely con-cerned with their appearance when they begin towear the dentures. Patients should not be permittedto observe the trial dentures in the mouth until thedentist is satisfied with the composition as it iscreated. The premolars should be in the properarch form, and the wax denture bases should becarved to approximate the final form. Initialreactions of patients can be longlasting, and anunsatisfactory reaction to a partially completedarrangement of anterior teeth may cause continuedproblems even though the final appearance of thedentures is perfectly satisfactory.

Because the dentures will be seen most often byother people during normal conversation, patientsshould first observe themselves in this situation.The patient is positioned 3 to 4 feet (1 to 1.3 m) infront of a large mirror with the trial dentures in themouth and given the opportunity to observe thedentures during normal conversation and facialexpression. The reaction at this time can be criticalto the eventual success of the dentures, so thisphase must not be done hurriedly or haphazardly.The patient should be encouraged to bring alongthe most critical family member or friend to assistin evaluating the appearance of the trial dentures.

The dentist should listen carefully to all com-ments made by the patient and never dismiss any ofthem as silly or of no consequence. Some changesthat the patient may suggest can be incorporated.However, other suggestions may not be advisable,and it will be necessary to explain that they are notanatomically feasible and would prevent the mus-cles in the cheeks and lips from properly movingthe face. Many patients will be pleased with the

Figure 18-73 Vertical (A) and horizontal (B) over-laps. C, Incisal guidance angle.

Figure 18-74 Opposing anterior teeth should notcontact when the posterior teeth are in centric occlusion.

appearance of the dentures and request few, if any,changes when the position of the artificial teethapproximates that of the natural teeth.

When the dentist and staff and the patient andany critical friends are satisfied with the appearance,it is helpful to have the patient sign a statement thatwill be placed in the patient’s chart (Figure 18-75).

This statement protects the dentist againstthe occasional patient who will claim that oppor-tunity was not given to view the teeth whilearranged in wax or that the requested changes werenot done.

BibliographyFrush JP, Fisher RD: How dentogenic restorations interpret the

sex factor, J Prosthet Dent 6:160-172, 1956a.Frush JP, Fisher RD: How dentogenics interprets the personality

factor, J Prosthet Dent 6:441-449, 1956b.Frush JP, Fisher RD: Age factor in dentogenics, J Prosthet Dent

7:5-13, 1957.Frush JP, Fisher RD: The dynesthetic interpretation of the den-

togenic concept, J Prosthet Dent 8:558-581, 1958.Lombardi RE: The principles of visual perception and their clin-

ical application to denture esthetics, J Prosthet Dent 29:358-382, 1973.

Swoope CC: The try-in—a time for communication, Dent ClinNorth Am 14:479-491, 1970.


I, (insert patient’s name), have been given the opportunity to look at the finalarrangement of the artificial teeth (while positioned in wax). Any necessarychanges have been made, and I am happy with the general appearance of thedentures.

_______________________________________________________________ Signature Date

Figure 18-75 Patient’s statement of satisfaction with the arrangement of artificial teeth.

C H A P T E R 19Speech Considerations with CompleteDenturesStig L. Karlsson

379

Speech is a very sophisticated, autonomous, andunconscious activity. Its production involves neu-ral, muscular, mechanical, aerodynamic, acoustic,and auditory factors. Because orodental morpho-logical features also may influence an individual’sspeech, the dentist should therefore recognize thepossible role of prosthetic treatment on speechactivity. The specific relationship between den-tistry and speech pathology is still emerging.However, considerable clinical experience andresearch provide a reliable background for address-ing this essential topic.

Oral motor functions, such as mastication andspeech production, share many common features.They are intimately related because the mouth,lower jaw, lips, teeth, and tongue are used forboth activities. Any alteration of these structureswill inevitably mediate a disturbance in the sys-tem. This may be minor or more substantial inimportance, depending on individual responses.Articulatory deficits may be generally classifiedinto three categories: omission of a phoneme, sub-stitutions, and distortions. The latter is the mostusual consequence after prosthodontic treatment.Fortunately, the phonetic problems that arise whenspeaking with new dentures rarely pose serious dif-ficulties. Because most patients’ ability to adapt isgood, initially experienced speech disturbanceswill be transient. Nevertheless, the treatment objec-tive is to make complete dentures conform to theindividual patient’s existing neuromuscular pat-terns, rather than rely too much on the patient’sability to adapt.

In this chapter, some basic background factorsfor speech production are described to provideknowledge of possible speech problems induced

by the fabrication and wearing of completedentures.

SPEECH PRODUCTION: STRUCTURALAND FUNCTIONAL DEMANDSControlling the airstream that is initiated in thelungs and passes through the larynx and vocalcords produces all speech sounds. Speech soundsneed substantially more air than does quiet exhala-tion; consequently, subtle adjustments in air flowcontribute to variations of pitch and intensity ofthe voice. The structural controls for speech soundsare the various articulations or valves made inthe pharynx and the oral and nasal cavities (Figure19-1). Each sound is affected by the length, diame-ter, and elasticity of the vocal tract and by thelocations of constrictions along its length.

Because nearly all speech sounds are emittedfrom the mouth, the nasopharynx (airway into thenose) is closed off from the oropharynx duringspeech. Closure is performed by an upward lift ofthe soft palate. A rapid, continuous movement of theentire length of the soft palate takes place duringspeech. Intimacy of pharyngeal wall contact, as wellas magnitude of movement by the soft palate, varieswith the nature and sequence of the speech sounds.As the outgoing air passes through the mouth,tongue, lips, and mandibular oscillations modify it.The tongue has a critical impact on speech produc-tion and needs optimal mobility to lift, protrude, flat-ten, form a groove(s), and contact adjacent tissuesfreely. Jaw and tooth relationships enable the tongueto articulate against the maxillary teeth or alveolus,permit the maxillary teeth and lower lip to makeeasy contact, and allow the lips to touch.

NEUROPHYSIOLOGICAL BACKGROUNDA very complex and imperfectly understood neuro-physiological mechanism governs the productionof speech. A large number of oral mechanosensi-tive receptors (tactile and kinesthetic) are involvedin its motor control. Therefore all prosthodontictreatment will, more or less, have an influence onspeech performance because a great number ofthese structures will be involved.

Speech production includes large numbers andsequences of innate and learned motor acts pro-duced in rapid sequences of 12 to 16 sounds persecond in a rhythmic behavior, similar to chewing.In this context, the theory of “least effort” also hasbeen discussed among researchers in the field. Ithas been hypothesized that less cortex area isrequired for processing of skills as they becomeautomatic. Once automatized, speech controlbecomes localized in certain areas such as thepremotor and motor cortex. For the precise move-ments executed in speech production, the pyramidalmotor system has the primary role. Still, there is noconvincing evidence to explain fully the mecha-nisms behind these very rapidly occurring events.

Feedback plays a dynamic and flexible role in thecontrol of most motor events, including sequencing

and timing of speech movements. There seems to bea subconscious but learned type of pattern recogni-tion, or feedback, of afferent information used toguide central pattern generators (CPGs) and a centralprogram. The CPGs are thus important in the basicrhythm generation and timing of motor activity.Other neural networks are probably also very activein the rapid transformations of the shape of the oralcavity from one fixed configuration to another.Proprioceptive mechanosensitive afferents will estab-lish the timing of certain aspects of the very fastmotor pattern and will, in synergy with cortical infor-mation, generate the final motor output and rhythm.A precise coordination between different articulatorsis essential for the final sound production.

A prerequisite for satisfactory speech soundsand adaptation is an intact general feedback sys-tem; that is, orosensory and audio feedback (Figure19-2), which is regarded as an important mecha-nism. Gradual hearing loss could be present atolder ages, and the process of adaptation of dentalprostheses could be impaired. Adaptation after anoral rehabilitation also may create problems in theformation of a new speech motor programming.

It appears that adaptation to complete denturesmay be explained by feedback mechanismsrelated to speech motor programming. Initially, acomplete denture wearer attempts to overcomeproblems related to the new prosthesis by the helpof auditory and orosensory feedback during func-tion. After a while, only the patient will be awareof remaining articulatory difficulties, which oftenare related to certain specific sounds. The listener(dentist) is, however, not able to detect any speechproduction disturbances. At this stage, there isstill sensory stimulation from orofacial afferentsto central areas. Finally, if the process of adapta-tion proceeds, the patient will not be aware of anyarticulatory difficulties or distortional sounds dueto the prosthesis. New speech production centralengrams have been established, and adaptationand habituation to the complete denture occur.

SPEECH PRODUCTION AND THE ROLEOF TEETH AND OTHER ORALSTRUCTURES

Because speech production can be used as a guideto position artificial teeth, it is necessary to be


Nasopharynx

Epipharynx

Hypopharynx

Figure 19-1 Schematic picture of the differentvalves and articulators.

familiar with how various speech sounds are pro-duced. Tooth positions are sometimes critical to theproduction of certain sounds and not at all for oth-ers. Because the teeth are being arranged for esthet-ics, it is not the speech sound itself that is criticalbut rather, the interrelationships of the tongue,teeth, denture base, and lips. Speech productionmade by patients at the try-in appointment cannever be as accurate as when the processed acrylicresin denture base has been substituted for the trialbases, and the patient has become accustomed tothe new dentures. The following definitions andexamples provide information for a tabular presen-tation of various sounds (Table 19-1). Vowels arevoiced sounds, that is, the vocal cords are activatedby vibration in their production. They are the freeemission of a speech sound through the mouth andrequire subglottic pressure for the production. Thevowels in English are a, e, i, o, and u. Consonantsmay be either voiced or produced without vocalcord vibration, in which case they are calledbreathed sounds. Consonants are produced as aresult of the airstream being impeded, diverted, orinterrupted before it is released, such as p, g, m, b,s, t, r, and z. Most consonants may be classified inpairs that are formed in the same manner, except

that one is breathed and the other voiced. For exam-ple, p is breathed; b is voiced. Consonants also aredivided into groups, depending on their characteris-tic production and use of different articulators andvalves. Plosive consonants are produced when anoverpressure of air has been built up by contactbetween the soft palate and the pharyngeal wall andreleased in an explosive way, such as p and t. On theother hand, fricatives, such as s and z, also are calledsibilants and are characterized by their sharp andwhistling sound quality created when air issqueezed through the nearly obstructed articulators.Affricative consonants are a mix between plosiveand fricative ones. Nasal consonants are producedwithout oral exit of air (m, n, and ng). Liquid con-sonants are, as the name implies, produced withoutfriction, and finally, glides, that is, sounds charac-terized by a gradually changing articulator shape.

According to Table 19-1, six different valvesexist, of which five may be affected by teethposition.

Bilabial Sounds

The sounds b, p, and m are made by contact of thelips. In b and p, air pressure is built up behind the

Chapter 19 Speech Considerations with Complete Dentures 381

Feed

back

Speaker Listener

Engrams

Emotions

perception

Ear

Reception

Engrams

Emotions

Cortical areas

Motor nervesEar

Sound

Sound

Articulation,Speech production

Figure 19-2 Speech production and communication.

382Part Three

Rehabilitation ofthe Edentulous Patient: Fabrication of

Complete D

entures

Table 19-1English Consonants: Their Position and Modes of Production

Mode ofproduction

Plosives (stops) Fricatives Affricatives Nasals Liquids Glides

Position Breathed Voiced Breathed Voiced Breathed Voiced Breathed Voiced Breathed Voiced Breathed Voiced

Bilabial p (pay) b (bay) m (man) w (witch)Labiodental f (fan) v (van)Linguodental th (thumb) th (there)Linguoalveolar t (to) d (dot) s (so) z (zoo) n (name)Linguopalatal sh (shoe) z (vision) ch (chin) j (jar) r (rose) y (you)Linguovelar k (back) g (bag) h (who) ng (bang)

lips and released with or without a voice sound.Insufficient support of the lips by the teeth or thedenture base can cause these sounds to be defec-tive. Therefore the anteroposterior position of theanterior teeth and thickness of the labial flange canaffect the production of these sounds. Likewise, anincorrect vertical dimension of occlusion (VDO) orteeth positioning hindering proper lip closuremight influence these sounds.

Labiodental Sounds

The labiodental sounds f and v are made betweenthe upper incisors and the labiolingual center to theposterior third of the lower lip. If the upper anteriorteeth are too short (set too high up), the v sound willbe more like an f. If they are too long (set too fardown), the f will sound more like v (Figure 19-3).

However, the most important information to besought while the patient makes these sounds is therelationship of the incisal edges to the lower lip.The dentist should stand alongside the patient andlook at the lower lip and the upper anterior teeth. Ifthe upper teeth touch the labial side of the lower lipwhile these sounds are made, the upper teeth aretoo far forward, or the lower anterior teeth are toofar back in the mouth. In this situation, the rela-tionship of the inside of the lower lip to the labialsurfaces of the teeth should be observed while thepatient is speaking. If the lower lip drops away

from the lower teeth during speech, the lower ante-rior teeth are most probably too far back in themouth. If, on the other hand, imprints of the labialsurfaces of the lower anterior teeth are made in themucous membrane of the lower lip or if the lowerlip tends to raise the lower denture, the lower teethare probably too far forward, and this means thatthe upper teeth also are too far forward.

If the upper anterior teeth are set too far back inthe mouth, they will contact the lingual side of thelower lip when f and v sounds are made. This mayoccur also if the lower anterior teeth are too far for-ward in relation to the lower residual ridge.Observing from the side and slightly above thepatient will provide the necessary information fordetermining which changes should be made.

Linguodental Sounds

Dental sounds (e.g., th in this) are made with the tipof the tongue extending slightly between the upperand lower anterior teeth. This sound is actuallymade closer to the alveolus (the ridge) than to thetip of the teeth. Careful observation of the amountof tongue that can be seen with the words this, that,these, and those will provide information as to thelabiolingual position of the anterior teeth. If about3 mm of the tip of the tongue is not visible, theanterior teeth are probably too far forward (exceptin patients with a Class II malocclusion), or there


Figure 19-3 Effects of tooth positioning on f and v. A, Upper anterior teeth too long.During the pronunciation of f, they will contact the lower lip in a position similar to v, andthe sounds may sound alike. B, Effects of anteroposterior positioning of the teeth from left toright are correct, too far posterior, and anterior.

A B

may be an excessive vertical overlap that does notallow sufficient space for the tongue to protrudebetween the anterior teeth. If more than 6 mm ofthe tongue extends out between the teeth whensuch th sounds are made, the teeth are probably toofar lingual.

Linguoalveolar Sounds

Alveolar sounds (e.g., t, d, s, z, v, and l) are madewith the valve formed by contact of the tip of thetongue with the most anterior part of the palate (thealveolus) or the lingual side of the anterior teeth.The sibilants (sharp sounds) s, z, sh, ch, and j (withch and j being affricatives) are alveolar soundsbecause the tongue and alveolus form the control-ling valve. The important observation when thesesounds are produced is the relationship of the ante-rior teeth to each other. The upper and lower inci-sors should approach end to end but not touch(Figure 19-4). A phrase such as “I went to churchto see the judge” will cause the patient to use thesecritical sounds, and the relative position of theincisal edges will provide a check on the totallength of the upper and lower teeth (including theirvertical overlap).

More important, a failure of the incisal edges toapproach exactly end to end indicates a possibleerror in the amount of horizontal overlap of the ante-rior teeth (Figure 19-5). This test will reveal the error

but will not indicate whether it is the upper teeth orthe lower teeth that are incorrect labiolingually.

From a dental point of view, the s sound is themost interesting one because its articulation is mainlyinfluenced by the teeth and palatal part of the maxil-lary prosthesis. Clinical experience suggests that sand t can cause most problems in a prosthodonticcontext. In nearly all languages of the world, s is acommon speech sound. Some languages (e.g.,Finnish and Spanish) have diverging s pronunciation,but generally the interlanguage quality variation issmall. On the other hand, the interindividual variationin articulatory details may be great because of indi-vidual variation in teeth, palate, lower jaw, and tongueshape and size. Given this variation, different speak-ers have to shape the detailed s gestures differently toachieve a similar s quality. The following phoneticproperties, however, are common to all s sounds:

Articulatory Characteristics

1. The tip of the tongue is placed far forward,coming close to but never touching theupper front incisors.

2. A sagittal groove is made in the upper frontpart of the tongue, with a small cross-sec-tional area.

3. The tongue dorsum is flat.4. Normally, the mandible will move forward

and upward, with the teeth almost in contact.


Figure 19-4 Vertical length of the anterior teeth during sibilant production from left toright are correct, excessive, and inadequate vertical overlap.

Acoustic Characteristics

1. The comparatively strong sound energy isconcentrated to a high-frequency range, witha steep energy cutoff at about 3 to 4 kHz.

Auditory Characteristics

1. The sound is fairly loud, with a light, sibi-lant (sharp) quality.

The s sounds can be considered dental and alve-olar speech sounds because they are producedequally well with two different tongue positions, butthere can be some variation even behind the alveo-lus. Most people make the s sound with the tip ofthe tongue against the alveolus in the area of the rugae,with but a small space for air to escape between thetongue and alveolus. The tongue’s anterior dorsumforms a narrow groove near the midline, with a crosssection of about 10 mm2. The size and shape of thissmall space will determine the quality of the sound.Part of the sibilant sound is generated when the teethare being hit by a concentrated air jet. If the openingis too small, a whistle will result. If the space is toobroad and thin, the s sound will be developed as ansh sound, somewhat like a lisp. The frequent cause ofundesired whistles with dentures is a posterior den-tal arch form that is too narrow.

Creation of a sharp s requires accuracy of theneuromuscular control system, for the creation ofthe groove and directioning of the air jet. Evensmall deviations of only 1 mm will influence the

quality. For example, if the tip of the tonguetouches the upper front teeth, the result will be alisped sound. The fact that the teeth play an impor-tant part in articulating this sound often has beenneglected, and the oral aerodynamics involved arestill an unexplored area.

Linguopalatal and Linguovelar Sounds

The truly palatal sounds (e.g., those in year, she,vision, and onion) present less of a problem fordentures. The velar sounds (k, g, and ng) have noeffect on dentures, except when the posteriorpalatal seal extension encroaches on the softpalate.

METHODS FOR SPEECH ANALYSISA number of methods are available for speechanalysis, with some more useful for the dentist thanothers. There are basically two categories: percep-tual/acoustic analysis, and kinematic methods formovement analysis.

When patients have severe speech pathologyproblems, their clarity and pronunciation shouldpreferably be analyzed by a speech pathologist. Itwould be valuable to do this before starting prostho-dontic rehabilitation, just to establish a basis for futurecomparisons and, if possible, identify problems.

An acoustic analysis is based on a broad-band spectrogram recorded by a sonograph dur-ing the uttering of different phrases containing


Figure 19-5 Horizontal relation of the anterior teeth during sibilant production fromleft to right are correct, excessive, and deficient overlapping.

key phrases. By doing this, an objective opinionof the performance of certain sounds may beachieved.

Kinematic analysis includes such methodsas ultrasonics, x-ray mapping, cineradiography, opto-electronic articulatory movement tracking, and elec-tropalatography (EPG). Some of these methods playan essential part in both experimental and routineclinical evaluations of speech defects and treatmenteffects. They also could be a useful tool for assess-ment of tongue contact positions and movements. Anumber of these methods are very exclusive and notaimed for routine examinations, whereas others, suchas cineradiography, may have undesirable sideeffects. EPG is used for registrations of tongue con-tact patterns during speech production and a map-ping of the contacts could be achieved (Figure 19-6).

None of these methods is, however, aimed foruse in routine practice but rather after the failure ofconventional means to improve an impaired speechproduction.

PROSTHETIC CONSIDERATIONSSpeech problems usually are identified immedi-ately after prosthetic treatment. When comparedwith younger individuals, older complete denturewearers experience greater difficulties in adaptingtheir speech to new prostheses and also needlonger time to regain their natural speech. A frequentcause is impaired auditory feedback, and there-fore a simple auditory test might be useful in suchpatients to make a proper diagnosis. It also is impor-tant to listen to and analyze patients’ speech soundsbefore the rehabilitation starts and even more impor-tant to inform patients that temporary speech sounddeterioration may result from the oral rehabilitationtreatment.

Speech adaptation to new complete denturesnormally takes place within 2 to 4 weeks afterinsertion. If maladaptation persists, special meas-ures should be taken by the dentist or by a speechpathologist, if the problem continues. Particularattention should be paid to patients with long expe-rience of wearing complete dentures. When newprostheses have to be made for these patients, cer-tain difficulties in learning new motor acts maydelay and obstruct the adaptation. Consequently, avirtual duplication of the previous denture’s archform and polished surfaces, especially the palate ofthe maxillary denture, will ensure a minimal periodof postinsertion speech adaptation. Old denturesmay be of guidance when designing new ones and,if necessary, a virtual copy of the denture could bemade. This procedure will frequently solve a prob-lem that may arise due to speech and adaptationdifficulties.

A prudent way to overcome possible prob-lems is to study the profile form and lip line of thepatient’s face, which often is representative ofthe natural anterior tooth inclination. In such a sit-uation, it would be logical to assume that this pro-file parallels a correct positioning of the anteriorteeth, both for speech production and harmony inesthetics. If the teeth are too far lingual, the t intend will sound more like a d. If they are too faranterior, the d will sound more like a t. The palateof a denture base that is too thick in the area of therugae could have the same effect.

A cramped tongue space, especially in the pre-molar region, forces the dorsal surface of thetongue to form too small an opening for the escapeof air. The procedure for correction is to thicken thecenter of the palate so the tongue does not have toextend up as far into the narrow palatal vault. Thisallows the escape way for air to be broad and thin.


Figure 19-6 Typical electropalatography diagrams for the sounds in oh sadist. Shadedarea represents the contact between tongue and palate. Note the sagittal groove createdwhen the s sound is uttered.

A lisp with dentures can be corrected when the pro-cedure is reversed and a narrow concentrated air-way is provided for the s sound.

About one third of patients make the s soundwith the tip of their tongue contacting the lingualside of the anterior part of the lower denture andarching itself up against the palate to form thedesired shape and size of airway. The principlesinvolved in such a palatal valve are identical to thoseinvolved in the other tongue positions. However, themandibular denture can cause trouble. If the anteriorteeth are too far back, the tongue will be forced toarch itself up to a higher position, and the airway willbe too small. If the lingual flange of the mandibulardenture is too thick in the anterior region, the resultwill be a faulty s sound. It can be corrected when theartificial teeth are placed in the same position thatthe natural teeth occupied and the lingual flange ofthe mandibular denture is so shaped that it does notencroach on the tongue space.

When the vertical dimension is established dur-ing the maxillomandibular registration, speech canbe used for guidance to assess a correct VDO. Sucha procedure is recommended by many dentists, buta dentist using this method needs longtime experi-ence and knowledge to perform properly. Duringthe pronunciation of the s sound, the interincisalseparation, vertical distance, should average 1 to1.5 mm. This also is referred to as the closestspeaking space.

In a recent study, influence of alterations ofVDO and palatal configuration on three conso-nants, k, c, and s, was investigated. It was con-cluded that malformation of the palatal parts of thedenture influenced speech production more thandifferences in VDO did.

SUMMARYSpeech difficulties as a sequel of oral rehabilitationwith complete dentures is generally a transient prob-lem. When encountered, the difficulties may not beeasily solved. Therefore efforts should be made toavoid them by pretreatment records or assessmentof speech and provision of information to patientsabout likely initial deviations from normal speech,immediately after the oral rehabilitation. If persist-ent difficulties to pronounce certain sounds orother speech disorders persist for more than 2 to 4

weeks, the dentist is recommended to follow thisprotocol:

1. If the patient has a previous complete den-ture experience, compare the new set withthe old one to diagnose possible design dif-ferences of significance for speech produc-tion. If, on the other hand, a remainingnatural dentition is to be converted into acomplete denture, a transfer of the originalposition of the natural teeth to the dentureshould facilitate adaptation.

2. Listen to the patient and then try to pro-duce the very same distorted sound yourself.Observe the position of your own articula-tory structures, tongue, lips, mandible, andso on, when producing this sound and trans-form them to the patient, thereby making itpossible to identify the structures hinderinga correct speech production.

3. Make the necessary modifications; soft waxmight be helpful.

4. Have the patient’s hearing checked. An audi-tory deficit will prolong the adaptationperiod and render it more difficult.

5. If the reported/perceived problem cannot beresolved by dental methods, the patientshould be referred to a speech pathologist.

BibliographyAbbs JH, Connor NP: Motorsensory mechanisms of speech

motor timing and coordination, J Phonetics 19:333-342,1990.

Benediktsson E: Variation in tongue and jaw position in “s”sound production in relation to front teeth occlusion, ActaOdontol Scand 15:275-281, 1958.

Bladon RA, Nolan FJ: A video-fluorographic investigation oftip and blade alveolars in English, J Phonetics 5:185-193,1976.

Fletcher SG, Neuman DG: (s) and (f) as a function of lingualpalatal contact place sibilant groove width, J Acoust Soc Am89:850-858, 1991.

Grillner S: Possible analogies in the control of innate motor actsand production of sound in speech. In Grillner S, LindblomB, Lubker J, Persson A, editors: Speech motor control,Oxford, 1982, Pergamon Press.

Hardcastle W, Gibbon F, Nicolaidis K: EPG data reductionmethods and their implications for studies of lingual coar-ticulation, J Phonetics 19:251-266, 1991.

Ichikawa T, Komoda J, Horiuchi M et al: Influence of alterationsin the oral environment on speech production, J OralRehabil 22:295-299, 1995.


Jacobs R, Manders E, Van Looy et al: Evaluation of speech inpatients with various oral implant-supported prostheses, ClinOral Impl Res 12:167-173, 2001.

Lindblad P, Karlsson S, Heller E: Mandibular movements inspeech phrases. A syllabic quasiregular continuous oscilla-tion, Scand J Log Phon 16:36-42, 1991.

Lindblom B, Sundberg J: Acoustic estimations of the frontcavity in apical stops, J Acoust Soc Am 88:1313-1317,1990.

Lundqvist S, Karlsson S, Lindblad P et al: An electropalato-graphic and optoelectronic analysis of (s) production, ActaOdontol Scand 53:372-380, 1995.

Lundqvist S, Lohmander-Agerskov A, Haraldson T: Speechbefore and after treatment with bridges on osseointegratedimplants in the edentulous upper jaw, Clin Oral Impl Res3:57-67, 1992.

McCord JF, Firestone HJ, Grant AA: Phonetic determinants oftooth placement in complete dentures, Quintessence Int25:341-345, 1994.

Petrovic A: Speech sound distortions caused by changes in com-plete denture morphology, J Oral Rehabil 12:69-79, 1985.

Runte C, Lawerino M, Dirksen D et al: The influence of maxil-lary central incisor position in complete dentures on /s/sound production, J Prosthet Dent 85: 485-495, 2001.

Seifert E, Runte C, Riebandt M et al: Can dental prosthesesinfluence vocal parameters?, J Prosthet Dent 81:579-585,1999.

Shadle HC: The effect of geometry on source mechanisms offricative consonants, J Phonetics 19:409-424, 1991.

Stevens KN: Airflow and turbulence noise for fricative and stopconsonants: statistic considerations, J Acoust Soc Am50:1180-1192, 1971.


C H A P T E R 20Waxing and Processing the Dentures,Their Insertion, and Follow-upRhonda F. Jacob, George A. Zarb, Charles L. Bolender

389

SECTION I: WAXING AND PROCESSING THE DENTURES

WAXING AND POLISHING SURFACESThree principal surfaces are involved in the func-tional stability of dentures: the basal or impressionsurface (often called the intaglio surface), theocclusal surface of the teeth, and the polished sur-faces. The latter is defined by the width of the bor-der, the buccolingual position of the teeth, and thefullness given the wax to obtain convexity or con-cavity both facially and lingually. These three sur-faces of the denture are positioned in harmony withfacial form and the anatomy and physiologicalmovements of the tissues and muscles of the oralcavity. Appropriate position of the dentition andwaxing of the polished surface contours and borderthickness should be determined at the try-inappointment. This will give the patient and the den-tist the opportunity to evaluate esthetics, phonetics,and comfort. Ideal position of the prosthetic denti-tion has been discussed in previous chapters, but thischapter discusses the details of the final form of thepolished surface as it relates to achieving optimalphonetics and enhanced stability and retention.

The form of the polished surfaces of a dentureinfluences its stability and retentive quality. Inaddition, it influences denture esthetics. The den-ture bases between the teeth and the border shouldbe shaped in such a manner as to aid retention bythe mechanical directional forces of the musclesand tissues. Generally speaking the contours arefull on the buccal aspect of the denture but arequite concave on the palatal and lingual surface

because of the functional and “at rest” spacerequirements of the tongue.

Because the mandibular denture rarely achievesthe desired retention and has a limited surface areacompared with the maxillary denture, the tongueand cheek muscles can easily dislodge it. Musclesof the cheek and tongue approximate the externaldenture surface and exert forces on the lateralinclined planes of the dentition and the polishedsurfaces. Figure 15-1 suggests action of the cheekand tongue in gripping a bolus of food. This actionmay be described by the illustration of a patientchewing a small grape, with the tongue and cheekholding the grape in place over the occlusal sur-faces of the teeth while closing pressure is exertedon it. In addition, a horizontal force is exertedalong the occlusal plane by the tongue and cheek.

A further study of Figure 15-1 suggests thesemuscular forces on the inclined planes of the pol-ished surfaces that can serve as a mechanical aid ora detriment to retention. For instance, when the lin-gual and buccal borders of a mandibular dentureare being shaped, they can be made concave to con-form to the tongue and check so their muscles willgrip and tend to seat the denture. In the oppositesituation in which the lingual and buccal surfaceare made convex beyond the confines of the border,the inclined plane forces resulting from pressuresof the tongue and cheeks will tend to unseat the den-ture. The correct buccolingual position of the teethis important because lateral forces are also exertedon the dentition during function. Teeth positionedtoo buccally or too lingually allow the musculatureof the cheek or tongue to create unfavorable forceson the inclined plane of the surface of the teethand the polished denture. These forces will tend to

unseat the denture. The contours of the polishedsurface begin at the gingival collars of the pros-thetic dentition. A buccal position of the teethwould likely not allow an adequate concavity of thedenture base between the gingival collar and den-ture border; the muscle action of the cheeks wouldtend to unseat the mandibular denture.

The buccal surface of mandibular dentures inthe first premolar region should be vertical to con-cave in shape so as not to interfere with the actionof the modiolus, connecting the facial muscles withthe orbicularis oris muscle. This connecting pointof muscles can displace the mandibular denture ifthe polished surface inclines toward the cheek or ifthe dental arch in the premolar region is too wide.The lingual flange of the mandibular dentureshould have the least possible amount of bulk,except at the border (which must be quite thick).This thickness is under the narrower portion of thetongue, and it greatly enhances the seal by contact-ing the mucolingual fold.

In the maxillary denture, the speech of thepatient will be handicapped unless the dentistdevelops a contour comparable to that of the palatebefore the natural teeth were lost. The thickness ofthe vertical walls of the maxillary alveolar area willvary with the loss of bone from the residual alveo-lar ridge. The horizontal palatal bones and the mid-line of the palate experience minimal resorption inthe edentulous patients. Therefore the thickness ofthe palatal surface of the maxillary denture shouldbe waxed to a uniform thickness of 2.5 mm. Thuswhen the processed resin is smoothed and polished,the palate will be as thin as possible and yet suffi-ciently thick to provide adequate strength.

In the maxillary denture, additional care shouldbe taken with the contours of the palatal alveolarsurface in the area of the premolars and canines.Airflow for speech sounds is greatly affected by thecontact or approximation of the lateral tongue inthese areas. There should be a gentle concave con-tour of the denture base extending from the palatalsurface of these teeth to the horizontal shelf of thepalate. If this contour is a deep concavity or a nearright angle between the vertical alveolar processand the horizontal shelf, the lateral border of thetongue will not control air during speech.Particularly, the s sound will be distorted, soundingmore like a “sh.” Fricative sounds of f and v may

also be distorted. Wax should be flowed along thejunction of the alveolar ridge and the horizontalshelves to create a gentle concave curve. Patientscan also be given water during the try-in of the den-tures. With a slightly wet mouth, they can be askedto speak. If water escapes from the lips, wax shouldbe added in the area of the premolars and canineson the offending side. When these ideal contoursare created, the technician must be advised not toalter these contours during the final wax-up or fin-ishing of the denture.

If the technician is using a laboratory techniquethat routinely removes the palate of the trial-basebefore final wax-up of the maxillary denture, thefinal contours of the junction of the alveolarprocess and the horizontal palate is left to the tech-nician. The technician may create too much con-cavity in the final wax-up resulting in “slurring ofspeech” when the patient wears the final denture.The dentist and technician must be aware of thebulk required in this area. Although most of thesecontour considerations are addressed at the try-inappointment, they may have to be refined furtherwhen preparing the dentures for processing; there-fore there is this reemphasis on fine-tuning the pol-ished surfaces while still in wax.

WAXING THE POLISHED SURFACESBefore the addition of wax to finalize the wax-up,it is important to evaluate the prosthetic occlusion.Wax shrinks when it loses temperature; therefore itis not uncommon for teeth to move slightly out ofocclusion. This is particularly visible when viewingfrom the posterior of the articulator into the lingualaspect of the dentition. Often the lingual aspect ofthe teeth needs to be lifted to meet the occlusalplane. Use of the metal occlusal plane is useful toevaluate that the teeth are set in harmony with eachother and the metal occlusal plane.

The wax surfaces around the teeth are known asthe art portion of the polished surface and should,for esthetic reasons, imitate the form of the tissuesaround the natural teeth. Any fancy or artificial fes-tooning is distinctly out of place. A slight projec-tion of the root to follow the individual tooth can bemade, however. The upper part of the polished sur-face, known as the anatomical portion, should beformed in such a way as to lose none of the origi-


nal border width of the impression. An excess ofbaseplate wax is added on the buccal and labial sur-faces of the mandibular and maxillary trial denturesand along the cervical collars of the teeth. The waxis cut back to the outer border of the cast (Figure20-1), and then the small end of a knife is held at a45-degree angle to the tooth surface to form thewax gingival margin (Figure 20-2). Care should betaken to expose the complete clinical crown of theincisors. This adds to the esthetics because mostadult natural dentition reveals the teeth to thecemento-enamel junction (CEJ). Also, the lessacrylic resin that is visible around the teeth, themore natural the appearance is. The common ten-dency is to cut the line too straight from interprox-imal to interproximal, not leaving enough wax in

the interproximal spaces (Figure 20-3). This willlead to food traps in the final denture, making themless self-cleansing during eating. It is well to havea surplus of wax along the gingival line and then toretrim when a complete view of the entire waxingis possible. Triangular markings can be placed as aguide to the length and position of the root indica-tions, as long as it is kept in mind that the root ofthe maxillary canine is the longest, the root of thelateral incisor is the shortest, and the root of the cen-tral incisor is a length between these two (Figures20-4 and 20-5). On the mandibular denture the rootof the canine is the longest, the root of the centralincisor is the shortest, and the root of the lateralincisor is between these two. The wax is scrapedout of these triangular areas, after which the rootindications will become manifest (Figure 20-6).The sharp and rough indications are now roundedwith a large scraper and the spatula (Figure 20-7).They should not be overemphasized.

Chapter 20 Waxing and Processing the Dentures, Their Insertion, and Follow-up 391

Figure 20-1 A and B, The amount of wax to be added. C and D, The correct reduction toenhance both stability and esthetic result.

A B C D

Figure 20-2 The angle at which the wax knifeshould be held for cutting the gingival line.

Figure 20-3 Gingival line cut with the propercontour. The dotted line shows incorrect cutting.

The lingual surface of the mandibular denturemay be made slightly concave without extendingthe depth of the concavity under the lingual surfaceof the teeth. A projection of the tooth beyond thepolished surface acts as an undercut into which thepatient’s tongue will slip, thereby causing the den-

ture to be unseated and also allowing food to accu-mulate (Figure 20-8).

In the maxillary denture, palatal festooningrestores part of the palatal surface of the tooth thatis not supplied in artificial teeth. Wax is added andcarved on the artificial teeth to imitate the normalpalatal contours of each tooth (Figures 20-9 and20-10).

FORMATION AND PREPARATION OFTHE MOLDAfter the trial dentures have been waxed, they areprepared for flasking. An ejector-type (three-piece)flask is used to facilitate removal of the dentureafter processing without danger of breaking thedenture. The pieces of the flask are usually referredto as the drag (bottom), cope (middle portion thatwill capture the teeth of the denture), and the cap(which is the thin top of the flask). Dental stone isused to invest the dentures and create the moldwithin the flask. A limited number of steps are nec-essary to create the mold, but optional steps are


A

B

C

Figure 20-4 A, Root indications on the skull. B, Continued gingival prominences. C,contour of the gingival line.

Figure 20-5 Location and lengths of rootindications to be made in wax.

often taken during the investing procedure to allowthe multiple portions of the stone mold to “fallapart” during deflasking. This offers ease indeflasking the denture and decreases the risk offracturing the denture or teeth during removal ofthe denture from the flask (divesting). Theseoptional steps are described as such.

The denture with master cast is placed in theflask to establish its height in relation to the heightof the drag of the flask (Figure 20-11). The cope ofthe flask is placed in position to ensure that theteeth do not project beyond the top of the flask.

Ideally, approximately ¹⁄₈ to ¹⁄₄ inch (3 to 6 mm) ofspace should be available between the occlusal sur-face of the teeth and the top of the flask. If the teethare too high, the cast must be reduced in thickness.The artificial rim of the cast (land area) should beflush with the drag of the flask to prevent possiblebreakage of the cast in later separation of the twohalves of the flask (Figure 20-12).

The distal ends of the lower cast may be high inrelation to the remainder of the cast and extendclose to the posterior edge of the flask. This condi-tion causes the distal ends of the cast to be at an


Figure 20-6 Preliminary removal of wax from between the root indication lines (arrows).

Figure 20-7 Depressions between the root indication lines (arrows) that will besmoothed with the wax spatula.

acute angle to the rim of the flask. Thus the distalends are vulnerable to breakage when the flask isseparated; care should be taken to avoid creating anundercut or too vertical a surface in this area whenthe cast is invested.

A mix of artificial stone is placed in the bottomhalf of the flask, and the cast, which has beenpainted with separating medium (Figure 20-13), isplaced down into the stone until its rim is nearlylevel with the top edge of the flask. The stone isleveled between the edge of the cast and the rim ofthe flask.

After separating medium has been applied tothe exposed stone in the flask, a core of artificialstone 2- to 4-mm thick is developed around thelabial and buccal surfaces of both wax dentures, on

the lingual surface of the lower wax denture, and thepalatal surface of the upper. The top of the coresshould be 2 to 3 mm below the occlusal plane of theteeth (Figure 20-14). V-shaped grooves are placed inthe cores so they will separate with the top half ofthe flask. This step is arbitrary. It allows easierdivesting of the denture and decreases the risk ofbreakage of the denture. However, many techni-cians do not create this incremental making of themold in the cope.

Separating medium is applied on the exposedsurfaces of the core, and the top half (cope) of theflask is set in position. The two flask halves must


Figure 20-8 A, Proper form of the lingual polished surface contour. B, Position of thetongue relative to the lingual surface of the denture base is accommodated in the concavitydesigned in the denture’s lingual polished surface.

A B

Figure 20-9 The normal lingual contour ofartificial posterior teeth is established during thewaxing procedure.

Figure 20-10 The lingual contour of the uppercentral incisor is reestablished in the waxing procedure.This particular contour will aid phonetics and provide anatural feel to the patient’s tongue.

meet exactly. Then a mix of artificial stone is pouredup to the level of the incisal edges of the anteriorteeth and the tips of the cusps of the posterior teeth(Figure 20-15). The exposed stone is painted withseparating medium, the flask is completely filledwith artificial stone, and the cap of the flask is set in

position. Some technicians do not expose the toothsurfaces with this pour of stone, but rather place onecomplete pour of stone up to the superior level of thecope and then place the cap. If the teeth are exposedand an additional thin pour of 2 to 3 mm is used, thispour will easily be separated during the divestingprocedure, and the technician will be aware of theposition of the teeth when using any mechanicaldevices to break away the stone mold. This “protec-tive” step might be especially useful when easilybreakable porcelain teeth are used on the denture.The flask is placed in boiling water and allowed toremain 4 to 6 minutes to soften the wax. Then it isremoved from the water, and the drag and cope por-tion are “opened” from the side opposite the greatestundercut. The wax is removed, and the residual waxis washed out with a stream of boiling water. Whenthe water has been drained from the flask, the moldis washed again with boiling water containing a pow-dered detergent and then with clean boiling water.Liquid detergents have a greater tendency to leave aresidue, which is undesirable, especially with acrylicresin teeth, and solvents such as chloroform are notused because of their chemical contamination of themold, thereby negatively effecting polymerization ofthe acrylic.

After the stone is dry, but while still hot, the insideof the mold and the cast are painted with a tinfoil


Figure 20-11 The lower wax denture pattern andits cast in the bottom half of the lower flask. Bevelingof the posterior height of the land area can reduce therisk of creating an undercut in this area when investingthe cast.

Figure 20-12 First half of flasking of the maxillary trial denture. A, Cast too high inareas 1 and 2. B, Areas 1 and 2 at a favorable level. C, Areas 1 and 2 should be beveled.D, Areas 3 and 4 to be beveled.

A B

C D

substitute with a camel hair brush (Figure 20-16).The tinfoil substitute must not come in contact withthe teeth or pool in the mold around the teeth. It isallowed to dry, and a second coat is painted on theinside of the mold. The flask is allowed to cool toroom temperature. When acrylic resin teeth are used,the exposed surfaces of the teeth must be free of waxand tinfoil substitute and any other debris. Residueon the teeth is the main cause for adhesive failure.

PACKING THE MOLDAn acrylic resin dough is made by mixing the pow-der (polymer) and liquid (monomer) in accordancewith the manufacturer’s directions. Monomer isa sensitizer that can cause an allergic contacteczematous reaction on the skin or mucous mem-brane. Consequently, it is advisable to wear rubbergloves and work under proper ventilation. Whenthe monomer is completely polymerized, it rarelyelicits an allergic reaction. When the mixture hasreached a doughy consistency, it is placed betweentwo plastic sheets and formed into a roll that is flat-tened about ¹⁄₄ inch (6 mm) thick, and pieces arecut and systematically placed over the teeth inthe flask (Figures 20-17 and 20-18, C). If thereare severe undercuts in the anatomical portion of theedentulous ridge (in the drag of the flask), a smallportion of resin may be placed in these undercutareas also. The flask is closed in a press with asheet of separating plastic between the two halvesuntil they are almost in approximation. Then theflask is opened, the excess flash resin is cut awayprecisely at the denture border, and additional resinis added at any places where no flash was evi-dent (Figure 20-18). This trial packing procedureis repeated until the mold is filled and no flash isformed. It is usually not necessary to continue toadd resin after the first trial pack; however, repeated


Figure 20-13 Separating medium applied with acamel hair brush on the exposed stone of the land.

Figure 20-14 Labial, buccal, and lingual coreswith V-shaped grooves coated with a separatingmedium.

Figure 20-15 After the upper half of the flask hasbeen put in place, a heavy mixture of dental stone ispoured to the level of the tips of the cusps.

packs reveal a need to continually remove the flash.Then the flask is closed completely without theseparating sheet. The slightest discrepancy in clo-sure of the two halves of the flask will cause anerror in the occlusion.

The flask is transferred to a spring clamp for pro-cessing. The clamp is closed tightly but not fullycompressed. This will allow the resin to expand uponprocessing and then finally contract while still underpressure. Most methylmethacrylate denture resinsare processed for 9 hours in a cooling bath of waterheld at a constant temperature of 165˚ F (73.5˚ C).

However, acrylic resins can be processed at tempera-tures of 135˚ to 180˚ F. Distortion is reduced whenthe resin is processed at or below the manufacturer’srecommended temperature. However, the amount ofmonomer remaining in the cured resin clearly affectsthe degree of cytotoxicity of the denture base mate-rial. Potentially more monomer will be present at theprocessing temperatures. The flask must cool toroom temperature before deflasking begins. It is cru-cial that sufficient time be allowed for cooling insidethe flask. If this precaution is not taken, increaseddistortion of the resin will occur.


Figure 20-16 A, The flask has been separated and the wax removed. The tissue surfaceof the upper cast is painted with a tinfoil substitute. B, All wax has been removed, and theteeth are in their proper places in the mold. The stone is painted with a tinfoil substitute,which must be kept out of contact with the teeth.

A B

Figure 20-17 A, A section of the dough is placed in the mold for the upper denture. Itis carried to place with cellophane to prevent contamination. B, The dough has beendistributed throughout the upper mold.

A B

PRESERVING THE ORIENTATIONRELATIONSDeflasking is usually carefully completed with anair chisel, and the processed dentures are left on thecasts. The casts and dentures are returned to themountings on the articulator, and the processingchanges are observed. Usually the change is notedby observing the occlusal pin on the anterior guid-ance platform and is often in the realm of 1 to 2mm. Minor processing changes are usually cor-rected at this time. However, new interocclusalrecords and final adjustment of the dentition willbe done at insertion time. It should be noted thatadjusting the occlusion after processing and atdelivery could sacrifice too much tooth stock.

The upper cast is attached to the upper mount-ing, and a record of its relationship to the articula-tor is made in plaster on the remounting jig.Fast-setting plaster is spread on the jig, and theteeth of the upper denture are pressed into the plas-ter while the cast is in its keyed position on thearticulator (Figure 20-19). This index can also bemade after the final waxup, just before investingthe maxillary denture.

SHAPING AND POLISHING THE CUREDRESIN BASESThe dentures are removed from the artificial stonecasts. The feather edges of the denture base mate-rial are removed with files, scrapers, and burs.


Figure 20-18 A, Excess acrylic resin in the mold has been forced between the halves ofthe flask during the initial trial packing. B, Excess resin in the upper mold removed througha series of trial packings. C, The dough is distributed throughout the lower mold. D, Flashshould extrude from the entire periphery of the denture. If it does not extrude on the firstpressing, that area requires the addition of more dough. Trial packing with excess removalshould continue until no more flash appears.

A B

C D

The feather edges around the gingival line of theteeth are cut down by means of chisels and knivesto conform with the desired contour; care is takennot to cut acrylic resin teeth. With burs, stones,chisels, and sharp scrapers, the surface is shapeduntil it is smooth and clean. No plaster and nodeep scratches should remain before polishing.Any difficulty during polishing of the dentures isdue to their not being properly prepared forpolishing.

A rag wheel and felt cone with pumice are goodfor smoothing the palatal portion of the upper den-ture. A single-row brush wheel and a rag wheelabout ¹⁄₄ inch (6 mm) in width are used withpumice to smooth the labial and buccal surfaces ofthe denture without destroying the contour. A finalhigh polish is given to all the surfaces with a ragwheel and polishing material (tripoli, tin oxide, andwater).

CONSTRUCTION OF REMOUNTINGCASTSRemounting casts serve as an accurate, conven-ient, and time-saving method of reorienting the

completed dentures on the articulator for occlusalcorrections. All undercuts on the tissue surface ofthe dentures are filled with wet tissue paper, clay,or wet pumice (Figure 20-20, A). Block-outshould be only at the undercuts. Most internaldenture anatomy should remain to support thedentures during occlusal adjustments. Remountcasts that only duplicate the flanges often allowthe dentures to rock or shift during the occlusaladjustments.

Fast-setting plaster or artificial stone is pouredinto the denture. After the plaster has set, the excessis trimmed down to the border (Figure 20-20, B)and the dentures are removed from the casts. Thecasts are examined to ensure that the groovesformed by the border of the dentures are not deeperthan 1 mm to allow accurate seating of the dentures(Figure 20-20, C).

With the remounting jig and index positionedon the mandibular member of the articulator, themaxillary denture and remounting cast are placedin the plaster indentations. The maxillary remountcast is attached to the maxillary member of thearticulator by means of fast-setting plaster (Figure20-21).


Figure 20-19 A, The upper cast and processed upper denture are returned to thearticulator mounting and attached with sticky wax. The remounting jig is positioned on thelower member of the articulator. B, The upper denture is closed into the plaster on theremounting jig so the occlusal surfaces of the teeth will make an imprint in plaster. This willpermit the denture, after removal from the artificial stone cast, to be repositioned in properrelation to the upper member of the articulator.

A B

Figure 20-20 A, Undercuts are eliminated from the tissue surface of the denture whenthey are filled with wet tissue paper. Only block out the undercut areas, not the entiredenture ridge. Too much block-out will allow the cast to “rock” during occlusal adjustments.B, Upper remounting cast poured in the upper denture. C, Upper denture removed from theupper remounting cast. All the block-out material should be removed, and the dentureshould fit accurately on the cast.

A

C

B

Figure 20-21 A, Occlusal index previously made on the Dentatus articulator before the waxed-up maxillarydenture was removed from the original mounting. B, Remounting cast attached to the mounting ring on the uppermember of the articulator with fast-setting plaster.

A B

SECTION II: DELIVERY OF THE COMPLETED DENTURES

CRITIQUING THE FINISHEDPROSTHESESThe moment new dentures are placed in apatient’s mouth, all of the procedures involved indenture construction are subject to review andreevaluation. The choice of materials, the techni-cal and clinical effectiveness of procedures used,and the skill in carrying out the procedures areexposed to three evaluations. These are by thedentists who rendered the service, the patientswho are to use the dentures, and the friends andfamily of the patients who will be viewing thedentures.

Dentists’ Evaluations

Evaluations made by dentists should be the mostcritical because these are the professionals whoknow the potentialities and limitations in the treat-ment of the patient. Dentists must recognize defi-ciencies in the prosthodontic service provided.Some of these may become manifest at delivery,and some may become evident during follow-upexaminations. If dentists are not knowledgeableabout the type of observations that should be madeand are not critical of the results of the treatment,they are not rendering a truly professional service.If dentists cannot find anything that they wouldchange in treating the same patient again with com-plete dentures, they are not being as critical of theirown efforts as they should be. The maintenance ofquality of prosthodontic service depends on a con-stant vigilance and self-discipline. A critical evalu-ation by the dentist of every prosthodontic servicerendered will tend toward a constant improvementof the service.

Patients’ Evaluations

Patients’ evaluations of their new dentures aregenerally made in two phases. The first is thereaction to the completed dentures when they arefirst placed in their mouth. This can range fromenthusiastic acceptance to fear and apprehension.

The patient’s frame of mind will greatly dependon the dentist’s tempering the patient’s expecta-tions, but it may be affected by previous experi-ences in denture wearing and by comments ofother people. If adequate diagnoses were madebefore any treatment was started, all misconcep-tions and inaccurate information should havebeen discussed. Limitations in denture wear as aresult of the patient’s particular anatomy andfunction will have been addressed. It is especiallyimportant to spend adequate time at the try-inappointment to avoid patient dissatisfaction atinsertion. If confidence cannot be earned andestablished before the day the dentures are placedin the mouth, the treatment after this time willbe more complicated. Skilled practitionerswill have demonstrated to their patients that theyare treating them professionally and thatthey have used the utmost care in the clinical andtechnical procedures involved in fabricating theirdentures.

Friends’ Evaluations

When patients leave the dental office with theirnew dentures, it is generally with mixed emotions.They want their friends to notice their improvedappearance; they hope their friends and relativeswill compliment them and confirm their judgmentand choice of dentist; and they still wonder howthey will progress with eating and speaking. If peo-ple comment about the new teeth, some patientsmay wonder if the teeth look natural; if they do notcomment, the patients may wonder if their friendsare just being kind. The evaluations by friends maynot be accurate. Friends cannot know how the den-tures feel. They cannot judge the efficiency of thedentures in eating and speaking. They cannot knowthe difficulties encountered by the dentist becauseof the poor anatomical foundation. They cannotunderstand the possible lack of coordination of thepatient or the ineptness of some patients in attempt-ing to follow instructions or to use the dentures.The patients themselves may recognize thesedifficulties as partly their responsibility, but the com-ments of friends may cause them to blame the den-tist for problems that may have been beyondthe dentist’s control. Such well-meaning friendscan add to a patient’s difficulties because they have


not been exposed to the information supplied to thepatient by the dentist. The way to guard againstpatients being misinformed by their friends is totake the lead and make certain that patients havebeen correctly informed. This process is a continu-ing one and should start at the time the diagnosis ismade. Enlisting the aid of a patient’s most criticalfriend or relative in critiquing the appearance at thetry-in or having this person available during themany denture appointments can be very helpful.

TREATMENT AT THE TIME OFDENTURE INSERTIONThere are certain technical procedures that mustbe carried out to ensure a successful prosthodon-tic service. Inaccuracies in the materials andmethods used to get the dentures to this stagemust be recognized and eliminated before thepatient wears the dentures. The inaccuracies maybe the result of (1) technical errors or errors injudgment made by the dentist, (2) technical errorsdeveloped in the laboratory, or (3) inherent defi-ciencies of the materials used in the fabrication ofthe dentures.

Ideally the patient should be instructed to keepany previous dentures out of the mouth for 12 to24 hours immediately before the insertionappointment. This is essential if the new denturesare to be seated on healthy and undistorted tis-sues. If the tissues are being distorted by old den-tures, the new dentures will not seat perfectly,even if they fit perfectly. Improper seating of den-tures at this time can cause the appearance oferrors in occlusion or fit that would not exist if thetissues were undistorted. Adjustments of any typeto correct such apparent errors, if made at thistime, may be unnecessary and can cause irrepara-ble damage to the dentures. This caution is predi-cated on the requirement that the patient bewithout any dentures for 24 hours (sometimeslonger) to get the tissues healthy before the finalimpressions are made.

As mentioned in Chapter 18, many patients willfind leaving the dentures out of their mouth for 12to 24 hours an unreasonable request. An acceptablealternative is to have the existing dentures relinedwith a soft temporary material to minimize tissuedistortion problems.

ELIMINATION OF BASAL SURFACEERRORSBefore the placing of dentures in the patient’smouth, the dentures should be inspected to besure that there are no imperfections on the tissuesurface, the polished surface is smooth, the den-ture flanges have no sharp angles and are not toothick, and the denture borders are round andsmooth with no obvious overextension. If care-fully border-molded impressions have beenmade, the flanges and borders should require lit-tle if any alteration. The dentist’s objective shouldbe to make the impressions and casts so perfectlythat there is no doubt in the mind of the techni-cian as to the form and extent of borders andflanges when the dentures are trimmed and pol-ished.

Using a magnifying glass, in addition to digi-tally inspecting the denture bases, can be effectivein locating and correcting such irregularities. Alldenture borders, especially the frenal notches,must be examined carefully for sharp edges.Sharp borders in the frenal notches must be care-fully rounded before the initial placement of thedentures. The use of pressure indicator paste isessential to evaluate the accuracy of tissue con-tact. It is especially helpful when bilateral under-cuts on the residual ridge interfere with the initialplacement of dentures or when pressure spotswere present in the final impression. The paste isbrushed on the tissue surface of the denture basein a thin layer so the brush marks are visible andrun the same direction. In this manner, tissueinterferences during placement of the dentures orexcessive pressure on the residual ridge can bemore easily interpreted than without the paste.The painted surface may be sprayed with a sili-cone liquid or wetted with water. The denture iscarefully placed in the mouth and pressure isapplied by the dentist on the teeth to reveal anypressure spots in the denture base that would dis-place soft tissue (Figures 20-22 and 20-23). Themarks in the paste indicate where the denture baseshould be adjusted to relieve the interference(Figure 20-24). Pressure indicator paste should beused for every new denture, and any necessaryadjustments should be made before proceedingwith the occlusal adjustment.


Despite the methods used to make or finish theborders, overextension may occur, causing tissuetrauma if not corrected. A thick layer of paste canbe applied to an incremental area of the dentureborder. The entire border should not be painted

because the paste will be smeared in some areasupon placing it in the mouth. The denture shouldbe placed in the mouth, avoiding any inadvertentcontact of the disclosed area. After complete seat-ing of the denture, the dentist can “border mold”


Figure 20-23 A, The pressure spots in Figure 20-22 have been carefully relieved with ano. 8 round bur. A minimum of denture base material was removed. B, The severely undercutarea of the retromolar lingual flange must be carefully disclosed on the periphery and inter-nal aspect of the periphery. Each side should be evaluated independently so as not to disturbor displace the paste on insertion. The denture should be slightly twisted and pulled forwardwhen evaluating this area because the denture can be expected to move under function. Thisthin lingual mucosa surface is very vulnerable to ulceration with denture movement.

Figure 20-22 A, Marks showing through the pressure indicator paste reveal the location ofpressure spots exerted by the denture on areas that are not primary stress-bearing areas. The spotin the region of the left hamular notch also was present on the final impression. The posteriorpalatal seal bead is visible through the pressure indicator paste and shows that the desired seal isbeing provided. B, Pressure areas visible through the alveolar groove anteriorly in both canineareas and the retromolar fossa (arrow). These should be relieved because they are not allowingthe denture to seat; therefore there is little disruption of the surface texture of the neatly appliedpressure paste. This reveals that there is no contact on the remainder of the denture-bearingsurface, particularly not in a primary stress-bearing area for the mandibular denture.

A B

A B

that area of the border. On removal of the den-ture, any pressure area or overextension will be vis-ible. These areas can be adjusted; this adjustmentensures that border tissues and frena are notdisplaced.

ERRORS IN OCCLUSIONMaxillomandibular relations are bone-to-bonerelations and as such represent the status betweentwo solid objects: the maxillae and the mandible.These bones are covered by mucosa and sub-mucosal tissues, which are resilient and displace-able. Errors in occlusion might not be apparentunless specific procedures are used to test forthem. Because of tissue displaceability, somedentists have considered that the dentures willsettle into the tissues and small errors in occlu-sion will correct themselves. If this is true, it isdone at the expense of the health of soft tis-sues and eventually at the expense of bonebecause bone is a more plastic tissue thanmucosa. Bone, in time, will change to relieve softtissues of excess pressure. Thus failure to correctocclusion before the patient wears the denturescan cause destruction of the residual alveolarridges.

Errors in occlusion can result from a number offactors. These include a change in the state of thetemporomandibular joints (TMJs), inaccurate max-illomandibular relation records by the dentist,errors in the transfer of maxillomandibular relationrecords to the articulator, ill-fitting temporaryrecord bases, change of the vertical dimension ofocclusion on the articulator, incorrect arrangementof the posterior teeth, failure to close the flaskscompletely during processing, or use of too muchpressure in closing the flasks. Occlusion errors maybe the result of unavoidable changes in the denturebase material (Figure 20-25). Acrylic resins shrinkwhen they change from a moldable to a solid form.They have a high coefficient of thermal expansion,and in cooling after polymerization they shrink,causing dimensional changes. The greatest amountof change occurs when the dentures are removedfrom the casts. Further change may occur if toomuch heat is generated in polishing the dentures.Subsequently, the acrylic resin absorbs water whilein use, resulting in expansion. Processing changesare inevitable, though some can be minimized bycareful handling of the materials and prostheses bythe dentist and laboratory technician.

Some of the errors in occlusion can be cor-rected after deflasking the master casts with the


Figure 20-24 A, Interference in the left posterior buccal flange area is noted beforeseating the maxillary denture in its correct position. B, After careful adjustment, a newrecording of the indicator paste indicates proper seating of the denture.

A B

processed dentures still on them, in their originalmountings in the articulator, and modifying theocclusal surfaces of the teeth by selective grinding(see Figure 20-25). This will eliminate most of theerrors caused by processing changes. However, itwill not eliminate errors produced by the impres-sions or jaw relation records, nor will it eliminateerrors that develop when the dentures are removedfrom the casts or are polished. Therefore new inte-rocclusal records should be made at the time newdentures are first inserted in the patient’s mouth.Denture base acrylic resins absorb water and saliva.This absorption causes a 1% to 3% expansion andcan alter the relationships of the cusps’ inclinedplanes. After finishing of the dentures, the prosthe-ses should be maintained in water so this dimen-sional change occurs before the final occlusalrefinement that is accomplished at the insertionappointment. To avoid dimensional and occlusalchanges, patients should be advised to store den-tures in water.

Checking for Occlusion Errors

The technique to determine whether there areerrors in occlusion is not difficult, but it doesrequire the willingness to see an error. Given themyriad of reasons for occlusal discrepancies, den-tists must assume that an error exists and work tofind it. If they simply tell the patient to close theirjaws and then observe the occlusal contact, theerror in occlusion will unlikely be detected. The

dentures may shift on the ridges, the soft tissue sup-porting the dentures may distort or be displaced, orthe mandible may move into an eccentric position;the occlusal error will be obscured, at the expenseof tissue damage. To observe the error, the dentistshould guide the mandible into centric relation(CR), while supporting the lower denture intrao-rally. The patient is instructed to close until the first“feather touch” is felt on the posterior teeth. At thefirst contact, the patient is instructed to open andrepeat this closure, stopping the instant tooth con-tact is felt; then the patient is instructed to “closetight.” This procedure will reveal errors in CR bythe touch and slide of teeth on each other (seeFigure 18-1). The amount of occlusal error and thelocation of the deflective contacts will be deter-mined after the dentures have been remounted inthe articulator. They are usually minute, and theiraccurate localization requires remounting. If artic-ulating paper is used in the mouth to locate inter-ceptive or deflective occlusal contacts, shifting ofthe denture bases, tissue distortions, or eccentricclosures by the patient, as well as the presence ofsaliva, can prevent the articulating paper marksfrom accurately recording errors. Much of theselective grinding done in the mouth according toarticulating paper marks made actually increasesthe amount of error in the occlusion. Occlusionerrors are ideally detected and corrected whenthe dentures are accurately mounted in thearticulator.

INTEROCCLUSAL RECORDS FORREMOUNTING DENTURESThe dentures must be remounted on the articulatorby means of accurate interocclusal records (CR andprotrusions are necessary for this procedure) for theselective grinding necessary in perfecting the occlu-sion. When new accurate interocclusal records aremade and the completed dentures are remounted onthe articulator, the errors in occlusion are easily vis-ible, easily located, and easily corrected by selectivegrinding. Properly made interocclusal records willnot cause the denture bases to slip or rotate in relationto their bony foundations. Furthermore, on the artic-ulator, the dentures will be firm on their remountcasts. The points of contact and errors of occlusioncan be observed visually, with magnification if


Figure 20-25 Processed dentures are replaced onthe articulator while still on their casts. The changesthat occurred in processing of the acrylic resin havecaused errors in the occlusion.

desired, and articulating paper marks are quite eas-ily made on the dry teeth.

There is another advantage to making these cor-rections without the patient present. The interocclusalrecords, of course, are made in the patient’s mouth;from the patient’s standpoint this is just anotherstep in the construction of the dentures. On theother hand, if the grinding of occlusion is attemptedin the presence of the patient, the operation mayappear to the patient to be one of correcting anerror made by the dentist. Thus there is a psycho-logical advantage in doing the selective grinding inthe laboratory.

INTEROCCLUSAL RECORD OF CENTRICRELATIONTwo pieces of wax wafer (e.g., Aluwax) are placedover the mandibular posterior teeth. A thickness ischosen to eliminate the danger of making contactwith the opposing teeth when biting pressure isexerted. The teeth must be completely dry and thewax pressed firmly on them to eliminate voids. Thetwo thicknesses of wax are sealed with a warmspatula (Figure 20-26). The maxillary denture isplaced in the patient’s mouth, and just the Aluwaxportion is immersed in a water bath of 130˚ F(54˚ C) for 30 seconds (Figure 20-27). Both the tem-perature and the time are critical in achieving a uni-formly softened wax. The Aluwax retains heatlonger than baseplate wax, thereby providing timefor the next step.

The occlusal surfaces of the maxillary teeth arelightly lubricated with petroleum jelly, and the max-illary denture is firmly seated in the mouth. Themandibular denture is then seated with the indexfingers bilaterally positioned on the buccal flanges.The mandible is guided into CR by placing thethumbs on the anteroinferior portion of the chin insuch a way that some guidance is directed towardthe condyles. The patient is guided in a hinge move-ment, closing lightly into the wax. As contact withthe wax approaches, the fingers are slightly raisedfrom the buccal flanges and the patient is instructedto close into the wax until a good index is made(Figure 20-28). Care must be taken to prevent thepatient from penetrating the wax and making toothcontact; a minimal amount of occlusal pressureshould be exerted. Because the wax slightly distortswhen the mandible is opened, this “drag” of thewax can be reduced by having the patient open onlya few millimeters on the arc of closure and “tap”lightly into the wax.

The mandibular denture is carefully removedfrom the mouth and placed in ice water to chill thewax thoroughly (Figure 20-29). Next, the denturesare removed from the ice water and dried. Theimprint of the opposing teeth must be crisp andabout 1 mm deep, with no penetration of the inte-rocclusal wax record by opposing teeth (Figure20-30). If there is direct tooth contact through thewax, there is the possibility that the bases siftedand an incorrect record was made. The record mustbe repeated.


Figure 20-26 The two thicknesses of Aluwax aresealed with a warm spatula.

Figure 20-27 The Aluwax is immersed in 130º F(54º C) water for 30 seconds.

The Aluwax is thoroughly chilled before the den-tures are returned to the patient’s mouth and thepatient is guided into CR, as previously described.The record is acceptable if there is no tilting ortorquing of the dentures from initial contact tocomplete closure (Figure 20-31). Underlying soft-tissue displacement may cause a slight movementof the bases and must be taken into account whenevaluating the contact. If the record does not satisfythese criteria, the procedure must be repeated.

REMOUNTING THE MANDIBULARDENTURESThe maxillary denture will have been mounted inthe articulator by means of the remount occlusalindex (see Figure 20-21), which will have preservedthe face bow orientation of the dentures. As a result,the horizontal condylar setting recorded at the try-inappointment should be valid, and it is not necessaryto repeat the face bow or protrusive record.

After the dentures and wax are chilled and thor-oughly dried, the mandibular denture is positionedon the remount cast (Figure 20-32). Next, the max-illary denture teeth are carefully positioned in thewax index and secured with a drop of sticky wax in


Figure 20-28 The mandible is guided into centricrelation with the thumb on the anteroinferior part ofthe chin and the index fingers lightly seating themandibular denture in a downward and forwarddirection. The patient is instructed to close lightly intothe softened wax. Then the patient should beinstructed to gently “tap-tap” into the wax in the hingemotion, before removal of the denture from the mouth.

Figure 20-29 The Aluwax attached to themandibular denture is chilled in ice water.

Note vertical imprints

Figure 20-30 The occlusal record is approximately1 mm deep and free of any penetration by theunderlying teeth. The imprint of the opposing teethis vertical with no evidence of a slide (arrows).

the canine and second molar regions bilaterally(Figure 20-33). (Sticky wax can be used to secureboth dentures to their remount casts, if necessary.)The incisal pin should be adjusted to allow for thethickness of the interocclusal wax record by raisingthe upper member of the articulator about a mil-limeter and dropping the incisal pin. The condylarcontrols must be locked into centric position. Plasteris used to secure the mandibular denture to the lowermember of the articulator.

VERIFYING CENTRIC RELATIONThe CR record should be verified for accuracybefore any tooth adjustments. The Aluwax is used,and the CR recording is repeated. After chilling anddrying of the wax record, the dentures are returnedto the articulator. With the articulator locked in CR,the maxillary teeth should fit precisely into the newwax record (Figure 20-34). If all the teeth dropsimultaneously into the wax record, the mounting iscorrect. If the opposing teeth do not fit exactly intothe indentations in the new record, either the origi-nal mounting was incorrect, or the patient gave anincorrect relation when making second record. To


Figure 20-31 Checking the accuracy of the chilledinterocclusal wax record. There should be no tilting ortorquing of the dentures from initial contact tocomplete closure.

Figure 20-32 The mandibular denture with thewax interocclusal record attached is positioned on andsecured to the mandibular mounting cast with stickywax. The maxillary denture has been previouslypositioned on the upper member of the articulatorwith the occlusal index (see Figure 20-21) and securedto place with sticky wax.

Figure 20-33 The maxillary teeth are secured to thewax index with a drop of sticky wax in the canine andsecond molar areas and secured with fast-setting plaster.

Figure 20-34 The original cast mounting isverified when the maxillary teeth fit precisely into thewax index on the articulator with locked centric controls.

evaluate this, the dentist returns the dentures withthe chilled wax record to the mouth and evaluatesthe accuracy, as previously described. If the recordstill appears correct in the patient’s mouth, theoriginal CR registration or mounting was incorrect.In this situation, the mandibular cast should beseparated from the mounting ring and the castremounted according to the second interocclusalwax record. The new mounting is again checked inthe same manner to validate its correctness.

PROTRUSIVE INTEROCCLUSAL RECORD(OPTIONAL)The original face bow orientation of the denturescan be preserved by means of the remount occlusalindex; thus the optimal condylar setting recorded atthe try-in appointment should still be valid. If thereis any question as to the accuracy of the originalcondylar setting, a new protrusive record is made(Figure 20-35). As previously stated in the chaptersrelated to articulators and lateral excursive records,precise lateral records are difficult to recordbecause of denture instability and tissue resiliency.Therefore most clinicians agree that average lateralcondylar settings are sufficient for denture con-struction.

Eliminating Occlusal Errors in AnatomicalTeeth

Final correction of occlusal disharmonies is madeat this time by means of methodical selective grind-ing that will give simultaneous contact around thearch in CR occlusion and in eccentric movementsand also maintain tooth form. Unlike occlusalphilosophies in natural dentition, it is desirable forworking and balancing contacts to occur simulta-neously. The goal is for balancing side contacts toappear across the arch and within the tooth on theworking side of the arch. During evaluation of con-tacts and selective grinding, tooth contacts will pre-vent other teeth around the arch from makingcontact. The goal is to maintain the integrity of the“stamp” or central bearing cusp tips in both arches(maxillary lingual and mandibular buccal cusps)and allow all cusps to move through the “sluceways of the opposing dentition” (working and bal-ancing grooves and mesial and distal inclines). The

central bearing cusp tips are not reduced, but ratherthe opposing fossae are made deeper. Also, if the“high” contact is on the central bearing cuspinclines, the cuspal inclines can be reduced, therebygradually moving the contact more toward thebearing cusp tip. In lateral excursions, if a centralbearing cusp is “high,” creating simultaneous con-tacts of other teeth, the opposing fossa can bewidened. Balancing cusp tips and inclines areadjusted similarly, but adjustments to the cusp tipscan be accomplished if needed, without the risk of


Figure 20-35 A, Protrusive interocclusal records inplace, and the horizontal condylar guidance loosenedand rotated to a neutral position. B, The horizontalcondylar guidance is adjusted so both denturesstay seated on their plaster mountings and in theprotrusive interocclusal records. Lateral condylarguidance is usually set at an average position fordenture fabrication.

A

B

decreasing vertical dimension of occlusion. CRocclusion is established first with the condyles intheir locked position. During this CR grinding pro-cedure, the incisal guide pin is relieved of contacton the incisal guidance table to allow for the slightreduction in vertical dimension that must necessar-ily take place. Articulating ribbon of minimumthickness is used for marking contacts of the teethbecause thicker articulating paper gives deceptivecontacts. Ribbon is interposed between the teeth,and markings are obtained by tapping the teethtogether in the CR position. This can be recordedon both sides at the same time. After the first fewtaps on the articulating paper, only a few high con-tacts appear (Figure 20-36). Representativeocclusal errors and adjustments are depicted inFigure 20-37. Grinding is done with small stones ora number 8 round bur. The marking process and thegrinding are repeated until all except the anteriorteeth contact in CR. Ideally all bearing cusps of themaxillary and mandibular posterior teeth will makesimultaneous contact. However, it is not uncommonfor one or two bearing cusps not to make contactafter establishing the final CR occlusion. It is notnecessary to continue adjusting until these cuspsmake contact because that aggressive adjustment

will sacrifice the established vertical dimension ofocclusion. The final articulating marks shouldremain on the dentition to maintain a reminder of theCR contacts during the upcoming adjustment of lat-eral excursions.

After the CR contacts have been established,the pin is placed in contact with the incisal guidetable and is kept in contact throughout the remain-der of the adjustment procedure. One of the articu-lator condyles can be released to allow a unilateralworking movement. With a different color articu-lating ribbon, the ribbon is placed over the teeth onboth sides, the articulator is moved into a workinglateral position, and the contacts are marked onboth sides for the same lateral movement (Figure20-38). Care is taken not to grind on working cusptips or the opposing fossae contact of the workingcusp tips that were established in CR occlusion andremain marked with the original color ribbon.Grinding to correct lateral occlusion is limited toaltering the lingual inclines of the maxillary buccalcusps and the buccal inclines of the mandibular lin-gual cusps on the working side and the lingualinclines of the mandibular buccal cusps on the bal-ancing side (Figure 20-39). Because the lateralwings of the incisal table are set very shallow (oftenbetween 0 and 5 degrees), initially the pin will riseaway from the table during lateral movements.Adjustments as previously described should con-tinue until the pin remains on the table during lat-eral excursions. This marking and grindingprocedure is repeated for the right lateral move-ment (Figures 20-40 and 20-41). Three types ofocclusal errors can exist in adjustment of CR and


Figure 20-36 Articulating paper marks made incentric relation show interceptive or deflective occlusalcontacts in centric occlusion. Grinding should be doneonly in fossae and not on cusps.

Figure 20-37 Correction of errors in centricocclusion. Grind the shaded areas. A, Teeth too long.B, Teeth too nearly end to end. C, Too much horizontaloverlap.

A B C

as many as eight errors in excursive movements.The types of interceptive occlusal contacts and thenecessary adjustments are depicted in Figures 20-42through 20-44. In most instances the lateral move-ment of the incisal guide pin need not exceed 3 mm.This amount of lateral movement usually moves theposterior cusp tips in an end-to-end position andmeets the functional demands of the patient.

Inasmuch as denture teeth are fastened togetheras a unit, it is permissible to relieve the centric con-tact of the four incisors. This relief may be madeat the time of setting the teeth, which will permitthe use of a vertical overlap without increasing theincisal guide angle. Depending on the amount ofanterior horizontal overlap, it will often be necessaryto adjust the palatal aspect of the maxillary incisorsand the length and cuspal inclines of the mandibularcanines and incisors. Interceptive lateral and protru-sive contacts in the anterior area must be eliminated.The sacrifice of tooth structure is usually accom-plished on the mandibular anterior teeth so as not tocompromise maxillary esthetics, although incisalwear patterns on the maxillary anterior teeth can bevery natural appearing. The dentist may choose tomake anterior adjustments on both arches.


Figure 20-38 Articulating paper is used to locatedeflective occlusal contacts in left lateral occlusion.Notice the position of the incisal guide pin, which hasresulted from movement of the articulator into a leftworking position.

Figure 20-39 Marks on the buccal cusps of themaxillary teeth and the lingual cusps of the mandibularleft posterior teeth indicate contacts in left lateralocclusion. These surfaces are ground to developuniform contacts. The lingual cusps of maxillary teethand the buccal cusps of mandibular teeth are notground, even though they show marks from thearticulating paper.

Figure 20-40 The articulator is moved betweenright lateral occlusion and centric occlusion, witharticulating paper between the teeth to locatedeflective occlusal contacts in the lateral excursion.Notice the position of the pin on the incisal guidancetable.

If the grinding has been done in right and leftlateral and intermediate movements, grinding inprotrusion will also have been accomplished;however, a straight protrusive movement should beevaluated. Again, the dentist may wish to use a

third colored ribbon to protect the central bearingcontacts and to note what “new” protrusive contactshave occurred that may be severely lifting the ante-rior pin from the incisal guide table. Usually onlyfew teeth reveal a heavy discluding contact andrequire adjustment. Testing with articulating ribbonshould show uniform protrusive contact throughoutthe arches of the maxillary and mandibular dentures(Figure 20-45).Carborundum paste should not be indiscriminatelyused to eliminate errors in the occlusion of cuspedteeth. Aggressive use of the paste could decreasevertical dimension and the sharpness of the cusps.If carborundum paste is used, smoothing of minuteirregularities must be limited to only a few glidingmovements of the articulator (Figure 20-46).

Eliminating Occlusal Errors in NonanatomicalTeeth

Previous chapters of this text describe several differ-ent tooth arrangements. Lingualized occlusion can be


Figure 20-41 Articulating ribbon markings in rightlateral excursion. Marks on the buccal cusps ofmaxillary right posterior teeth and the lingual cusps ofmandibular right posterior teeth indicate the contactsin right lateral occlusion. These surfaces are ground todevelop uniform contacts. The lingual cusps of themaxillary teeth and the buccal cusps of the mandibularteeth are not ground, even though they show marksfrom the articulating paper. (These marks shouldoverlay the previous colored marks representing thecentral bearing contacts.)

Figure 20-42 Correction of errors on the workingside. Shorten interfering cusps as indicated bythe shaded areas. A, Buccal and lingual cusps too long.B, Buccal cusps too long. C, Lingual cusps too long.

Figure 20-43 Correction of errors in the mesiodistalrelationship. Grind where areas are shaded. D, Distalsurface; M, mesial surface.

Figure 20-44 Eliminating deflective occlusalcontact on the balancing side. Grind the lingual inclineof the mandibular buccal cusp. B, Buccal surface; L,lingual surface.

A B C

established by a variety of tooth designs and evenwith differing tooth molds in opposing arches.Nonanatomical or so-called functional posterior teethare frequently set to establish anterior and lateralcompensating curves. There can be an attemptto establish some balancing and working contactsin monoplane teeth with a “buccal-lingual tilt” ofthe posterior teeth with the addition of an anterior-posterior compensating curve. Complete monoplaneteeth with a “flat plane” occlusion have gained inpopularity. No attempt is made to achieve balanced

occlusion in eccentric movements. Some practition-ers modify the plane of the second molar in this flatplane design to set this tooth completely out of occlu-sion, and others use this tooth as the sole tooth set“on a curve” to achieve balance with the premolararea, which tends to remain in contact during excur-sions. All of the proposed philosophies of teetharrangement require attention to CR occlusion. Therefinement of balancing and working occlusion isoften possible across the arch, but it is often more dif-ficult to achieve balancing and working contactssimultaneously within the same tooth as comparedwith anatomical tooth designs. It may be difficult toachieve excursive contacts in all posterior teeth.There may be only a few working or balancing con-tacts on each side of the arch. However, because den-tures function as a unit, often only these fewexcursive contacts are adequate for a balanced occlu-sion. Whatever the occlusal philosophy established attry-in, it should be carried through with the requiredcorrection of occlusion at prosthesis insertion.

Examination of the occlusion at the time ofdenture insertion often reveals one or more dis-crepancies that may be attributable to teeth comingout of alignment during the final stages of the lab-oratory procedure. An interocclusal CR record ismade in a bite registration material with the oppos-ing teeth just out of contact. As in the insertionappointment of dentures with anatomical teeth, it isrecommended that the dentist use remount casts,maintain the original position of the maxillary castand condylar settings from the try-in appointment,and make a second (verification) CR record beforebeginning any occlusal adjustments.

After being detected by articulating ribbonbetween the teeth, gross premature (interceptiveocclusal) contacts in CR are adjusted (Figure 20-47).The same procedures are used to locate and removeall interceptive interferences in lateral and protru-sive occlusions as the occlusal philosophy dictates.The grinding is done on the occlusal surfaces ofteeth that appear to have been tipped or elongatedin processing. In the use of monoplane occlusionwhere an attempt is being made to create balancein eccentric occlusion, there are no cuspal inclineswithin the tooth anatomy to adjust. One can usethe following method of complimentary opposingarch adjustment: in eccentric occlusion, no grind-ing is done on the distobuccal portion of the


Figure 20-45 Markings made by movements in alldirections indicate uniform contacts.

Figure 20-46 Final smoothing can be done byabrasive paste in one or two gliding movements of thearticulator.

mandibular second molar; rather, balancing-sidegrinding is done on the lingual portion of theocclusal surface of the maxillary second molar.

Abrasive paste is placed on the teeth in thearticulator. These teeth are milled when the uppermember of the articulator moves in and out of pro-trusive and right and left lateral excursions. A bitmore aggressive use of the abrasive paste can assistin creating an almost imperceptible gentle curve inthe nonanatomical tooth. Care should be taken notto excessively sacrifice vertical dimension or ante-rior esthetics with the paste. When the teeth slidesmoothly through all excursions, the dentures areremoved from the articulator and washed. Spotgrinding is done to correct any small discrepanciesin CR that remain after the grinding with abrasivepaste. The dentist adjusts them after identifying thediscrepancy with articulating ribbon, using a lighttapping motion with the articulator, and grinding

the marks to ensure even occlusal contact in centricocclusion (CO).

If all occlusal correction steps were properlyperformed, the contacts achieved in the mouthshould be the same as those achieved on the artic-ulator when the dentures are inserted (Figure20-48). The mounted casts and articulator shouldbe maintained until the adjustment period is over.Finally the remount casts can be sent home with thepatient to bring at follow-up visits.

ADVANTAGES OF BALANCEDOCCLUSION IN COMPLETE DENTURESWhat is the advantage of balanced occlusion indentures when a bolus of food on one side sepa-rates the teeth so that they cannot possibly be inbalancing contact on the opposite side? This ques-tion has caused many dentists to speculate that bal-ancing occlusion is a fetish of college professorsand a few specialists. Many dentures that are deliv-ered are not balanced in excursive movementsbecause a large proportion of the profession is notthoroughly convinced of the value of balancedocclusion in relation to the effort involved inachieving it. If a bolus of food were between theteeth during most of the day, there would not bemuch merit in having an exactly balanced occlu-sion. However, teeth make contact many thousandsof times a day in both eccentric nonfunctionalmandibular movements and centric positions, withno food in the mouth. Even while a person chewsfood, the teeth cut through to contact every fewfractions of a second. A balanced occlusion ensureseven pressure in all parts of the arch, which main-tains the stability of the dentures.

SPECIAL INSTRUCTIONS TO THEPATIENTEducating patients to the limitations of dentures asmechanical substitutes for living tissues must be acontinuing process from the initial patient contactuntil adjustments are completed. However, certaindifficulties that will be encountered with new den-tures and the information related to the care ofdentures should be reinforced at the time of initialplacement of the dentures. Forewarning makes the


Figure 20-47 A, Gross interceptive occlusalcontact in the premolar region is removed. B, Maximalintercuspation now occurs in centric relation.

A

B


Figure 20-48 Occlusal contacts on the articulator following selective occlusaladjustment. A and B, Centric occlusion, buccal and lingual views. C and D, Right lateralocclusion, labial and lingual views. Notice in the lingual how balance has been achieved inthe molar region. E, Protrusive position. Here, multiple balancing contacts exist because ofthe shape of the compensating curve. F, In this clinical view, notice the uniformity ofcontacts as established on the articulator (A). Color photographs of this patient are presentedin Plate 18-1, D to F.

A B

C D

E F

patient more tolerant of problems and less likely torelate them incorrectly to the fit of the dentures.Explanations provided after problems developoften are interpreted as excuses by the dentist fordentures that function less than satisfactorily.

Individuality of Patients

Patients must be reminded that their physical, men-tal, and oral conditions are individual in nature.Thus they cannot compare their progress with newdentures to other persons’ experiences. Denturecomplaints that are annoying and painful to somepatients may be of secondary importance to others.Chewing and speech patterns considered success-ful by some persons may be interpreted as unsuc-cessful by others. Patients tend to forget the severityof problems with the passage of time. Many per-sons indicate that their dentures have always beencomfortable, even though they may have had a dif-ficult adjustment period. In addition, adaptabilityto new dentures is modified by age. Persons whomake the adjustment to new dentures during mid-dle age may experience considerably more diffi-culty with dentures 15 years later, even though thenew dentures may be technically superior to theoriginal ones. These remarks can be discouragingto patients with new dentures unless they have beenadvised of this possibility.

Appearance with New Dentures

Patients must understand that their appearance withnew dentures will become more natural with time.Initially, the dentures may feel strange and bulky inthe mouth and will cause a feeling of fullness of thelips and cheeks. The lips will not adapt immedi-ately to the fullness of the denture borders and mayinitially present a distorted appearance. Muscle ten-sion may cause an awkward appearance, which willimprove after the patient becomes relaxed andmore confident. Patients should be instructed torefrain from exhibiting their dentures to curiousfriends until they are more confident and compe-tent at exhibiting them. When patients are not care-ful in following these instructions, they may likelybecome unfairly critical of the dentures anddevelop an attitude that will be difficult for the den-tist to overcome. During the edentulous or partially

edentulous period, gradual reduction of the inter-arch distance and collapsing of the lips will haveoccurred. These changes usually have been sogradual that family and friends were not aware thatthey existed. Therefore a repositioning of the orbic-ularis oris muscle and a restoration of the formerfacial dimension and contour by the new denturesmay seem like too great a change in the patient’sappearance. This can be overcome only with thepassage of time, and patients are advised to perse-vere during the period.

Some dentists advise patients to change a hair-style or change glasses along with their new den-tures. This allows onlookers to notice the overallchange in the face. Often the dentures are not evennoticed by the observer as being responsible for thechange in appearance, but rather the pleasing changein the overall face will be observed. A change inglasses or hairstyle also allows the patient to respondto the comments with a discussion about the glassesor the hair and not confide about the new dentures,unless he or she wishes.

Mastication with New Dentures

Learning to chew satisfactorily with new denturesusually requires at least 6 to 8 weeks. Patients willbecome discouraged unless they are aware that thislearning period is to be expected. New memorypatterns often must be established for both thefacial muscles and the muscles of mastication.Once the habit patterns become automatic, thechewing process can take place without consciouseffort. The muscles of the tongue, cheeks, and lipsmust be trained to maintain the dentures in positionon the residual ridges during mastication. Patientscan be told that “these muscles must learn whatthey should and should not do.”

Patient comfort and mastication may beimpaired because of the elicited excess flow ofsaliva for the first few days after placement of newdentures. However, in a relatively short time thesalivary glands accommodate to the presence of thedentures, and normal production of saliva returns.

Patients should begin chewing relatively softfood that has been cut into small pieces. If thechewing can be done on both sides of the mouth atthe same time, the tendency of the dentures to tipwill be reduced. Patients should be told that during


this early period, mastication is best attempted onsimple types of food such as crackers, soft toast, orchopped meat and that no attempt should be madeto masticate more resistant foods. First-time den-ture wearers may be advised to eat foods thatrequire little mastication, but those that are readyfor swallowing with a simple push of the tongueagainst the palate. This will give the patients confi-dence in stabilizing the dentures. Also, during thelearning period, patients are advised to avoid obser-vation by friends or members of the family becausethe patients will be awkward in the beginningphases of chewing and susceptible to embarrass-ment and discouragement. Kindly but misplacedjoking remarks and comments by members of thefamily may readily lead a patient to become self-conscious about the dentures, and this will bereflected in the attitude toward the dentist and thedentures.

When biting with dentures, patients should beinstructed to place the food between their teethtoward the corners of the mouth, rather thanbetween the anterior teeth. Then the food should bepushed inward and upward to break it apart ratherthan downward and outward as would be done ifnatural teeth were present. Inward and upwardforces tend to seat the dentures on the residualridges rather than displace them.

Occasionally, edentulous patients have gonewithout dentures for long periods and have learnedto crush food between the residual ridges or per-haps between the tongue and the hard palate. Thesepersons usually experience increased difficulty inlearning to masticate with new dentures, and thetime for adjustment will likely be extended.

Patients should be told that the position of thetongue plays an important role in the stability of alower denture, particularly during mastication.Patients whose tongues normally rest in a retractedposition relative to the lower anterior teeth shouldattempt to position the tongue farther forward so itrests on the lingual surfaces of the lower anteriorteeth. This will help develop stability for the lowerdenture.

Speaking with New Dentures

Fortunately, the problem of speaking with new den-tures is not as difficult as might be expected. The

adaptability of the tongue to compensate forchanges is so great that most patients masterspeech with new dentures within a few weeks. Ifcorrect speech required exact replacement of tis-sues and teeth in relation to tongue movement, nopatient would ever learn to talk with dentures. If itwere not for the extreme adaptability of the tongue,the necessity of additional bulk over the palatewould cause a lasting speech impediment. Even a0.5-mm change at the linguogingival border of theanterior teeth would cause a speech defect, espe-cially in the production of s sounds. Therefore toothpositions that restore appearance and masticatoryfunction usually do not produce phonetic changesthat are too great to be readily compensated.

Speaking normally with dentures requires prac-tice. Patients should be advised to read aloud andrepeat words or phrases that are difficult to pro-nounce. Patients usually are much more consciousof small irregularities in their speech sounds thanthose to whom they are speaking. It should benoted that elderly patients with dentures often havehearing impairments and will have a greater diffi-culty in changing speech patterns without auditoryfeedback. An understanding of tongue positionsduring speech is valuable. Dentists should have anappreciation of tooth position, palatal contours,and lingual contours of the mandibular denture, andthese should be technically addressed at try-inand insertion, rather than complete reliance onpatient adaptation.

Oral Hygiene with Dentures

Patients must be convinced of the importance ofmaintaining good oral hygiene for the health of theoral cavity. Plaque, stains, and calculus accrue ondentures and oral mucosa of edentulous patients ina similar fashion as in the mouths of dentulouspatients. Dental plaque is an etiological factor in den-ture stomatitis, inflammatory papillary hyperplasia,chronic candidiasis, and offensive odors, and it mustbe removed.

Patients should be instructed to rinse their den-tures and their mouths after meals whenever possi-ble. Once a day, it is essential that the dentures beremoved and placed in a soaking type of cleanserfor a minimum of 30 minutes. This time is requiredfor effective killing of microorganisms on the


dentures, as well as removal of all stains. Commercialcleaners are quite effective, and leaving the den-tures in the cleanser overnight is even better.Before the dentures are placed in the cleanser, theyshould be brushed gently with a soft brush. Patientsneed to be instructed that the brushing is requiredto remove plaque because the soaking will not doso. The dentures should be brushed over a basin par-tially filled with water or covered with a wet wash-cloth to prevent breakage in case they are dropped.Patients should be discouraged from using tooth-pastes because most contain an abrasive materialthat will wear away the surface of acrylic resin. Aninexpensive alternative soaking cleanser is one thatcan be made up with 1 teaspoon of householdbleach and 2 teaspoons of water softener (Calgon)in 8 oz of water. The mucosal surfaces of the resid-ual ridges and the dorsal surface of the tongue alsoshould be brushed daily with a soft brush. This willincrease the circulation and remove plaque anddebris that can cause irritation of the mucous mem-brane or offensive odors.

Preserving the Residual Ridges

The residual ridges were not intended to bear thestresses of mastication created by complete den-tures. Therefore patients, especially when theirgeneral health is somewhat impaired, may expectsome irritation and discomfort of the oral tissues.No two patients’ mouths will react alike becausesome tissues tolerate stress better than others.Therefore it is impossible to predict exactly what toexpect. Patients must be aware of these varying andunpredictable conditions.

If some irritation of the tissues is experienced,patients are advised to remove their dentures andrest the mouth for a time. It may be harmful to thepatients’ tissues and their psyche by telling patientsthat they must keep their dentures in the mouthconstantly during this initial adjustment period.They may become highly nervous and fatigued andbe unnecessarily discouraged. However, patientsare requested to wear the dentures for several hoursbefore an adjustment appointment so any sorespots will be visible and accurate corrections of thedentures can be made. Patients must be cautionedconcerning the critical nature of adjustments to thedentures. They must be convinced that the dentist is

the only person qualified to undertake this mostimportant aspect of denture service. Obviously,patients should never attempt to adjust the denturesthemselves.

Patients should be told that dentures must be leftout of the mouth at night to provide needed rest fromthe stresses they create on the residual ridges. Failureto allow the tissues of the basal seat to rest may be acontributing factor in the development of serious orallesions, such as inflammatory papillary hyperplasia,or may increase the opportunity for microbial infec-tions, such as candidiasis. When dentures are left outof the mouth, they should be placed in a containerfilled with water to prevent drying and possibledimensional changes of the denture base material.

Residual ridges can be damaged by the use ofdenture adhesives and particularly home-reliners,to compensate for ill-fitting dentures. Patientsshould therefore be cautioned about this. If thesematerials are used, patients soon feel insecure with-out them. Adhesives, and especially home-reliners,can modify the position of the denture on the resid-ual ridge that can result in a change of both verticalrelations and CRs or a change in occlusal contacts,which may cause irreparable damage to the resid-ual ridges in a short time.

The special instructions must include direc-tions for continued periodic oral examinations forall edentulous patients. The tissues supporting den-tures change with time, and the rate of changedepends on both local and general factors. Gooddentures eventually become ill fitting and can dam-age the mouth without the patient’s being awarethat anything is wrong. Pathosis, which may or maynot be associated with the dentures, can develop inthe edentulous oral cavity. All edentulous patientsshould be examined by a dentist at least once ayear, and their names should be placed on a recalllist for that purpose.

Educational Material for Patients

Because the education of patients is so critical tothe success of new dentures, many dentists providewritten instructions or other formal educationalmaterial that has been developed. In studying thematerial, patients become aware that dentures arenot permanent, that the mouth changes, and mostimportant, that the care they provide themselves


may be a deciding factor in the success they expe-rience with dentures. People remember less of whatthey hear than of what they see. For this reason, itis wise to provide denture-wearing patients withprinted information about their new teeth, about thecare and cleaning of the teeth, about their use, andmost important, about the periodic inspections thatwill be necessary.

SECTION III: MAINTAINING THE COMFORT AND HEALTH OF THE ORAL CAVITY IN A REHABILITATED EDENTULOUS PATIENT

The complete denture service cannot be adequateunless patients are cared for after the dentures areplaced in the mouth. In many instances, the mostcrucial time in the patient’s perception of successor failure of dentures is the adjustment period. Thedentist is responsible for the care of the patientthroughout this period, and this occasionallyrequires a number of appointments. The completecooperation of the patient during the adjustmentperiod is essential. In educating patients, the dentistmust explain to them the problems that they arelikely to face during the adjustment phase and theprocedures that both the patient and the dentistmust follow to alleviate these problems. It is impor-tant that the dentist and the patient have a clearunderstanding as to the financial implications ofthe adjustment period, which reflects the dentistpractice management protocol.

TWENTY-FOUR-HOUR ORALEXAMINATION AND TREATMENTAn appointment for a 1- to 3-day adjustmentshould be made routinely. Patients who do notreceive this attention have more trouble than thosewho are cared for the first several days after theinsertion of the new dentures. This is the criticalperiod in the denture-wearing experience of thepatient. When the patient returns for the first adjust-ment, the dentist can ask, “How are you gettingalong with the sore mouth?” This invites patients todescribe their experiences and soreness, if any. Thedentist must listen carefully to the patient and on

the basis of these comments can learn approxi-mately where to look for trouble. The statementsmay also furnish valuable information aboutesthetic, functional, and mental attitude problemsthat may be developing.

Examination Procedures

The occlusion should be observed before the den-tures are removed from the mouth. To do this, themandible is guided into CR by placing a thumbdirectly on the anteroinferior portion of the chinand supporting the mandibular denture intraorally,directing the patient to “open and close your ‘lowerjaw’ until you feel the first feather touch of yourback teeth.” At the first contact, the patient isdirected to open and repeat this closure, “only thistime stop the instant you feel a tooth touch and thenclose tight.” If the teeth touch and slide, there is anerror in CO. When such an error is detected, thedentures are placed on their remount casts on thearticulator, and the occlusion is rechecked there.If the same error is found on the articulator, itrequires occlusal adjustment. If there is an error inthe mouth and none is found on the articulator, newinterocclusal records must be made. The mandibu-lar remount cast is removed from the articulator,and the mandibular denture is remounted beforethe occlusion is corrected.

After the occlusion has been tested and cor-rected (if necessary), a thorough visual and digitalexamination of the oral cavity is performed so thelocation of sore spots can be determined. The exam-ination begins with the mucosa of the maxillarybuccal vestibule and proceeds around through thelabial and the buccal vestibules on the other side ofthe mouth, with careful observation of the frena.The hamular notches and the hard and soft palatesare examined for signs of abrasion. The area of thecoronoid process is palpated, and the patient isasked if there is any tenderness in this region.

The mandibular dental arch and associated den-tal structures are systematically examined bothvisually and digitally. The tissues lining thevestibular spaces and the alveololingual sulci, par-ticularly the mylohyoid ridges and the retromylo-hyoid spaces, are observed carefully. The sides ofthe tongue and the mucosal lining of the cheeksmust also be inspected.


Adjustments Related to the Occlusion

A number of problems can result from errors in theocclusion. Soreness may develop on the crest of theresidual ridge from pressures created by heavy con-tacts of opposing teeth in the same region. Sorenessalso may be seen on the slopes of the residual ridgeas a result of shifting of the denture bases fromdeflective occlusal contacts (Figure 20-49). Beforeunnecessarily shortening or excessively relieving thedenture base, the dentist must observe the occlusioncarefully in the mouth and on the articulator, givingparticular attention to the possibility of heavy bal-ancing-side contacts that could cause rotation of themandibular denture base. Such occlusion errors arealmost impossible to locate in the mouth because ofmovement of the denture bases on the supporting softtissues.

Small lesions on the buccal mucosa of thecheek in line with the occlusal plane indicate thatthe patient is biting the cheek during mastication.This problem usually can be corrected by reducingthe buccal surface of the offending mandibulartooth to create additional horizontal overlap, thusproviding an escape for the buccal mucosa.

A patient may complain, “My dentures are tightwhen I first put them in my mouth, but they seem toloosen after several hours.” This symptom usually isan indication of errors in the occlusion that can becorrected after new interocclusal records are made,

the dentures are remounted, and the occlusion isadjusted on the articulator. The dentures becomeloose because the deflective occlusal contacts cause acontinual shifting of the denture base, which in turncauses distortion of the tissues in the basal seat.Although this problem may develop by the time of the1- to 3-day adjustment, it is more likely to be seen alittle later on.

Adjustments Related to the Denture Bases

A number of problems with new dentures arerelated to the denture bases themselves. Irritationto the vestibular mucosa is most often caused bydenture borders that are too sharp or dentureflanges that are overextended. This is often seen atthe hamular notch area, along the mandibularretromylohyoid area, mandibular buccal area, andprominent anterior frena. Before any adjustmentsare made, a heavy coating of pressure paste in theoffending area, with border molding, will deter-mine if the problem is overextension or contactpressure along the bone at the flange extension.Lesions in the region of the hamular notch must beconsidered carefully. If the irritated tissue is poste-rior to the notch, the denture base is too long andmust be shortened. However, if the soreness is inthe notch itself, the posterior palatal seal is likelycreating too much pressure, and the inside of the


Figure 20-49 A lesion (arrow) on the lingual slope of the mandibular residual ridge islikely due to errors in the occlusion that caused the denture base to shift and thus impingeon the mucosa. A, Sublingual caruncles; B, mandibular labial frenum.

tissue surface of the denture base will need to berelieved very cautiously so as not to loosen borderseal. Use the following three steps to evaluatethis area with paste: (1) one notch with adjustment,(2) the other notch with adjustment, and (3) then theposterior border length and posterior palatal seal onthe denture surface with adjustment. The use ofthese steps will minimize making an error in read-ing the pressure paste and overreducing the seal(Figures 20-50 and 20-51). The remainder of den-ture borders are shortened and rechecked with pasteagain. Finally they can be polished with pumice anda rag wheel. Irritated frena or paste-disclosed pres-sure in the notches will require that the notches bedeepened slightly (Figure 20-52). Widening of thenotch may not be necessary and, if done to excess,could reduce denture retention. The notch is deep-ened with a fissure bur and polished with a stone orsmall wheel. Pressure indicator paste should beused to evaluate pressure areas on the basal surface,regardless of whether sores or ulcerations are evi-dent. It should be applied and read in the same wayas described during the insertion phase. When pres-sure areas are found, they need to be adjusted andthe entire denture disclosed again. It will be com-mon that additional pressure areas will present, andneed relieving. Finally the contact will be uniform

throughout the denture. Use of an indelible mark-ing pencil placed on the ulcerative tissue as a pres-sure transfer should never be used as the only meansof tissue recall evaluation. Only focusing on the acuteproblem will likely move the pressure to another areaof the denture, causing another acute ulcer to be dealtwith a few days later. Skilled practitioners may use acombination of paste and markers, but the studentwho watches the faculty use the indelible pencil mayincorrectly assume it is the faster and easier diagnos-tic tool of choice. Students should be encouraged tolearn to “read” the subtle but very diagnostic signsderived from correctly manipulated pressure paste(Figures 20-53 through 20-55).

Excessive pressure from the mandibular buccalflange in the region of the mental foramen maycause a tingling or numbing sensation at the cornerof the mouth or in the lower lip. This results fromimpingement on the mental nerve and occurs par-ticularly when excess resorption has caused the men-tal foramen to be located near the crest of themandibular residual ridge. A similar situation canoccur in the maxillae from pressure on the incisivepapilla transmitted to the nasopalatine nerve. Thepatient may complain of burning or numbness in theanterior part of the maxillae. Relief may be requiredin the maxillary denture base in this region.


Figure 20-50 A, The sore spot (arrow) is posterior to the hamular notch, indicating thatthe denture base is too long in this region. B, After adjustment of the denture, notice thatthe spot is posterior to the border.

A B

Patients may return for the initial adjustmentappointment complaining that their dentures causethem to gag. This problem may actually be relatedto the dentures themselves, or there may be a psy-chological component. When the problem is den-

ture related, usually the maxillary denture is theculprit, although on occasion the mandibular den-ture or both will be involved. Most often, the gag-ging relates to the posterior border of the maxillarydenture. The border may be improperly extended,or the posterior border seal may be inadequate(Figure 20-56). Gagging often occurs when theposterior border seal is disrupted as the tissue dis-tal to the vibrating line moves upward and down-ward during function. When the vibrating line hasbeen properly located, it is not necessary (and usu-ally not desirable) to extend the posterior border ofthe maxillary denture more than 2 mm beyond thispoint. If the posterior palatal seal is inadequate,modeling compound can be added to reshape thispart of the maxillary denture and help alleviate thesituation. Then the modeling compound can be


Figure 20-51 A, The distobuccal flange of this maxillary denture is too thick below theborder (arrow). Using paste along the border periphery and thickness of the flange in thisarea reveals the pressure created in the hamular area. B, This flange is of proper thickness.

A

B

Figure 20-52 Labial notches must be sufficientlydeep, with borders that are rounded and smooth.

replaced with acrylic resin. The occlusion may alsobe a factor because shifting of the denture basesaffects the posterior palatal seal.

On occasion, patients will state that the maxil-lary denture comes loose when they open their

mouth wide to bite into a sandwich or to yawn.Generally, this complaint indicates that the disto-buccal flange of the maxillary denture is too thickand interferes with normal movements of the coro-noid process (see Figure 20-51). The borders of the


BFigure 20-53 A, Spiny projections of bone (arrows) underlie the mucosa covering thecrest of this mandibular residual ridge. B, Pressure spots in the indicator paste show whererelief will be needed. The denture base will be adjusted with a no. 8 round bur.

Figure 20-54 This lesion on the mucosa lining the retromylohyoid fossa (arrow) wascaused by excessive length and pressure from the denture base. Pressure paste that is placedin this area will likely rub off the border as well as reveal a pressure area along the bonymandible just internal to the flange. Both the flange and basal surface will requireadjustment. Often patients will complain of soreness when they swallow or state that theyfeel as if they have a sore throat. Complaints of soreness during swallowing also arefrequently related to irritation in the region of the mylohyoid ridges.

A

maxillary buccal flanges should properly fill thebuccal vestibule. However, the distal corners of thedenture base below the borders must be thin toallow the freedom necessary for movement of thecoronoid process.

Again, in discussions with patients, it may berevealed that the maxillary denture tends to loosenduring smiling or other forms of facial expression.

Excessive thickness or height of the flange of themaxillary denture in the region of the buccal notchor distal to the notch may cause this problem (Figure20-57). As the buccal frenum moves posteriorly dur-ing function, it encroaches on a border that is toothick, and the denture becomes loosened. Reductionof the width of the border posterior to the maxillarybuccal notch often will relieve this problem.


Figure 20-55 A, This line of irritation (arrows) was caused by an overextended buccalflange of the mandibular denture. Pressure paste that is placed on the flange edge of theflange only will reveal the area causing the problem. It should be repeatedly checked andadjusted until none of the paste rubs off the denture. B, The pressure spot in indicator pasterepresents the part of this denture base that has been placing excessive pressure on thebuccal shelf and is not related to the length of the flange causing the ulcers in A.

A

B

SUBSEQUENT ORAL EXAMINATIONSAND TREATMENTSDentures require inspection and sometimes furtheradjustment after they have been used by the patient.During the first several weeks, the acrylic resinabsorbs water. This can result in small changes inthe size and shape of the dentures. Even though the

alterations are small, they may be sufficient tochange the occlusion. Minute changes in the occlu-sion can create discomfort by making the denturesshift or slide in function. Soreness reported bypatients in this situation is most likely on the lin-gual side of the mandibular ridge in the region ofthe canine and first premolar and is most likely dueto deflective occlusal contact between the lastmolar teeth diagonally across the mouth, oftenbetween the balancing inclines of the mandibularsecond molars.

In most instances, the occlusal error can beobserved and corrected by placement of the den-tures in their original remount casts on the articula-tor. If, however, the bases have so changed that theyno longer fit the remount casts the way they didoriginally, it will be necessary to make newremount casts and new interocclusal records. Theremount jig record will permit the maxillary den-ture to be remounted without making a new facebow transfer record.

After the new records are made, the occlusion iscorrected by selective grinding with the same proce-dure as was used at the time of the dentures’ inser-tion. It is interesting that the occlusal changes willlikely be small, but the soreness they produce is veryreal and disturbing. Dentists should not succumb tothe temptation to grind from the denture base withoutdetermining the real cause of the trouble.

Sometimes generalized irritation or soreness ofthe basal seat will develop. Although this conditionmay be attributable to a number of factors (such asan excessive vertical dimension of occlusion, nutri-tional or hormonal problems, or unhygienic den-tures), it more likely is due to the occlusion. Asindicated previously, errors in occlusion should besuspected whenever a patient states that the den-tures are “tight when I first put them in my mouthin the morning but seem to loosen later in the day.”A collection of calculus on the teeth on one side ofthe denture also indicates the need for correctingthe occlusion.

Certain symptoms at an adjustment appointmentsuggest an insufficient interocclusal distance. Thepatient may comment, “After I’ve worn the new den-tures for several hours, my gums get sore and themuscles in the lower part of my face seem tired.” Onremoval of the dentures, the mucosa of the basal seatoften will exhibit a generalized irritation. These


Figure 20-56 Overextended posterior border of amaxillary denture. When the border was shortened tothe approximate length indicated by the dotted line,the denture no longer caused the patient to gag.

Figure 20-57 Notice the excessive thickness of theright buccal border in the region of the buccal notch(arrows). The buccal frenum, moving posteriorly overthis border during facial expression, can loosen orunseat a maxillary denture. This area can be discernedfrom patient complaint and pressure paste on the border.

symptoms indicate that when the patient’s mandibleis in the resting position, there is not sufficient spacebetween the opposing teeth to allow the supportingstructures of the residual ridge and the involvedmuscles to rest normally. If this is true, severaloptions exist. Sometimes creating a small amount ofadditional interocclusal distance will solve the prob-lem, and the dentist can do this by returning the den-tures to the articulator and grinding the artificialteeth to reduce the vertical dimension of occlusion;esthetics and the amount of clearance between theanterior teeth are the limiting factors in this proce-dure, and another 1 to 1.5 mm of interocclusal dis-tance can thus be created. Other times it may benecessary to reset the artificial teeth of one or bothdentures; the decision as to which teeth should bemoved is based on esthetics and the vertical dimen-sion of occlusion. Finally, in some instances, thedentures will have to be remade.

Periodic Recall for Oral Examination

When patients are judged to be successfully treatedand the necessary adjustment appointments after

denture insertion are completed, patients areinstructed to call for an appointment if they haveany problems. Patients with some of the more dif-ficult problems should be scheduled for appoint-ments periodically, perhaps at 3- to 4-monthintervals. This will help their morale and may tendto eliminate their seeking adjustment appointmentson a weekly basis or even more often.

Every denture-wearing patient should be in arecall program, just as any other dental patient is.The dentist should not hesitate to inform a patientthat occlusal corrections, relining, new dentures, orother fairly involved procedures may be necessaryas changes in the mouth continue to occur. A12-month interval is the suggested time betweenrecall appointments for most patients with com-plete dentures.

BibliographyJohnstone EP, Nicholls JI, Smith DE: Flexure fatigue of 10 com-

monly used denture base resins, J Prosthet Dent 46:478-483, 1981.

Spratley MH: An investigation of the adhesion of acrylic resinteeth to dentures, J Prosthet Dent 58:389-392, 1987.


C H A P T E R 21Single DenturesAlan B. Carr

427

As mentioned earlier, the edentulous state can beconsidered equivalent to the absence of a body partwith specific morphological functional and psy-chological sequelae. This chapter discusses thepatient with a single edentulous arch. For such apatient, the clinical challenge is one of appreciatingthe biomechanical differences in the supporting tis-sues for the two arches and applying the appropri-ate management procedures to produce andmaintain the conditions necessary for long-termtreatment success. In this chapter, a basic treatmentprotocol is also described.

SINGLE EDENTULOUS ARCHThe prevalence of the condition in which one eden-tulous arch opposes a natural or restored dentitionis common, and it has been estimated that in somepatient populations mandibular canines are retainedfor the longest time—four times longer than otherteeth. After the mandibular canines, the next longest-lasting teeth are mandibular incisors. This docu-mented arch discrepancy in tooth survival suggeststhat the maxillary arch exhibits earlier tooth loss.The reasons for the loss of the maxillary teethbefore the mandibular teeth are unclear and areinfluenced by a combination of factors. One majorfactor might be the dental profession’s perceptionof the ease of construction of maxillary denturescompared with mandibular ones and the compara-tive functional success of maxillary versus mandibu-lar complete dentures. It is therefore important forthe clinician to have an appreciation of some oralconditions that may predispose this specific patientpopulation to complications after treatment with con-ventional complete dentures. Such an understand-

ing will help the clinician determine when preser-vation of useful maxillary teeth is warranted overtheir extraction. Because mandibular anterior teethare preserved the longest, most of the discussion inthis chapter focuses on the oral condition in whichthe maxillary arch is edentulous and opposed by anatural or restored mandibular dentition.

CHALLENGE OF VARYING SUPPORTThe qualitative and quantitative difference betweennatural tooth and complete denture support hasbeen emphasized earlier in this book. The differ-ence is one of adaptability versus maladaptability:the natural dentition is capable of sophisticatedresponses to occlusal demands that largely preservefunctional capability, whereas mucoperiosteal bonesupport is incapable of such favorable adaptation.Unfavorable responses exhibit a spectrum of sever-ity for varying population groups. For example, thepostmenopausal white female is more likely toexhibit a rapid and severe morphological change inthe denture-bearing tissues than a younger whitemale who has been edentulous for the same length oftime. However, even with the same patient popula-tion, the group ability to adapt to comparable mor-phological features differs among patients. In otherwords, for a group of patients in the same age, sex,and racial category, the patient response to com-plete denture use will be variable. This does notappear to be the case for patients with fixedprostheses in whom treatment response appears tobe more predictable. Consequently, managing thereplacement of the missing maxillary dentition musttake into account the variation in opposing archsupport and provide for an optimum distribution of

occlusal forces to minimize the negative effects inthe compromised edentulous arch. This willdemand an understanding of factors that magnifythe inherent risk of regressive changes in the eden-tulous arch. Early identification of these factors andtheir likely impact on complete denture prognosismust be addressed with the patient.

DIAGNOSIS AND TREATMENTPLANNINGThe commonly cited long-term goal in prosthodon-tics is the preservation of that which remains. Thisdemands an appreciation of occlusal biomechanicsas referred to in Chapters 16 and 17. Salient con-siderations include: (1) acceptable interocclusaldistance, (2) stable jaw relationship with bilateraltooth contacts in retruded closure, (3) stable toothquadrant relationships with axially directed forces,and (4) multidirectional freedom of tooth contactthroughout a small range (within 2 mm) ofmandibular movements. These characteristics of aphysiological occlusion are frequently encounteredin fully dentate mouths. They also can be almostinvariably achieved when treating fully edentulouspatients. However, when only one arch is edentu-lous, tooth positions in the dentate arch may pre-clude such objectives being reached. Unfavorable

force distributions may then cause adverse tissuechanges that compromise optimum function. It istherefore important to identify such clinicalchanges and to correct them.

These changes include: (1) extensive morpho-logical changes in denture foundation that canresult in arch relationship or occlusal plane dis-crepancies, (2) jaw relationship extremes, and (3)excessively displaceable denture-bearing tissue.Routine morphological changes occur after toothextraction and result in a generally smaller maxillawhen compared with the dentulous state. This cre-ates a horizontal discrepancy between the archesanteriorly and posteriorly (Figure 21-1) and makesit difficult to direct occlusal forces to the denture-bearing surfaces because the support is at a dis-tance from the denture tooth position. The beststrategy for correcting this discrepancy posteriorlyis to place the teeth in a reverse horizontal overlapor crossbite arrangement. However, such a correc-tion procedure for the anterior discrepancy is notpossible because of the esthetic impact on the max-illary lip of such a tooth position.

Changes in the denture foundation also canoccur because of longstanding uncontrolledocclusal forces (Figure 21-2). This elicits a combi-nation of morphological and spatial changes, forexample, a maxillary complete denture opposed by


Figure 21-1 A, Posterior left horizontal ridge–opposing tooth discrepancy. Noticethe location of the mandibular molar is directly beneath the maxillary vestibule. B, Samelocation with the maxillary molar denture tooth placed in normal intercuspation. Notice thedistance from the tooth to the ridge and the potential for tilting to result, given the lack ofsupport directly beneath the denture tooth.

A B

Continued

anterior mandibular teeth only or by a mandibulararch restored with a Kennedy Class I removablepartial denture that has not maintained the denturesupport. Both conditions are characterized byocclusal forces that are concentrated exclusively onthe premaxillary region. When such a force distri-

bution is allowed to go uncorrected, the premaxil-lary region undergoes destructive changes thatallow displacement of the denture superiorly, andthe resultant change in the occlusal plane can allowa downgrowth of the maxillary tuberosities. If notaddressed through the necessary preprosthetic sur-gery, as well as provision and maintenance of pos-terior occlusion, such a combination of changes inthe maxillary arch may predispose new prosthesesto failure because of the inability to prescribe anormal occlusal plane and denture foundation thatprovide optimum occlusal force distribution andsupport around the arch.

Extremes of jaw relationship also make it diffi-cult to place the denture teeth in a position thatallows the denture-bearing area to be in line withthe occlusal support. This is most often the situa-tion with a Class III skeletal relationship, and thedilemma is similar to the previously mentionedarch discrepancy seen with the normal postextrac-tion ridge changes. The most common procedurefor addressing the problem is to place the posteriorteeth in a reverse horizontal overlap or crossbiterelationship. The anterior teeth, however, cannot beplaced lingual to the mandibular teeth, and thepotential for dislodgement with anterior tooth con-tact is problematic.

The dilemma posed by excessively displaceabletissue is one of differential support capability to the

Chapter 21 Single Dentures 429

Figure 21-1 cont’d C, The same location; however, the maxillary denture tooth is placedin a reverse horizontal occlusion and in such a position presents less of a tilting potential onmastication. D, A sagittal view of the anterior region of the same mouth reveals the horizontaldiscrepancy between the mandibular incisors and the opposing maxillary anterior ridge.

C D

Figure 21-2 The entire maxillary denture-bearingridge area has been replaced by mobile, hyperplastictissue. Its surgical removal will result in a nonretentiveprosthesis because the vestibule will be virtuallyobliterated. This morphological predicament has partlyresulted from the complete maxillary denture’sopposing an intact natural dentition after many yearsof denture wearing.

same load. The forces of occlusion are resisted bythe mucoperiosteum, which allows some move-ment of the denture base by virtue of its resiliency.When tissue changes allow excessive displacementin one area but not in another, the movement of theprosthesis under load is greater in the region ofgreater tissue displacement, with resultant dis-lodgement.

Conditions in the opposing arch also can pre-dispose the patient to problems with a single com-plete denture. The most common condition is anirregular occlusal plane (Figure 21-3). This often isseen as a tilting or extrusion of teeth after theextraction of a mandibular first molar, and the sec-ond and third molars exhibit an anterior inclinationand possibly a superior position compared withthe normal relationship. This results in an irregularocclusal plane and consequent unfavorable forcedistribution. Assessment of the irregularity presentin an occlusal plane is necessary to guide therequired selective grinding. It can be achieved witha template or curved occlusal plane such as thatused in setting denture teeth. When placed on thedental arch, this device rests on the teeth thatare most prominent in the vertical plane and canbe used to determine the selective grinding ofthe most prominent teeth to ensure that a sufficientnumber of teeth are in contact. This provides a uni-form reduction but may not meet the needs of aspecific denture arrangement for stable cross archbalance.

CLINICAL AND LABORATORYPROCEDURESIn the case of a single maxillary denture, a finalimpression is made of the maxillary arch, and anopposing impression is made of the mandibulararch. If a cast metal base (nonprecious or goldalloy) is prescribed, this is now made in a fullpalatal coverage design with mesh extensions overthe edentulous ridges and extending to the poste-rior palatal seal area. A maxillary occlusion rim isfabricated, and if bilateral or tripod stable centricstops can be established on this rim, a centric rela-tion (CR) record is made in wax or fast-settingplaster. When stable centric stops are not feasiblebecause of a reduced mandibular dentition, a par-tial mandibular occlusion rim must be used for the

CR record. A face bow registration is made, and thecasts are mounted on a semiadjustable articulator.The condylar guidances on the articulator are seteither to an average value or to settings provided byprotrusive records. The incisal guidance is set at theangle considered necessary for the denture’s occlu-sion. Horizontal settings will allow for shallowinclines and a more stable denture during eccentriccontact movements. Esthetics will influence theangle of the incisal guide because the vertical posi-tion of the anterior teeth varies with the amount ofvertical overlap used.

The teeth are arranged with the proper inclina-tions and vertical overlaps but without followingthe exact occlusal plane of the opposing naturalteeth when their arrangement is not ideal. As men-tioned before, a nonideal occlusal plane is fre-quently encountered because of the loss of someteeth and the shifting of adjacent teeth. For exam-ple, because the mandibular first molar is the mostfrequently missing tooth, resultant drifting of thesecond and third molars creates steep inclines inthe occlusal plane. If the maxillary teeth were to bepositioned into a maximum intercuspation rela-tionship with these molars, the result would behorizontal movement of the denture base on clo-sure, which would tend to dislodge the denture.Consequently, the maxillary molars should not beplaced into maximum intercuspation with teethexhibiting steep inclines; rather, the denture teethare prepared with reduced inclines to diminish lat-eral stress and encourage occlusal stability bydirecting occlusal forces vertically toward the sup-porting tissues.

The teeth placed in the hard baseplate–waxocclusion rim are then evaluated on the articulatorin eccentric positions. Modifications to tooth posi-tion are made to provide stable cross arch balancewithin a functional range of eccentric movement(2 mm). In deciding the best possible denture toothpositions, given the opposing tooth positions, thedentist may find that the best option is to alter thenatural tooth contours through selective toothreduction. The denture arrangement is completed,and the necessary natural tooth modifications areaccomplished on the opposing stone cast, with caretaken to mark the location and extent of modifica-tion. When it is clinically determined that naturaltooth modification can be carried out, the modifi-



Figure 21-3 Extrusion of the mandibular molars in both A and B will require modification oftheir coronal shape to ensure an optimally stable occlusal scheme. In C and D, the mandibularposterior teeth have been restored to rectify drifting and extrusion of teeth, a disruption in theocclusal plane. A similar clinical and laboratory strategy ensured a balanced occlusion in E.

A B

CD

E

cation is accomplished at the final prosthesis inser-tion appointment. If, however, it is determined thatthe natural tooth modification that is required toensure a stable denture prosthesis would result inperforation of the enamel and a restoration of thenatural tooth is necessary, discussion with thepatient as part of the overall treatment plan will berequired. It also may be observed that the requiredtooth positions will place the maxillary prosthesisat risk of fracture because of required occlusal rela-tions coupled with prosthesis design. If this is sus-pected, a cast metal base should be recommendedfor the patient.

After denture tooth placement is accomplishedand if an opposing fixed or removable partial den-ture is part of the treatment, it is finalized at thisstage. The most predictable control of the occlusioncan be provided if the prostheses are fabricated andinserted at the same time. After verification of theocclusal requirements on the articulator and at thewax trial denture stage, the prosthesis is processedand completed. At insertion, the tissue surface ischecked for fit and retention, the borders arechecked for proper extension, and the occlusion ischecked for duplication of the articulator mount-ing. Significant occlusal discrepancies should beadjusted after a clinical remount procedure. Anynecessary minor adjustment of the natural dentitionis accomplished with the adjusted stone cast as aguide. With a thin articulating paper to record thesteep inclines that require adjustment, the teeth aremarked, checked against the cast markings, andreduced to the predetermined inclination.Preliminary adjustment can be accomplished with adiamond bur, followed by fine adjustment witha fine carborundum or similar stone. The adjustedcontacts are again checked against the stone cast toverify completion of the CR adjustments. Next,simulated excursive movements are performedand adjusted with the same procedure. The objec-tive at this stage is to provide smooth excursivemovement within a 2-mm functional range withcross arch tooth contacts to ensure prosthesisstability. Completion of the occlusal refinementinvolves careful pumicing of the occlusal sur-faces. If the clinician chooses to allow the patientto complete the refinement by using an intraoralpaste (carborundum paste) as the patient goesthrough excursive movements, care must be taken

to prevent excessive adjustment to the CRposition.

POTENTIAL ADVERSE TREATMENTOUTCOMESTwo of the most common adverse sequelae of treat-ment using a single complete denture include natu-ral tooth wear (Figure 21-4) and denture fracture.The use of maxillary porcelain denture teeth, espe-cially when adjusted during the occlusal correctionphase, can lead to rapid wear of the opposing natu-ral or restored dentition. Teeth restored with vari-ous cast restorations are often less resistant to thewear from unglazed porcelain, and the best strategyis to use new generation acrylic/composite resindenture teeth in conjunction with periodic exami-nations. This is the most practical approach giventhe average life expectancy of the conventionalcompleted denture. If the clinician desires to estab-


AFigure 21-4 A and B, An increased interocclusaldistance (therefore a collapsed vertical dimension ofocclusion) resulted from the consequences ofunfavorable occlusal relationships in this elderlypatient. The biological price of such an unserviced,long-term prosthetic experience frequently manifestsitself as advanced residual ridge resorption in bothmaxillary and mandibular edentulous segments, plusa perpetuation of adverse concentration of anteriorstresses as evidenced by severe tooth wear matchingthe concentrated hyperplastic ridge replacement in theopposing arch

Continued


Figure 21-4 cont’d (C, D, and E). Clinical management demands optimal occlusal rela-tions, which were readily incorporated into a removable partial overdenture/RPD type ofmandibular prosthesis opposing a complete maxillary denture. F to I, Optimal esthetics andfunction were restored to preclude further morbidity.

B C

D E

F G

Continued

lish similar material occlusal surfaces and the sin-gle denture opposes cast restorations, there aretechniques to follow that allow the use of cast metalfor the production of the denture occlusion.

Because the single denture is often opposed bya full or near full complement of natural teeth, acommon complication is fracture of the denturebase. Specific conditions that encourage such frac-ture include heavy anterior occlusal contact, deeplabial frenal notches (especially when in conjunc-tion with midline diastema), and high occlusalforces due to strong mandibular elevator muscula-ture. Careful attention to the occlusion, an ade-quate denture base thickness, and control of thedenture labial notch are frequently the only neces-sary requirements to prevent fracture. When theclinician is unable to control these factors or issuspicious that fracture potential is high, a castmetal base is best used to resist deformation andfracture.

Considerations during maintenance visits forthe patient with a single denture include verifica-tion of the occlusal contacting relationships thatprovide stable occlusal forces in CR and eccen-tric contact positions. Also, the condition of thesupporting tissues should be evaluated, and whenthe tissues exhibit changes that would encour-age excessive movement, measures should betaken to reduce movement and the potential fordislodgement.

RATIONALE FOR IMPLANTS IN THEEDENTULOUS MAXILLAAs described earlier, change in the denture-sup-porting tissues is variable but inevitable. The majortissue change is an irreversible bone loss resultingfrom both local and systemic effects. Such mor-phological change in the maxillary denture-bearingfoundation can lead to difficult functional stabilityproblems. Even for those patients who have demon-strated remarkable skill in manipulating biomechan-ically challenging prostheses, the need to improvethe denture foundation to ensure better functionalstability often arises.

Providing improved stability to a prosthesisthrough the use of dental implants allows bothenhanced function and a reduction in the irreversiblebone loss that led to the instability. Well-distributedimplants used to stabilize an overdenture prosthesisdesign have been shown to be an effective treat-ment modality for the edentulous maxillary arch(Figure 21-5).

MANDIBULAR SINGLE DENTUREThe single mandibular denture opposing a restoredcomplete or partial maxillary dentition poses aneven greater challenge to the clinician. The situationoften is compounded by severe residual ridge resorp-tion of the edentulous mandible, which makes con-


Figure 21-4 cont’dH I

ventional treatment nearly impossible (Figure21-6). The edentulous mandible is always at a dis-advantage because of a limited quantity of mucosa,the amount of denture border adjacent to moveablemucosa, and the impact of occlusal forces fromthe moving mandible contacting the static dentatemaxillary arch. These conditions frequently makeconventional treatment unwise and have been bestaddressed through the use of endosseous dentalimplants to provide retention and support for themandibular complete denture and to retard residualbone resorption.

When the clinician is unable to provide the optionof endosseous dental implants, treatment with a sin-gle denture should proceed only after a clear discus-sion of the potential for problems, given the clinicalfindings, between the patient and clinician. The clin-ical and laboratory procedures are very similar tothose described earlier in this chapter. However,many clinicians think that the use of a resilient linerin the mandibular denture is beneficial. With such aprocedure the dentist attempts to provide a stress-reducing element in the denture base to resist theforces of functional and parafunctional loads.


Figure 21-5 Composite illustrations of an edentulous maxilla in a patient struggling withmaxillary denture stability due to the combination of an intact mandibular natural dentitionand a regressing edentulous maxilla. Placement of implants allowed construction of anoverdenture with enhanced functional stability. A and B, Panoramic radiographs of anedentulous maxilla before and after placement of eight well-distributed implants with aconnecting bar that supports the overdenture prosthesis. C, Clinical view of the implantconnecting bar. D, Overdenture prosthesis in occlusion with natural mandibular dentition.

A B

C D

SUMMARYThe patient who requires a single denture oppos-ing a natural or restored dentition challenges theclinician even more than the completely edentu-lous patient does. This is due to the biomechanicaldifferences in the supporting tissues for the oppos-ing arches. Certain conditions must be evaluated

and corrected early in treatment to provide for amore stable prosthesis. The unique biomechanicalfeatures of the patient with a single denture havebeen emphasized, and methods for controllingdenture tooth and opposing tooth position to max-imize stable functional relationships have beenpresented.

BibliographyDenissen HW, Kalk W, van Waas MA et al: Occlusion for max-

illary dentures opposing osseointegrated mandibularimplants, Int J Prosthet 6:446-450, 1993.

Hansen CA, Clear K, Wright P: Simplified procedure for mak-ing gold occlusal surfaces on denture teeth, J Prosthet Dent71:413-416, 1994.

Jacobs R, van Steenberghe D, Nys M, Naert I, et al: Maxillarybone resorption in patients with mandibular implant-supported overdentures or fixed prostheses, J Prosthet Dent70:135-141, 1993.

Kelly E: Changes caused by a mandibular removable partialdenture opposing a maxillary complete denture, J ProsthetDent 27:210-215, 1972.

Kiener P, Oettertli M, Mericske E et al: Effectiveness of maxillaryoverdentures supported by implants: maintenance and pros-thetic complications, Int J Prosthodont 14:133-140, 2001.

Koper A: The maxillary complete denture opposing naturalteeth: problems and some solutions, J Prosthet Dent 57:704-707, 1987.

Schneider RL: Diagnosing functional complete denture frac-tures, J Prosthet Dent 54:809-814, 1985.


Figure 21-6 The mandibular denture-bearing areahas been adversely affected by long-term wear of acomplete lower denture opposing a partially edentulousmaxillary dentition restored with a removable partialdenture.

C H A P T E R 22The Retention of Complete DenturesKenneth Shay

437

Optimal outcome of complete denture treatmentdepends on the successful integration of the prosthe-sis with the patient’s oral functions plus psychologi-cal acceptance of the dentures by the patient. Theseparameters require that patients perceive their den-tures as stationary or well retained during functionand that the prostheses and their effects on the facemeet the esthetic and psychodynamic requirementsof the patient. In this chapter, the factors involved inachieving denture retention (the resistance toremoval in a direction opposite that of insertion) arereviewed, and the role that a denture adhesive agentmay play in the context of the patient’s adjustment toand acceptance of the dentures is discussed.

FACTORS INVOLVED IN THERETENTION OF DENTURESInterfacial Force

Interfacial force is the resistance to separation oftwo parallel surfaces that is imparted by a film ofliquid between them. A discussion of interfacialforces is best broken into separate comments oninterfacial surface tension and viscous tension.

Interfacial surface tension results from a thinlayer of fluid that is present between two parallelplanes of rigid material. It is dependent on the abil-ity of the fluid to “wet” the rigid surrounding mate-rial. If the surrounding material has low surfacetension, as oral mucosa does, fluid will maximizeits contact with the material, thereby wetting it read-ily and spreading out in a thin film. If the materialhas high surface tension, fluid will minimize itscontact with the material, resulting in the formationof beads on the material’s surface. Denture base

materials vary in their surface tension (also termedwettability), with processed materials displayinggreater wettability than autocured products. Alldenture base materials have higher surface tensionthan oral mucosa, but once coated by salivary pelli-cle, their surface tension is reduced, which pro-motes maximizing the surface area between liquidand base. The thin fluid film between the denturebase and the mucosa of the basal seat therefore fur-nishes a retentive force by virtue of the tendency ofthe fluid to maximize its contact with both surfaces.

Another way to understand the role of surfacetension in denture retention is through capillaryattraction, or capillarity. Capillarity is what causes aliquid to rise in a capillary tube because in this phys-ical setting the liquid will maximize its contact withthe walls of the capillary tube, thereby rising alongthe tube wall at the interface between liquid andglass. When the adaptation of the denture base to themucosa on which it rests is sufficiently close, thespace filled with a thin film of saliva acts like a cap-illary tube in that the liquid seeks to increase its con-tact with both the denture and the mucosal surface.In this way, capillarity will help to retain the denture.

Interfacial surface tension may not play asimportant a role in retaining the mandibular den-ture as it does for the maxillary one. Interfacialsurface tension is dependent on the existence of aliquid/air interface at the terminus of the liquid/solid contact: if the two plates with interposed fluidare immersed in the same fluid, there will be noresistance to pulling them apart. In many patients,there is sufficient saliva to keep the external bor-ders of the mandibular denture awash in saliva,thereby eliminating the effect of interfacial surfacetension. This is not so in the maxilla. Interfacial

viscous tension refers to the force holding two par-allel plates together that is due to the viscosity ofthe interposed liquid. Viscous tension is describedby Stefan’s law.* For two parallel, circular plates ofradius (r) that are separated by a newtonian(incompressible) liquid of viscosity (k) and thick-ness (h), this principle states that the force (F) nec-essary to pull the plates apart at a velocity (V) in adirection perpendicular to the radius will be

F = (3/2)πkr4V

h3

The relationship expressed by Stefan’s lawmakes it clear that the viscous force increases pro-portionally to increases in the viscosity of the inter-posed fluid. The viscous force drops off readily asthe distance between the plates (i.e., the thicknessof the interposed medium) increases. The forceincreases proportionally to the square of the areaof the opposing surfaces. When applied to dentureretention, the equation demonstrates the essentialimportance of an optimal adaptation between den-ture and basal seat (a minimal h), the advantage ofmaximizing the surface area covered by the denture(a maximum r), and the theoretical improvement inretention made possible by increasing the viscosityof the medium between the denture and its seat. Italso explains why a slow, steady displacing action(small V) may encounter less resistance and there-fore be more effective at removing a denture than isa sharp attempt at displacement (large V).

In application, interfacial forces are furtherenhanced through ionic forces developed betweenthe fluid and the surrounding surfaces (adhesion)and the forces holding the fluid molecules to eachother (cohesion).

Adhesion

Adhesion is the physical attraction of unlike mole-cules for each other. Adhesion of saliva to the mucousmembrane and the denture base is achieved throughionic forces between charged salivary glycoproteinsand surface epithelium or acrylic resin. Through itspromoting contact of saliva to both oral tissue anddenture base, adhesion works to enhance further theretentive force of interfacial surface tension.

Another version of adhesion is observedbetween denture bases and the mucous mem-branes themselves, which is the situation inpatients with xerostomia (sparse or absentsaliva). The denture base materials seem to stickto the dry mucous membrane of the basal seatand other oral surfaces. Such adhesion is not veryeffective for retaining dentures and predisposesto mucosal abrasions and ulcerations because ofthe lack of salivary lubrication. It is annoying topatients to have denture bases stick to the lips,cheeks, and tongue. An ethanol-free rinse con-taining aloe or lanolin, a water-soluble lubricat-ing jelly, or a saliva substitute containingcarboxymethylcellulose (CMC) or mammalianmucin can be helpful in this situation. Forpatients whose mouths are dry because of irradi-ation or an autoimmune disorder such asSjögren’s syndrome, salivary stimulation througha prescription of 5 to 10 mg of oral pilocarpinethree times daily can be very beneficial if thepatient can tolerate the likely adverse effects ofincreased perspiration and (occasionally) excesslacrimation.

The amount of retention provided by adhesionis proportionate to the area covered by the denture.Mandibular dentures cover less surface area thanmaxillary prostheses and therefore are subject to alower magnitude of adhesive (and other) retentiveforces. Similarly, patients with small jaws or veryflat alveolar ridges (small basal seats) cannotexpect retention to be as great as can patients withlarge jaws or prominent alveoli. Thus the dentures(and therefore the impressions that serve as thepatient analogue for their fabrication) should beextended to the limits of the health and function ofthe oral tissues, and efforts should be made at alltimes to preserve the alveolar height to maximizeretention.

Cohesion

Cohesion is the physical attraction of like mole-cules for each other. It is a retentive force becauseit occurs within the layer of fluid (usually saliva)that is present between the denture base and themucosa and works to maintain the integrity of theinterposed fluid. Normal saliva is not very cohe-sive so that most of the retentive force of the den-ture-mucosa interface comes from adhesive and


*Stefan J, Sitzberger K: Akad Wiss Math Natur 69:713, 1874.

interfacial factors unless the interposed saliva ismodified (as it can be with the use of dentureadhesive).

Thick, high-mucin saliva is more viscous thanthin, watery saliva, yet thick secretions usually donot result in increased retention because watery,serous saliva can be interposed in a thinner filmthan the more cohesive mucin secretions. Stefan’slaw makes it clear that if all other factors areequal, then an increase in fluid viscosity cannotbe accompanied by an equal increase in filmthickness if displacement force is to be kept thesame.

Oral and Facial Musculature

The oral and facial musculature supply supplemen-tary retentive forces, provided (1) the teeth are posi-tioned in the “neutral zone” between the cheeks andtongue and (2) the polished surfaces of the denturesare properly shaped (see Chapter 15). This is not tosay that patients must hold their prosthetic teeth inplace by conscious effort but that the shape of thebuccal and lingual flanges must make it possible forthe musculature to fit automatically against the den-ture and thereby to reinforce the border seal(Figures 22-1 and 22-2). One of the objectives inimpression making and arch form design is the

Chapter 22 The Retention of Complete Dentures 439

Figure 22-1 Complete dentures have three surfaces that must harmonize with the oralbiological environment. A, The dentures’ polished surfaces are so contoured as to supportand contact the cheeks, lips, and tongue. B and C, The impression or basal surfaces are fittedto the basal seats.

A B

C

Continued

harnessing of a patient’s unconscious tissue behav-ior to enhance both retention and stability of theprostheses. If the buccal flanges of the maxillarydenture slope up and out from the occlusal surfacesof the teeth and the buccal flanges of the mandibu-

lar denture slope down and out from the occlusalplane, the contraction of the buccinators will tend toretain both dentures on their basal seats.

The lingual surfaces of the lingual flangesshould slope toward the center of the mouth so the


Figure 22-1 cont’d D and E, The occlusal surfaces of one denture must fit those of theopposing denture.

D E

A

B

C

Figure 22-2 Frontal section showing dentures properly filling the available space. A, The buc-cinator. B, The lingual flange and border are placed under the tongue. C, The mylohyoid ridge.Notice that both upper and lower dentures are so shaped that the action of the tongue and cheekstends to seat rather than unseat them. If posterior artificial teeth are too wide buccolingually, theform of the dentures will be changed and the tongue and cheeks will tend to unseat them.

tongue can fit against them and perfect the borderseal on the lingual side of the denture. The base ofthe tongue is guided on top of the lingual flange bythe lingual side of the distal end of the flange,which turns laterally toward the ramus. This part ofthe denture also helps ensure the border seal at theback end of the mandibular denture. Strain-gaugemeasurements of the retentive forces exerted bypatients’ tongues demonstrate significant increasewhen the flange, particularly in the anterior, is soconfigured.

The base of the tongue also may serve as anemergency retentive force for some patients. Itrises up at the back and presses against the distalborder of the maxillary denture during incision offood by the anterior teeth. This is done withoutconscious effort when the experienced denturewearer bites into an apple or sandwich or otherfood. It is seldom that a patient needs to be taughthow to do this. For the oral and facial musculatureto be most effective in providing retention for com-plete dentures, the following conditions must bemet: (1) the denture bases must be properlyextended to cover the maximum area possible,without interfering in the health and function of thestructures that surround the denture; (2) theocclusal plane must be at the correct level; and (3)the arch form of the teeth must be in the neutralzone between the tongue and the cheeks.

Atmospheric Pressure

Atmospheric pressure can act to resist dislodgingforces applied to dentures, if the dentures have aneffective seal around their borders. This resistanceforce has been called suction because it is a resist-ance to the removal of dentures from their basalseat, but there is no suction, or negative pressure,except when another force is applied. (Suctionalone applied to the soft tissues of the oral cavityfor even a short time would cause serious damageto the health of the soft tissues under negativepressure).

A suction cup pressed against a pane of glassstays in place because the rubber of the squeezedcup elastically seeks to return to a larger shape,thereby causing air pressure within the cup to beless than the pressure outside the cup. A denturecannot be distorted like a suction cup, but oral

mucosa can be. When a force is exerted perpendi-cular to and away from the basal seat of a properlyextended and fully seated denture, pressure betweenthe prosthesis and the basal tissues drops below theambient pressure, resisting displacement.

Retention due to atmospheric pressure isdirectly proportionate to the area covered by thedenture base. For atmospheric pressure to be effec-tive, the denture must have a perfect seal aroundits entire border. Proper border molding withphysiological, selective pressure techniques isessential for taking advantage of this retentivemechanism.

Undercuts, Rotational Insertion Paths, andParallel Walls

The resiliency of the mucosa and submucosa over-lying basal bone allows for the existence of modestundercuts that can enhance retention. Althoughexaggerated bony undercuts or less overt ones cov-ered by thin epithelium may compromise dentureretention by necessitating extensive internal adjust-ment of the denture, less severe undercuts of thelateral tuberosities, maxillary premolar areas, dis-tolingual areas, and lingual mandibular midbodyareas can be extremely helpful to the retention ofthe prosthesis.

Some “undercuts” are only undercut in relation-ship to a linear path of insertion or relative to a pre-sumed vertical path of insertion. However, if theundercut area is seated first (usually in a directionthat deviates from the vertical) and the remainder ofthe denture base can be brought into proximity withthe basal seat on rotation of the prosthesis around theundercut part that is already seated, this “rotationalpath” will provide resistance to vertical displace-ment. One common example of this is to be found inthe area inferior to the retromolar pad, into which thedistolingual extensions of the mandibular base canbe introduced from the superior and posterior beforerotating the anterior segment of the denture downover the alveolar process. The opposite sequence iscommon in the maxilla, where a prominent or evenundercut anterior alveolus may dictate an insertionpath that begins with seating the anterior in a poste-rior and superior direction and ends with rotation ofthe posterior border over the backs of the tuberosi-ties. This concept increases in importance as


other retentive mechanisms decline in strength. Forinstance, in a patient who has undergone loss ofnormal anatomical contours due to tumor resectionor trauma, surgically created relative undercuts maymean the difference between prosthetic success andfailure.

Prominent alveolar ridges with parallel buccaland lingual walls may also provide significantretention by increasing the surface area betweendenture and mucosa and thereby maximizing inter-facial and atmospheric forces. Prominent ridgesalso resist denture movement by limiting the rangeof displacive force directions possible. Very flatridges may bear dentures that display strong resist-ance to displacement perpendicular to the basalseat, due to interfacial and atmospheric forces.However, these same prostheses are very suscepti-ble to movement parallel to the basal seat, analo-gous to sliding a suction cup along a pane of glassor sliding apart two glass pieces separated by inter-vening fluid.

Gravity

When a person is in an upright posture, gravity actsas a retentive force for the mandibular denture anda displacive force for the maxillary denture. Inmost cases, the weight of the prosthesis constitutesa gravitational force that is insignificant in com-parison with the other forces acting on the denture,but if a maxillary denture is fabricated wholly orpartially of a material that increases its weightappreciably (e.g., a metal base or precious metalposterior occlusal surfaces), the weight of the pros-thesis may work to unseat it if the other retentiveforces are themselves suboptimal. Increasing theweight of a mandibular denture (through the addi-tion of a metallic base, insert, or occlusal surfaces)may seem theoretically capable of taking advantageof gravity. Anecdotal evidence suggests that thismay indeed prove beneficial in the mandible incases where the other retentive forces and factorsare marginal, although a controlled study of 12subjects failed to find subjective or objective bene-fit. Curiously, another report focusing on maxillarydenture base materials in patients with xerostomiafound strong patient preference for metal-based(and therefore heavier) prostheses in the upperarch.

ADJUNCTIVE RETENTION THROUGHTHE USE OF DENTURE ADHESIVESComplete denture treatment needs to be cus-tomized for each patient’s particular needs.Successful treatment combines exemplary tech-nique, effective patient rapport and education, andfamiliarity with all possible management optionsto provide the highest degree of patient satisfac-tion. Commercially available denture adhesivesare products that have the capacity to enhancetreatment outcome. This reality is compellinglyunderscored by two facts: (1) consumer surveys inthe United States reveal that approximately 33% ofpatients with dentures purchase and use one ormore denture adhesive products in a given yearand (2) denture adhesive sales in the United Statesexceeded $200 million in 2001 (12% more thanfor denture cleaners and nearly twice the spendingon dental floss). Dentists need to know about den-ture adhesives for two reasons: (1) to be able toeducate all denture-wearing patients about theadvantages, disadvantages, and uses of the productbecause adhesives are a widely used dental mate-rial and patients rightfully expect their dentiststo be accurately informed about over-the-counteroral care products and (2) to identify those patientsfor whom such a product is advisable and/ornecessary for a satisfactory denture-wearingexperience.

In this chapter, denture adhesive is used to referto a commercially available, nontoxic, solublematerial (powder, cream, or liquid) that is appliedto the tissue surface of the denture to enhance den-ture retention, stability, and performance. It doesnot refer to insoluble patient-directed efforts atimproving denture fit and comfort, such as homereliner kits, home repair kits, paper or cloth pads,or other self-applied “cushions,” many of whichhave been anecdotally linked with incidents of seri-ous soft-tissue damage, alterations in occlusal rela-tions and vertical dimension of occlusion, andexacerbated alveolar bone destruction. Included inthis second category are thin wafers of water-soluble material that are adherent to both basal tis-sue and denture base and that lack the abilityto flow and therefore do not have the capacity todirect uneven and point pressures against the bearingtissues.


Components and Mechanism(s) of Action

Denture adhesives augment the same retentivemechanisms already operating when a denture isworn. They enhance retention through optimizinginterfacial forces by (1) increasing the adhesive andcohesive properties and viscosity of the mediumlying between the denture and its basal seat and (2)eliminating voids between the denture base and itsbasal seat. Adhesives (or, more accurately, thehydrated material that is formed when an adhesivecomes into contact with saliva or water) are agentsthat stick readily to both the tissue surface of thedenture and the mucosal surface of the basal seat.Furthermore, because hydrated adhesives are morecohesive than saliva, physical forces intrinsic to theinterposed adhesive medium resist the pull moresuccessfully than would similar forces within saliva.The material increases the viscosity of the salivawith which it mixes, and the hydrated materialswells in the presence of saliva/water and flowsunder pressure. Voids between the denture base andbearing tissues are therefore obliterated.

Denture adhesive materials in use before theearly 1960s were based on vegetable gums (e.g.,karaya, tragacanth, xanthan, and acacia) that dis-play modest, nonionic adhesion to both denture andmucosa and possessed very little cohesive strength.Gum-based adhesives (still commercially avail-able) are highly water soluble, particularly in hotliquids such as coffee, tea, and soups, and thereforewash out readily from beneath dentures. Allergicreactions have been reported to karaya (and to theparaben preservative that the vegetable derivativesrequire), and formulations with karaya impart amarked odor reminiscent of acetic acid. Overall,the adhesive performance of the vegetablegum–based materials is short-lived and relativelyunsatisfactory.

Synthetic materials presently dominate the den-ture adhesive market. The most popular and suc-cessful products consist of mixtures of the salts ofshort-acting (CMC) and long-acting (polyvinylmethyl ether maleate], or “gantrez”) polymers. Inthe presence of water, CMC hydrates and displaysquick-onset ionic adherence to both dentures andmucous epithelium. The original fluid increasesits viscosity and CMC increases in volume,thereby eliminating voids between prosthesis andbasal seat. These two actions markedly enhance the

interfacial forces acting on the denture. Polyviny-lpyrrolidone (“povidone”) is another, less com-monly used agent that behaves like CMC. Over amore protracted time course than necessary for theonset of hydration of CMC, gantrez salts hydrateand increase adherence and viscosity. The “long-acting” (i.e., less soluble) gantrez salts also displaymolecular cross-linking, resulting in a measurableincrease in cohesive behavior. This effect is signif-icantly more pronounced and longer lived incalcium-zinc gantrez formulations than in calcium-sodium gantrez. Eventually, all the polymersbecome fully solubilized and washed out by saliva;this dissolution is hastened by the presence of hotliquid.

Other components of denture adhesive prod-ucts impart particular physical attributes to theformulations. Petrolatum, mineral oil, and polyeth-ylene oxide are included in creams to bind thematerials and to make their placement easier.Silicone dioxide and calcium stearate are used inpowders to minimize clumping. Menthol and pep-permint oils are used for flavoring, red dye forcolor, and sodium borate and methylparaben orpolyparaben as preservatives.

Some Objective and Subjective Responses toDenture Adhesive

With the exception of uncommon allergic reactionsto either karaya or paraben, as just mentioned, therehave been no reports of tissue reactions to dentureadhesive products. For example, before 1990, a fewof the commercially available denture adhesivescontained very low levels of benzene, which isregarded as a carcinogen. These products wererecalled by the Food and Drug Administration.Today’s adhesives are either free of benzene or con-tain trace amounts considered to be harmless.Commercially available formulations in the UnitedStates must pass laboratory animal tests of skin andeye sensitivity and oral toxicity before they areacceptable for sale to the public. Clinical studies ofmucosal tissues underlying adhesive-bearing den-tures reveal lessened inflammation in patients whoperform adequate denture hygiene daily. Dentistsmust ensure that they are cognizant of any sequelaethat may be associated with the prescription of allmaterials used in routine dental practice.


Incisal bite force exerted by well-fitting den-tures overlying well-keratinized ridges with favor-able anatomical features (square arch form; broad,prominent alveoli without undercuts; mild orabsent frena) is improved significantly with the useof an adhesive. More interesting, incisal bite forceof well-fitting dentures overlying inferior basal tis-sues (tapering arch form, little or no keratinization,spiny or absent alveolar ridges, frena extending toridge crests) can be increased to the range of theadhesive-bearing dentures overlying ideal basal tis-sues. The frequency of dislodgment of denturesduring chewing also is markedly decreased with theuse of adhesive. Vertical, anteroposterior, and lateralmovements (short of full dislodgment) of new andold maxillary dentures retained on their mucosalseats under chewing and speech function can bedecreased between 20% to 50% for up to 8 hoursafter placement of denture adhesive and up to 4hours after placement of the mandibular denture.

Objective comparison of chewing performancefails to show an improvement after use of adhesive,although subjects report increased confidence andsecurity in chewing with the use of denture adhe-sive. Not all products are the same, and patients cantell them apart: subjects are able to identify pre-ferred adhesive characteristics and products incomparison trials of different formulations.Improvement in chewing efficiency during adjust-ment to new dentures progresses further in patientswho use a denture adhesive product.

Patient response to the use of these materials isnot universally positive. Some patients object to the“grainy” or “gritty” texture of powder or to thetaste or sensation of semidissolved adhesive mate-rial that escapes from the posterior and otherperipheries (often due to use of excessive quantityor use in an inadequate prosthesis). Others object tothe difficulties encountered in removing adhesivefrom the denture and the oral tissues, as well as tothe cost of the material.

Indications and Contraindications

Scientific evidence favoring the support of routineand safe use of adhesives is lacking, yet clinicalexperience indicates that prudent use of adhesivesto enhance the retentive qualities of well-madecomplete dentures is sound clinical judgment.

Denture adhesives are indicated when well-madecomplete dentures do not satisfy a patient’s per-ceived retention and stability expectations.Irrespective of the underlying reasons (e.g., psy-chological, occupational, morphological, and func-tional) for a patient’s reported dissatisfaction thedentist must recognize that a patient’s judgment ofthe treatment outcome is what defines prosthodon-tic success. Such maladaptive patients are clearlycandidates for an implant-supported prosthesis (seeChapter 25). However, health, financial, or otherconsiderations can preclude this, and then a well-organized protocol of functional do’s and don’t’smay be the best palliative measure the professionalcan offer. Specific patient populations who canbenefit from this strategy include patients withsalivary dysfunction or neurological disorders andthose who have undergone resective surgical ortraumatic modifications of the oral cavity.

Patients who have xerostomia due to medica-tion side effects, a history of head and neck irradi-ation, systemic disease, or disease of the salivaryglands have great difficulty managing completedentures because of impaired retention and anincreased tendency for ulceration of the bearing tis-sues. The use of denture adhesive can compensatefor the retention that is lacking in the absence ofhealthy saliva and can mitigate the onset of oralulcerations that result from frequent dislodgments.Patients with xerostomia must be educated, how-ever, that the adhesive-bearing denture will need tobe deliberately moistened (e.g., with water fromthe tap) before it is seated in the otherwise drymouth to initiate the actions of the material.

Several neurological diseases can complicatethe use of complete dentures, but adhesive mayhelp to overcome the impediments imposed. Cere-brovascular accident (stroke) may render part of theoral cavity insensitive to tactile sensation or partiallyor wholly paralyze oral musculature. Adhesives canassist in helping these patients accommodate to newdentures or to prostheses that were fabricated beforethe stroke but that the patient is now unable to man-age because of lost sensory feedback and neuromus-cular control. Orofacial dyskinesia is a prominentside effect of phenothiazine-class tranquilizers (e.g.,fluphenazine, trifluoperazine, thioridazine, or thio-thixene), other neuroleptic drugs (e.g., haloperidol),and even gastrointestinal medications (e.g., proch-


lorperazine and metoclopramide). This move-ment disorder, sometimes termed tardive dyskine-sia because it is often a late-onset side effect ofdopamine-blocking drugs, is characterized by exag-gerated, uncontrollable muscular actions of thetongue, cheeks, lips, and mandible. In such sit-uations, denture retention, stability, and functionmay be a virtual impossibility without adjunctiveretention, such as that made possible with dentureadhesive.

Patients who have undergone resective surgeryfor removal of oral neoplasia or those who have lostintraoral structures and integrity due to trauma mayhave significant difficulty in functioning with a tis-sue-borne prosthesis unless denture adhesiveis used, even if rotational undercuts have beensurgically created to resist displacement of theprosthesis.

It must be emphasized that a denture adhesiveis not indicated for the retention of improperly fab-ricated or poorly fitting prostheses.

Patient Education

It is incumbent upon dentists to educate patientswith dentures about denture adhesives: their use,abuse, advantages, disadvantages, and availablechoices. The major information resource for apatient should be the dentist and not magazine andtelevision advertisements or the testimonials of rel-atives and acquaintances.

The choice between cream and powder islargely subjective, but certain facts may underscorea patient’s selection. Powder formulations, as arule, do not confer the same degree of “hold,” nordo their effects last as long, in comparison withcomparable cream formulations. However, powderscan be used in smaller quantities, are generally easierto clean out of dentures and off tissues, and are notperceived as “messy” by patients. Furthermore, theinitial “hold” for powders is achieved sooner than itis with cream formulations.

Obtaining the greatest advantage from the useof an adhesive product is dependent on its properusage (Figures 22-3 to 22-7). For powder andcream products, the least amount of material that iseffective should be used. This is approximately 0.5to 1.5 g per denture unit (more for larger alveolarridges, less for smaller ones). For powders, the

clean prosthesis should be moistened and then athin, even coating of the adhesive sprayed onto thetissue surface of the denture. The excess is shakenoff and the prosthesis inserted and seated firmly. Ifthe patient has inadequate or absent saliva, the


Figure 22-3 Before powder adhesive formulationsare applied, the denture must be cleaned and thenthoroughly moistened.

Figure 22-4 The moistened denture surface is thencovered with a slightly excess coating of the powder.


sprayed denture should be moistened lightly withwater before being inserted. For creams, twoapproaches are possible. Most manufacturers rec-ommend placement of thin beads of the adhesive inthe depth of the dried denture in the incisor andmolar regions; an anteroposterior bead should beplaced along the midpalate in the maxillary unit.However, more even distribution of the materialcan be achieved if small spots of cream are placedat 5-mm intervals throughout the fitting surface ofthe dried denture. Regardless of the patternselected, the denture is then inserted and seatedfirmly. As with powders, use of denture adhesivecream by patients with xerostomia requires that theadhesive material be moistened with water beforeinserting the denture.

Patients must be instructed that daily removalof adhesive product from the tissue surfaces of thedenture is an essential requirement for the use ofthe material (Figure 22-8). Removal is facilitatedby letting the prosthesis soak in water or soakingsolution overnight during which the product will befully solubilized and can then be readily rinsed off.If soaking is not possible before new adhesive

Figure 22-5 When the excess powder is shaken off,a thin, even coat remains.

Figure 22-7 An alternative application procedurefor cream adhesive. To the clean and dried denture,small dots of product are placed at 5-mm intervals. Ifadhesive is expressed around the periphery of thedenture in function, the dots should be distributedfarther apart.

Figure 22-6 Before cream denture formulationsare applied, the denture must be cleaned and thenthoroughly dried. Most manufacturers recommend thedistribution of product as shown. For the mandibulardenture, a series of thin beads at the crest of the ridgeis recommended. If adhesive is expressed around theperiphery of the denture in function, a lesser quantityshould be used.

material needs to be placed, removal is facilitatedby running hot water over the tissue surface of thedenture while scrubbing with a suitable hard-bristledenture brush. Adhesive that is adherent to thealveolar ridges and palate is best removed by rins-ing with warm or hot water and then firmly wipingthe area with gauze or a washcloth saturated withhot water.

Finally, patients need to be educated aboutthe limitations of denture adhesive. Discomfortwill not be resolved by placing a “cushioninglayer” of adhesive under the denture. In fact, painor soreness signals a need for professional man-agement. A gradual increase in the quantity ofadhesive required for acceptable fit of the dentureis also a clear signal to seek professional care. Inall cases, denture patients need to be recalledannually for oral mucosal evaluation and pros-thesis assessment, but they also need to be edu-

cated about the warning signs that should alertthem to seek professional attention between thecheck-ups.

Professional Attitudes toward DentureAdhesive

Denture adhesive products can improve patientacceptance of and comfort and function with den-tures. They are, however, regarded frequently asunesthetic and an impediment to a dentist’s abilityto apprise accurately the health of a patient’s oraltissues and the true character of denture adaptation.The fact that ill-fitting dentures often are retainedby large amounts of adhesive material has regret-tably led many dentists to presume a correlationbetween denture adhesive and severe alveolar ridgeresorption, although recent surveys of denture fac-ulty at U.S. dental schools suggest that these mis-givings about the material may no longer be asstrong as they once were.

If a correlation did indeed exist between den-ture adhesive use and increased alveolar ridgeresorption, it would provide a strong basis for cau-tioning patients against the use of adhesives, yetthere is no scientific basis for presuming thisalleged correlation.

Denture adhesives themselves are not capableof exerting forces that would accelerate resorption.Adhesives are liquid materials that are no morecapable of directing forces than is saliva. There isno mechanism through which adhesives can“exert” forces to further accelerate resorption; asfluids, adhesives will transmit occlusal forcesevenly to the basal tissues, just as would an inti-mately fitted acrylic base. If they fail to do so inone or more areas, the patient will experience dis-comfort and seek professional attention.

Denture adhesives merely reduce the amount oflateral movements that dentures, even well-fittingdentures, undergo while in contact with basal tis-sues. Admittedly, this benefit can mislead a patientinto ignoring his or her need for professional helpwhen dentures actually become ill fitting. This isan inherent risk when using any form of adjunctivetherapy. However, it should not preclude prudentclinical strategies. Denture adhesives are an inte-gral part of a professional service, and their adjunc-tive benefits must be recognized.


Figure 22-8 Daily thorough cleaning of thedenture is essential. Removal is facilitated by runningwarm or hot water over the tissue surface of thedenture while scrubbing with a suitable hard-bristledenture brush. The sink should be partially filled withwater, or a washcloth or towel should be placed in thesink beneath the denture to prevent accidental damagein the event the prosthesis is dropped during cleaning.

BibliographyAydin AK, Terziogly H, Ulubayram K et al: Wetting properties

of saliva substitutes on acrylic resin, Int J Prosthdont 10:473-477, 1997.

Berg E: A clinical comparison of four denture adhesives, Int JProsthodont 4:449, 1991.

Boone M: Analysis of soluble and insoluble denture adhesivesand their relationship to tissue irritation and bone resorp-tion, Compend Contin Educ Dent (4):S22-S25, 1984.

Grasso J, Gay T, Rendell J et al: Effect of denture adhesive onretention of mandibular and maxillary dentures during func-tion, J Clin Dent 11:98-103, 2000.

Hummel SK, Marker VA, Buschang P et al: A pilot to evaluatedifferent palate materials for maxillary complete dentureswith xerostomic patients, J Prosthodont 8:10-17, 1999.

Kapur KK: A clinical evaluation of denture adhesives,J Prosthet Dent 18:550, 1967.

Miller WP, Moneith B, Heat R: The effect of variation of the lin-gual shape of mandibular complete dentures on lingualresistance to lifting forces, Gerodontology 15:113-119, 1998.

Ohkubo C, Hosoi T: Effect of weight change of mandibularcomplete dentures on chewing and stability; a pilot study,J Prosthet Dent 82:636-642, 1999.

Shay K: Denture adhesives: choosing the right powders andpastes, J Am Dent Assoc 122:70-76, 1991.

Slaughter A, Katx RV, Grasso JE: Professional attitudes towarddenture adhesives: a Delphi technique survey of academicprosthodontists, J Prosthet Dent 82:80-89, 1999.

Tarbet WJ, Boone M, Schmidt NF: Effect of a denture adhesiveon complete denture dislodgement during mastication,J Prosthet Dent 44:374, 1980.

Tarbet WJ, Grossman E: Observations of denture-supporting tis-sue during six months of denture adhesive wearing, J AmDent Assoc 101:789, 1980.

Tarbet WJ, Silverman G, Schmidt NF: Maximum incisal bitingforce in denture wearers as influenced by adequacy of den-ture-bearing tissues and the use of an adhesive, J Dent Res60:115, 1981.

Vinton P, Manly RS: Masticatory efficiency during the period ofadjustment to dentures, J Prosthet Dent 5:477, 1955.

Zissis A, Yannikakis S, Jagger RG et al: Wettability of denturematerials, Quintessence Int 32:457-462, 2001.


C H A P T E R 23Maxillofacial Prosthodontics for theEdentulous PatientRhonda F. Jacob

449

Maxillofacial prosthodontics focuses on optimizingthe rudimentary functions of speech and swallow-ing. These functions are disrupted because of con-genital, organic, traumatic, or surgical abnormalitiesinvolving the oral cavity and related anatomicalstructures. Modifying routine dental procedures, thedentist creates static prostheses to fill voids createdby missing tissues or to approximate organs withsuboptimal function. Although rehabilitation ofthese rudimentary functions often is considered theprimary goal by the health care provider, no lessimportant to the patient is restoration of normalesthetics and mastication. These prostheses can becritical requirements to improve quality of life forindividuals whose rehabilitation will be a lifelongproposition. Normal function may not be achieved,but optimal function should always be attained, andnormalcy should always be sought.

ANATOMICAL AND PHYSIOLOGICALCONSIDERATIONS: NORMAL FUNCTIONThe superior aspect of the oral cavity includes thehard and soft palate. As the beginning of the upperaerodigestive tract, the oral cavity serves to move airfor speech and respiration and food and liquids fornutrition. The hard palate is the static “roof ” of theoral cavity and the “floor” of the nasal cavity andmaxillary sinuses. It serves to separate the oral cavityfrom the nasal cavity as required for speech, respira-tion, and swallowing. The soft palate is a dynamicseparator of the oral cavity and nasal cavity.

During respiration, an individual either inspiresor expires through the nose or the mouth, but never

both simultaneously. During expiration, air passesfrom the lungs, through the pharynx, and thenthrough the oropharynx. Either the air then passesbehind the soft palate into the nasopharynx, thenasal cavity, and out the nose, or the soft palate ele-vates to block the nasopharynx and the air passesout the oral cavity. During inspiration, the airpasses in the opposite direction, through either thenasal cavity or the oral cavity.

For appropriate separation of these cavitiesduring speech, respiration, and swallowing, thesoft palate elevates in the middle third to separatethe oropharynx and nasopharynx. The soft palatemusculature extends from the pharynx at the levelof the palate, inferiorly to the tonsillar area. Theright and left muscles of the soft palate attach tothe distal aspect of the hard palate and then inter-mingle on the entire midline length of the softpalate, forming an aponeurosis. Simultaneous con-traction of these bilateral muscles causes the mid-line elevation of the soft palate. As the soft palateelevates, the pharyngeal wall simultaneouslymoves anteriorly and medially at the level of thesoft palate elevation, which is in line with theplane of the hard palate. The sphincter formed bythe soft palate and pharyngeal wall tightly closesand prevents any passage of liquid or food into thenasopharynx during deglutition. During phona-tion, the soft palate also elevates, and the pharyn-geal wall moves anteriorly and medially; however,the movement of both structures is usually lessdramatic than the sphincteric movement thatoccurs in swallowing. These functional move-ments of the soft palate and pharyngeal wallsduring speech and swallowing are called velopha-ryngeal closure (Figure 23-1). In the English

language, there are very few sounds that requireair to travel from the oral cavity, behind the softpalate, and escape from the nose. These “nasalsounds” are n, m, and ng and resonate in the nasalcavity before exiting the nose. All “oral sounds”require that air be impounded in the oral cavity bythe elevation of the soft palate and closure of thepharyngeal walls.

The inferior aspect of the oral cavity includesthe tongue, muscles, and tissues of the floor ofmouth, and the mandible. These inferior structuresact in concert during speech. The tongue acts as theprimary articulator. Airflow and the sounds ema-nating from the larynx are modulated through spe-cific sites of contact and approximation of thetongue with the hard palate, the soft/hard palatejunction, and the dentition. Accurate and rapidtongue movements are required for intelligiblearticulation.

During mastication, the tongue constantlymoves the food bolus on the occlusal surfaces. Itfinally forms the food into a mass and pushes themass posteriorly against the hard palate and intothe oropharynx. The soft palate simultaneously ele-vates as the pharynx squeezes. The pharyngealsqueeze pushes the food into the esophagus.

FUNCTIONAL DEFICITS OF SPEECHAND SWALLOWINGThere are a myriad of functional interactions in theoral cavity, nasal cavity, nasopharynx, and orophar-ynx that influence speech and swallowing. Disrup-tion of any of these interactions can lead to deficitsin speech and swallowing. These disruptions resultfrom congenital malformations, central nervous sys-tem trauma, or surgery. They are seen as tissue loss,muscular denervation, or both. The most commoncongenital deficit is a cleft palate, seen as missingtissue in the hard and/or soft palate. Central nerv-ous system deficits result from head injuries andcerebrovascular accidents. Tissues remain intactbut are centrally denervated. Surgery for neoplas-tic disease results in tissue loss and local dener-vation; in addition, closure of the surgical siteoften tethers remaining tissues and restricts theirmovement.

When a patient has disruption of velopharyn-geal closure or defects in the hard palate, airescapes inappropriately from the nose in nonnasalspeech sounds. The patient is said to have hyper-nasal speech. As the volume of air that inappropri-ately escapes from the nose increases, the patientbecomes more hypernasal until his or her speechbecomes unintelligible. During swallowing, thesesame functional defects allow reflux of food andliquids into the nasal cavity. In the case of velopha-ryngeal inadequacy, dysfunction of the pharynx orsoft palate may be the cause. When the soft palateis partially resected, the bilateral synchronousmovement of the right and left muscles is dis-turbed. Unilateral soft palate function will not closethe sphincter. Limited movement of any of thewalls of the pharynx will not close the sphincter.Lack of adequate movement of the pharynx or thesoft palate may result from surgical resection ofthese structures, causing lack of tissue, surgicalscarring, or denervation of muscles. Head traumaor stroke can centrally denervate the soft palate orpharynx.

When the tongue or its contiguous structures inthe inferior aspect of the oral cavity are resected,tissue loss, denervation of tongue muscles, or teth-ering of the tongue from surgical closure of thefloor of the mouth inhibits the appropriate tongue-palate contact necessary for articulation. Loss of


Figure 23-1 These lateral videofluoroscopicframes show the “at-rest” position of the soft palate(left) that postures against the base of the tongue andleaves the nasopharynx open for respiration. Duringswallowing (right), the soft palate sharply elevates asthe pharyngeal wall constricts, thereby forming asphincter that separates the nasopharynx andoropharynx.

lateralization of the tongue inhibits movement ofthe food bolus onto the teeth, and mastication isimpaired (Figure 23-2). Loss of elevation and“curling” of the tongue will inhibit moving thefood bolus into the oropharynx to initiate theswallow.

MAXILLOFACIAL PROSTHODONTICSWhen patients have disruption of the rudimentaryfunctions of speech and swallowing, as previouslydescribed, various intraoral prostheses are made tocompensate for loss of function. There are partic-ular prosthetic considerations that are universalfor edentulous maxillofacial prosthesis, and thesewill be addressed before individual prostheses arediscussed.

Facial Form

Patients who have received trauma or surgicalresection for neoplastic disease to the face or oralstructures can be expected to have altered facialcontours. This is due to scarring and tissue con-tracture, lack of bony support for the soft tissues ofthe face, and tissue edema. The patient and clini-cian should expect that it may take several monthsafter an operation or trauma for the soft tissues toreach a final, stable position. These changes neces-sitate fabrication of interim prostheses and repeated

prosthesis adjustments to conform to soft tissuechanges. Constant wearing of an interim prosthesismay slightly decrease tissue contraction and col-lapse, but this decrease is minimal. Because of lackof retention in an edentulous prosthesis, contrac-ture of tissues and prosthesis overextension willunseat the prosthesis. When making an intraoralprosthesis, the clinician is very cognizant of theneed to support the lips and cheeks, but soft tissuesupport and esthetics must be compromised toachieve prosthesis retention and stability.

Loss of Vertical Opening and AlteredMandibular Movements

Surgical resection, or trauma to oral cavity struc-tures, can lead to loss of vertical opening of themandible and altered mandibular range of motion.When there is surgical resection of the posterioraspect of the hard palate for neoplastic disease, themuscles of mastication are frequently detachedfrom the maxilla or they are partially resected. Thisoperation most often involves the medial and lat-eral pterygoid muscles. Trauma to the mandible inthe area of the muscles of mastication also candamage the muscles. Trismus is the immediateresult of muscular trauma, and the patient will havedecreased vertical opening and range of motion ofthe mandible. As the area heals, the patient usuallyis given manual exercises to improve range ofmotion and opening. As time progresses, the trau-matic muscular injury may become fibrotic andscarred. A decreased vertical opening often will bepresent in these patients and can make oral hygiene,prosthetic treatment, and manipulation of a foodbolus difficult.

Partial resection of the posterior mandibleremoves the ipsilateral temporomandibular joint(TMJ) and its muscles of mastication and allowsthe remaining mandible to function on the oppos-ing joint and muscles. Unilateral joint and musclecontrol causes mandibular deviation and alteredrange of motion. The medial pull of the ipsilateralpterygoid muscles pulls the mandible toward theside of the resection. The muscles on the floor ofthe mouth that are attached to the remainingmandibular body rotate the chin inferiorly,causing loss of anterior vertical overlap. When thepatient attempts to occlude, the mandibular body is

Chapter 23 Maxillofacial Prosthodontics for the Edentulous Patient 451

Figure 23-2 After a right partial glossectomy, thispatient’s residual tongue was used to cover the exposedmandible and right floor of the mouth. It is notpossible for the patient to move the tongue or any foodbolus laterally onto the occlusal surfaces of her teeth.

positioned lingually to its appropriate position, andthe anterior mandible is positioned inferiorly.

Processed Bases

Processed bases have definite advantages in thepatient with a maxillofacial prosthesis. Numeroussoft tissue and bony undercuts exist after an oralcavity surgery or maxillectomy that may be used asprosthetic-bearing surfaces. When conventionalrecord bases are made, the undercuts are blockedout to allow removal of the record bases from themaster cast. Blocking out of these undercuts canresult in lack of tissue contact of the record basewith the periphery and the bearing surfaces withinthe surgical site (Figure 23-3). Without bearing sur-face contact, the occlusal plane and the centricrelation (CR) record often are inaccurate. Usingprocessed bases and denture adhesive in both themaxillary and mandibular prostheses will aid inachieving accurate records. Without peripheralextension of the base, it is difficult to set teeth in theappropriate buccal position, and it is not possible todiscern how much additional lip and facial supportmay be gained from the teeth. Processed bases willallow the clinician to judge prosthesis retention andposition of soft tissues supported by the base. At thetry-in appointment, the patient and the clinician willbe able to arrive at the ideal tooth position to con-

sider esthetics, speech, retention, and stability of theprosthesis given the less than ideal postsurgicalintraoral and extraoral tissue contours.

Border Molding the Velopharyngeal Area:Patient Movements

Border molding the velopharyngeal area includesmaking an impression to restore missing tissues ofthe soft palate and pharynx. Missing tissues mayinclude portions or all of the soft palate or surgeryto the pharyngeal wall. After placement of theimpression material, the patient is asked to swal-low. The greatest restriction of the size of the pha-ryngeal extension of the prosthesis occurs duringthe swallow; thus it is important to perform thisfunction while the material is the least viscous. Thepatient will then open and close the mouth, movethe mandible from side to side, turn the head fromside to side, place the chin down to the chest, movethe head from side to side, and extend the headbackward.

Border Molding Peripheries of MaxillaryResections and Hard Palate Defects:Patient Movements

The hard palate is a static structure. Border mold-ing its bony margins requires no special patient


Figure 23-3 The conventional trial base (left) has been blocked out at the peripheries ofthe maxillary resection to allow removal from the master cast. The processed base (right)made from the same master cast allows maximum tissue contact and stability for thearrangement of teeth and jaw relationship records.

movements. Border molding the posterior and lat-eral area of a maxillectomy requires that the patientgo through head and mandible movements similarto border molding the velopharyngeal area.Mandibular movement has the greatest effect onthe lateral and posterolateral borders. Swallowingis important to move the cut edge of the soft palateat the posteromedial margin of the prosthesis.

Testing the Prosthetic “Seal” between the OralCavity and the Nasal Cavity

Drinking liquids is the usual test for prosthetic clo-sure of an anatomical defect in the soft or hardpalate. If the patient drinks in an upright position,water should not reflux into the nasal cavity.Placing the head downward will allow gravity tocarry the liquid into the nasal cavity as well as theesophagus: the patient will need to keep the headupright when swallowing. Patients state that refluxis a particular problem when eating soup or drink-ing from a fountain because in both of theseinstances, the patient has the chin and head tucked.It is unlikely that most patients will be able to drinkfrom a straw, even though the “seal” may ade-quately stop reflux of liquids.

Listening to speech sounds is the usual way totest for appropriate separation of airflow from theoral cavity and nasal cavity. There are particularsounds that are very sensitive to airflow. To test forpossible hypernasality, have the patient say theword “beat” with the prosthesis in position. Pinchthe patient’s nares closed and have him or her say“beat.” There should be no nasal air escape whensaying this word, and there should be no differencein the sound of this word with or without the narespinched together. If there is a difference in thesound of the word “beat” with and without pinch-ing the nares, air is inappropriately escapingaround the prosthesis periphery. Also, if the word“beat” sounds more like “meat,” there is inappro-priate air escape. Patients will report that they aremisunderstood when using words that start with B;rather, the listener thinks that patients are using theletter M. To test for hyponasality, or lack of airescape through the nose on nasal sounds, have thepatient say the phrase, “Momma made lemon jam.”If the air is not allowed to escape from the oral cav-ity through the nose, the phrase will sound more

like “Bobba, bade lebon jab.” These are the speechsounds of a person with the common cold and indi-cate that air is not escaping through the nose as itshould on nasal sounds. In this regard the prosthe-sis may be too large or overextended; however, cre-ating hyponasal speech with an obturator isuncommon. It is more likely that the obturator issatisfactory, but that the patient really is congestedin the nasal passages.

MAXILLARY OBTURATOR PROSTHESISAn obturator prosthesis is required for patients whohave undergone tumor resection of the hard palatefor neoplasms that originate in the paranasalsinuses or superior aspect of the oral cavity.Resection of the hard palate causes disruption ofarticulation and airflow during speech productionand allows nasal reflux during deglutition. Theobturator prosthesis serves to restore continuity ofthe hard palate and separate the nasal cavity andmaxillary sinus from the oral cavity. This prosthe-sis also is used for hard palate defects in the patientwith a cleft palate.

The patient who undergoes maxillary resectionis rehabilitated in three phases. Each phase requiresan obturator prosthesis that supports the patientthrough various stages of healing. These three pros-theses are surgical obturator, interim obturator, anddefinitive obturator.

Surgical Obturator Prosthesis

The surgical obturator serves some rudimentarygoals: (1) to support the surgical packing placed inthe resection cavity created by removal of the wallsof the maxillary sinus and (2) to restore continuityof the hard palate. This prosthesis allows thepatient to take oral nutrition immediately postoper-atively and, if the swallowing mechanism is not dis-rupted by extensive surgery to the pharynx,precludes use of a nasogastric feeding tube. Speechis generally quite normal with this prosthesis also.This prosthesis will be in service for approximately5 to 10 days.

The patient must have a presurgical dentalexamination, and a maxillary cast must be made.This will be used to make the surgical and interimprosthesis. The clinician will also plan treatment


for the patient for necessary preprosthetic surgeryto remove epuli, reduce pendulous tuberosities, andrelieve bony undercuts. Ideally, these are per-formed concurrently with the tumor resection.

A baseplate with routine denture extensions oran existing well-fitting denture may be used for thesurgical obturator. The clinician should be aware,however, that if an existing denture is used, thepatient usually expects that the denture will be usedfor the interim prosthesis also.

If the tumor is altering the normal contours of thehard palate, the cast should be altered to restoreappropriate palatal contour. No other alteration of thecast is needed. The clinician should not attempt todelineate the exact posterior surgical margin on thesoft palate, lateral surgical margins into the infratem-poral fossa or pharynx, or superior margin into thesinus cavity. Appropriate design of the prosthesisallows fabrication of only one prosthesis. Extensionof an acrylic resin prosthesis beyond the confines ofthe oral cavity would likely be overextended andrequire major adjustments in the operating roombefore it could be inserted. The packing placed supe-riorly into the surgical site will be supported by thebaseplate and obturate any discrepancies betweenthe surgical margins and the prosthesis borders.

Edentulous surgical obturators must be securedby circumzygomatic wires, sutures, or bonescrews. Retentive holes for zygomatic wires areplaced bilaterally with a no. 8 round bur in the pre-molar area through the prosthesis flanges. For theprosthesis to be sutured in position, the same bur isused to drill six holes in the periphery of the ante-rior and lateral flanges (Figure 23-4). A single bonescrew may be placed through the vomer bone,through a predrilled hole in the midpalate at thejunction of the premaxilla and hard palate. Thishole should be drilled from the oral side of thepalate and angled posteriorly (with the oral side ofthe hole anterior to the intaglio side of the hole) toallow manipulation of a screwdriver in the patient’smouth. The bone screw should be freely movable inthe predrilled hole, but the diameter should not belarge enough for the head of the screw to passthrough (Figure 23-5). The hole should be counter-sunk to recess the head of the screw away from thepatient’s tongue. If the hole is not drilled with anoversized diameter, the screw often binds on theprosthesis as it engages the vomer bone. A self-

tapping screw may be sharp enough to be placeddirectly into the vomer, but a “starter hole” drilledin the vomer aids placement of the screw. As a pre-caution, the screw should be covered with a tissueconditioner material to keep it in the denture in theunlikely event that it works loose from the bone. Ifthe midpalate is crossed during the operation, thevomer will not be present. Two bone screws canthen be placed in the residual alveolar process atantagonistic angles. Rarely is a starter hole neces-sary in the alveolar process. The maxillary sinusthat has not been operated on may be entered withthe screws, but healing is uneventful when thescrews are removed. Removal of the bone screwand sutures is easily accomplished in an outpatientsetting. Removal of zygomatic wires should bedone with the surgeon’s assistance and usuallyrequires an operating room setting.


Figure 23-4 The 2-0 silk sutures are placedthrough the predrilled holes at the periphery of theobturator, knotted, and tagged with a hemostat beforebeing placed into the mouth and suturing into thepatient’s vestibule.

Interim Obturator Prosthesis

The interim obturator is delivered when the surgi-cal obturator is removed. The prosthetic goals areto restore deglutition and speech by restoringpalatal contours and separating the nasal cavity,maxillary sinus, and nasopharynx from the oralcavity. The patient and dentist understand that thisprosthesis will be altered considerably as thepatient heals and facial contours change. This pros-thesis will be in service for approximately 2 to 6months. A baseplate without dentition or thepatient’s existing denture can be used for the max-illectomy in the edentulous patient. Retention ofthe edentulous obturator prosthesis is always aproblem. The dentist should be certain that the bor-der extensions and palatal tissue contact are opti-mal for maximal contact on the intact maxilla.Relining the existing denture may be requiredbefore modifying the surgical area. Denture adhe-sives usually are required. Constant adjustmentsand relining are necessary because even slight bor-der overextension in the edentulous maxillofacialprosthesis will unseat the prosthesis. Keeping theprosthesis hollow in the surgical site will decreaseweight and aid retention.

The prosthesis is modified with an intermedi-ate denture liner to conform to the periphery of thesurgical site. The bulb portion should be kept hol-low during the relining procedure to limit theweight of the prosthesis. The material is added tothe periphery in incremental fashion as when bor-der molding any removable prosthesis. An idealmaterial should have enough body to support itselfduring the initial impression procedure and for sev-eral weeks (Figure 23-6).

As the patient heals, the periphery of the surgi-cal site will become smaller. The material can bereduced with a carbide bur and readapted with theaddition of more liner. The primary areas requiringreadaptation are the posterolateral and the anteriorborders. The greater the volume of bone resected,the greater the amount of postsurgical soft tissue con-tracture and the more time it will take before thesurgical site is stable. As the tissue contracts,the prosthesis borders will be overextended, and thepatient will have difficulty seating the prosthesis.The intermediate denture liner borders should thenbe relieved and resurfaced. The patient may return,complaining that there is discomfort on the nonsur-gical area of the maxilla or that the prosthesis is nolonger retentive. Adjustments should not be madeto the nonsurgical side of the prosthesis becausethe problem is likely to be tissue changes in the


Figure 23-5 A 14- to 16-mm palatal bone screwcan be placed into the vomer of the edentulousmaxillectomy patient. The hole should be drilled inthe midline with sufficient space to allow the screw tomove freely in the hole, but not allow the head of thescrew to pass through.

Figure 23-6 The edentulous baseplate is bordermolded with a low-viscosity tissue conditioner materialthat can be relieved and modified as facial contractureoccurs (Tru-Soft, Henry J. Bosworth, Skokie, Ill).

surgical area shifting the entire prosthesis. The pros-thesis must be worn constantly, removed only forcleaning of the surgical site or prosthesis. If thepatient removes the prosthesis nightly, the tissuechanges will be rapid, and the patient will not beable to seat the prosthesis after only a few days.These contour changes are usually a combinationof edema and tissue contracture.

When the surgical site is changing shape lessrapidly (in approximately 1 month), the prosthesiscan be flasked, replacing the denture liner materialwith acrylic resin. For the prosthesis to be deliveredin the same day, autopolymerizing resins usuallyare used. One should not keep the prosthesisovernight; major tissue changes of the entire surgi-cal border can occur, requiring relief of the periph-ery and another relining impression. Over time,slight tissue changes will continue, exemplified byincreased nasal reflux and hypernasal speech.These usually occur at the medial junction of theprosthesis and cut edge of the soft palate. Theseisolated areas can be addressed with tissue condi-tioning material or chairside autopolymerizing resinas needed.

The clinician and patient should be aware thatusing the existing maxillary denture as an interim

obturator prosthesis will be successful only for 2 to3 weeks, and then a new prosthesis or resetting ofteeth usually is required. If the resection includesany of the premaxillary area, facial collapse is pro-nounced (Figure 23-7). The original border exten-sion and the teeth will soon be overextended in ahorizontal direction. The flange must be reduced,and the anterior teeth will need to be reset morepalatally. The posterior teeth also may requirepalatal repositioning, but the problem is most evi-dent in the anterior area. In addition, repeated relin-ing of the prosthesis, while attempting to maintainocclusion with a mandibular denture, is very diffi-cult. For patient satisfaction, it may be necessary toremake the maxillary and mandibular prostheses orreset teeth more than once during the healingprocess. The patient must understand that mastica-tion is rarely restored in the interim phase becauseof the constant transition of the tissues and fit of thedentures. These necessary modifications must befactored into the treatment plan and may be beyondthe available time and finances of many patients.

For this reason, an alternative edentulousinterim obturator prosthesis is a simple baseplate. Itwill restore speech and deglutition and satisfy mostpatients if they understand that complete dentures


Figure 23-7 The patient’s original denture has normal anatomical borders (left);however, the obturator prosthesis relined at 4 weeks after surgery (right) has markedlyaltered contours in the anterior of the prosthesis because of facial contracture. A trayextension over the soft palate into the pharynx was added to support an impression of thepharynx in function, which was necessary because the patient’s velar movement wasinadequate in the weeks after surgery (see Figure 23-11).

are the goal when postsurgical healing is complete.The surgical baseplate can be border molded andrelined with a tissue conditioner material on thenonsurgical side. This step stabilizes the prosthesis,and then the surgical site may be relined. The base-plate can be flasked as a wax pattern. The relinedbaseplate is then removed from the flask during theboil-out procedure and replaced with resin. Thistechnique ensures a well-fitting baseplate duringthe interim obturator phase. Subsequent reliningwill be necessary in the surgical site.

Definitive Obturator Prosthesis

This prosthesis is fabricated when tissue healingand contraction are complete. When irradiation fol-lows surgery, resolution of radiation mucositis alsois necessary. Proceeding with a definitive prosthe-sis before tissue contours are stable may requiremajor adjustments that will involve changing toothpositions or gross adjustments to the prosthesisperiphery. It may be 2 to 6 months postoperativelybefore the tissues are stable.

Preliminary impressions are made with irre-versible hydrocolloid. It is desirable to capture theperiphery and height of the surgical site in the pre-liminary impression so that maximum extension ofthe definitive impression tray is possible (Figure23-8). It is not necessary to block out the surgicaldefect with gauze to prevent the impression mate-rial from entering this space. (The only time theopening to the sinus needs to be protected is whenthe opening is a fistula.) Some impression materi-als lack body and therefore do not “carry” into thesurgical defect without adding wax or compoundsupport into the defect or injection of the materialwith a large custom syringe. There are irreversiblehydrocolloids with considerable viscosity. These givegood border extensions for edentulous and max-illofacial impressions without support from the trayor need to inject the material. This significantlyreduces operator time.

Decreased vertical opening is often a problemin the patient undergoing a maxillectomy becauseof surgical trauma and fibrosis of the muscles ofmastication in proximity to the maxillary resection.It may be difficult to carry impression material intothe surgical defect because of the limited oral open-ing, but because of the lack of dentition, the clini-

cian usually has enough access in the oral cavitydespite the decreased opening.

A maxillary custom impression tray extendedinto the maxillary defect will decrease operatortime when fabricating the final impression. Thepreliminary cast should be “blocked out” to allowspace for compound and wax/impression material.Undercuts in the cast also must be blocked outbefore making the tray, or after the final impressionis poured, the tray will not separate from the mas-ter cast. Border molding the nonsurgical side andmaking the final impression before border moldingthe surgical site ensures that the tray is reseated ina consistent manner when the surgical site isimpressed. The clinician should always be awarethat manual seating pressure of the tray during bor-der molding and impression making should beobliquely directed against the remaining alveolarridge and not against the midpalate as is done whenseating a normal maxillary denture tray. Seatingagainst the midpalate often causes the tray to rotateinto the surgical site and away from the residualalveolar ridge without operator awareness.

Compound is incrementally added to the trayto record the periphery of the surgical site. The clini-cian must support the tray during these move-ments because the patient must perform a variety of


Figure 23-8 It is desirable to capture the totalmaxillary cavity in the preliminary impression foradequate extension of final impression trays. It is notnecessary to “block out” the cavity with gauze(Supergel, Harry J. Bosworth, Skokie, Ill).

movements to shape the compound. The clinicianshould constantly look at the anatomical form andlandmarks of the surgical site to determine that thecompound is not underextended. There is commonlya soft tissue undercut at the junction of the oralmucosa and skin graft that lines the maxillary cavitycalled a cicatricial line or scar band. The clinicianshould see this anatomical landmark and the cut edgeof the soft palate in the compound. If the impressiontray moves during the patient’s movements, an area ofcompound is overextended. The clinician mustfind this area of overextension and readapt it beforeproceeding any further. With partial maxillectomyprocedures, some bony walls of the maxillary sinusmay remain. When these walls have been graftedwith skin, it is possible to use them for vertical sup-port. They should be captured in the border mold-ing of the surgical site. At completion of bordermolding, the compound can be slightly relieved andan impression wax painted over the surface or a finalimpression material used. The advantage of usingwax is that areas of pressure will show throughthe wax and the compound can be further relieved.The easiest method of using the wax is to cover therelieved compound, quickly dip the area in the warmwater bath, place it in the mouth, and have the patientgo through the border molding movements.

Maxillary and mandibular processed bases anddenture adhesive are used to ensure maximum sta-bility and soft tissue support. The clinician shouldmanually stabilize the least stable base when mak-ing the record and watch very carefully for shifts ofthe bases. In the case of a patient undergoing amaxillectomy, this would be the maxillary base. Ifthe bases shift, the record should be remade.Because of the instability of the obturator prosthe-sis, monoplane occlusion is recommended for thecompletely edentulous patient.

Because of facial contracture on the surgicalside, it often is necessary to place the anterior teethin an end-to-end or reverse horizontal articulatimsituation. The facial position of the anterior teethmay be verified at the try-in appointment Estheticsand lip support are often compromised to aid reten-tion. An end-to-end occlusion in the posterior teethshould be avoided. Horizontal overlap is necessaryto avoid cheek biting. When decreased vertical open-ing is seen in these patients, interocclusal space atmaximum opening may be only 1 to 1.5 cm. The

clinician may choose to slightly close the verticaldimension of occlusion to allow the patient morefunctional space; however, lip and cheek bitingmay become a problem, and attention to horizontaloverlap is very important. Decreased verticaldimension of occlusion also can lead to periodicangular cheilosis that requires treatment.

The palatal contour should be evaluated in anobturator prosthesis. The contour on the surgicalside should mimic that of the nonsurgical side.Making these contours too low constricts thetongue, which will then lift the prosthesis into thesurgical site during speech and swallowing.Making the contour too high will not allow propertongue/palate contact during speech, affectingarticulation and the impounding of air in the oralcavity. If the posterior teeth were placed in reversearticulation bite, it may be necessary to remove thepalatal half of these teeth. The height of the palatemay be examined visually and with pressure indi-cator paste. The patient should be asked to swallowand speak. The paste can be checked for uniformcontact of the tongue. If additional acrylic resin isneeded to refine the palatal contours, this may beadded when the teeth are processed onto the base.

At insertion of the prostheses, it is not necessaryto perform a clinical occlusal remount procedurebecause processed bases were used and a laboratoryremount was done at deflasking. Final evaluation ofthe prostheses fit should be done. Evaluating pres-sure areas and border extensions is best done witha combination of pressure-indicating paste andtissue-conditioning material. The pressure paste iseffective for the intaglio surface of the prosthesisbut often smears on insertion or removal of theprosthesis, and therefore accurately interpreting thepressure areas on the obturator portion of the pros-thesis is quite difficult. A fast-setting, contrasting-color, tissue-conditioning material is ideal (Softone,Harry J. Bosworth, Skokie, Ill.). The obturator por-tion should be lightly coated with petroleum jelly.The material should be mixed with enough body soit will not flow off the prosthesis. The patient shouldswallow and go through all head and jaw move-ments. A uniform, thin, functionally formed coatingof material remains with obvious “show through” ofthe acrylic resin in pressure areas.

Denture adhesive can be used to aid in reten-tion, and the prosthesis extension into the surgical


site can be made hollow to decrease the weight ofthe prosthesis. Some clinicians leave the hollowedarea open superiorly, and some clinicians choose toplace a cap from the superior aspect or the palatalaspect. Placing a cap precludes any reflux of foodor liquids into the extension and the need for thepatient to clean this area of the prosthesis.

Troubleshooting an Obturator Prosthesis

Lack of Retention Overextension of borders inan interim prosthesis is the result of soft tissuechanges, and the prosthesis borders will need to berelieved and relined. Adhesives are almost alwaysrequired for any edentulous obturator prosthesis.The patients should be advised to masticate as lit-tle as possible on the defect side because this tendsto unseat the prosthesis. Retention is a very diffi-cult problem for the edentulous patient. Whenplanning the treatment for a patient with poor den-tition, before maxillectomy, the plan should be tosave teeth for denture retention. Severely cariousteeth are often problematic because of cost of rootcanals, need for crown lengthening, and the lack ofvertical opening after surgery and postoperativeradiotherapy. For this reason grossly decayed orperidontally involved molars are of limited value.However, saving some anterior teeth that have atleast 50% bone remaining with limited soft tissuepockets can create adequate retention and lastmany years. Often, eventual loss of single-rootedteeth in the irradiated maxilla will heal unevent-fully. If only one to two teeth are remaining, anoverdenture with magnetic attachments can be con-sidered. These attachments, in addition to adhesive,can serve patients very well. This is true for thepatient undergoing a maxillectomy and a mandibulec-tomy (Figures 23-9 and 23-10).

Nasal Reflux Explain to the patient that the pros-thesis cannot function as a “cork in a bottle,” andsome reflux is to be expected. An upright headposition is required during swallowing. Check thepalatal contours with pressure indicator paste. A palatal form that is too low constricts the tongueand unseats the prosthesis. Check the tissue adapta-tion at the posteromedial and posterolateral margins(at the prosthesis/soft palate junction). Place petro-

leum jelly on the prosthesis surface and functionallydisclose the area with a viscous tissue conditioner, aspreviously described. If the tissue conditioner mate-rial is thick and successfully decreases reflux, thisarea should be addressed for a relining procedure.When the required relining area is only 1 to 2 cm andthe remainder of the obturator portion is well fitting,a chairside relining should be considered. Cut finishlines to demarcate the area indicated by the tissueconditioner. These finish lines will confine the relin-


Figure 23-9 This patient had two teeth withrecession and wear. Both teeth were reduced withoutneed for root canals. A ferrous metal was used tocreate copings.

Figure 23-10 The magnets were incorporated inthe denture. This magnetic system was in service forover 10 years until the patient died of cardiac arrest.

ing material. An autopolymerizing relining resin or alight-cured composite resin material can be addedand border molded in the patient’s mouth.Conversely, if the tissue conditioner material is quitethin and indicates a well-fitting prosthesis, the sealcannot be improved.

Hypernasality When reflux has been minimizedbut hypernasality exists, one should consider thatthe velopharyngeal closure may be compromisedfrom surgery. The soft palate may elevate, but theremay not be enough elevation to close the nasophar-ynx. If the resection also includes a portion ofthe soft palate, the remainder may be too short tocontact the pharyngeal walls. The clinician shouldattempt to add a pharyngeal extension, as in the softpalate obturator prosthesis, over the inadequatelyfunctioning soft palate to obturate the pharynx(Figure 23-11).

SOFT PALATE OBTURATOR PROSTHESISA soft palate obturator or speech aid prosthesis isrequired for patients who have a resection of theirsoft palate or have a soft palate deficit from a cleftpalate. Absence of soft palate tissue disrupts speech

and swallowing by allowing nasal escape of air dur-ing speech and nasal reflux during swallowing. Animmediate surgical soft palate obturator prosthesisusually is not inserted. If the pharynx is obturatedwith any rigid material or a tissue-conditioningmaterial in the operating room, the extension willinvariably be overextended, and the patient willexperience postoperative pain in the pharynx whenhe or she awakens and resumes swallowing andmovement of the head. Even small, arbitrary acrylicresin extensions made on a surgical cast to supporta surgical gauze packing placed in the pharynx willlikely be overextended in some areas with the post-operative sphincteric closure of the pharynx.

A pharyngeal extension can be added to a den-ture prosthesis or baseplate within a few days afterresection. When only the soft palate is resected,patients will resume swallowing with minimal dis-comfort; however, if the resection is more extensive,patients may not resume normal swallowing imme-diately because of additional surgical involvement ofthe pharynx. They may require nasogastric tubefeeding or gastrostomy until they can swallow with-out aspiration. In these situations, the obturator’smajor function will be to restore speech.

A posterior extension is added to a dentureprosthesis to contact the patient’s pharyngeal wallwhen it closes during speech and swallowing. Theextension should be made at the level of the hardpalate and at the level of the most active movementof the pharyngeal sphincter. This movement can bevisualized by asking the patient to say “ahh” or bystroking the posterior wall with a mirror handle,initiating a gag reflex. Often a prominent muscularridge on the pharyngeal wall, called Passavant’sridge, is present when the patient says “ahh”(Figure 23-12). This ridge has been called a com-pensatory mechanism because it is present in mostpatients with cleft palates and has been seen toincrease and become more obvious with time inpatients with cleft palates and resected soft palates.

A small acrylic resin posterior projection can beadded to the denture as a tray to support the impres-sion material. A viscous tissue conditioner materialor compound can be added. The patient should gothrough the necessary movements to capture thefunctional movements of the pharynx at the area ofmost movement. The impression should be exam-ined for contact with the pharynx bilaterally and


Figure 23-11 This patient who underwent amaxillectomy had lack of appropriate velar movementafter surgical contracture of the velum. A pharyngealextension was added to the prosthesis to obturate thepharynx and correct hypernasality.

posteriorly. If any of the acrylic resin tray projectsthrough the material, it should be generouslyrelieved and that portion of the impression remade.The inferior extent of the pharyngeal extensionshould be at or slightly below the inferior aspect ofthe pharyngeal sphincter. The overall height of theextension should not be more than 1 cm. This willsuccessfully cover the area of pharyngeal constric-tion without adding excessive weight. The com-pound may be relieved and covered with impressionwax. If the clinician wants the wax to flow during theimpression, the wax-coated extension will need tobe quickly dipped in a hot water bath before inser-tion, or the patient will need to wear the prosthesisfor approximately 30 minutes while repeatedlygoing through swallowing and head movements. Theclinician may test the final impression for closure ofthe nasopharynx in swallowing by asking the patientto drink water. Hypernasality and hyponasality maybe tested at this time. Ideally, airflow in speechshould be appropriate.

Troubleshooting the Soft Palate ObturatorProsthesis

Prosthesis Feels Too Long The patient complainsthat they “feel the prosthesis in the back” of theirpharynx. They also may describe that they have dif-ficulty initiating a swallow reflex. The prosthesis

should be disclosed with a functional tissue condi-tioner rather than pressure indicator paste. A pastedoes not reveal the overextension as accurately astissue conditioner. If the patient continues to com-plain, it may be necessary to reduce the entireextension and make a new functional impression.

Hypernasality Evaluate for appropriate tissuecontact in swallowing using a tissue conditioner. If auniformly thin coating is evidenced but hypernasal-ity persists, the difference in pharyngeal wall con-striction in swallowing versus speech is the problem.During swallowing, pharyngeal constriction is usu-ally more pronounced than in speech. As the differ-ence between pharyngeal function in swallowingand speech becomes greater, the more likely it is thatthe patient will have hypernasal speech. It usually isnot possible to add more material to the extension, orthe patient begins to complain of overextension.Increased “compensatory” pharyngeal constrictionmay be seen as time passes. This compensatorymovement may decrease or even eliminate hyper-nasality, but predicting this compensation for anindividual patient is not possible.

PALATAL AUGMENTATION PROSTHESISDuring speech, swallowing, or mastication, thetongue contacts the palate and teeth to move the


Figure 23-12 Passavant’s ridge (arrows) is prominent in this patient who had undergonea total soft palate resection. The pharyngeal obturator prosthesis is approximately 1 cm inheight, and the ridge is evident in the posterior contour of the prosthesis.

food bolus and articulate speech sounds into lan-guage. When the tongue or contiguous oral cavitystructures are resected for neoplastic disease, thedeficits in tongue function are related to loss of tis-sue bulk, denervation, and tethering of the remain-ing portion of the tongue. Hypoglossal nervedamage causes the tongue to deviate toward theaffected side on protrusion, and the tongue tip maynot elevate. If the remaining tongue is used to sur-gically close the oral cavity wound, it will besutured to the cheek, impairing range of motionand posturing it in an abnormal position. Whenmandibular deviation occurs in a nonreconstructedpartial mandibulectomy patient, the tongue devi-ates with the mandible and does not make appro-priate tongue/palate contact.

Clinical Examination

Patients with any of the preceding surgical findingsshould be considered for a palatal augmentationprosthesis. Look for normal range of motion of thetongue, evaluate if food collects on the palate orpools in other areas of the oral cavity, ask patients ifthey aspirate when they eat, and finally, listen forarticulation errors. These errors may include slurredspeech on the s and sh sounds and lack of intelligi-bility with k, g, t, l, and d. If it has been some timesince the operation and if the patients have not beenwearing dentures, they may have accommodated tothe lack of tongue mobility and are makingtongue/palate contact by inappropriate “overclosure”of the mandible. The only obvious clinical finding inthis “overclosed” patient may be abnormal range ofmotion of the tongue and perhaps a slight dysarthria.

Attachments of the tongue and floor of mouthsoft tissues to the mandible may preclude makingdentures. The ridge may be entirely covered withthe tongue flap or with bulky tissue brought fromdistant sites, such as the pectoralis or rectus mus-cle. Thinner tissues, such as from the forearm, maybe used for reconstruction, but if these are freelymovable over the mandible, a stable mandibulardenture may not be possible.

Informing the Patient

Patients should be aware of the difficulties of wear-ing a mandibular denture without normal tongue

range of motion. If they are experienced denturewearers, they will probably accommodate betterthan the first-time wearer. Patients will equatereceiving dentures with an advancement of theirdiet to more solid foods; however, mastication maynot be possible. Lateral tongue movement and anability to elevate the tongue to the height of themandibular occlusal table are necessary for masti-cation; some patients will not have lateral motion.Patients who have accommodated to the alteredtongue function by overclosure of the mandibleshould be aware that delivering dentures and restor-ing the correct vertical dimension of occlusion willrequire an augmentation prosthesis. A period oflearning new compensatory speech and swallowingmechanisms will be necessary. These individualsmay be very disappointed with the immediate dif-ficulties experienced with their new prostheses andthe apparent “backward” step in their rehabilita-tion. Adhesives for the mandibular denture usuallyare required. Speech and swallowing therapy arenecessary to optimize function. Finally, the deci-sion may be not to deliver a mandibular denturebecause of mandibular retention problems.Maxillary prostheses with anterior teeth and anaugmentation for function and esthetics may be thedefinitive prosthodontic care.

Usual denture fabrication techniques should beused. The vertical dimension will be established bylooking at facial form and speaking space. Thesounds may be quite distorted, but the relationshipof the maxillary and mandibular anterior teethwhen the patient attempts the s sound should benormal. At the try-in stage, the augmentation maybe added. A processed maxillary base is suggestedbecause the bulk of acrylic resin needed in thepalate could cause considerable processing distor-tion if the base and augmentation are processedsimultaneously.

If a speech and swallowing therapist is avail-able, he or she can assist in evaluating the contours.The area of loss of tongue bulk should be corre-spondingly augmented on the palate with baseplatewax. Additions should include evaluation with pres-sure indicator paste, looking for uniform tonguecontact. The tongue may not be able to move to allquadrants of the mouth, so there may not be animpression of the tongue on the entire surface of theaugmentation. Placing a tissue conditioner material


on the palatal surface of the denture can be used tocreate a functional impression of the residualmobile tongue made during swallowing. This tech-nique usually will achieve an improvement in artic-ulation also.

Fine tuning for subtle changes in articulationand air flow (needed for such sounds as s, sh, andt) usually is better accomplished with small addi-tions and subtractions of wax after the gross con-tours needed for swallowing are established. Theseminute refinements are more difficult to accom-plish if tissue conditioner material, rather thanbaseplate wax, is used to form the initial swallow-ing contacts. Specific target sounds to assess ante-rior and posterior contact are used. Posteriorsounds include k and a hard g. If these sounds arenot distinct, the posterior palate must be lowered.The tongue tip may not be centered in the palatebecause of tethering or deviation toward the surgi-cal side due to hypoglossal nerve damage.Additional wax may need to be added to allow themost elevated portion of the tongue (if the tonguetip no longer elevates, this new area of elevation inthe body of the tongue becomes the tongue tip) tomake definite contact for the t and d sounds. As forthe routine denture wearer, a lisp may be presentduring the s and sh sounds. During these sounds,the normal tongue does not contact the anteriorpalate, but rather it curls and approximates thepalate in the midline to create an air channel. A nar-row channel forms the s sound, and the same chan-nel is made wider by flattening the tongue for thesh sound. Patients undergoing glossectomy maynot be able to curl the tongue or approximate theanterior palate in the midline. Placing a groove inthe anterior palate may create the necessary airchannel. This groove will not necessarily be in themidline but must coincide with the deviation of theanterior tongue.

Patients with the best results will have most oftheir tongue remaining and have a tongue tip that isnot tethered, although they may have speech errorsin connected speech. The impaired tongue will notbe able to move to all positions of the mouth rapidly;therefore the patient must slow the rate of speech.Despite the best prosthodontic efforts, patients withgreater range-of-motion deficits may be able to eatonly pureed foods or a liquid diet, and they maycontinue to have errors in certain target sounds.

MANDIBULAR RESECTION PROSTHESESSpecial maxillofacial prostheses for the mandibleusually are required because of surgical resectionfor neoplastic disease. A discontinuity resection ofthe mandible implies that a portion of the mandibleis resected, and the condyle-to-condyle continuityof the mandible is disrupted. A marginal mandibulec-tomy implies that a margin of bone is resected, butthe continuity of the mandible is maintained.Usually, the margin of resection is at the superioraspect and is involved with epithelial neoplasms ofthe mouth.

Marginal Mandibulectomy Prostheses

A marginal mandibulectomy can be restored with acomplete mandibular denture provided the soft tis-sue reconstruction over the mandible is not grosslymobile or compressible. If the tongue or floor-of-mouth tissues are sutured over the mandible tothe cheek, the tissue mobility will unseat the den-ture (Figure 23-13). Thin microvascular flaps fromthe forearm are commonly used in the floor ofmouth over the mandible, but these tissues do notattach to the bone and are also too mobile for den-ture stability (Figure 23-14). The ideal closure is asplit-thickness skin graft placed over the bone andsutured to the buccal and lingual tissues. The skin


Figure 23-13 This patient had a left marginalmandibulectomy and floor-of-mouth resection. Theremaining tissues of the floor of the mouth and buccaltissues of the cheek were closed primarily over themandible, precluding fabrication of a stable denture.

graft will attach to the marrow bone and behavesimilarly to attached gingiva. The mobile lingualand buccal tissues are separated by nonmobile skinover the mandible (Figure 23-15). This skin-graftedmandible will respond well to radiotherapy also.Surgeons should be encouraged to use a skin grafton marginal mandibulectomies, unless consider-

able soft tissue is required to restore gross resectionof the tongue and floor of mouth. If a skin graft isnot used for primary reconstruction, secondarydebulking of the movable flap and placement of askin graft often are necessary before making amandibular denture. Processed bases are advanta-geous.

Discontinuity Mandibulectomy Prostheses

Mandibular discontinuity resections are usually inthe lateral aspect of the mandible and result fromepithelial lesions in the oral cavity overlying themandible. Recently, predictable use of microvas-cular bone grafts has allowed immediate recon-struction of mandibular resections, and delayedparticulate bone grafts can be used; however, thisreconstruction is not available in all institutions,and not all patients are candidates for these sec-ondary complex operative procedures. These unre-constructed lateral resections will continue torequire prosthetic rehabilitation.

A custom border molded tray should cover theavailable mandibular body. There is often a desireto extend the denture beyond the mandible into theresected area to gain a broader area of contact or tosupport the lip. The soft tissues in the resected area


Figure 23-14 This patient had a free soft tissue flap from the forearm placed over amarginal mandibulectomy, replacing missing soft tissue of the floor of mouth and mandible.The right cast reveals the contour changes after connective tissue debulking 1.5 cm of softtissue; however, because the flap does not attach to the mandible, the tissue is very mobile,and the patient could not successfully wear dentures.

Figure 23-15 This patient had a marginalmandibulectomy and floor-of-mouth resection that wasreconstructed with a split-thickness skin graft from thethigh. Given the excellent posterior mandibular heightand nonmobile tissue in the anterior mandible, thepatient did very well wearing conventional dentures.

should be scrutinized because they usually movewhen the tongue moves or when the patient opensthe mouth. These movements will unseat the pros-thesis. If the tongue is “pulled” to the surgical sidewith the surgical closure, a deep anatomical spaceis created on the posterior lingual aspect of theremaining mandible. Because the tongue lacksmobility, this space does not change. Extension ofthe denture flange into this space improves denturestability. A processed base will allow a thoroughevaluation of the base stability before the additionof teeth.

Making maxillomandibular relationship recordsfor this patient is challenging. Patients do not havea condylar hinge movement. Because of unilateralmuscle attachments to the intact mandible on thenonsurgical side, as the patient opens the mouth,the chin and midline deviate as much as 1 to 2 cmto the surgical side. As the patient closes the mouth,the anterior mandibular path is not vertical, butrather it follows a diagonal path toward the nonsur-gical side. At final closure, the patient usuallyreaches the vertical dimension of occlusion with themandible positioned palatal to the maxillary teeth.Besides the problem of unilateral muscle attach-ments, there often is scarring in the surgical areathat also prevents the mandible from returning to itspresurgical relationship with the maxilla.

When shaping the maxillary rim, it may be nec-essary to decrease the upper lip support slightly soas not to accentuate the Class II appearance of thepatient. This appearance occurs as a result ofthe deviated and recessed chin point. Do not “push”the mandible laterally to achieve normal maxil-lary/mandible horizontal overlap. It is unlikely thatthe patient will be able to achieve this relationshipduring function. Patients should move the mandibletoward the surgical side using their own muscles ofmastication. This patient-generated position is usedas the centric occlusion (CO) position. The patientundergoing a lateral mandibulectomy has proprio-ception for a “repeatable position” within anocclusal area, but it will not be an exact repeatableposition as is seen in a CR position of the nonre-sected mandible. Adapt the occlusal wax rims inharmony with this position.

Vertical dimension of occlusion should be deter-mined by assessing lip competence, facial appear-ance, and speaking space. Normal lip closure often

is compromised in these patients because of bisect-ing of the lower lip during surgery, damage to themarginal mandibular branch of the facial nerveand lack of bony support; therefore it is impor-tant that the patient can close the lips withoutstraining to prevent loss of liquids or food bolus.Lip closure and an unstrained facial appearancemay be the best determinant of the correct verti-cal dimension of occlusion. Closest speakingspace may be a helpful parameter, but because ofpossible articulation problems and mandibulardeviation, this parameter may deviate greatlyfrom normal.

After the occlusion rims are formed for hori-zontal alignment and equal contact in CO position,the interocclusal record may be made. Using anymaterial with resistance will cause the mandible torotate as the denture encounters the resistance.Using a plaster for the recording material requiresthat the patient maintain a position until the mate-rial sets. Maintaining a mandibular position with-out occlusal contact or moving the mandible to aspecific location often is difficult for a patient witha partial resection. An alternative is to have thepatient close repeatedly and observe the repeat-able occlusal table “area.” The occlusal rims shouldbe adapted to coincide with this position to offermaximum maxillomandibular wax rim contact.Make large notches on the buccal of the occlusalrims. Have the patient lightly close into themaximum rim contact and then inject impres-sion plaster along the buccal surfaces of thetwo occlusion rims (Figure 23-16). In this man-ner, the patient’s mandible is in its most stableposition, and the vertical dimension of occlusionis accurate.

Mount the processed bases on remount casts.Use of a face bow to achieve a relationship of thecondyles to the maxilla is not an issue in the patientwith a resection because the condylar function isunilateral. However, mounting the maxilla in thecorrect relationship to the upper member of thearticulator will give the clinician an appreciationfor the rotation of the mandible. When the relation-ship of the mandible with the maxilla is viewed, thedeviation toward the surgical side, the medial rota-tion of the mandibular body, and the inferiorrotation of the chin point will be evident. Monoplaneocclusion is recommended to allow patients freedom


to function in an occlusal area. Given the medialmandibular rotation, it is likely that the posteriormandibular teeth may be positioned on the buccalshelf, which is now the functional ridge crest.Placing the anterior teeth more buccal than thevestibule will decrease the Class II appearance butusually serves to decrease denture stability. Ifprocessed bases are used, this tooth position can beassessed at the try-in appointment. If the basesbecome less stable when positioning the mandibu-lar anterior teeth, the teeth should be set more lin-gually. The mandibular plane will coincide with themaxillary plane. Because of the inferior rotation ofthe anterior mandible, the vertical height of themandibular denture in this area may be consider-ably more than the posterior denture height.Vertical overlap of the anterior teeth may be con-sidered. Because incising or movement of themandible into a normal “s position” during speechis unlikely in this patient population, vertical over-lap may not unseat the denture in function. Duringthe try-in stage, anterior vertical overlap can beassessed in relation to denture stability and its ben-efit to speech.

For proper maxillary buccal corridors to beachieved, the maxillary teeth are set in the appro-priate buccal/lingual position. Because of mandibu-lar deviation, it may be necessary to place a flatocclusal platform palatal to the maxillary teeth onthe nonresected side to achieve occlusal contact.

Making a sloped platform to guide the mandiblefarther toward the nonresected side and achieve amore normal occlusal buccal/lingual alignmentusually unseats the mandibular denture rather thanmoves the mandible. A sloped platform should beavoided in the edentulous patient, unless it is asloped platform that corresponds to the slope of thepath of closure.

Placing prostheses and establishing a verticaldimension of occlusion may alter tongue/palatecontact. The patient should be considered for apalatal augmentation prosthesis. It may be formedat the try-in appointment or added later. After pro-cessing on the teeth, the dentures are returned tothe remount casts, and a laboratory remount isdone.

Troubleshooting Prostheses for the Patientwith an Edentulous Mandibulectomy

Unstable Mandibular Denture Stability of thebase should be evaluated with processed bases atthe time of maxillomandibular relationship recordsbefore placement of wax rims. Overextension ontomovable tissue will unseat the prosthesis. Over-extensions should be reduced before makingrecords. If the prosthesis is unstable at the try-inappointment, inappropriate tooth position may beunseating the prosthesis. Denture adhesive often isnecessary.

Inability to Chew or Inability to Chew beyond aSoft Diet Tongue lateralization is very importantfor moving a food bolus onto the teeth. Patientswith partial mandibulectomies often have impairedrange of motion of the tongue. A liquid diet or asoft diet that is washed down with liquids may beall that the patient can accommodate despite theinsertion of dentures. Hard food substances requireconsiderable masticatory power that the edentulousmandibulectomy patient lacks. The patient shouldbe educated to these possible limitations before theprostheses process is begun.

Prostheses for Bone-Grafted Mandibles

Restoration of continuity with bone grafting offersa major advantage by maintaining the condyles inthe appropriate relationship to each other and to the


Figure 23-16 For interocclusal records, impressionplaster is injected along the buccal surfaces of theocclusion rims while the patient is sitting upright andhis mandible is in the postsurgical centric occlusionposition.

maxilla, thereby negating mandibular deviation. Arepeatable CR position can be achieved. Forimprovement of prosthetic rehabilitation, an ade-quate volume of bone and soft tissues overlying thebone graft must not be bulky, compressible, ormovable. These soft tissue difficulties usually areseen when soft tissue flaps are required to replaceconsiderable intraoral soft tissues resected with thetumor. Secondary preprosthetic surgical proce-dures often are necessary to alter these soft tissues.The ideal situation would be debulking of the flapand placement of a split-thickness skin graft overthe mandibular graft (Figure 23-17). Routineprosthodontic procedures with processed bases areused. As previously described, in the patient with apartial mandibulectomy, selecting the anteriortooth position and vertical dimension of occlusionso as not to hinder lip competence is important.The need for a palatal augmentation prosthesis alsoshould be assessed.

MAXILLOFACIAL IMPLANT-SUPPORTEDPROSTHESES FOR THE EDENTULOUSPATIENTThe edentulous patient with a maxillofacial pros-thesis will arguably benefit from implants more

than a patient with any other removable prosthesis.The loss of bilateral bony support in either arch, thelack of tongue mobility to stabilize mandibulardentures, movable soft tissue/bone attachments inthe oral cavity, and need to use the prosthesis tosupport facial contours can lead to prosthetic com-promise or failure, without the use of dentalimplants.

Despite these decided advantages, implantsare not widely used in this patient population.Adjuvant radiotherapy often is required in thepatient with head and neck cancer, which can hin-der osseointegration of the implants. A few reportshave been published of hyperbaric oxygen therapyadministered to assist in osseointegration in theirradiated patient, but this method of treatment isexpensive, time-consuming, and geographicallyunavailable to some patients. Many patients areunwilling to undergo the secondary surgical proce-dures needed to prosthetically prepare the oral cav-ity soft tissues and place the implants. Until it isquite certain that patients are disease free, physi-cians and dentists are unwilling to embark onthese additional surgical procedures. The shortestelapsed time from cancer resection to insertion ofthe implant prosthesis in patients at my institutionwas 14 months. These individuals had the minimalnumber of secondary operations and no adjuvanttherapy. In most individuals, the time frame wasmuch longer.

The complications seen in patients with rou-tine implants also are seen with this patient popu-lation. Because so few patients have been treated,experience is limited. Loss of implants orimplants placed that cannot be used because ofsoft tissue complications or malposition appear tobe more common in the patient with a maxillofa-cial prosthesis compared with the patient with aroutine implant. Just as in the insertion of den-tures in the patient with a maxillofacial prosthe-sis, insertion of an implant prosthesis will notensure that a normal diet will be achieved or thatany advancement in diet will occur. Lack oftongue control or a dysfunctional swallow reflexwill not be changed with the delivery of animplant prosthesis. This method of retention maynot be a panacea. The use of implants in the max-illofacial patient should be encouraged (Figures23-18 through 23-22).


Figure 23-17 This patient has had an anterior freefibular bone graft. The intraoral soft tissue contours arebulky and freely mobile over the bone graft. Noanterior vestibule exists. A debulking of the tissues,including epithelium and connective tissue down tothe periosteum, and placement of a split-thickness skingraft will improve denture support.

LABORATORY PROCEDURESBoxing and Pouring Impressions

Because of the unusual three-dimensional shapesof some of the maxillofacial prostheses andbecause impression wax is sometimes used, boxingthe impression with a thick half plaster and halfpumice mixture may be preferred to using a wax-beading technique. Excess water in the mix can beremoved with paper towels and the plaster/pumicematerial positioned around the impression. The

pumice is then trimmed to create the appropriateland area, boxed with wax, coated with a separatingmedium, and poured.

Using Processed Bases: Adding Teeth, AddingPalatal Augmentations, or ReliningObturators

During flasking, the entire processed base shouldbe covered with stone except where the addition ofnew acrylic resin or teeth is desired. This includespouring stone into the intaglio surface of the pros-thesis. Do not block out any undercuts with pumiceor wax. This will make the deflasking procedureeasier but will also leave some of the acrylic resinof the processed base unsupported. This unsup-ported area of the prosthesis may crack when pack-ing the acrylic resin addition or distort when theadditional acrylic resin is cured. The additionalresin may be processed at a lower temperature fromthe original curing temperature of the base, or anautopolymerizing denture resin may be used. In thecase of final processing of teeth onto a base, themaxillary and mandibular prostheses can be fin-ished and placed on the remount casts that havebeen maintained on the articulator from the try-in appointment. The final occlusion may be refinedand the prostheses inserted without anothermaxillomandibular relationship record.


Figure 23-18 Radiograph of the fibular graft andthree implants placed in the patient in Figure 23-17.

Figure 23-19 The debulking of soft tissues andskin graft were completed, as well as implantplacement, in the patient in Figure 23-17. This patientfunctions very well with an implant-assisted mandibulardenture; however, lack of normal tongue movementprecludes a diet requiring heavy mastication.

Figure 23-20 This patient had a large benignpleomorphic adenoma requiring total soft palateresection, left alveolar resection and total hardpalate resection. The right anterior and right posterior alveolus remained.

“Capping” Hollow Obturator Prostheses

Shortcuts in making the lids to cover the hollowobturator portion or shortcuts to sealing the lid andthe prosthesis together can be taken, but the finalresult of shortcuts may be a prosthesis that leakswater around the lid/prosthesis interface. The pros-thesis can be “capped” from the palatal side, butone must keep in mind that the lid contours must bein harmony with the remainder of the palate and thepatient’s tongue. Making a lid for the superioraspect of the prosthesis does not have these contourconstraints.

The easiest researched method used at mostinstitutions is the making of a light-cured resin lid(Triad Reline, Dentsply International, Inc., York,Pa.) bonded to the acrylic resin base with the samelight-cured resin. After a 1-mm ledge around theinternal periphery of the hollow obturator portionis created, the hollow obturator can be filled with athick mix of plaster and pumice. The superiorsurface should be slightly convex to allow mak-ing a convex lid. The ledge should be exposed.Laboratory foil is adapted to the ledge and the driedplaster/pumice surface. A few drops of cyanoacry-late glue onto the plaster/pumice will secure thefoil. The light-cured resin can be adapted over thefoil and pressed into the ledge. The entire prosthesisand lid should be placed in the curing unit. Aftercuring, the lid can be removed. The impression ofthe ledge should be visible in the undersurface of thelid. (Sharp detail is not necessary, but enough ofthe ledge impression should be present to delin-eate the borders of the lid.) The lid is then trimmed.The plaster/pumice is removed from the hollowprosthesis. Monomer is used to clean the lid andthe prosthesis ledge, and the bonding agent isapplied to the ledge and lid. An approximately 2-mmwide strip of light-cured resin is placed around the1-mm ledge, and the lid is manipulated into posi-tion by hand. Excess material will flow at theperipheries of the lid. This can be adapted to theperiphery of the lid/obturator portion with a cotton-tipped applicator and monomer. The prosthesis iscured, and the excess material at the margins of thelid is trimmed with laboratory burs. Before inser-tion of the prosthesis, the entire obturator prosthe-sis should be submerged in a pressure pot, heldunder water with a weight and 30 lb of pressureapplied to the pot for approximately 1 minute. The


Figure 23-21 A and B, The patient had an iliaccrest graft placed with a sinus lift, followed by skin graftvestibuloplasty and placement of four implants. The leftanterior implant failed, but the three right posterior 18-mm implants have remained in function for 12 years.

A

B

Figure 23-22 The patient had to wear a veryunstable maxillary prostheses before uncovering theimplants, and the pressure on the buccal bone causedstripping of the threads very early in the clinical course(reversed mirror image).

prosthesis should then be removed and shaken tocheck for water inside the sealed obturator. If wateris present, continuing to shake the prosthesis orplacing it under pressure again in a dry pressure-pot will force the water through the area of the lidthat is leaking. Usually, the leak is in a very smallarea and limited to one or two places. The leakingareas can be opened with a no. 8 round bur, thenwater is blown out of the bulb (at least two holesare necessary to blow the water out of the hollowprosthesis) and the holes sealed with a smallamount of light-cured resin. Again, the prosthesisshould be checked for leaks before final delivery ofthe prosthesis to the patient (Figure 23-23).

BibliographyAramany MA, Downs JA, Beery QC: Prosthodontic rehabilita-

tion for glossectomy patients, J Prosthet Dent 48:78-81,1982.

Beumer J, Curtis D, Firtell D: Restoration of acquired hardpalate defects. In Maxillofacial rehabilitation: prosthodon-tic and surgical considerations, St Louis, 1979, Mosby.

Brown KE: Complete denture treatment in patients withresected mandibles, J Prosthet Dent 21:443-447, 1969.

Cantor R, Curtis TA: Prosthetic management of edentulousmandibulectomy patients. Part II: Clinical procedures,J Prosthet Dent 25:546-555, 1971.

Christensen JM, Hutton JE, Hasegawa A et al: Evaluation of theeffects of palatal augmentation on partial glossectomyspeech, J Prosthet Dent 50:539-543, 1983.

Desjardins RP: Occlusal considerations for the partialmandibulectomy patient, J Prosthet Dent 41:308-315, 1979.

Franzen L, Rosenquist JB, Rosenquist KI et al: Oral implantrehabilitation of patients with oral malignancies treated withradiotherapy and surgery without hyperbaric oxygen ther-apy, Int J Oral Maxillofac Implants 10:183-187, 1995.

Jacob RF: Duplication of interim speech aid for definitive impres-sion tray fabrication, J Prosthet Dent 68:561-562, 1992.

Jacob RF, Martin JW, King GE: Modification of surgical obtu-rator to interim prosthesis, J Prosthet Dent 54:93, 1985.

Jacob RF, Reece GP, Taylor TD et al: Mandibular reconstructionfor the cancer patient: microvascular surgery and implants,Tex Dent J 119:23-26, 1992.

Jacob RF, Yen TW: Processed record bases for the edentulousmaxillofacial patient, J Prosthet Dent 65:680-685, 1991.

King GE, Jacob RF, Martin JW et al: Rehabilitation of the nasaland paranasal sinus area. In Thawley S, Panke W, BatasakisJ, Lindberg R, editors: Comprehensive management of headand neck tumors, vol 1, Philadelphia, 1986, WB Saunders.

Logemann JA: Can data on normal swallowing improve treat-ment selection. In Myers EN, Barofsky I, Yates JW, editors:Rehabilitation and treatment of head and neck cancer, USDepartment of Health and Human Services, NIHPublications No. 86-2762, Washington, DC, 1986.

Logemann JA, Bytell DE: Swallowing disorders in three types ofhead and neck surgical patients, Cancer 44:1095-1105, 1979.

Martin JW, Jacob RF, King GE: Boxing the altered cast impres-sion for the dentate obturator: plaster and pumice, J ProsthetDent 59:382-384, 1988.

McKinstry RE, Aramany MA, Beery QC et al: Speech consid-erations in prosthodontic rehabilitation of the glossectomypatient, J Prosthet Dent 53:384-387, 1985.

Paprocki GJ, Jacob RF, Kramer DC: Seal integrity of hollow-bulb obturators, Int J Prosthodont 3:457-462, 1990.

Robbins KT, Bowman J, Jacob RF: Post-glossectomy degluti-tory and articulatory rehabilitation with palatal augmenta-tion prostheses, Arch Otolaryngol Head Neck Surg113:1214-1218, 1987.

Taylor TD, LaVell WE: Dental management and rehabilitation.In Thawley S, Panje W, Batasakis J, Lindberg R, editors:Comprehensive management of head and neck tumors, vol 1,Philadelphia, 1986, WB Saunders.

Taylor TD, Worthington P: Osseointegrated implant rehabilita-tion of the previously irradiated mandible: results of a lim-ited trial at 3-7 years, J Prosthet Dent 69:60-69, 1993.


Figure 23-23 This very large hollow prosthesiswas required to obturate the hard and soft palate,opposing a mandibular Kennedy Class I partial denture.

C H A P T E R 24Prolonging the Useful Life of CompleteDentures: The Relining ProcedureGeorge A. Zarb, Rhonda F. Jacob

471

Both biological supporting tissues and materialsused in complete denture fabrication are vulnerableto time-dependent changes. The denture base mate-rial may discolor or deteriorate, whereas the artifi-cial teeth can also discolor, fracture, or becomeabraded. These material changes be rectified; how-ever, irreversible change in the tissues supportingthe prostheses can only be partially compensatedfor. This point was emphasized in Part I as anunavoidable sequela of the edentulous state.Meticulous attention and care in the construction ofcomplete dentures can minimize adverse changesin the supporting tissues and in associated facialstructures as well, but it cannot preclude them.Thus the need for “servicing” complete dentures tokeep pace with the changing surrounding and sup-porting tissues becomes mandatory. The clinicalefforts that aim at prolonging the useful life ofcomplete dentures involve a refitting of the impres-sion surface of the denture, occlusal correction,and a minor spatial reorientation of the prosthesis.Two techniques are available: (1) reline, a proce-dure used to resurface the tissue side of a denturewith new base material that provides accurateadaptation to the changed denture-foundation area,and (2) rebase, the laboratory process of replacingthe entire denture base material in an existing pros-theses. The alternative (at some point a necessaryone) to this sort of “servicing” is the more expen-sive periodic remake of the complete dentures.

TREATMENT RATIONALEThe foundation that supports a denture changesadversely as a result of varying degrees and rates ofresidual ridge resorption (RRR). These changes

may be insidious or rapid, but they are progressiveand inevitable, and they usually are accompaniedby one or more of the clinical changes listed inFigure 24-1. The variable reduction in verticaldimension of occlusion (VDO) and resultant spa-tial reorientation of the dentures also lead toesthetic changes in circumoral support and, conse-quently, in the patient’s appearance. The changes inocclusal relationships can also induce moreadverse stresses on the supporting tissues, whichincreases the risk of further ridge resorption.

One compelling conclusion that can be drawnfrom clinical experience and research involvingdenture-wearing patients is that dentures need reg-ular attention for maintenance purposes. Suchattention can be achieved only by patient educationand a regular recall schedule. During the recallappointments the dentist reconciles a patient’sreported denture experiences with informationderived from clinical examination. The magnitudeof the observed changes allows a decision to bemade as to whether the prescribed servicing of theprosthesis will necessitate a laboratory reline, arebase, or a remake.

The relining procedure is the most frequentlyprescribed intervention and involves adding a newlayer of processed denture material to the denturebase. This can be done without adversely affectingthe occlusal relationships or the esthetic supportof the lips and face. When minimal or moderatechanges are evident, relining is the treatment ofchoice. A thin layer of impression material is addedto compensate for resorptive changes that haveoccurred in the basal seat. Then, in the dental labo-ratory, the material is replaced by a new layer ofacrylic resin that bonds to the original fitting

surface of the denture. The compensation for theresorbed tissues results in a slightly thicker acrylicresin denture base.

If extensive changes are encountered, the den-tist must compensate not only for the reduced sup-porting tissue but also for the reorientation of thedentures, and this necessitates a simultaneous refit-ting of the impression surface of the denture with areorienting of its vertical and horizontal position inthe mouth. The resultant bulky denture base willlikely require a thinner palatal section in the maxil-lary denture, that is, the dental laboratory descrip-tion of a rebasing procedure. This reorientation ofthe dentures may require that the clinician use var-ious materials and techniques to stabilize the den-ture in position before making the impression ofthe entire basal seat.

Relines can be done simply, accurately, and inex-pensively. However, rebasing a complete dentureinvolves all the problems of making new dentures,and the teeth cannot be moved around as easily aswhen a new denture is made. Consequently, a rebaseprescription may be regarded as an inferior clinical

alternative to the more expensive and time-consumingdecision to make new dentures. Therefore at times aclinician may choose to reline one prosthesis butchoose to remake its counterpart rather than rebase it.Socioeconomic realities and common sense dictatethat these techniques must be provided frequently,and clinical experience certainly justifies their use.

DIAGNOSISPatients who have worn dentures successfully for along time often return for further service becauseof looseness, soreness, chewing inefficiency, orperceived esthetic changes. These difficulties mayhave been caused by (1) an incorrect or unbalancedocclusion that existed at the time the dentures wereinserted or, more likely, (2) changes in the struc-tures supporting the dentures that are now associ-ated with a disharmonious occlusion. It is essentialthat the cause or causes of the reported difficultiesbe determined before any attempt is made to cor-rect them. Therefore a diagnosis of the changes thathave occurred must be made before any clinical


Reline

Minimal to moderatechanges

Moderate to maximalchanges

Rebase

I Loss of retention and stability

II Loss of vertical dimension of occlusion

III Loss of support for facial tissues

IV Horizontal shift of dentures : incorrect occlusal relationship

V Reorientation of occlusal plane

Observed clinical changes include :

Figure 24-1 A number of changes can occur in the tissues that support complete dentures.They are more common under mandibular than under maxillary dentures, but they may beencountered under either, particularly when an upper denture is opposed by the natural dentition.The magnitude of the changes is what determines the nature of the resurfacing or refittingprescribed. If a new thin layer of resin is added to the denture base, the resurfacing is called areline. If more material is added (as for a maxillary denture resting on severely resorbed residualridges), extensive refitting and polymerized material is necessary, and this is called a rebase.

procedures are started. It is necessary to determinethe nature of the changes as well as their extent andlocation. The dentist must understand what changesare possible and what symptoms illustrate them.

Dentures with built-in errors in occlusion maynot need relining. They may only need to have theocclusion corrected. Simple tests of individual den-ture bases may show that stability and retentionhave not been lost, even though the patient reportsthat the dentures are loose. The stability and reten-tion of the bases are examined for each prosthesisindependently. The prosthesis is lightly seatedagainst the ridges and moved horizontally and lat-erally and also moved in an anterior and posteriordirection. A well-adapted denture will unlikelymove more than 1 to 2 mm, which is consistentwith tissue displaceability. Seating the denture oneach ridge independently may exhibit rocking.Pushing on the anterior maxillary dentition or pullingon the anterior dentition may cause the denture tounseat with minimal force. Generally, denture move-ment or rocking indicates the need for a relineprocedure.

If this evaluation reveals a stable and retentiveprosthesis, the occlusion may be the culprit. In thissituation, the supporting tissues may show moreirritation or inflammation on one side of the mouththan on the other. The apparent looseness resultsfrom uneven occlusal contact. Treatment involveskeeping the dentures out of the mouth for 1 to 2days and then reevaluating the denture withpressure indicator paste. After adjustments, thedentures should be remounted and occlusal adjust-ment performed. These procedures will eliminatethe cause of the oral discomfort and make thedentures comfortable and serviceable withoutrelining.

A change in the basal seats of the dentures usu-ally is revealed by looseness and movement of theprosthesis on clinical examination, general sore-ness and inflammation, discernible loss of theocclusal vertical dimension and compromisedesthetics, or disharmonious occlusal contacts. Anexamination of the oral mucosa that supports thedentures will disclose the state of its health. Whenthis tissue is badly irritated, occlusal disharmonyassociated with loss of the vertical dimensionshould be suspected. Unsatisfactory changes inesthetics indicate a loss of the vertical dimension,

even though the teeth may seem to occlude prop-erly. Overextention of denture flanges can beobserved as ulcerations or hyperplastic tissue inthe sulci. If the supporting tissue is traumatized,surgical correction to eliminate the hyperplasiamay be necessary before relining impressions aremade. When gross adjustments of the flanges arerequired plus addition of tissue conditionerreline, or the patient does not wear the denturesfor 1 to 2 weeks, the result is often completeresolution of the soft tissue hypertrophy withoutsurgery.

The amount of change in the occlusal verticaldimension that has resulted from the loss of sup-porting structure must be carefully noted. Theproblem is not simply a change in the occlusal ver-tical dimension; it also can be a change in the hor-izontal relations of the dentures to each other andto their basal seats. A loss of vertical dimensionwill automatically cause the mandible to have amore forward position in relation to the maxillaethan it would at the original occlusal verticaldimension. This situation can exist even though thejaws are maintained in centric relation (CR) posi-tion. What must not be overlooked is the unpre-dictability of bone morphological changes. Thisoutcome will in turn influence the dentures’ posi-tions (Figure 24-2).

Resorption of the bone of the maxillae usuallypermits the upper denture to move up and back inrelation to its original position. Patients may com-plain of pain in the anterior vestibule below thenose. However, the occlusion also may force themaxillary denture forward. The lower denture usu-ally moves down and forward, but it may movedown and back relative to the mandible as resorp-tion occurs. Concurrently, the mandible closes, andthe patient’s vertical dimension is less when theteeth are in occlusion than the vertical dimensionoccupied with the teeth in occlusion before theresorption occurred. This movement is rotaryaround a line approximately through the condyles.Because the occlusal plane and the body of themandible are located below the level of this axis ofrotation, the mandible moves forward as the spacebetween the maxillae and mandible is reduced fromthat existing when the dentures were constructedoriginally. Such rotational forward movement of thebody of the mandible is not necessarily an eccentric

Chapter 24 Prolonging the Useful Life of Complete Dentures: The Relining Procedure 473

forward movement of the mandible; rather the CRposition of the condyles may be retained despite theapparent forward movement of the mandible whenobserved in relation to the maxilla.

The effects of this rotary movement vary frompatient to patient and appear to result from a com-plex interaction of several features, particularly theduration and magnitude of bone resorption and themandibular postural habit. The mandible’s rotationmay be associated with a number of consequencesthat frequently occur simultaneously: (1) losingcentric relation occlusion (CRO) in the dentures;(2) changing the structures that support the upperdenture; (3) forcing the lower denture backward soit impinges on the lower ridge or forcing the lower

denture anteriorly, with an ensuing prognathicappearance (Figure 24-3).

It appears then that mandibular rotation canelicit severe damage in the denture-supporting tis-sues over a long period of unsupervised denturewear. The stresses are probably augmented by theuse of cusped posterior teeth and by the resultantincisal guidance, which now locks the mandibulardenture into the maxillary denture. Although pro-ponents of the “noncusp” school of thought fre-quently indict the other school’s choise of “cusped”teeth as accelerating tissue damage in such situa-tions, no research evidence is available to supporteither school’s claim that its tooth choice mini-mizes changes in the denture-supporting tissues.


2 days after extraction

5 years after extraction

21 years after extraction

Figure 24-2 Bergman’s and Carlsson’s research comprised cephalometric tracings fromthe mandibular symphysis region. They studied 13 patients who had been treated withimmediate complete dentures and observed the patients for 21 years after their extractions.All 13 composite tracings underscore the range and unpredictability of the morphologicaloutcome. All patients wore opposing complete maxillary dentures. Clinical judgmentregarding the mandibular denture’s repositioning for relining purposes requires anunderstanding of resultant bone resorption outcomes. Comparable information of similarchanges in edentulous maxillae is not as compelling.

Figure 24-3 A, Loss of bone structure under both dentures permits the mandible tomove upward a corresponding amount. As the mandible rotates to a closed position withouttranslation of the condyles, it frequently moves forward. The problem is to determine theamount of change that has occurred in both basal seats. The occlusion may not appear to becorrect when observed in the mouth of patient B, or it may appear deceptively adequate andin patient C. The extraoral close-mouthed appearance can be almost identical in both cases.

A

B

C

The horizontal position of each denture in rela-tion to its own supporting ridge must be considered,so a determination can be made as to whether thedenture has moved forward or backward because ofocclusal forces applied to it. Furthermore, one orboth dentures may have rotated in relation to thesupporting structures. The occlusion in the mouthcannot therefore be used as a guide to the horizon-tal repositioning of either denture. A new determi-nation of the vertical dimension of the face must bemade by reestablishing a normal interocclusal dis-tance. Again, the principles used in the constructionof complete dentures are called on. Examination ofthe esthetics in profile, as far as the support of thelips in an anteroposterior direction is concerned,will serve to guide the orientation of the dentures inrelation to their respective foundations. The relationof the teeth to the ridges must be observed for accu-racy. If resorption has been only in the verticaldirection (allowing the jaws to approach each othermore closely than they should when occlusal con-tacts are made), the occlusion cannot be correct,even though there has been no anterior or posteriormovement of the dentures.

It also must be determined whether remodel-ing of the jaws has been uniform under both den-tures or whether one ridge has been destroyedmore than the other. Greater shrinkage in one archwill change the orientation of the occlusal plane.This will cause occlusal disharmony in eccentricocclusions, even though the occlusal verticaldimension has been reestablished by relining.A visual comparison of the size of the ridge withthe size of the alveolar groove in the denture willserve as a guide.

PRELIMINARY TREATMENTIt is probable that if the dentures were made by theclinician within the last few years so that resorptionmay not have been too dramatic, the esthetics offacial profile are only compromised by a few mil-limeters, and the teeth are still in place over themandibular ridge, then a reline procedure of bothdentures should be successfully accomplished.However, if greater errors in fit, occlusion, occlusalplane, esthetics, and overextension of teeth beyondthe ridge are evident, the clinician may be wise totell the patient that new dentures are necessary or

that any changes in the existing dentures will beperformed for diagnostic purposes and for thepatient’s comfort. “Juggling” so many variables indenture rebasing, without having control of thedentition, may end up with a revised denture thatrequires major modification of the teeth to achieveocclusal harmony. Severe revisions of the dentitionoften produce poor esthetic results that the patientwill not accept.

If the clinician chooses to go forward withexisting denture modifications of basal seat andpossibly occlusion, some preliminary steps areundertaken before the actual reline procedure.These steps aim at the following objectives: (1)reestablishing the height, orientation, and estheticsof the occlusal plane by manipulation of themandibular denture (usually, though not necessar-ily, done first) and (2) relating the maxillary to themandibular denture while the correct occlusal andesthetic position of the maxillary denture is beingestablished. Both objectives are achieved more orless automatically with a tissue conditioner as aprovisional reline material, particularly if theadverse changes to be corrected are mild to moder-ate. On the other hand, severe changes maynecessitate using combinations of compoundstops, tissue conditioners, occlusal adjustment, and tooth-colored autopolymerizing augmentation ofthe denture’s occlusal surfaces. This is routinelydone to compensate for extensive vertical occlusalchanges.

The obvious advantages of using tissue condi-tioners include simultaneous restoration of ahealthy basal seat and the ease with which the lin-ers can be modified for maximal function and cos-metic results.

After making certain that the tissues arehealthy, the dentist looks for errors in the occlusionand occlusal vertical dimension that should be cor-rected, as well as other changes that might be madebefore the final procedure is undertaken. Theimplication is that these procedures may take sev-eral patient visits over several weeks to obtainhealthy tissues and establishment of appropriateocclusion. If the magnitude of the adjustmentsrequires more than minor occlusal adjustments, theclinician may choose to maintain the patient inthese “temporary” dentures while new prosthesesare fabricated, according to the diagnostic findings


determined by working with the patient over thepast several weeks.

CLINICAL IMPRESSION PROCEDURESThe clinical relining or rebasing can be achieved by(1) the static impression technique, (2) the func-tional impression technique, or (3) the so-calledchairside technique.

Impression Technique

The static impression technique involves the use ofeither the closed- or open-mouth relines/rebasesvariation. In the closed mouth variation, the den-tures are used as impression trays and either theexisting CRO is used to seat the dentures with lin-ing impression material or else the CR is recorded(in the registration medium of choice) before theimpressions are made. Often only the mandibulardenture requires reline, and it can be relined againstthe maxillary denture. It is suggested that the max-illary denture be additionally secured with dentureadhesive powder. The mandibular denture is seatedas close as the clinician thinks its appropriate posi-tion is, and then the patient closes into the selectedocclusal position. If the maxillary denture needsrelining, it can then be relined against the mandibu-lar denture. Care should always be taken that theposterior borders of the dentures do not make con-tact during the impression procedures. This canoften go unobserved and cause severe occlusal dis-crepancies at delivery.

In the so-called open-mouth technique, thedentures are used essentially as trays for makingthe new impressions. Relining/rebasing of bothmaxillary and mandibular dentures can be done atthe same appointment. The existing CO is not used,and a new CRO record is obtained after the impres-sions are made. This is a demanding and laborioustechnique. Again, it is assumed that before placingthe impression material in the denture, the clinicianwould have made some type of tissue stops in thedentures with low-fusing compound while placingboth dentures in the mouth and maintaining theappropriate occlusal contact, occlusal plane, andesthetic position of the anterior teeth. Establishingthese stops, to direct the clinician to the correctplacement of each denture against the basal tissues

during the impression procedure, will ensure thatthe occlusal relationship will be maintained withina reasonable proximity that can be corrected with aremount procedure.

The closed-mouth reline/rebase technique ispreferred when the static impression method isused. Several variations have been suggested, allbased on the same theme: using the denture as animpression tray with the denture occlusion (cor-rected in preliminary treatment or stabilized intra-orally by wax or compound) and holding the traysteady while the impression material sets. Box 24-1presents three primary areas that must be addressedand meticulously followed when making a denture


Integral Steps for a Closed-MouthReline Technique

Centric RelationExisting correct intercuspation (CRO) used to

stabilize denturesWax interocclusal record made at CRCorrected during reestablishment of a new

vertical dimension of occlusion by occlusaladjustment or use of autopolymerizing onthe occlusal surfaces of posterior teeth

Denture PreparationsLarge undercuts relievedHard resin surfaces relieved 1.5 to 2 mmTissue conditioner removed or relieved”Escape” holes drilled, particularly in maxillary

base; this will also assist easy removal ofpalatal portion during laboratory rebase

Denture periphery shortened to create flat border

Impression ProcedureBorder molding achieved with preferred material

(i.e., low-fusing compound)Border molding retained from polymerized

tissue-conditioning materialPosterior palatal seal achieved with low-fusing

compoundBorder molding achieved by choosing impression

material that is soft and yet viscous enough tosupport and register peripheral detail (one ofthe polyether impression materials)

Box 24-1

reline impression. Doing so will produce repeat-edly good results. Finally, the dentures are sent tothe laboratory with an accompanying work author-ization form that contains specific directions to thelaboratory technician and other information, suchas the specifications for alterations, materials, fin-ish, remount casts, and remounting of the upperdenture.

For many years, it was thought that the strainsinherent in the processed denture base would bereleased by subsequent processing and cause somedegree of warpage. The change in the resin has beenreported at 1.5% to 3% by many authors. Certainlythe laboratory technicians should attempt to use alow temperature in the heat processing, as opposedto using a boiling technique. However, dentures canbe adequately relined with one of the autopolymer-izing resins, allowing trial packing to control verticaldimension and thickness of material, without con-cern for temperature changes and warpage.

When autopolymerizing resin is used, theprocessed dentures can be ready for insertion on thesame day the impressions are made. The protocoldescribed in Part 3 is followed, and occlusal refine-ment is done intraorally or on the articulator.Follow-up instructions are similar to those providedat the time the new dentures are inserted.

Functional Impression Technique

The functional impression technique is both simpleand practical and has gained considerable clinicalsupport. It is technique we routinely use. It dependson a thorough understanding of the versatile proper-ties of tissue conditioners as functional impressionmaterials. The relative ease with which these tempo-rary soft liners can be used as functional impressionmaterials has regrettably led to their abuse andto criticism by many dentists. However, they areexcellent for refitting complete dentures when usedcarefully and meticulously. Improvements in thesematerials include their retaining compliance for manyweeks, their good dimensional stability, and theirexcellent bonding to the resin denture base.

When a denture needs to be refitted, thepatient’s complaint or the dentist’s oral prostheticevaluation usually indicates undermined retention,sore spots, and variable denture-bearing tissuehyperemia. The denture is observed intraorally to

assess the need for peripheral reduction or exten-sion, and a posterior palatal seal extension is devel-oped with an autopolymerizing resin on modelingcompound on maxillary dentures. (Infrequently, ifextensive ridge resorption and overt loss of VDOhave occurred, three compound stops may berequired on the impression surface of the denture toreestablish a proper occlusal relationship or toimprove the occlusal plane orientation.) A treat-ment liner is next placed inside the denture. Thelining material should flow evenly to cover the wholeimpression surface and the borders of the denturewith a thin layer. If voids are evident, they shouldbe filled with a fresh mix of liner material. Unsupported parts of the liner may occur on the bor-ders of the denture, and this indicates that localizedborder molding with stick modeling compoundmay be needed before the placement of a fresh mixof liner. Occasionally borders are formed that arethin and very flexible, and this too is indicative ofinadequate peripheral extension of the denture.Again, the borders must be corrected by bordermolding with one of the autopolymerizing resinsbefore they are covered with the lining material.Remember: these materials have a tendency toslump during setting unless they are adequatelysupported. The patient’s mandible is guided into aretruded position, which is one of maximum inter-cuspation, to help stabilize the denture while thelining material is setting. Excess material istrimmed away with a hot scalpel. Most of the mate-rials used for this purpose progress through plasticand then elastic stages before hardening, which cantake several days (Figure 24-4). The plastic stagepermits movement of the denture base or bases sothey are more compatible with the existing occlu-sion. This also allows the displaced tissues torecover and assume their original position. Thepatient is instructed regarding care of the prosthe-sis and its lining material. It should be noted thatthe actual strength of the processed resin may beweakened by the addition of a tissue conditioner.The processed resin may have to be “reinforced” onthe polished denture surface, and the patient shouldbe warned about risk of denture fracture.

Research has shown that a number of denturecleansers and other preparations that may be help-ful in the control of plaque on dentures can causesignificant deterioration of tissue conditioners in a


short time. Apparently, simple rinsing of the tem-porarily lined denture and gentle brushing with asoft toothbrush are good interim measures to mini-mize damage to the lining. Clinical experienceindicates that 10 to 14 days should elapse beforethe material is firm enough to proceed with theclinical reline sequence.

At the next appointment, the temporarilyrelined denture will usually be well retained, withwell-rounded peripheral borders and a healthy-appearing mucosa. It has been observed that the tis-sue-conditioning materials can create problemswhen used for impressions. The gradually increas-ing elasticity of the material in the mouth can leadto a recovery of the compressed material when theload is removed, that is, when the impression isremoved from the mouth; thus is the importance ofnot pouring the cast before the material has reachedthe firm stage (see Figure 24-4).

Furthermore, these materials tend to deterioratein some mouths, which precludes their use in thismanner. If the dentist has any doubt about the qual-ity of the surface appearance of the hardened liner,

the reline procedure can be carried out as describedearlier in the chapter, after the interim treatmentliner has been removed or relieved. If the surface orperipheral deterioration is slight, these areas can betrimmed with a carbide bur and the denture or den-tures prepared for a secondary, or wash, impressionwith a light-bodied material.

The stone cast must be poured immediately afterremoval of the relined denture base from the mouth.The material should not be plastic, or in the “self-flow” stage, because the material’s own weight maydeform the impression; therefore the use of a newmix of tissue conditioner material as the final impres-sion material is not recommended. It also is possiblethat the weight of the stone poured into the impres-sion surface will cause distortion of the impression.Maxillary working casts may have to be scored inthe selected posterior palatal seal area because thelong period of plasticity of the material may not cre-ate sufficient displacement action in this area.Alternatively, a thin bead of compound material maybe used to augment the posterior palatal seal beforemaking the impression.


Plastic stage(Tissue conditioner)

Elastic stage(Tissue conditioner)

Firm stage(Reline impression)

Tissue conditioner in dentures

Denture base responds to functional/parafunctional stresses; fit is improved

Stress is cushioned; tissuerecovery takes place

Surface is similar to polymerizedresin surface, except it is vulnerable

to deterioration

(Few hours to few days)

(1 to 2 weeks)

Figure 24-4 The physical stages of tissue conditioners/treatment liners allow the dentistto use them for different objectives.

The making of a new CRO record and theremount procedure are recommended to ensure anoptimal prosthodontic occlusion. Researchers havedemonstrated that the functional status of denturesrelined with treatment liners used as impressionmaterials is as good as the status of denturesrelined by border molding and then refined with alight-bodied impression material.

The recent introduction of visible light–cured(VLC) resin systems has produced promisingresults when used in a wide range of prosthodonticactivities. Biological testing indicates that they arenontoxic and biocompatible. Ongoing researchalso appears to have improved their properties(such as fit, strength, ability to polymerize withoutresidual components, ease of fabrication andmanipulation, patient acceptance, ability to bondwith other denture base resins, and low bacterialadherence).

One promising application of VLC resin mate-rial is its use for chairside relining. It is used in asimilar manner as a tissue conditioner, with all thepossibilities of instant modifications because theflow of the material can be regulated by selectionof appropriate viscosity, warming and coolingmeasures in water baths, and partial intraoral poly-merization with a handheld curing light. Therelined denture is then taken to the laboratory forimmediate light-curing of the new layer of mate-rial. These materials have been known to be quitebrittle, but when supported by the originalprocessed denture base, the VLC material withinthe denture and at the denture peripheral role hasappropriate clinical strength for denture longevitybased on the authors’ clinical experience. Althoughlong-term clinical results on treatment effective-ness and material integrity maintenance areunavailable, the VLC materials seem to hold con-siderable promise.

Both the static technique (or versions of it) andthe functional impression technique are wellaccepted and experience-proved procedures. Theycan be used for simple situations (denture settlingis minimal) and complicated situations (excessivetissue changes have taken place). It appears that thechoice between the two methods is based on thedentist’s skill in manipulating the materials and thepatient’s convenience.

Chairside Technique

Several attempts have been made to produce anacrylic or other plastic material that could be addedto the denture and allowed to set in the mouth toproduce an instant chairside reline/rebase. Thesehave met with failure for several reasons: (1) thematerials often have produced a chemical burn onthe mucosa; (2) the result often was porous andsubsequently developed a bad odor; (3) color sta-bility was poor; and (4) if the denture was not posi-tioned correctly, the material could not be removedeasily to start again. At this stage of its develop-ment, the chairside technique has been of very lim-ited use in clinical practice because of theseattendant difficulties, and it is not recommended.

BibliographyBergman B, Carlsson GE: Clinical long-term study of complete

denture wearers, J Prosthet Dent 53:56-61, 1985.Boucher CO: The relining of complete dentures, J Prosthet Dent

30:521-526, 1973.Braden M: Tissue conditioners. I. Composition and structure,

J Dent Res 49:145-148, 1970.Javid NS, Michael CG, Mohammed HA et al: Three dimen-

sional analysis of maxillary denture displacement duringreline impression procedure, J Prosthet Dent 54:232-237,1985.

Kazanji MNM, Watkinson AC: Influence of thickness, boxing,and storage on the softness of resilient denture lining mate-rials, J Prosthet Dent 59:677-680, 1988.

Klinger SM, Lord JL: Effect of common agents on intermediarytemporary soft reline materials, J Prosthet Dent 30:749-755,1973.

Nassif J, Jumbelic R: Current concepts for relining completedentures: a survey, J Prosthet Dent 51:11-15, 1984.

Newsome PRH, Basker RM, Bergman B et al: The softness andinitial flow of temporary soft lining materials, Acta OdontolScand 46:9-17, 1988.

Osle RE, Sorensen SE, Lewis EA: A new visible light–curedresin system applied to removable prosthodontics, J ProsthetDent 56:497-506, 1986.

Rantanen T, Sirilä HS: Fast and slow setting functional impres-sion materials used in connection with complete denturerelinings, Suom Hammaslaak Toim 68:175-180, 1972.

Smith DE, Lord JL, Bolender CL: Complete denture relineswith autopolymerizing resin processed in water under airpressure, J Prosthet Dent 18:103-115, 1967.

Starcke EN, Marcroft KR, Fischer TE et al: Physical propertiesof tissue-conditioning materials as used in functionalimpressions, J Prosthet Dent 27:111-119, 1972.

Wilson HJ, Tomlin HR, Osborne J: Tissue conditioners andfunctional impression materials, Br Dent J 121:9-16,1966.


C H A P T E R 25Implant-Supported Prostheses forEdentulous PatientsGeorge A. Zarb, Steven E. Eckert, Regina Mericske-Stern

483

The applied content of the preceding chapters inPart 3 ensures a satisfactory complete denture expe-rience for most edentulous patients. However, clini-cal experience confirms the fact that manyedentulous patients do not tolerate complete den-tures. This is neither an indictment of professionalskills nor a condemnation of the patient’s responseto the dentist’s efforts. It must simply be acceptedthat many patients who wear complete dentureseither do not like the experience or encounter diffi-culty adapting to their prostheses. Other patientsmay have adapted to dentures for several years butmay become maladaptive as a result of regressivetissue changes or systemic health-related considera-tions. Still others’ dentures may be perfectly adap-tive, but these patients regret or resent the fact thatwearing dentures is their only treatment option, andsome patients simply cannot wear dentures at all.The quality of life of all such individuals is pro-foundly affected by their predicament. Treatmentfor these patients usually entails considerableefforts of both the clinical-technical and the emo-tional-supportive variety, albeit with unpredictableresults. The dentist may even be tempted to dismisssuch patients as having difficult or “impossible”mouths or, worse, as lacking motivation or learningskills. These situations are very frustrating for bothparties, especially when it becomes clear that con-ventional complete denture therapy is not the solu-tion for the patient’s edentulism.

MALADAPTIVE DENTURE BEHAVIORDiverse reasons are presented in the dental literatureto explain the etiology and frequency of chronic

inability to wear dentures. In the past it was temptingfor clinicians to regard the maladaptive problem asresulting mainly from adverse anatomical changes inthe denture-bearing surface. However, clinical expe-rience and some research have also identified physi-ological and psychological contributions to such aresponse. Apart from the extensive anecdotal evi-dence favoring optimized denture construction tech-niques, the major adjunctive treatment proposed forsuch patients has been preprosthetic surgery. The goalof this approach is to enlarge the denture-bearing areaby deepening the buccal or labial vestibules or aug-menting the residual ridge area (see Chapter 8).Implicit in this prescription is the conviction that anenlarged denture-bearing surface will significantlyincrease the chances of denture stability and thereforepatient adaptation. Apart from the inherent morbidityrisks associated with such procedures, however, lon-gitudinal assessment of this approach has failed toproduce a predictable therapeutic outcome.

Some dentists have understandably pioneeredother methods, such as endosseous dental implants,in an effort to treat or preclude maladaptive denturebehavior. Implants can serve as substitutes fortooth roots and help provide support and retentionfor overlying prostheses. They are made out of avariety of biocompatible alloplastic materials andconsist of diverse designs, from so-called blades tocylindrically shaped tooth root analogues. They aresurgically placed in selected edentulous host bonesites with a prosthetic superstructure subsequentlyfitted onto transepithelial posts or abutments joinedto the buried implants.

The scientific premise in prescribing dentalimplants is the predictable and safe provision of

alloplastic tooth root substitutes to stabilize andretain a prosthesis (Figure 25-1).

THE SCIENTIFIC ERA IN IMPLANTPROSTHODONTICSThe required evidence-based clinical application ofdental implants was ushered in by the osseointe-gration research work of Per Ingvar Brånemark andhis colleagues during the late 1970s and was first

presented to the scientific dental communityat the 1982 Toronto Conference. Several clinicalresearchers embarked on clinical trials that involvedvariations on a theme of inserting machine-turnedand machine-threaded cylindrical titanium implantsinto mandibular and maxillary edentulous sites andusing these to support a variety of prosthesesdesigns. Their trials were first conducted in Swedenand subsequently in various teaching centers aroundthe world. The original commercially pure (cp)

484 Part Four Implant Prosthodontics

Figure 25-1 Treating the edentulous state with complete dentures presumes that acrylicresin is a reasonable substitute for the absent periodontal ligament and its participation inthe maintenance of its surrounding alveolar bone. The shadow between the prosthetic teethand the underlying bony support in A reflects the reduced and profoundly changed supportfor an occlusion. Attempts to compensate for this inherently compromised supportmechanism have included a diversity of implant designs, such as B and C. Regrettably, thissort of endosseous anchorage yielded unpredictable results because of the high risk of thebone interface changing to a poorly differentiated connective tissue one. The introduction ofthe osseointegration technique led to a predictable and long-lasting interfacial osteogenesisthat ensures predictably favorable and prolonged functional outcomes as in D.

A B

C

D

titanium implants were inserted with a meticuloustechnique that aimed at creating a direct contactbetween the implant material and living bone.

Several authors had already hypothesized theinduced interfacial osteogenesis (or osseointegra-tion). The belief was that certain implant materi-als could possess a dynamic surface chemistrythat induces histological changes at the implantinterface with the host bone site. However, it wasBrånemark who first produced laboratory and clin-ical results that demonstrated the close spatial rela-tionship between titanium and living bone, aninterface investigated with radiographs and histo-morphometry. The described “osseointegration”suggests a highly differentiated interfacial boneresponse to the careful placement of cp titaniumtooth root analogues. Moreover, this responseappears to become organized according to func-tional demands. Brånemark’s clinical technique hasnow been replicated in several teaching centers inwell-designed longitudinal trials and marks a veryimportant advance in this field of implant prostho-dontics. Currently, many commercial and some sci-entific initiatives have also yielded diverse implantdesigns and materials that have expanded the scopeof the technique.

Regrettably, a sort of knee-jerk response toimplant replacement of most types of teeth has nowemerged. This is alarming for the following impor-tant reasons:

1. There is a serious risk of ignoring the merits(functional, esthetic, and financial) of tradi-tional treatment modalities in the manage-ment of extensive partial edentulism. Oftenan exclusive surgically driven treatment planis proposed; however, efficacy and effec-tiveness outcomes demand prosthodonti-cally directed treatment rather than anexclusive surgical preoccupation with animplant survival strategy. This reflects asubtle yet profound shift in the requiredemphasis on what best addresses patient-mediated concerns.

2. The commercial explosion in implant sys-tem production has already led to a regres-sion in the scientific rigor required to selectscientifically acceptable clinical protocols.Few controlled clinical studies are available

to compare results of different implantdesigns, materials, or surfaces (Eckert,Parein, Myshin et al., 1997). In fact, toomany reports claiming improved outcomesare often based on short-term studies thatare wishfully assumed to equate with long-term clinical success. Although historicalcontrols are thought to be useful, studydesigns are so different that the utility ofsuch controls is limited. The risk of this stateof a quasi-scientific anarchy is a return to ananecdotally driven era in implant prostho-dontics—thus our preference for prescribingimplant systems that reflect scrupulous mul-ticenter and long-term endorsement. Ourpreferred choices remain the Nobel Biocareand ITI systems. Both are made from cptitanium with different macroscopic andmicroscopic surface features. Both systemsmay be used as one- or two-stage surgicalprocedures. The implants can be either imme-diately attached to a healing abutment or areelse buried submucosally until the time-dependent osseointegration is achieved. Thelatter will then permit a secondary surgicalexposure for prosthetic abutment attachmentand subsequent screw-retained or cementedprosthesis loading. Current preliminary yetlimited research even suggests the feasibilityof immediately loading implants in specificlocations, most particularly the anterior eden-tulous mandible.

PATIENT CONSIDERATIONSThe psychological reactions to various forms ofbodily organ loss have been investigated in patientswho have undergone procedures such as hysterec-tomies and mastectomies. However, remarkably lit-tle interest has been shown in the psychologicalreaction to tooth loss. This apparent lack of inter-est is probably attributable to the prevalence ofedentulism and the impressive success enjoyedby the dental profession in treating the condition.Furthermore, edentulism will neither result in deathnor likely elicit profound sympathy in a societypreoccupied with youthful appearances. The senseof shame and inferiority that many edentulouspatients feel is rendered even more poignant by the

Chapter 25 Implant-Supported Prostheses for Edentulous Patients 485

inability of some of them to tolerate a dentureat all.

Patients who cannot wear dentures or who wearthem with varying degrees of difficulty usually haveone or more of the features listed in Box 25-1. Suchpatients are candidates for an implant prosthodonticprescription. Also, even the most successful denturewearer frequently regrets his or her dependence on aremovable prosthesis and the attendant sequelaeassociated with its long-term wear. These patientscould also be added to the list of treatment candi-dates because compelling longitudinal research con-firms the safety and predictability of implantprocedures. It is expected that this advance couldvery well lead to therapeutic strategies in prostho-dontics that considerably reduce the conventionalrole of removable prostheses.

The objective in prescribing implants is to pro-vide the patient with an analogous attachmentmechanism for the lost periodontal ligament (PL)without the latter’s vulnerable qualities. The result-ing availability of dentist-placed abutment(s) canthen be used to support diverse prosthetic super-structure designs. This is achieved through thefollowing:

1. Selection of patients whose systemic healthdoes not preclude a minor oral surgical pro-cedure. Furthermore, the quality and quan-tity of the selected edentulous host bonesites must be surgically assessed by a care-ful and comprehensive radiographic evalua-tion.

2. Meticulous surgical protocol. The pre-dictability of a favorable healing response asmanifested by subsequent interfacial tissuedifferentiation must not be compromised.Surgical judgment and skills have beenshown to be successful outcome determi-nants.

3. Use of a biocompatible alloplastic material,preferably cp titanium, because it has beenshown to yield the best long-term resultsreported to date. However, titanium alloysand different surface treatments appear tooffer equally good prognosis, at least in theshort term.

4. Implant design that ensures immediate stabil-ity and excellent stress distribution. Thescrew’s cylindrical design appears to bethe optimal one; however, preliminary evi-dence indicates that implants with alternativemacroscopic and microscopic design featuresmay be equally good.

5. Unloaded healing of the implant, althoughsome preliminary evidence supports site-specific immediate loading.

6. Ensuring optimal occlusal stress controlview; a passive fit of the prosthetic super-structure and correct occlusal relationships.

The last item in the list is a standard objective intraditional prosthodontics, but the absence ofresilient PL support in implant prosthodontics indi-cates a need for technical accuracy that may verywell exceed what is required when using toothabutments to support cast fixed prostheses.

It should be recalled that the PL’s qualitative andquantitative determinants are arguably the goldstandard for a dentist-induced attachment mecha-nism. It is now obvious that the osseointegratedinterface is a worthy functional substitute for the PL,even if the area of interfacial attachment is signifi-cantly less. On the other hand, a fascinating differ-ence lies in their behavioral nature, given the origins


Patients’ Signs and Symptoms That Frequently Preclude

an Adaptive Complete DentureExperience

1. Severe morphological compromise of thedenture-supporting areas that significantlyundermines denture retention

2. Poor oral muscular coordination3. Low tolerance of the mucosal tissues4. Parafunctional habits leading to recurrent

soreness and instability of the prosthesis5. Unrealistic functional prosthodontic expec-

tations6. Active or hyperactive gag reflex elicited by a

removable prosthesis7. Psychological inability to wear a denture, even

if adequate denture retention or stability ispresent

Box 25-1

of either interface. The PL is the result of a develop-mental phenomenon, whereas osseointegration is theresult of a carefully planned and, to a larger extent,controlled, healing response. This profound differ-ence accounts for the different pathogenesis of attach-ment mechanism failure—periodontal disease or lossof osseointegration. Because an induced “ankylotic-like” response is unlikely to be vulnerable to peri-odontal pathogens, we strongly suspect that implantsfail only when the induced healing response is animperfect one. This is reflected in the fact that mostimplant failures occur during the prescribed healinginterval. Other failures may occur a few months afterhealing is presumed to be complete or else after avariable period of traumatic occlusal loading whenthe imperfectly healed interface is overloaded.Infection then becomes the secondary super-imposedinsult to the failed or failing interface. This chain ofevents has regrettably been misunderstood by manydentists who often bring a PL mind-set to the fasci-nating debate on the infrequently encounteredpostloading or late osseointegration failure.

TREATMENT OUTCOME CONSIDERATIONSThe most important reason for establishing criteriaof success in any treatment method is to safeguardthe oral health of the public. Each patient whoreceives implant prosthodontic treatment has theright to know the potential benefits and risks aswell as an accurate prognosis of the method. Thesecriteria protect the patient, whose informed consentbefore undertaking implant therapy should includean awareness of the highest standard of service cur-rently available.

A clinical working definition for osseointegra-tion is “the time-dependent healing process wherebyclinically asymptomatic rigid fixation of alloplasticmaterials is achieved and maintained in bone dur-ing functional and parafunctional loading.” Thedefinition implies a short list of determinants—asymptomatic, immobile, and time-dependent func-tions—that underscore treatment outcome criteriareflecting the method’s efficacy and effectiveness.

Chapter 25 Implant-Supported Prostheses for Edentulous Patients 487

Determinants of Treatment Outcome in Implant Prosthodontics

Box 25-2

The Following Considerations for SuccessfulOutcomes with Implant-Supported Prostheseswere Proposed:1. Implant therapy is prescribed to resolve prostho-

dontic problems and permits diverse prostho-dontic treatments, which in turn may have animpact on the economics of the service. Suchprostheses should meet the clinically evolvedstandards of function, comfort and esthetics.They should also allow for routine maintenanceand should permit planned or unplanned revi-sions of the existing design. Criteria of treatmentoutcome success for implant-supported prosthe-ses should be assessed in the context of time-dependent considerations for any requiredretreatment.

2. Criteria for implant success apply to individualendosseous implants and include the following:a. At the time of testing, the implants have been

under functional loading.b. All implants under investigation must be

accounted for.

c. Because a gold standard for mobility assess-ment is currently unavailable, the methodused must be specifically described in opera-tive terms.

d. Radiographs to measure bone loss should bestandard periapical films with specified refer-ence points and angulations.

The Success Criteria Comprise the FollowingDeterminants:1. The resultant implant support does not preclude

the placement of a planned functional andesthetic prosthesis that is satisfactory to bothpatient and dentist.

2. There is no pain, discomfort, altered sensation,or infection attributable to the implants.

3. Individual unattached implants are immobilewhen tested clinically.

4. The mean vertical bone loss is less than 0.2 mil-limeters annually after the first year of func-tion.

These criteria are still regarded as less than perfectin clinical research circles because they are par-tially based on fallible resolution levels (e.g., officeradiographic imaging) and they do not lend them-selves to a range of so-called success norms thatare quantifiable. On the contrary, they support adichotomous, all-or-none diagnosis (e.g., mobile orimmobile implant, absent or present interfa-cial radiolucency, painful or painless). The criteria,however, reflect the outcome of numerous interna-tional, scrupulously monitored scientific investiga-tions and have proven to be useful and reliable inthe formulation of a yardstick to measure clinicalsuccess. Box 25-2 sums up the recommendationsof a Consensus Conference on Treatment OutcomeCritieria held at the University of Toronto in 1998.We acknowledge their merits and endorse the scopeof the proposed and described clinical yardstickpackage.

BibliographyBerg E: Acceptance of full dentures, Int Dent J 43:299-306,

1993.Blomberg S: Psychological response. In Brånemark PI, Zarb

GA, Albrektsson T, editors: Tissue-integrated prostheses,Chicago, Tokyo, 1985, Quintessence Publishing Co.

Brånemark PI, Zarb GA, Albrektsson T: Tissue-integrated pros-theses. In Osseointegration in clinical dentistry, Chicago,1985, Quintessence Publishing Co.

Brånemark PI, et al: Osseointegrated implants in the treatmentof the edentulous jaw—experience from a ten-year period,Stockholm, 1977, Almquist and Wiksell.

Brunski JB, Moccia AF Jr, Pollack SR, Korostoff E et al: Theinfluence of functional use of endosseous dental implants onthe tissue-implant interface. II. Clinical aspects, J Dent Res58:1953-1969, 1979.

Carlsson G, Haraldson T: Functional response. In Brånemark PI, Zarb GA, Albrektsson T, editors: Tissue-integrated pros-theses, Chicago, 1985, Quintessence Publishing Co.

Carmichael RP, Apse P, Zarb GA et al: Biological, microbio-logical and clinical aspects of the peri-implant mucosa. InAlbrektsson T, Zarb GA, editors: The Brånemark osseoin-tegrated implant, Chicago, 1989, Quintessence PublishingCo.

Eckert S, Parein A, Myshin HL et al: Validation of dentalimplant systems through review of literature suppliedby system manufacturers, J Prosthet Dent 77:271-279,1997.

van Steenberghe D, Quirynen M, Calberson L et al: A prospec-tive evaluation of the fate of 697 consecutive intraoral fix-tures modum Brånemark in the rehabilitation of edentulism,J Head Neck Pathol 6:53-58, 1987.

Zarb GA: The edentulous milieu. Toronto conference on osseoin-tegration in clinical dentistry, J Prosthet Dent 49:825-831,1983.

Zarb GA, Albrektsson T: The University of Toronto SymposiumProceedings from Toward Optimized Treatment Outcomesfor Dental Implants, Int J Prosth 11: 5, 1998.

Zarb GA, Schmitt A: The longitudinal clinical effectiveness ofosseointegrated implants: the Toronto study. Part I: surgicalresults, J Prosthet Dent 63:451-457, 1990a.

Zarb GA, Schmitt A: The longitudinal clinical effectiveness ofosseointegrated dental implants: the Toronto study. Part II:the prosthetic results, J Prosthet Dent 64:53-61, 1990b.


C H A P T E R 26The Science of OsseointegrationTomas Albrektsson, Ann Wennerberg

489

Osseointegration, or predictable long-term anchor-age of tooth root analogues in bone, is defined as“a time-dependent healing process whereby clini-cally asymptomatic rigid fixation of alloplasticmaterials is achieved, and maintained, in bone dur-ing functional loading” (Zarb and Albrektsson,1991). Such stable bone implants have an interfacethat consists mainly of bone tissue. This attachmentmechanism differs from the one retaining the natu-ral dentition because teeth are anchored to theirsurrounding bone by means of a highly differenti-ated connective tissue attachment with orderedfibers: the periodontal ligament. To this day, nobodyhas succeeded in creating and maintaining a replicaof a periodontal ligament around an implanted allo-plastic tooth root. In fact, past implant efforts endedup anchored in poorly differentiated soft tissues,with unpredictable clinical results. Consequently,typical 5-year survival figures were in the order of50%. This predicament provided the backdrop forthe breakthrough introduction of osseointegratedoral implants in the early 1980s. It became possibleto insert oral implants with a favorable predictableoutcome, for example, a success rate of more than90% over a follow-up of 5 years in the anteriorregion of the mandible. At the beginning of the1980s, oral implants were prescribed in small num-bers and rarely in university clinics. Today, the sit-uation is quite different, and the science andclinical epidemiology underscoring osseointe-grated implants are an integral part of most univer-sity curricula. The current popular notion that everycommercially available osseointegrated implantsystem will result in a success rate of more than90% is, however, misconceived. In the absence of

scientific evidence, there is a serious risk that somecommercially available systems will yield long-term failure as a likely treatment outcome becauseof adverse reactions to untested implant materials,designs, surfaces, or diverse therapeutic prescrip-tions. Furthermore, secondary failures have alsobeen reported to occur in previously osseointe-grated implants.

Considered in this chapter is the unique self-repairing ability of the surgically prepared bonyinterface, which, if not unduly disturbed, will remodelsufficiently to carry clinical loads. The specific natureof the osseointegrated interface and its bondingimplications are also discussed to provide informa-tion about how the osseointegrated interface is sus-tained or threatened.

OSSEOINTEGRATED INTERFACEIn the past, direct contact (without interposed softtissue layers) between bone and metallic implantswas regarded as impossible to achieve. The operat-ing notion was that a soft tissue interface wasinevitable, which in turn implied that the interfacewas of maximal strength at the time of surgery andthereafter gradually lost holding power. Experimentalstudies performed at our laboratories by the late1960s indicated that this notion was not necessarilycorrect, even if the methodological shortcomings ofthose days did not allow for definite evidence ofdirect contact between bone and implant. In the1980s, when the bone and implant specimen cut-ting and grinding techniques were developed at thelaboratories of Karl Donath in Germany, it was firstpossible to clearly demonstrate that metallic

implants could be anchored in bone without a sep-arating soft tissue interface (Figure 26-1). Subsequentinvestigations further demonstrated that the bone tometal interface did not achieve ultimate strength atthe time of insertion. In fact, the specific interfacialresponse between host bone and commercially pure(cp) titanium interface developed a stronger attach-ment with time because of increasing bone forma-tion. After 1 year or longer, depending on theimplantation site, full strength is developed overthe interface. The unique capacity of bone toremodel in accordance with imposed functionalloads appears to be a time-dependent procedure,but the end result is a very strong interface if theimplant is not overloaded during its incorporationor interfacial organization. If overloading occurs,this process is compromised, and a poorly differen-

tiated interface will result with ensuing implantloosening.

Knowledge of such basic interfacial reactionsguides dentists’ clinical decisions. If, for example,an implant is inserted in a previously irradiatedmaxillary bone bed of poor bone quality and quan-tity, unloaded periods up to a year or more may benecessary for the remodeling response to result in a“full strength” interface. This situation is in greatcontrast to oral implants with an inherently com-promised anchorage, which constantly run the riskof overload and failure, even if relatively minorforces act over their interface (Figure 26-2). If suchsoft tissue–anchored implants function at all, theydo so within a narrow range of loading.

The bond acting over an osseointegrated implantis probably a biomechanical one (Brånemark, Zarb,Albrektsson, 1985). This means that bone will growinto surface irregularities of the implant with aresultant three-dimensional stabilization. Designcharacteristics, such as implant threads, representsurface enlargements in the macroscale. Completebone ingrowth may occur in such macroscopic sur-face enlargements, provided that a minimum of100 μm of space is available. However, calcifiedbone ground substance may invade pores in the 1- to10-μm of size, and some investigators have evensuggested, albeit without proper experimental evi-dence, that nanometer size defects in the implant


Figure 26-1 A thread of a screw-type implantdemonstrates good bone-to-implant contact. Theimplant was stable in its bed and presumablyosseointegrated.

Figure 26-2 Portion of a blade vent implant,surrounded by soft tissue with some inflammation.The implant was mobile, had for years caused pain,and was removed for this reason.

surface may be important for proper load carrying(Figure 26-3). Some investigators have suggestedthat strong chemical bonds may develop betweenbone and certain ceramic implant materials andsuggested such implants to be “biointegrated.”However, there is no conclusive evidence of suchchemical bonds, even if they remain theoreticallypossible. The available evidence for chemical bondsis represented by electron microscopic photographs

of tissue coalescence with the implant or an other-wise unexplainable interfacial attachment strength.

Oxidized (anodized) implants have likewisebeen suggested as being capable of bioactivity (i.e.,establishing a chemical bond between foreignmaterial and host tissues). Sul (2002) has recentlydemonstrated a very strong bone reaction to certainanodized implants with surface-embedded calciumions. After implantation, calcium cations will move

Chapter 26 The Science of Osseointegration 491

100 mm; limitfor completebone ingrowth

mm irregularities;bone ground substance incontact with implant surface.

nm irregularities;of unknown significance

Figure 26-3 Bone tissue including ground substance and cellular components will needpores of a minimal size of 100 μm for ingrowth. Calcified ground substance of bone respondsdifferently to irregularities in the micrometer size that are important for the strength of theosseointegrated response. Implant irregularities in the micrometer range are, to date, ofundetermined significance for osseointegration.

from the implant surface toward the extracellularbody fluid. Electrostatic ion bonding of calciumions with polyanionic molecules of bone matrixproteins will follow. The calcium cations will stim-ulate particular surface receptors and trigger fur-ther recruitment of osteoprogenitor cells andosteoblasts through calcium-signaling pathways.Certain anodized implants show a uniquely strongbone reaction that cannot be explained by their sur-face roughness alone. However interesting theseimplants are, it must be observed that publishedclinical scrutiny of such implants is limited to a fol-low-up period of about 2 years.

FACTORS THAT DETERMINE SUCCESSAND FAILURE OF OSSEOINTEGRATEDIMPLANTSCompelling evidence confirms that a soft tissueinterface leads to unpredictable clinical results incontrast to a bone to implant interface. However, itdoes not necessarily imply that the osseointegratedimplant will always remain successful. There aresecondary reasons for failure of osseointegratedimplants, with overload and infection the mostcommonly cited. The overload theory reconcilesthe notion of a primary compromised osseointegra-tion response with the adverse effects of subse-quent adverse loading. It also recognizes thepotential for adverse loading per se to compromisea favorable osseointegrated response. In the infec-tion theory, the osseointegrated interface has thesame vulnerability to periodontal pathogens thatthe periodontal ligament may have. It appears to bea popular theory among some periodontists but isnot subscribed to by us. Whatever the final reasonfor failure, there is a range of implant- and implan-tation-related factors that may cause long-term fail-ure. Such compromising factors may be the reasonfor progressive bone resorption that, in turn, makesimplants vulnerable to overload. The starting pointin failure may be poor implant biocompatibilitywith materials that corrode in the body, resulting inleaked-out ions that may secondarily disturb thesurrounding bone. Unsuitable implant designs maylead to a relative lack of implant stability, resultingin micromovements, resultant bone saucerization,and subsequent implant loss (Figure 26-4). Implant

surface topography may be too smooth, whichresults in primary failures, or too rough, which alsoprovide a potential risk of adverse bone reactionsand secondary loss of integration. A compromisedimplant bed (e.g., poor quality or irradiated hostbone) may demonstrate a disturbed bone remodel-ing response, leading to increasing failure rateswith time. Improper surgical technique is mostlikely the cause of primary failures, whereas dis-turbed loading conditions may result in secondaryfailures also. These six parameters were firstdescribed more than 20 years ago and remain themost relevant ingredients of the successful osseoin-tegration paradigm (Albrektsson et al., 1981).

Implant Biocompatibility

The most commonly used material for oral implantsis cp titanium. It has been proven to be the most bio-compatible in animal experiments (Sennerby, 1991),supporting the evidence for excellent long-termclinical function with cp titanium devices. Anothermaterial used for oral implants, titanium-6aluminum-


Figure 26-4 A hollow cylindrical implant designthat may lead to severe bone resorption.

4vanadium (Ti-6Al-4V) alloy, exhibits in vitro andsoft tissue reactions very similar to those reported tocp titanium. However, the development of a bonyinterface is retarded with Ti-6Al-4V implants com-pared with the situation for cp titanium. In compara-tive animal investigations at 3, 6, and 12 months,there were significantly stronger bone reactions tothe cp titanium than to the aluminum-vanadium alloy.The reason for this retarded bone formation aroundthe alloy has been suggested to depend on leaked-outaluminum ions that compete with calcium duringthe early stage of calcification and thereby causelocal osteomalacia (Johansson, 1991). Whether theseobserved differences in early bone responsebetween cp titanium and Ti-6Al-4V are of an exclu-sive academic nature or are clinically significant isdifficult to tell. However, at least in compromisedbone beds (e.g., maxillary bone, which hasunfavorable bone quality and quantity) where oneneeds as much bone support as possible for clini-cal success, cp titanium appears to be the safestalternative.

Hydroxyapatite (HA), one type of calciumphosphate ceramic material, was originally tried asa solid material for use as an oral implant.However, because of the brittle nature of HA andother ceramics, such as aluminum oxides, fracturesoccur too often for these materials to be suitable asload-bearing devices in their solid form. HA is par-ticularly interesting because there is clear docu-mentation that this specific ceramic results in amore rapid bone response than seen with cp tita-nium. Unfortunately, such findings from short-term animal experiments alone were regarded assufficient evidence for introduction of HA-coatedoral implants in the mid-1980s. Long-term resultswith HA-coated implants have been significantlyinferior to those cited for cp titanium implants, andsome clinicians have incriminated the HA materialfor the poor clinical outcome. However, one cannotexclude factors other than the HA material for thedisappointing clinical outcome, such as the pre-ferred cylindrical implant design. Nevertheless, itis clearly unacceptable to base clinical introductionof a new type of implant on results of short-termanimal experiments alone. Gottlander (1994) stud-ied short- and long-term reactions to HA-coatedimplants in animal models and confirmed the pos-itive short-term reactions reported by other investi-

gators. However, in long-term (6 months) animalexperiments, the control cp titanium implants had50% to 75% more interfacial bone than the HA-coated implants, which was possibly dependent onHA coat loosening, leading to macrophage activa-tion and bone resorption. It is, in fact, quite possi-ble that HA in forms other than plasma-sprayedcoats may show more advantageous tissue reac-tions than the hitherto investigated types of HA-coated implants. With techniques other than plasmaspraying for coating metals, it could be possible touse much thinner coats and thereby presumablyavoid the adverse reactions seen with the thickerplasma-sprayed coatings. Consequently, HA andother calcium phosphates remain interesting mate-rials that should be promising further.

Implant Design

The vast majority of commercially availableimplants claiming osseointegration status are cylin-drical in shape. Their design may be threaded orelse lack similar microscopic retentive/stabilizationaspects. Such implants, HA coated or not, havedemonstrated primary osseointegration and, inmany cases, quite adequate survival at 5 years.Unfortunately, the problem is that no such designhas ever been reported to maintain surrounding sta-ble bone levels. Reports indicate a continuing bonesaucerization of 1.5 mm during the first year andabout 0.5 mm annually thereafter, with even a ten-dency of an increasing rate of resorption in the fewreports of such implants that run over more than 5years of follow-up (Albrektsson, 1993). This accu-mulated bone loss may not be dramatic at 5 yearsbut may pose a serious problem thereafter. Someinvestigators explain the lack of a bone steady stateby overload due to micromovements of the cylindri-cal designs, whereas others incriminate an inflam-mation/infection caused particularly by the veryrough surfaces typical for these types of implants.In contrast, threaded oral implants have demon-strated maintenance of a clear steady state boneheight after the first year of function (Figure 26-5).

Implant Surface

The surface may be of importance based on itsquantitative or qualitative changes. Quantitative


changes may be exemplified by surface topograph-ical alterations. Qualitative changes refer to newpotentially bioactive surfaces best exemplified byoxidized implants or surfaces doped with poten-tially active substances. Today, new clinicalimplants are marketed that are either quantitativelyor qualitatively surface altered or that are even acombination of the two.

Surface roughness is an implant-related propertythat has been used extensively in marketing diverseoral implant systems. Because different machiningprocesses result in different surface topographies,several implant manufacturers have machinedimplants with a turning or milling process, which isa production method that has been the gold standardfor many years.

In a series of experimental studies performed inrabbits, as well as in a few human experiments,

moderately rough implants developed the best bonefixation as described by peak removal torque andbone-to-implant contact (Wennerberg, 1996).“Moderately rough” surfaces were produced byblasting to an average height deviation (roughnessparameter Sa) of 1.5 μm, an average distancebetween the individual irregularities of 11.1 μm(Sex) and a developed surface area ratio of 1.5 μm(Sdr) (Figure 26-6), and were positively comparedwith smoother (turned and blasted) as well asrougher-blasted implant surfaces. Very smooth sur-faces (Sa values below 0.2 μm), which are in factonly used experimentally for abutment and anchor-age studies, will often be surrounded by a soft tis-sue interface indicative of imminent failure. Thereasons as to why rough surfaces (Sa values aroundand above 2.0 μm) demonstrate less firm bone fix-ation when compared with less rough surfaces still


Figure 26-5 Soft tissue penetration (A) and bone tissue–anchored portion (B) of apostmortem preparation of a threaded implant design with excellent clinical documentation.There are no adverse reactions to the implant seen in the soft or hard tissue.

BA

need to be investigated (Figure 26-7). The concernswith any surface roughening involve an increasedrisk of corrosion. However, current knowledgeabout such increased corrosion appears to be onlya theoretical and not a practical problem.

In this context it is worth emphasizing that acareful topographical characterization is essentialfor a reliable interpretation of the role of implant sur-face roughness for bone incorporation (Wennerbergand Albrektsson, 2000). There is a need for equip-ment that can be used to measure arbitrary designsand different surfaces. For example, only someoptical instruments such as confocal profilometry

amd interferometry can be recommended forthreaded implants at this time.

In recent experiments researchers have investi-gated the possibility of doping surfaces with differ-ent kinds of bone-stimulating factors. Suchdopings can be done with implants of any surfaceroughness. A number of these bone-stimulatingfactors, growth factors, are present in our bodiesand serve as important stimuli for the initiation ofhealing processes. However, external administra-tion of growth factors may not necessarily improvethe healing situation. We have doped implants withbone morphogenetic proteins (BMPs) and othergrowth factors and found no influence on the boneresponse (Franke Stenport, 2002). One possibleexplanation of this lack of a positive influence ofgrowth factors may be the fact that we only triedthem on regularly placed implants (i.e., a kind ofpress fit healing situation). However, one cannotexclude a positive influence of external administra-tion of growth factors in gap healing cases, such asa tooth socket.

A rapidly growing number of publicationsunderscore the clinical popularity of certain oxi-dized implants, and these implants may showstrong bone responses quite independently of theirsurface roughness (Sul, 2002). However, othertypes of oxidized implants depend mainly on theirsurface roughness (Sul, 2002). In fact, oxidizedimplants are manufactured in galvanic elementsetups (thus the term anodized), and the usedelectrolyte will influence subsequent tissue res-ponses. The clinical use of oxidized oral implantsstarted some 10 years ago, but long-term out-come data are still lacking (for review see Sul,2002).

In essence, it is still unknown how much bonecontact is needed for an implant to be successful.Consequently, the clinical relevance of differentsurface (roughened and/or anodized) implantscan only be verified in controlled clinical studies.However promising these surface alterations are,to date, there is in most cases a lack of support-ive data from such studies to verify any clinicalsuperiority of them. In fact, so far, only one sur-face roughened system has been positively docu-mented in controlled, randomized clinical studies(Gotfredsen and Karlsson, 2001; Engquist et al.2002).


75 μm blasted,flank

Figure 26-6 A blasted surface with a roughnesscorresponding to the experimental ideal of 1.5 μm.

Summary of thesis

Bone tissue response

Roughness(Sa)0.5 1.1 1.5 2.0 2.5

Figure 26-7 Experimentally the strongest boneresponse has a surface roughness of about 1.5 μm (Sa).

Implant Bed

A healthy implant host site is required. Patientcharacteristics, such as age, and history of the pro-posed host site(s), such as previous irradiation, willaffect the outcome of the implantation procedure. Italso is believed that a history of smoking mayaffect the healing response in osseointegration.

Old age per se does not cause poorer implantresults. However, extreme young age is a relativecontraindication to the insertion of implants. Thegeneral recommendation is to await completion ofgrowth before inserting oral implants in youngindividuals. In selected cases, where strong psy-chological motivation is present, oral implants maybe inserted in children, but then preferably only inthe anterior part of the jaw and in combination withoverdenture therapy. In selected patients, bone-anchored hearing aids may even be attached toimplants when the child is only 2 or 3 years old.The motivation behind treating such young chil-dren is to avoid the potential social handicap ofsevere hearing impairment that cannot be treated inany other way. In the case of facial deformities, inser-tion of skin-penetrating, bone-anchored implantsusually is delayed until the child has reached puberty.

Smoking has been reported to yield signifi-cantly lower success rates with oral implants. Themechanism behind this lowered success is unknown,but vasoconstriction may play a role. Continuingsubstance abuse also may be a contraindication forimplant treatment.

Previous irradiation is a relative contraindica-tion for implant treatment (Jacobsson, 1985). Afterimplant therapy is decided, patients treated withirradiation should be transferred to special clinicswith sufficient experience with such patients. A1-year delay after irradiation before insertingimplants is recommended. Expected success ratesare about 10% lower than for nonirradiatedpatients. Hyperbaric oxygen treatment in divers’chambers has been shown to improve the outcomein at least one published 5-year clinical follow-upstudy. If, on the other hand, patients have implantsalready in situ and osseointegrated when the needarises for therapeutic irradiation, removal of theimplants before irradiation is not recommended.There is experimental evidence that osseointegratedoral implants will remain stable in bone despite irra-diation, whereas implants that are inserted immedi-

ately before irradiation will show a high failurerate.

Surgical Technique

Minimal tissue violence at surgery is essential forproper osseointegration. This objective depends oncontinuous and careful cooling while surgicaldrilling is performed at low rotatory rates, with sharpinstruments and the use of a graded series of drills.Proper drill geometry is important, as is intermittentdrilling, if the bone is of a very dense structure.The insertion torque should be of a moderate levelbecause strong insertion torques may result in stressconcentrations around the threads of a screw-typeimplant, with subsequent bone resorption.

Recent publications suggest the need to expandthe surgical parameter to also include surgical skill.It has been noted that individual surgeons’ successrecords may vary in both oral and orthopedicimplant placement. Furthermore, at least two surgi-cal reports on outcomes in poor bone quality revealthat technical excellence combined with a modi-fied surgical technique will yield predictably favor-able long-term outcomes. Both authors of thesereports used machine-turned implants, which weretherefore neither surface roughened or oxidized(Albrektsson, 2001)

Loading Conditions

The original recommendation to achieve osseointe-gration is still valid: a two-stage implant insertion.The implant is first inserted in the bone, and thenthe soft tissues are sutured back so that the implantwill be incorporated in bone under protected con-ditions. At a second surgical procedure (minimally3 to 6 months later), the buried implant is exposedand connected to the oral cavity by means of atransepithelial abutment. This procedure guaran-tees that the implant is well protected during itsincorporation in bone when the osseous interfacehas not been established properly, as evidencedfrom experimental and clinical studies. Clinical tri-als with various implant systems have now con-firmed the possibility of immediate functional(direct) loading protocols, particularly in themandible between the mental foramina. However,great caution is recommended with such an imme-


diate loading protocol in the maxilla, particularly ifthe bone is judged to be of a poor quality.Furthermore, such loading puts a special emphasison the skills of the surgeon, which is why we rec-ommend newly trained surgeons to only use a two-stage operation. A promising approach for thosewho prefer a one-stage surgical protocol in combi-nation with direct or rapid loading is to use reso-nance frequency analysis in an effort todifferentiate potentially mobile implants from sta-ble ones.

SUMMARYIt is important to observe that new biomaterials arein need of careful physical and engineering investi-gations to clarify if they are suitable for implanta-tion. In vitro studies may provide importantinformation, but one must remember that this isrelated to the controlled laboratory environment,which differs from in vivo testing with its hormonal,blood flow, and loading influences. It is thereforenot uncommon that in vivo findings are quite dif-ferent from those obtained in vitro. Short-term andlong-term in vivo experimental studies are impera-tive before commercial clinical testing of animplant system is initiated. It is only when a bio-material is found acceptable in such studies thatclinical trials should be started. The most importantstep in the testing procedure remains the controlled,preferably prospective, clinical study that shouldspan an adequate period, which is conventionally atleast 5 years.

In the summary of current knowledge about thefactors controlling implant function in the body, itis easy to say that the scientific community hasmade a great number of important findings in thepast 25 years. However, researchers may very wellbe climbing the lower slopes of a mountain ofunknown height. Major contributions will be gath-ered in the future from prospective and controlledtreatment outcome studies in patients. The funda-

mental message in clinical epidemiology is thatefficacy without effectiveness usurps the notion ofa compelling scientific claim.

ReferencesAlbrektsson T: On long-term maintenance of the osseointe-

grated response, Aust Prosth J 7(suppl):15-24, 1993.Albrektsson T: Is surgical skill more important for clinical suc-

cess than changes in implant hardware? Clin Implant DentRelat Res 3:174-175, 2001.

Albrektsson T, Brånemark PI, Hansson H-A et al: Osseointegratedtitanium implants. Requirements for ensuring a long-lasting,direct bone anchorage in man, Acta Orthop Scand 52:155-170, 1981.

Brånemark PI, Zarb GA, Albrektsson T: Tissue integrated pros-theses: osseointegration in clinical dentistry, Chicago, 1985,Quintessence Publishing Co.

Engquist B, Åstrang P, Dahlgren S et al: Marginal bone reactionto oral implants: A prospective comparative study of astratech and Brånemark system implants, Clin Oral Impl Res13:30-37, 2002.

Franke Stenport V: On growth factors and titanium implant inte-gration in bone, PhD thesis, Biomaterials/handicap research,2002, University of Göteborg.

Gotfredsen K, Karlsson U: A prospective 5-year study of fixedpartial prostheses supported by implants with a machinedand TiO2-blasted surface, J Prosthodont 10:2-7, 2001.

Gottlander M: On hard tissue reactions to hydroxyapatite-coatedtitanium implants, PhD thesis, Biomaterials/handicapresearch, 1994, University of Göteborg.

Jacobsson M: On bone behaviour after irradiation, PhD Thesis,Biomaterials/handicap research, 1985, University of Göteborg.

Johansson C: On tissue reactions to metal implants, PhD thesis,Biomaterials/handicap research, 1991, University of Göteborg.

Sennerby L: On the bone tissue response to titanium implants,PhD thesis, Biomaterials/handicap research, 1991, Universityof Göteborg.

Sul YT: On the bone response to oxidized titanium implants, PhDthesis, Biomaterials/handicap research, 2002, University ofGöteborg.

Wennerberg A: On surface roughness and implant incorporation,PhD thesis, Biomaterials/handicap research, 1996, Universityof Göteborg.

Wennerberg A, Albrektsson T: Suggested guidelines for thetopographic evaluation of implant surfaces, Int J OralMaxillofac Implants 15:331-344, 2000.

Zarb GA, Albrektsson T: Osseointegration: a requiem for theperiodontal ligament? Int J Periodont Rest Dent 11:88-91,1991 (editorial).


C H A P T E R 27Clinical Protocol for Treatment withImplant-Supported OverdenturesGeorge A. Zarb, Regina Mericske-Stern

498

Several compelling conclusions can be drawn fromthe chapters in Part 3:

1. Treatment outcomes with complete denturesdepend on both dentist- and patient-mediatedconsiderations. The former include clinicaljudgment and technical skills, combined withimpeccable laboratory technological support.The latter are defined by systemic plus localhealth and morphological considerations,together with individual adaptive traits.

2. An adaptive denture experience is the treat-ment goal, and it is frequently achieved.However, an ongoing long-term continuumof adaptation may be unpredictable becauseof time-dependent anatomical and physio-logical changes. These include reduced sali-vary flow, compromised motor skills, severeresidual ridge reduction, and an increasedtissue vulnerability.

3. The notion of a surgical solution for patientswith maladaptive dentures by means ofenlargement of the available denture-bearingarea (sulcus-deepening procedures, or ridgeaugmentation, or both) has failed to yield pre-dictable and long-term beneficial results thatare morbidity free. Also, this solution doesnot address the needs of patients who dislikethe idea of wearing dentures.

4. The introduction of the osseointegratedimplant protocol has eclipsed traditional pre-prosthetic surgical techniques. It ushered in anew era of versatile, predictable, and virtu-ally morbidity-free implant prosthodontictreatment. Although this development hasenhanced the life quality of the treated

patients, it also escalated the costs involvedin managing the edentulous predicament. Themerits of the traditional overdenture techniquecan therefore be combined with an implantprescription for a cost-effective version ofimplant-supported prostheses.

5. Clinical experience also shows that manypatients who request implant surgerybecause of denture-wearing problems arereally in need of new optimized dentures, atleast from an objective clinical point ofview. Patients must recognize that implantsdo not compensate for technically and func-tionally inadequate dentures.

We therefore regard implant-supported prostheses asa logical outgrowth of the previously noted conclu-sions and think that they should be considered thestandard of service for most edentulous patients, par-ticularly those with maladaptive dentures. However,fiscal realities, particularly in the context of agingpopulations with fixed incomes, frequently precludethe fixed option. The overdenture choice, on theother hand, could be regarded as more financiallyaccessible and offers virtually similar advantages.

In this chapter we describe the application ofthe implant overdenture protocol as a routinemeasure for managing the edentulous predicament.

OVERDENTURES TREATMENT GOALSOverdentures supported by natural tooth roots havebeen a long-standing and integral part of treatmentplanning. However, both their short- and long-term treatment outcome can be unpredictable (seeChapter 10).

Although tooth and implant abutment attach-ment mechanisms differ, their prosthetic role isquite similar. Both can provide enhanced prosthe-ses retention and stability, and positively influenceadjacent bone levels, although periodontal diseaseand caries are clearly not risk factors for the “anky-lotic-like” osseointegrated abutment. In fact, stud-ies of mandibular overdentures retained byimplants have shown that bone height is very wellmaintained in the area where implants werelocated. It should, however, be pointed out thatresorption of the posterior residual ridge wasincreased when compared with similar sites inpatients treated with implant-supported fixed pros-theses. It therefore seems prudent to suggest thatthe younger the edentulous patient, the greater thebenefit from implant-supported fixed prostheses toreduce overall long-term residual ridge reduction.On the other hand, overdentures should be recom-mended routinely for elderly edentulous patientsbecause residual ridge reduction of their basal boneappears to be less vulnerable to residual ridgeresorption.

The fabrication of complete dentures, partic-ularly mandibular ones for elderly patients withmaladaptive dentures, is complex and difficult.Therefore a simple protocol that may be readilyapplied to all elderly patients is a prudent objec-tive. Such an approach includes the followingconsiderations:

1. There should be a reduction in the number ofprescribed implants: two in the mandible andfour in the maxilla. Although mandibulartreatment has been extraordinarily success-ful, the moderate to severely resorbed maxillais a much bigger treatment challenge.

2. Both patient and tissue stresses should beminimized with a short surgical intervention.

3. Implant abutment availability that ensuresdenture retention and stability should notcompensate for technically and functionallyinadequate dentures. Traditional and impec-cable complete denture fabrication tech-niques must be combined with the requiredsurgical protocol to optimize the technique’spotential.

4. Esthetic denture design should not be com-promised by the location of implants and

their connection to retention devices. Thereis little doubt about the greater ease withwhich esthetic objectives can be addressedand achieved when using the overdenturetechnique. This is not easy to accomplishwith the fixed prescription, more particu-larly in the maxilla, when moderate residualridge resorption has occurred.

5. The dentist should seriously consider man-aging both the patient’s surgical and prostho-dontic needs. The educational implicationsof this conviction are profound ones indeed.

INCLUSION AND EXCLUSION CRITERIAImplant treatment decisions must be made for eachpatient according to individual circumstances. Themajor inclusion criteria underscore the quasi-uni-versal patient eligibility for the method (Box 27-1).Age itself is not an exclusion criterion; however,age-related factors frequently influence treatmentplanning in elderly patients. Common problemsencountered include communication difficulties(e.g., compromised hearing and cognitive skills)with consequent lack of cooperation; the likelyneed for short appointments; special attention topresurgical measures such as general health statusand information; oral hygiene state; and home careprovision. Poor general health is often found inelderly patients with consequent deterioration inbiological health that is far beyond their chronolog-ical age. Therefore medical consultation is fre-quently required and is of course mandatory for allsystemically compromised and therefore high-risk

Chapter 27 Clinical Protocol for Treatment with Implant-Supported Overdentures 499

Inclusion Criteria for ImplantProsthodontic Treatment

Patient desire for implant treatmentSystemic health status, which permits a minor

surgical procedureSufficient bone quantity to accommodate

prescribed implant dimensionsPatient willingness and ability to maintain oral

health status

Box 27-1


patients, if any suspicion of risk or unclear infor-mation is present. The patient’s family physicianshould be routinely consulted.

As mentioned earlier, problems with the wear-ing of dentures or adaptation to new ones are mul-tifactorial, including age-related considerations.Patient selection criteria must therefore be estab-lished with respect to a broad range of local andgeneral aspects. Clinical experience supports theproposed exclusion criteria listed in Box 27-2, butalso reveals that patients with a history of cardio-vascular disease, osteoporosis, and certainendocrine disorders are all able to undergo a suc-cessful implant operation as long as their systemiccondition is not a brittle one. Surgical treatmentshould also be carried out only when the patient’shealth status allows it and when a patient feels welland is able to undergo the procedure.

PRESURGICAL EVALUATION ANDTREATMENT PLANNINGThe treatment planning protocol is identical for alledentulous patients and is a result of clinical andradiographic assessments that yield the informa-tion contained in Box 27-3. The clinical oral

assessment provides information about shape,width, and height of the residual ridges and soft tis-sue conditions. Horizontal and vertical relation-ships of the residual ridges are examined, andavailable space for the proposed implants and theplanned retention devices is assessed. Most edentu-lous patients who are treated with implants fre-quently show advanced reduction of the residualridges and absence of a wide band of attachedmucosa. This does not seem to adversely affect thehealth of the soft tissue attachment around implants,and gingiva-mucosal grafting is very rarely pre-scribed. Where necessary, additional bone mappingwith a local anesthesia syringe needle helps iden-tify the contours of the maxillary bone. This maybe useful because of the thickness of the palatalmucosa, which may disguise the shape of the ridge.This is not necessary for the mandible and isoften impossible because the height of the floor ofthe mouth does not permit easy identification of thelingual shape of the mandibular bone.

Panoramic radiographs are made to overviewrequired bone dimensions, to “scout” anatomicalstructures, to discover possible pathological find-ings, and to obtain general information on bonequality or density. The panoramic film is, however,

Exclusion Criteria for ImplantProsthodontic Treatment

Patient’s current prosthetic experience is anadaptive one

Residual ridge dimensions do not accommodatepreferred implant dimensions

Communication with patient is not possiblebecause of his or her compromised cogni-tive skills

Patient has a history of substance abuseGeneral health conditions preclude a minor

surgical interventionLocal anesthesia with a vasoconstrictor is con-

traindicatedImmunosuppressive therapy, prolonged intake of

antibiotics or corticosteroids, or brittle meta-bolic disease history

Box 27-2

Specific Objectives of TreatmentPlanning for a Patient with

Implant-Supported Overdentures

To determine the optimum location and num-ber of implants in the context of themorphological aspects of the residual ridge

To design a favorable distribution for occlusalstresses on the implants and the prostheses-bearing tissues

To avoid discrepancies among the design ofthe dentures, the implants’ location, and thedentures’ retentive devices

To ensure an optimal esthetic result andhygiene protocol

Box 27-3

not entirely reliable, and additional radiographicimaging is frequently required. In the maxilla,loosely structured trabecular or cancellous bonewithout a dense cortical layer is frequently encoun-tered. As a result, the implants are frequently self-tapped into such bone of compromised quality. Inthe mandible, dense cortical bone frequently enclosesa tightly structural cancellous structure. Templates

with metallic markers of known diameter may beused to measure the available bone height on radi-ographs and to predetermine a favorable location ofthe implants with respect to the topography of theresidual ridge and adjacent anatomical landmarks,such as the mandibular nerve or the maxillary sinus(Figure 27-1). Cephalometric radiographs in par-ticular provide information about faciolingual


Figure 27-1 Correct imaging of potential host bone sites requires a mix of radiographs,which can be rendered more accurate by using a template with metallic markers of knowndimensions (A). These markers will show up on a frontal (B) or sagittal image and allow formeasurement adjustments in bone height or width. Required sagittal views of anterioredentulous zones are provided by means of cephalometric films or, less frequently, com-puted tomograms (C).

A

C

B

dimensions, plus the lingual aspect of the residualmandibular bone and the shape of the maxillaryridge. Tomographic images are rarely used formandibular interforaminal implant placement;however, they often are needed for maxillarytreatment.

Examination of existing dentures helps the den-tist decide whether they are adequate for temporaryuse during the postsurgical healing phase. This is aroutine measure with the two-stage surgical proto-col. However, the transmucosal aspect of theBonefit-ITI implants during the healing can be aproblem because the effort to prevent inadvertentloading in patients who are unwilling to remainwithout dentures during the whole healing periodmay not be easily controlled. New or optimizeddentures can be made before surgery if stability ofold dentures cannot be achieved by minor adjust-ments. Old dentures are also examined regardingtheir esthetic merits, plus the presence of loss ofvertical dimension of occlusion.

The following two planning concerns of majorprosthodontic treatment must also be considered:

1. Number of implants prescribed and theirlocation

2. Preferred denture retention devices

The number of implants placed for overdenturesupport differs in the mandible and the maxilla andis influenced by residual jaw shape. Maxillaryoverdentures require the placement of a minimumof three to four implants, which are usually joinedwith a connecting bar. In selected patients, twoimplants are used; however, the dentist must realizethat divergent implant axes, a curved shape of theridge, and unfavorable bone quality are specificcontraindications to the placement of only twomaxillary implants. In maxillary ridges, short barsegments connecting multiple implants are sug-gested because a segmented bar is more likely tofollow the ridge without encroaching on the palatalspace (Figure 27-2). Implant length should prefer-ably be 10 mm or longer, and several implantsshould be prescribed when resorbed host bone sitespreclude placement of 10-mm or longer fixtures.

Mandibular overdentures appear to be ade-quately supported by two implants. When the ante-rior mandibular ridge shows a slight curvature or a

straight line, a bar will connect the two implants onits shortest distance and preferably parallel to thepatient’s arbitrary hinge axis (Figure 27-3, A). Theinterimplant distance should preferably exceed 12mm to provide sufficient space to accommodateretentive components. When a pronounced curva-ture of the mandibular ridge is encountered, theplacement of more than two implants is recom-mended. This arrangement will, however, virtuallyconvert prostheses support from an implant/ridgeone to a near exclusive implant support (Figure27-3, B). A shorter design of the bar segments willnot interfere with the profile of the ridge.

Patients with advanced mandibular residualridge resorption will only accommodate shorterimplant lengths, and, consequently, more than twoimplants must be placed. In such situations, threeor preferably four implants should be prescribed toachieve sufficient intraosseous support.

Guidelines for selecting retentive devices arediscussed at the end of the chapter.

SURGICAL PROCEDURE AND THEOSSEOINTEGRATION PHASEThe surgical protocol is well documented, and theaim is to place the implants into predetermined hostsites that address prosthodontic design objectives.


Figure 27-2 The maxilla’s ridge contour isreflected in a segmented bar soldered to four implantabutments. Retentive clips can engage any or all of thefive available segments, ensuring good retention,optimal prosthetic teeth placement, and nonrestrictionof tongue space.

Therefore a surgical template or guide is recom-mended to ensure optimal implant alignment andlocation, and this is facilitated by duplicating theprevious denture and trimming it as needed. Thepatient’s informed consent is obtained, and appro-priate premedication is prescribed. The operation iscarried out as atraumatically as possible, with thepatient under local anesthesia. Postoperative phaseis almost always uneventful and is ensured bymeans of standard analgesia medication plus use ofice packs and chlorhexidine mouth rinses. After 7 to10 days, depending on the wound healing process,the sutures are removed, and the dentures are provi-sionally refitted with a tissue conditioner. The one-stage implants should also be protected fromcontact with the relined denture base, and thereforethe dentures are relieved overlying the implants’location. The soft reliner must be changed at regu-lar intervals, and patients are instructed to removetheir dentures while sleeping to avoid trauma to thehealing sites. Patients also are instructed about care-ful hygienic procedures with small soft brushes andthe use of a mouthwash containing chlorhexidine tofacilitate plaque removal.

A healing phase of 3 to 4 months for mandibu-lar implants and 6 months for maxillary implants isusually observed with a longer interval prescribedfor compromised bone quality sites. Publishedresearch suggests that the healing process is a veryindividual response that may be accelerated ordelayed in different sites in different patients. Thedentist may be tempted to shorten the healing inter-val, but this approach may be an imprudent one,and we strongly recommend the previously men-tioned guidelines.

PROSTHODONTIC PROTOCOLImplant-supported and implant-retained completedentures resemble the clinical situation of overden-tures supported and retained by specially preparednatural tooth roots. Despite a lack of a periodontalligament and its periodontal receptors, the anky-lotic-like osseointegrated attachment appears toprovide adequate sensorimotor feedback systemthrough receptors in the oral mucosa, bone, tem-poromandibular joint, and muscle spindles. As aresult, coordinated chewing activity in edentulous


Figure 27-3 A, Mandibular overdentures have been shown to perform well whensupported by only two implants. These prostheses are implant/ridge supported and can be sodesigned when implants are placed as far apart as possible between the mental foramina.Use of a bar that allows for rotation of the prosthesis around the interimplant axis can beachieved if anterior residual ridge shape is parallel to an arbitrarily determined hinge axisthat is only slightly curved. B, Residual ridge curvature (as opposed to the “flat” one in partA) usually necessitates placement of three or more implants to preclude the splinting bar’sencroachment on tongue space. However, a trade-off occurs if the bar’s segments follow theridge contour; the prosthesis is then virtually entirely implant supported. The same effectprobably results even if alternative retentive mechanisms are prescribed.

A B

and dentate subjects appears to be quite similar. Itseems that the masticatory stability of implant-sup-ported overdentures during function compensatesfor the absence of a periodontal ligament. Patientswith implants report high-functional satisfactionand a sensation that they have their natural teeth.

Denture Design

The design and fabrication of implant-supportedoverdentures follow the previously described prin-ciples of fabricating complete dentures as describedin Part 3. Stability and retention of complete den-tures are enhanced by provision of a well-fittingdenture base and properly extended flanges. Wheredesired by the patient, the denture base may beslightly reduced in its extensions because of theoverdenture’s relative immobility. This is usuallythe case with patients who object to prosthesisbulk. The replacement of lost tissue and the restora-tion of facial support are provided by the denturebase and the established vertical dimension ofocclusion. These also become very important forpatients with intraoral defects resulting from max-illofacial deficits that are caused by congen-tial anomalies, trauma, or oncological surgicalresections.

The arrangement of anterior teeth follows basicguidelines as determined by facial esthetic needs,whereas the arrangement of posterior teeth con-tributes to retention and stability of the dentures.Individual patient preferences frequently can befulfilled, but anterior teeth positions should notinterfere with the circumoral musculature. It is pre-sumed that a stable occlusion is likely to contributeto the protection of implants from overloading.

Clinical and Laboratory Procedures

Prosthodontic treatment planning will result inimplant- and tissue-supported overdentures,although a distribution of certain implant locationsmay lead to exclusive implant abutment support.The impression technique is a crucial first step.The preliminary impression is made with alginatein metal stock trays. The custom acrylic resin traysrequire openings for accommodating the transfercopings, which are placed on the implants. Thefinal impression is made, it is removed from the

mouth, and laboratory implant analogues are con-nected to the transfer copings. The master cast ispoured with the analogues in place. The subsequentclinical/laboratory protocol is identical to that usedfor complete denture fabrication. An exception isthe inclusion of the selected retentive elements inthe fitting surface of the prostheses. For example,whenever a clip bar mechanism is used, the bar (1)follows the shape of the ridge, (2) respects the posi-tion of the prosthetic teeth, and (3) provides accessfor oral hygiene procedures. The bar is cast, sol-dered to the prosthetic copings, and tried in themouth. The same orientation index is used to cast ametal framework, should this be indicated, afterfinal soldering of the bar. The female parts of barclip assembly are fixed directly in the denture baseduring the laboratory processing procedures(Figure 27-4). Some clinicians prefer to use a metalframework embedded in the acrylic resin denturebase. In this case the female components shouldnot be soldered to the metal framework. They areretained in the denture base with acrylic resin tofacilitate future changes or repairs. Step-by-stepclinical and laboratory procedures for fabricatingthe implant-supported overdenture are shown inBox 27-4.

Guidelines for Selecting Retentive/AnchorageDevices

Several methods for securing retention and stabil-ity of overdentures are available. They are arguablyequally efficient. However, certain considerationsinfluence the choice of retaining element. Theseinclude: (1) number of supporting implants andtheir distribution over the ridge, (2) length of thebar segments, (3) type and size of the single attach-ment or bars, (4) number of female retainers, and(5) degree of reduction of the residual ridge. Muchempirical discussion exists regarding the benefitsof different retentive mechanisms (resilient versusrigid) (Box 27-5). A resilient retention mechanismis widely recommended for anchorage of overden-tures to implants. The assumption is that this willprotect implants from overload. However, recentresults of comparative in vivo measurements ofpatients with two mandibular implants support-ing an overdenture do not reveal a preference ofone type of anchorage device or retention



Figure 27-4 The acrylic resin prosthesis may (A) or may not (B) be reinforced with aStellite alloy framework; this appears to be a subjective decision, although it clearly haseconomic implications. The retentive clips (sometimes referred to as the female parts of theclip bar) are processed and “fixed” in the acrylic resin denture base. This will make any futureclip replacement requirements a relatively easy procedure.

A B

Step-by-Step Prosthodontic Procedures

One● Preliminary impression with irreversible

hydrocolloid for custom tray fabricationLaboratory: custom trays with openings over

implants’ location

Two● Abutment components selected (may

include additional prosthetic copings)● Mounting of transfer copings● Full arch or two-stage impression with

custom trayLaboratory: master cast with implant ana-

logues, wax occlusion rims

Three● Jaw relation records● Tooth selectionLaboratory: mounting the casts on the articu-

lator, preliminary tooth setup

Four● Verification of occlusal records● Esthetic and functional assessment of

tooth setup with the patient

● Indexing of setups to allow for optimal bardesign

Laboratory: corrections as determined at try-inappointment; bar fabrication

Five● Complete try-in, obtain consent of the

patient● Try-in of bar assembly, correction of cast-

ing if a passive fit is not obtainedLaboratory: final corrections, preparation for

processing the denture: assembly ofclip/bar components

Processing the denture, occlusal equilibrationon articulator to rectify processing errors

Six● Delivery of dentures to the patient● Instruction about handling of the dentures● Cleaning instructions for implants, reten-

tion devices, dentures● Information about and enrollment in the

maintenance care program● Baseline radiographs for comparative

monitoring purposes (optional)

Box 27-4


mechanism over another. However, overdenturessupported by “unjoined” implants are also reportedto be successful.

A popular belief among dentists is that barsmay contribute to load sharing. The reported long-term success rate for mandibular implants is quitehigh, and slightly less so for maxillary implants.Because splinted multiple implants with a bar usuallyare prescribed for the maxilla, a horseshoe design ispossible (Figure 27-5; also see Figure 27-2). As aconsequence, this type of maxillary overdenturewill resemble a fixed prosthesis with regard to sta-bility and function. Therefore it is understandablethat this may not be regarded as a realistic and eco-nomic alternative to a tooth-supported overdentureor complete denture, as is the case with mandibularoverdentures supported by only two implants.

Indications for Single Attachments The use ofretentive anchors or magnets is the easiest andprobably the most cost-effective way to retain den-tures by means of implants. This is frequently rec-ommended when implants are placed underneath apatient’s presently worn dentures, that is, ones thatdo not have to be remade. Denture-wearing prob-lems of geriatric patients with impaired manualdexterity may be readily resolved with such reten-tion systems (Figure 27-6). They also may be used

for temporary use after the postsurgical healingphase and before the insertion of technically time-consuming prosthetic reconstructions. It should bepointed out that the belief that spherical attach-ments may be used to compensate for unfavorableand nonparallel alignment of the implants appearsto be a mistaken one.

Indications for Bars Patients frequently complainabout adequate lack of denture retention when singleattachments are used—thus our preference for rou-tine use of cast bars. Short distal extensions fromrigid bars may additionally contribute to stabiliza-tion and prevent horizontal shifting of the dentures.Bars are routinely recommended for maxillary over-dentures, atrophic residual ridges in the mandible,and mandibles with more than two implants due topronounced ridge curvature. When intraoral defectsare present, rigid bars are preferred in an effort tominimize overload on adjacent vulnerable softtissues (Figure 27-7).

MAINTENANCE CAREThe objective of regular recalls for all patients withoverdentures is to maintain the health of the oral

Figure 27-5 A horseshoe-shaped maxillaryprosthesis is made out of a combination of prostheticteeth, Stellite alloy (for strength with minimal bulk),and pink acrylic resin as a substitute for soft tissuereduction and for esthetic support. The undersurface ofthis prosthesis includes five retentive clips that engagethe bar segments shown in Figure 29-3. Note that theclips are retained in the acrylic resin segment tofacilitate any future repair needs.

Some Anchorage Devices Used forOverdentures

Single Elements● Single retentive anchors (stress-breaking

mechanism)● Single magnet anchors (stress-breaking

mechanism)● Individually cast telescopic copings (rigid

mechanism)

Splinted● U-shaped bar (rigid)● Round clip bar (stress-breaking mechanism)● Egg-shaped Dolder bar (stress-breaking mech-

anism)

Box 27-5

tissues, particularly the periimplant tissues, and tocheck the denture for ongoing fit, stability, andocclusion. The dental literature is full of scholarlydiscussions regarding the merits of periodontalparameters and diagnostic methods borrowed fromperiodontology. Quite interestingly, they appear tobe of limited use in osseointegration, at least withour two preferred implant systems. However, main-

tenance of optimal care to prevent and help diagnosepotential problems has proven to be advantageous.Most patients with overdentures who are in specialneed of oral health care are elderly. These patientsfrequently possess impaired manual skills andreduced visual capacity. They are likely to have dif-ficulties in following cleaning instructions andtherefore rely on their care providers and their pro-fessional assistance. They have to be taught indi-vidual hygienic procedures that best correspond totheir abilities. The wearing of overdentures cer-tainly enhances plaque accumulation and risk ofinflammatory soft tissue reactions, but it is not asominous a concern where successfully osseointe-grated implant abutments are used. Periimplant tis-sues do not appear to be as vulnerable to plaqueby-products as periodontal tissues are, yet a varietyof nuisance type gingival responses may developand should of course be avoided. When comparedwith an implant-supported fixed prosthesis, thecleaning of implants and prostheses is certainlyeasier with removable dentures (Figure 27-8).

Growth of hyperplastic soft tissue aroundimplants and particularly underneath the bars hasbeen observed and recorded. It usually is rectifiedby a program of vigorous massage and most infre-quently by surgical trimming of the excess tissue.The patient’s maintenance program also includescheckup and adjustment appointments. The latter


Figure 27-6 A large number of attachment devices have been commercially produced inan attempt to enhance and diversify claims for optimal implant/prosthesis retention. Severalof these methods are backed by strong anecdotal support. They include spherical Dalla Bonaattachments (A) and magnets (B).

A B

Figure 27-7 A right mandibular resectionunderscored the need for a stable prosthesis, otherwiseprecluded by resultant compromised tissues availablefor retention and stability of a complete denture. Theprescription of two implants connected by a rigid barmet this patient’s needs for comfortable prosthesisfunction.

include an assessment of the fit of the denture baseto determine the need for relining; an occlusalassessment to establish need for intraoral or“unmounted” occlusal adjustment; a check offemale attachment components (loose, broken,lost, or need for activation); and wear and tear ofany parts of abutment or retentive elements fromcontact with the denture base.

The precise response to occlusal transmissionof loads to the implants that might lead to boneresorption or loss of osseointegration is unre-solved. Research provides evidence that inade-quately fitting superstructures (even when notrecognized visually) may induce cumulative andadverse stresses on implants, with a risk of adversebone changes. Therefore a precise, passive fit of

denture bases, bars, and attachments is a prerequi-site for long-lasting health of the bone surroundingand supporting the implants.

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effect of intra-oral implant rehabilitation on health-relatedquality of life in a randomized controlled clinical trail,J Dent Res 79:1659-1663, 2000.

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Figure 27-8 Popular adjuncts for ensuring continued soft tissue health including brushingof circumimplant gingival tissue (A), deposit-free bar components (note use of a gauzesquare) (B), and stimulation of tissues adjacent to the implants (C).

A

B C


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C H A P T E R 28Clinical Protocol: Implant-SupportedFixed ProsthesesGeorge A. Zarb, Steven E. Eckert

510

Successful osseointegration enables the dentist andthe edentulous patient to consider one of two alter-natives to the traditional complete denture experi-ence. These alternatives are an implant-supportedfixed or an overdenture prosthesis. This chapterreviews some considerations that have an impacton the clinical decision making and protocol forfixed prostheses.

PATIENT SELECTIONPatients who have been shown to benefit most sig-nificantly from osseointegration have been thosewith a maladaptive denture experience. This truismhas also led many denture adaptive patients “totrade in” their prosthesis for implant-supportedfixed replacements. Consequently, this therapeuticoption should be presented to every edentulouspatient seeking prosthodontic treatment as an alter-native option to complete dentures. Currentresearch suggests that any patient whose systemichealth does not preclude a minor oral surgicalintervention and whose proposed host bone sitescan quantitatively and qualitatively accommodatethe dimensions of the dentist’s selected implantsystem and the entailed surgical protocol, as well asafford the procedure’s expense, may be regarded asa candidate for osseointegration.

A clinical assessment identical to the protocolarticulated in this book’s early chapters is carriedout. The scrupulous clinical examination is aug-mented with diagnostic cast and previous prosthe-ses’ analysis (Box 28-1). It is then matched by athorough imaging assessment. Usually, panoramicand cephalometric films provide enough informa-

tion to enable the dentist to determine whereimplants can be located (Figure 28-1). Occasionally,additional films such as tomograms or computer-ized tomograms (CAT scans) are requested. Moresophisticated imaging techniques offer the surgeonadditional information about potential sites forimplant placement and may be beneficial in deter-mining situations that are not conducive to implantplacement unless bone grafts are placed prior to, orin conjunction with, the implants. The treatmentdecision is influenced by (1) the magnitude of resid-ual ridge resorption; (2) the relationship to keyanatomical landmarks: incisive foramen, nasal cav-ities, and maxillary sinuses in the maxilla and men-tal foramina and inferior alveolar canal in themandible; and (3) the perceived quality of the pro-posed host bone sites. A validated and predictiveclassification system for bone quality and quantitythat is tied to implant outcomes is still to be devel-oped. However, clinical experience suggests thatcompromised bone quality and quantity may havean adverse impact on treatment outcomes. Thisappears to be a somewhat more compelling concernin the maxillary edentulous arch.

PRELIMINARY PROSTHODONTICDESIGNThe decision to treat an edentulous arch with animplant-supported fixed prosthesis is influenced bythe following five crucial considerations:

1. The number of the implant abutments. Theearly, albeit compellingly documented, clin-ical successes with implant-supported fixed

Chapter 28 Clinical Protocol: Implant-Supported Fixed Prostheses 511

prostheses suggested a quasi-general for-mula: five implants placed between themental foramina to support a 10- to 12-unitfixed mandibular prosthesis. However, thisformula did not address considerations ofarch form configuration (flat versus varyingdegrees of curvature), length of implants,length of cantilevers, and specific consider-ations regarding diverse occlusal forces plusthe configuration of the implant/arch form.The same applies to treatment planning themaxilla, with the additional proviso that six

or more implants should comprise a startingpoint for a fixed design.

2. The location of the implants. Implant loca-tion is more favorable when its distributionor configuration is a curved rather than a flatone. The former allows for more occlusalunits and an optimal cantilever design. A flatimplant arch form is probably a better can-didate for an overdenture design.

3. The quality of the host sites. Clinical expe-rience suggests that loosely textured cancel-lous bone makes for a potentially vulnerableosseointegrated response. Consequently,careful identification of optimal host sitelocators is essential, particularly because theloading capacity of individual implants isyet to be determined. The previously men-tioned “formula” (five in the mandible, sixin the maxilla) was gleaned from publishedand cumulative clinical experiences, and ithas clearly yielded impressive treatment out-comes. Furthermore, current clinical wis-dom has refined the formula aided byimproved and enhanced technology, forexample, self-threading implants with anoxidized surface, plus a range of implants ofdifferent lengths. It therefore appears pru-dent to continue to use a five-mandibularimplant abutment design as a starting pointfor a fixed prosthesis. The length of the pros-thetic cantilevers will depend on anticipatedpatient occlusal activity because mostpatients exhibit different degrees of magni-tude, duration, and frequency of functionalloading. However, the profession’s currentinability to accurately predict the outcome ofimplants in radiographically determinedpoor quality bone suggests a need for con-siderable caution when selecting such sites.

4. The quantity of the host bone sites or theamount of residual ridge reduction that hasoccurred. This is rarely a consideration inthe mandible because mandibles measuringless than 10 mm in vertical height in theintermental foramina region are infre-quently encountered. It is, however, a fre-quent problem in the maxilla, wheregrafting techniques may be required if afixed prosthesis is planned. Alternative

Considerations for Systemic Localand Prosthodontic Treatment

Medical History Contraindicating Treatment● Systemic condition that precludes a minor oral

surgical procedure (e.g., brittle diabetic, blooddyscrasia, immunologically compromised)

● History of chemical dependency● History of orofacial irradiation● Certain psychiatric disorders● Heavy smoking (possibly)

Local Considerations● Size of oral opening and interarch space● Status of opposing dentition, if present (peri-

odontal health, overeruption, occlusal rela-tions)

● Quality and quantity of proposed host sites,which also requires a radiographic evaluation

● Height of smile line (circumoral activity)

Prosthetic Considerations● Possible shortcomings in appearance, occlu-

sion, and support of previous dentures. Will thepresence of implants rectify such problems?

● Relationship of prosthetic teeths’ positions tounderlying residual ridges. Will a fixed pros-thesis resolve the perceived complaintsentirely, or will excessive anterior and poste-rior cantilevering be required?

● Is the desired optimal position and supportof the circumoral tissues compatible with theproposed prosthetic teeth placement and thelocation of the implants’ support?

Box 28-1


Figure 28-1 A comprehensive radiographic survey of edentulous jaws will enable thedentist to ensure the presence of a healthy host bone site compatible with both quality andquantity considerations. More than one view is necessary if a three-dimensional assessment is tobe made (unless there is access to tomography). All three views—panoramic (A), cephalometric(B), and occlusal (C and D)—provide magnified dimensions of differing degrees. E and F are thespecific preoperative films, and G is the postoperative film of the patient in Plate 1-1.

A

B

D

FG

E

C


surgical approaches include sinus lift proce-dures and consideration of placement ofimplants in the zygoma or pterygoid plates.Although both approaches offer excitingpossibilities, there is still a lack of well-documented prospective studies to justifytheir routine prescription.

5. Amount of circumoral activity or “generos-ity” of a patient’s smile line. This considera-tion applies almost exclusively to themaxilla, where both the combination of ahigh lip line and advanced residual ridgeresorption, or conversely, virtually noresorption at all, may indicate challengingproblems. The former will require the use ofa visible labial flange to compensate for theresorbed tissues. The size and design of sucha flange may preclude easy hygiene mainte-nance and therefore contraindicate a fixedprosthesis. As a rule, patients with extensivevertical and horizontal anterior maxillarybone resorption are candidates for implant-supported overdentures and not fixed pros-theses. On the other hand, where little or noresorption is present, a high smile line is notreadily reconcilable with ideal implant loca-tion and angulation, which lends itself to anoptimal emergence profile for the prostheticteeth. In such morphological situations, theimplant abutments cannot be readily locatedin the anterior part of the maxilla, and, if fea-sible, are placed in the posterior zone.

PRESURGICAL TREATMENTThe patient is carefully counseled about the pro-posed treatment. The edentulous mouth is preparedfor the osseointegration technique by ensuring tissuehealth, for example, correction of old prostheses anduse of tissue conditioners. Soft and hard tissuelesions that may have an impact on the surgicalphase of osseointegration (e.g., hyperplastic tissue,frena, and exostoses) usually are addressed dur-ing the surgical osseointegration operation.If there is inadequate bone, surgical proceduresdesigned to generate new bone (so-called site devel-opment) may be considered. Once an appropriatesite is established a surgical template is prepared,usually with the patient’s currently worn prosthesisas a guide.

SURGICAL STAGE(S)The surgical technique is well described in thedental literature and consists of a sterile procedurein which flaps are raised and holes are carefullyand gently drilled into the selected host bone sites.The holes conform to the chosen implants’ dimen-sions and accommodate the threaded tooth rootanalogues, which are frequently self-tapped intoplace. The reflected mucoperiosteal flaps arereadapted to completely cover the implants if theyare to be submerged and unloaded during thehealing period. Note that the implants are provi-sionally sealed with a cover-screw during thisinterim healing period. This is referred to as thetwo-stage surgical procedure. Alternatively, theimplants may be fitted with a “healing abutment”and the flaps readapted around them if the one-stage surgical procedure is selected. In eithercase, the soft tissues are sutured and the tissuesleft to heal undisturbed. During the 4- to 6-monthhealing period, the designated time required forosseointegration to occur in the mandible andmaxilla, respectively, the denture is relieved liber-ally and a tissue conditioner used to refit the den-ture. When a second-stage surgery is required,transepithelial abutments of selected dimensionsare attached to the implants and the prosthodonticprocedures started.

PROSTHODONTIC PROTOCOLThe prosthodontic phase of treatment has as itsobjective the fabrication of a cast prosthesis base(metallic frame) that joins the implants togetherand provides distal cantilever extensions (Plate28-1). Artificial teeth and a soft tissue analoguecould then be processed onto the framework. Thisprocedure allows for an electively removable pros-thesis that could be screwed to the osseointegratedabutments. Other techniques have also been devel-oped to allow the use of screw- or cement-retainedmetal ceramic prostheses. The discussion of suchprostheses’ construction is best left to publicationsthat specifically discuss fabrication of implant-supported prosthesis.

The design of the prosthesis, borrowed fromboth fixed and removable prosthetic protocols,seeks to reconcile traditional principles of occlu-sion with optimal design for soft tissue health

maintenance and esthetics. The clinical protocolused comprises the following stages:

1. Impressions are made in the dentist’s mate-rial of choice (e.g., a polyether material in acustom tray). An occlusal opening providesaccess to transfer copings that are screwedto the abutments. The transfer copings arewithdrawn in the impression and filled withlaboratory analogues. The impression isthen poured in artificial stone.

2. A trial denture base stabilized with twoprosthetic copings is used to register jawrelation records. Subsequently, the samebase is used for a trial arrangement of theartificial teeth. After patient approval andconfirmation of jaw relation records, anindex of the position of the artificial teeth ismade.

3. The proposed framework is designed in thecontext of the teeth index positions and castand then surrounded by processed acrylicresin. The metallic frames are cast in a silver-palladium alloy or a Class IV gold

alloy. Alternatively, a titanium frame can beemployed. The latter technique is currentlyregarded as being particularly accurate and,moreover, lends itself to employing porcelainfor both teeth and soft tissue replacement.Framework design has gradually evolved intoa standard that reconciles principles of fixedprosthodontic frame waxing protocols with apredetermined tooth orientation.

4. The framework is tried in the mouth, andwhere an imperfect or nonpassive fit isnoted, the framework is severed. It is reassem-bled on the implants with the retainingscrews and an index and returned to thelaboratory for soldering. The soldered,reassembled framework is tried again in themouth.

5. Processing of the metallic framework andthe stock acrylic resin teeth is completedwith a commercial acrylic resin; completedenture laboratory technology is used.

6. The completed prosthesis is inserted in themouth, new jaw relation records are made,and the occlusion is refined on the articulator.


A Comparison between Presumed Advantages and Disadvantages ofthe Three Current Therapies Available for Edentulous Patients

Box 28-2

Complete Dentures● Relatively straightforward to fabricate● Virtually universal in application● Inexpensive● A preliminary option for first-time denture wearers● All the shortcomings of artificial removable pros-

theses: psychological, tissue morbidity, risk of time-dependent maladaptation

● Lifelong maintenance

Implant-Supported Fixed Prostheses● Conceptually brilliant and supported by com-

pelling research data● Limited in application● Relatively complex to undertake● Expensive● Enormous psychological and functional benefits● A “cure” for patients with maladaptive dentures

● Esthetic outcomes may be difficult and unpre-dictable

● Maintenance not always easy ● Size of occlusal table has to be reduced

Implant-Supported Overdentures● Stability, retention, and esthetic problems are

readily rectified● A “cure” for patients with maladaptive dentures

without the disadvantages of the fixed approach● Professional fees are not significantly higher than

cost of complete dentures● Maintenance requirements do not appear to be

demanding● Exhibit minor movement during function and

likely to accumulate food debris under the den-tures’ fitting surface

● Size of occlusal table can be maximized


Each patient is counseled about tissue andprosthesis care. Thereafter, a protocol forannual patient recall is followed.

SUMMARYThe availability of a fixed treatment option is aremarkable advance in prosthodontics. It is one ofdentistry’s most gratifying treatment modalities, butit demands considerable skill and judgment and ahigh degree of patient commitment and understand-ing. It also is quite expensive and comprises verystrict inclusion and exclusion criteria as gleanedfrom this chapter and Chapter 27. A comparisonbetween conventional dentures, implant-supportedfixed prostheses, and overdenture treatments willhelp put these options in perspective (Box 28-2).

BibliographyAdell L, Lekholm U, Rockler B et al: A 15-year study of

osseointegrated implants in the treatment of the edentulousjaw, Int J Oral Surg 10:387-416, 1981.

Brånemark PI, Zarb GA, Albrektsson T: Tissue integrated pros-theses: osseointegration in clinical dentistry, Chicago, 1985,Quintessence.

Brunski, JB: Avoid pitfalls of overloading and micromotion ofintraosseous implants (interview), Dent Implantol Update4:77-81, 1993.

Desjardins RP: Implants for the edentulous patient, Dent ClinNorth Am 40:195-215, 1996.

Henry PJ, Tan AE, Uzawa S: Fit discrimination of implant-supported fixed partial dentures fabricated from implantlevel impressions made at stage I surgery, J Prosthet Dent77:265-270, 1997.

Jemt T: In vivo measurements of precision of fit involvingimplant-supported prostheses in the edentulous jaw, Int JOral Maxillofac Implants 11:151-158, 1996.

Jemt T, Book K: Prosthesis misfit and marginal bone loss inedentulous implant patients, Int J Oral Maxillofac Implants11:620-625, 1996.

Krekmanov L, Kahn M, Rangert B et al: Tilting of poste-rior mandibular and maxillary implants for improved pros-thesis support, Int J Oral Maxillofac Implants 15:405-414,2000

Rangert B: Biomechanics of the Brånemark system, AustProsthodont J 9(suppl):39-48, 1995.

Rangert B, Krogh PH, Langer B et al: Bending overload andimplant fracture: a retrospective clinical analysis, Int J OralMaxillofac Implants 10:326-334, 1995.

Rangert B, Sennerby L, Meredith N et al: Design, maintenanceand biomechanical considerations in implant placement,Dent Update 24:416-420, 1997.

Skalak R: Biomechanical considerations in osseointegratedprostheses, J Prosthet Dent 49:843-848, 1983.

White GE: Osseointegrated dental technology, Chicago, 1993,Quintessence.

Zarb GA, Schmitt A: The longitudinal clinical effectiveness ofosseointegrated implants: the Toronto study. Part I: Surgicalresults, J Prosthet Dent 63:451-457, 1990a.

Zarb GA, Schmitt A: The longitudinal clinical effectiveness ofosseointegrated implants: the Toronto study. Part II: Theprosthetic results, J Prosthet Dent 64:53-61, 1990b.

Zarb GA, Schmitt A: The edentulous predicament. I. A prospec-tive study on the effectiveness of implant-supported fixedprostheses, J Am Dent Assoc 127:59-65, 1996.

C H A P T E R 29Managing Problems and ComplicationsGeorge A. Zarb, Steven E. Eckert

516

Active treatment with osseointegrated implantsusually spans a period of several months, and it ispossible that problems or complications may occurat any time during this phase of treatment. Thoughinsertion of the finished prosthesis marks the endof active treatment, follow-up maintenance andmonitoring of the prosthesis, the implants, and thehost tissue’s response must continue for the life ofthe patient (Table 29-1).

The dental implant field is inundated with avariety of techniques, designs and, of course, man-ufacturers’ claims. In looking at this broad field thedentist is often confused by the different approachesused to place and restore dental implants. Likewise,the complications that can occur with dentalimplants seem to be quite varied.

An alternative to evaluation of the differencesis to discuss the similarities among bone-anchoredimplants. All endosseous implants are placed in asurgical procedure, all must be made of a materialthat is biocompatible and possesses favorable phys-ical and mechanical properties to function as reten-tive and supporting mechanisms for dentalprostheses, and all must undergo a healing processto ensure long-term survival. Although there arevariations on surgical techniques and implant mate-rials, these differences are generally minor. Therequired implant healing interval before occlusalloading, however, can and often does show greatervariety.

Implants that are designed to heal to the jaw-bone may do so after a period of no mechanicaltrauma. This remains the classic approach used toachieve osseointegration and requires a period ofundistributed implant placement beneath the oralmucosa for 3 to 4 months in the mandible and 6months in the maxilla. At the end of that healing

period the second stage of treatment begins, duringwhich the mucosa covering the implant is surgi-cally resected and transmucosal components areconnected to the implant. This is the two-stageapproach to implant surgery. In contrast to this pro-cedure, some implants are placed in such a way asto allow an attached healing abutment to passthrough the oral mucosa at the first stage of treat-ment. Because there is no mucosa covering theimplant, there is no stage II surgery; thus thisprocess is known as a one-stage approach. In bothsituations, efforts are made to avoid functionalloading of the implant until the bone has a chanceto heal adjacent to the implant and ensure anosseointegrated response.

There is also a current and renewed enthusiasmfor the concept of immediate implant loading. Thisapproach uses a rigid connection of implantsshortly after their placement within the jaw. Suchrigid implant fixation allows the implants to beused to support a prosthesis almost immediatelyafter stage I surgery. These implants are calledimmediate load implants. In another approach,implants are placed as freestanding supportingmechanisms for provisional individual dental pros-theses. These single implants are generally not con-nected to teeth or to other implants but are used toretain provisional restorations that are placed incosmetic, but not functional load, conditions. Thisapproach is referred to as of an immediate provi-sional implant.

Although it seems that there are many differentapproaches to implant use, careful scrutiny of thedifferent procedures demonstrates a number ofsimilarities. In the one-stage, two-stage, immediateload, and immediate provisional implant approachthere is a period during which the implant must be

protected from functional loading. The first twoapproaches address this protection by avoidingforce transmission to the implant during the earlyphases of healing. The immediate load approachsplints the implants to each other thereby creating arigid body that is relatively resistant to movement.In the immediate provisional implant therapy theimplant is placed under minimal functional loadwith the assumption that this load will not displacethe implant sufficiently to interfere with bone-to-implant healing. Without bone-to-implant healingthe long-term survival of the implant is unlikely tooccur because the process of osseointegration willbe compromised or prevented. This complication,failure to achieve or maintain osseointegration, isregarded as the most crucial problem in implantdentistry.

There are numerous ways to categorize the pos-sible complications that can be encountered. Theymay be referred to as early or late, surgical orprosthodontic, biological or structural, functionalor esthetic, or hard tissue or soft tissue related. Inthis chapter, they are divided under the main head-ings of surgical or prosthodontic origin. This cate-gorization relates to the phase of treatment ratherthan the specific type of complication that isencountered. However, it must be emphasized that

complications in one area may affect the other, and,consequently, at times there is no clear differentia-tion between them.

SURGICALLY RELATED COMPLICATIONSEndosseous implant surgery can be described as aone- or a two-stage procedure. Both techniquesdemand placement of the implant within theselected host bone site with a meticulous surgicalprocedure. A two-stage implant is placed in a posi-tion that allows the oral mucosa to be closed pri-marily over the implant, whereas a one-stageimplant is one that passes through the mucosa.Both approaches require primary closure of theoral tissues in the interimplant spaces. Likewise,both techniques require a period of undisturbedhealing before the implant can be placed into func-tion.

Surgically related problems can, in turn, besubdivided into chronological order: those relatedto stage I surgery, to the osseointegration timebetween the operations, and to stage II surgery. Thesurgeon will primarily deal with these occurrences;however, it is often the dentist, having made theoriginal diagnosis and treatment plan for thepatient, who will be consulted when a problemarises. As the prescribing and referring dentist, thepatient’s closest association is with him or her. Theprescribing dentist must therefore be regarded asthat treatment plan’s architect and should be awareof the possible complications that may occur dur-ing this early phase of treatment. The dentist alsoshould be prepared to deal with the patient’s appre-hensions and concerns and to make necessaryreferrals to the surgeon.

Stage I

Any surgical procedure carries with it the risk ofbleeding, infection, swelling, and ecchymosis, andsurgery for the placement of osseointegratedimplants is no exception. A meticulous sterile sur-gical technique, accompanied with appropriateantibiotic prescription and instruction to the patientregarding hygiene and oral rinses, is the best pre-ventive measure to reduce the chances of thesesequelae. Excessive bleeding, if it occurs, is usuallynoted at the time of surgery or soon after. If

Chapter 29 Managing Problems and Complications 517

Table 29-1Possible Problems and Complications

Time Description

Stage I surgery ● Unfavorable implant position/alignment

Post–stage I surgery ● Swelling/ecchymosis● Infection● Suture remnants, wound

dehiscence● Neuropathy

Stage II surgery ● Failure to osseointegrate● Unfavorable position or angle

makes implant unusablePostprosthodontic ● Prosthodontic complications

insertion ● Soft tissue complicationsDelayed ● Delayed loss of

complications osseointegration● Component fracture● Soft tissue complication

observed, excessive bleeding is treated by the sur-geon. Swelling is often not at its peak until at leastthe second day after surgery, but the measures nec-essary to minimize it must be taken immediatelyafter the surgical procedure. These include theapplication of pressure packs in the form of rolledsterile gauze and the use of cold compresses or icepacks. A transient and therefore insignificantecchymosis is also delayed in its appearance and ismost likely to occur in patients who have a historyof bruising easily. Good preparation and tutoring ofthe patient will make it easier for him or her toaccept this temporary but unfortunate estheticappearance.

Infection, if it does occur, may be evidentwithin a few days of the surgical insertion of theimplants, or it may not be manifested until a fewweeks or even a few months afterward. If it is soonafter stage I surgery, it will most probably be notedby the surgeon first and treated with a regimen ofantibiotic medication. If it is delayed, the patientmay consult the referring dentist with a complaintof discomfort or soreness under the prosthesis. Insuch instances, there will likely be redness andswelling, and in some cases the infection will beaccompanied by an exudate. Referral to the sur-geon for debridement and cleansing of the site andantibiotic therapy should be done without delay.

Suture removal is sometimes not completebecause of swelling or inaccessibility of the sutureremnants. It usually is seen as a localized redness orswelling and results in the patient experiencing dis-comfort when wearing the denture. This mucosalirritation, sometimes mimicking infection, often isongoing until the offending suture is removed.

Occasionally, especially when there is signifi-cant tugging on the sutures through movements ofthe circumoral muscles or if the sutures loosen early,the incision will reopen. If this occurs within a fewdays of stage I surgery, the surgeon may choose toclose the wound with new sutures. If it occurs later,after the deeper layers of the wound have begun toclose, the surgeon is unlikely to resuture choosing tomonitor the wound and request that the reinsertionof the denture be delayed 1 to 2 weeks.

In rare instances, damage to the inferior alveo-lar nerve may occur through a crushing injury dur-ing the degloving procedures, or it may occurbecause of violation of the canal or nerve by the

surgical instruments or by the implant itself. Withappropriate imaging techniques, paying attention tothe details of the anatomy of the surgical fieldrevealed in these images and careful instrumenta-tion will decrease the incidence of this complica-tion. In most instances, the altered sensation will betransient, though the transient time may vary froma few days to several months. If damage to thenerve has been severe, it may be permanent.

At stage I surgery, even when the most advancedimaging techniques are used, unexpected bony mor-phological deficits or poor bone quality may pre-clude ideal implant position, angulation, or thenumber of implants placed. This has obvious reper-cussions on the final prosthetic design and may leadto a decision to change the prosthodontic prescrip-tion. If a fixed prosthesis was originally prescribed,unfavorable implant angle or position could demanda change to a removable prosthesis. Unfavorableimplant position or angulation could require changeto a different retaining mechanism for an overden-ture if a removable prosthesis was initially pre-scribed. It will sometimes lead to a decision to abortthe surgery if it appears that not enough implants canbe placed to support an implant-retained prosthesis.The resolution of this complication is covered inother chapters of this book.

Interval between Stage I and Stage II

It is usual for patients to be requested to refrainfrom wearing their existing prostheses for a shorttime after implant insertion. At the end of thisperiod, the tissue surface of the denture is relievedsufficiently to allow for the placement of a tissueconditioner or temporary lining at least 1 to 2 mmthick in the region of the implants. An existing den-ture that is of minimal thickness may be perforatedduring this reduction unless it is made thicker bythe addition of acrylic resin to its polished surfacebeforehand. Because the surgical incision may befound in the labial vestibule, final resolution of theswelling in the site often is not complete at 2 weeksafter surgery. In this situation, it is usually neces-sary to trim several millimeters from the length ofthe labial flange to prevent patient discomfort andstress on the incision site. This is true in either arch.

Between the stages of the treatment, the softliner or tissue conditioner that has been applied to


the tissue surface of the denture should be kept ingood condition. Doing so will eliminate possibleulcerations caused by the rough and hard flanges ofthe dentures that develop as the soft liner ages. Softliners that are old and rough also present a goodmedium for increased bacterial growth. Keepingthe soft liner in good condition can be accom-plished either by replacing it every 4 to 5 weeks orby treating the temporary liner and especially theseam between the soft liner and the denture basewith a sealant that can be made up using anautopolymerizing acrylic resin powder and a sol-vent such as 1-1-1 trichloroethane (Box 29-1).

After the sutures are removed and the initialsoft tissue swelling has reduced, dehiscence of thecover screw of the implant through the mucosalcovering may occur. Experience with one-stageimplants demonstrates that implant exposure is nota threat to the success of the implant as long as thesite is kept clean. The patient may experience dis-comfort if the dehiscence of the cover screw is notcomplete and there is still mucosa partially cover-ing the screw. This tissue can be pinched betweenthe cover screw and the denture base. It can be alle-viated by trimming back the soft liner that has beenapplied to the tissue surface of the denture, thusallowing clearance in the area and preventing thepinching effect.

If a dehiscence occurs where an osteopromo-tive membrane has been used, this site should bemonitored very carefully by the referring dentistand the surgeon. The denture base acrylic resinshould be reduced more aggressively in the area toallow an extra thickness of tissue conditioner in aneffort to eliminate any possibility of pressure fromthe denture causing an increase in the size of thedehiscence. The patient should be instructed to keepthe site meticulously clean. Antibacterial rinses mayprove beneficial. At the first sign of infection, themembrane should preferably be removed.

The time interval between the two surgical pro-cedures often is difficult for the patient becausestage I surgery is a major event, and after initialhealing, an expected improvement in the denture-wearing experience seems logical. It is important tostress to the patient beforehand that it will not beany easier to wear the denture during the osseoin-tegration phase of treatment and that it may even bea little more difficult. It seems far easier for apatient to deal with this realization if informedbefore trying to deal with a difficult situationbetween the surgeries.

Stage II

Stage II surgery usually reveals whether an implanthas osseointegrated. There are times, however,when failure to osseointegrate is not detected untilthe further instrumentation involved in the impres-sion making or even the insertion of the prosthesisitself. If an implant is found to be mobile or tenderto percussion or to the stresses of attaching theabutment to it, it should be removed. Experienceshows that leaving it in place, with or withoutantibiotic therapy, will not result in a failed implantbecoming osseointegrated. It will merely delaydefinitive treatment and could result in the devel-opment of a larger bone defect (Figure 29-1).

At stage II surgery, the cover screw that pro-tected the internal threads of the implant is removedand replaced with a transmucosal abutment and cen-ter screw or with a healing abutment. If the regularabutment is attached at this time, it is important toensure that the hexagonal female portion of the abut-ment and the hexagonal male portion of the implantare properly aligned. If this is not the case, there maybe a soft tissue reaction or loosening of the compo-


Recipe for Varnish for TissueConditioner

50 ml 1-1-1 trichloroethane2 ml autopolymerizing acrylic resin powderUsing a glass bottle with a tightly closing lid, add

the autopolymerizing acrylic resin powder tothe trichloroethane solvent. This will take afew hours to dissolve completely. The result-ing solution should be as viscous as glycer-ine. If it is found that it is too thick, addsolvent; if it is too thin, add powder.

A small amount should be dispensed into a plas-tic medicine cup and applied to the entire sur-face of the tissue conditioner, paying specialattention to the seam between the denturebase and the tissue conditioner.

Box 29-1

nents. This particular complication does not occurwith the use of the healing abutment because there isno internal hexagon to engage the one at the top ofthe implant. The healing abutment does, however,seem to have an increased tendency to loosen. Thuscare should be taken to tighten it securely to theimplant, and the patient should be advised to seekattention immediately if loosening does occur.

Some of the complications encountered at stageI surgery become apparent only at stage II surgerywhen the implants are uncovered and the abutmentsare connected. This is especially true of implantsthat have an unfortunate buccal or lingual inclina-tion or that are spaced too closely. If it is obvious atthe time of uncovering that the spacing or the align-ment will make it impossible to use the implant tosupport a prosthesis, the implant may be recoveredor “put to sleep” during the surgical procedure.

PROSTHODONTIC-RELATED COMPLICATIONSOne of the earliest complications that can occurafter stage II surgery and before prosthesis inser-tion is loosening of the abutment, whether it is anabutment with a center screw or a healing abut-ment. This results in an inflamed and painful softtissue reaction as the soft tissue grows into thespace between the components and is pinched eachtime the patient occludes. Though it can happenwith any type of abutment, it seems to occur mostfrequently with healing abutments. When loosen-ing of the abutment or healing abutment is noted, itis important to evaluate the superior surface of theimplant to ensure that there is no soft or hard tissuecovering the implant platform. Bone on the implantplatform can prevent full seating of the abutment,which will in turn result in component malalign-ment and a tendency toward increased incidence ofcomponent loosening. To reduce this occurrenceand to streamline the prosthodontic appointments,the surgeon should leave the chosen final abutmentsattached to the implants after the final impressionfor the prosthesis has been made. The top of theabutments should be protected against damage withappropriate healing caps. It must be emphasizedthat abutments can be damaged from contact withopposing teeth and overlying hard material in theprovisional removable prosthesis.

Either immediately after stage II surgery or, ifpreferred, the week after, the tissue conditioner orthe soft liner that had been placed into the patient’sexisting denture after stage I surgery is removed.The position of the abutments attached to theimplants is transferred to the denture with an indeli-ble marker guide, and then the denture is adjusted toallow for a thickness of soft liner above the abut-ments. Occasionally, the dentist will find that theabutments emerge outside of the borders of the den-ture, and then either the denture base must beenlarged by the addition of autopolymerizing resinor a change to a very short healing abutment, or toan angled abutment is made.

Selecting the correct height of the abutment isnot always an easy procedure because there is usu-ally some swelling present even after stage II sur-gery. If the selected abutment is too short, themucosal swelling may lead to the tissue growing


Figure 29-1 The radiolucency surrounding theimplant on the left of the radiograph is indicative of animplant that has not osseointegrated. The implant wasmobile, and the patient reported mild discomfort whenit was tapped. On the right of the radiograph is animplant that has successfully osseointegrated and hasno accompanying symptoms or signs of failure.

over the top of the abutment or healing cap, therebyallowing it to be pinched between the abutment andthe relined denture base (Figure 29-2). If too longan abutment is selected, it will be difficult to seatthe denture completely without perforating thedenture base to make room for the height of theabutment. If the denture is not adjusted sufficiently,the denture base will not be properly seated, andthe result will be an opening of the vertical dimen-sion. In some cases, the patient will be able to copewith this increased height; in others, the resultingvertical dimension will be both esthetically andfunctionally so altered that the patient cannot orwill not manage. In all of these scenarios, the prob-lem can be solved by changing the length of theabutments.

The stage I surgical complication of insuffi-cient bone to allow ideal implant position and incli-nation becomes most apparent at the time ofprosthesis fabrication. Once the esthetic and func-tional try-in of the tooth arrangement has beenaccomplished and an index of the tooth arrange-ment has been made, discrepancies between theideal location and angulation of the implants andthe actual location and angulation become evident.Implant manufacturers have been ingenious in theirdesign of components to deal with these situations,but the basic problem remains. Implants that will

not be axially loaded by the forces of occlusionmay be adversely affected. In that event, steps willhave to be taken to reduce to a minimum the mag-nitude of these forces, either by changing the pre-scription to a removable prosthesis or by narrowingthe occlusal table or by shortening the potentialcantilever arms.

Implants that are too close together will make itvery difficult for patients with a fixed prosthesis tocarry out oral hygiene procedures (Figure 29-3). Inthe case of the overdenture, implants that are veryclose together do not leave space for the ideal 1 cmplus length of bar and clip, and when implants arecloser than 3 mm, it is difficult to use standard ballattachments. Recent introduction of the smallerball attachments with gold alloy or titanium keep-ers has helped to deal with this complication.

Impression

Obtaining an accurate impression for an implant-supported prosthesis is made relatively routinebecause of the nature of the fit of the impressionhardware that has been developed. There are, how-ever, a few complications that may occur. If theimplants are close together and also are converg-ing, the impression copings may interfere witheach other. If their bulk is not reduced to eliminate


Figure 29-2 One week after stage II surgery, the healing abutment, which was attached tothe center implant, is partially covered by mucosa. The patient reported acute pain and dis-comfort as the covering tissue was pinched during wear of his denture (A). Replacement ofthe shorter healing abutment with a longer one eliminated the discomfort and allowed theinflamed mucosa to heal (B).

A B

this contact, the impression is likely to be inaccu-rate. If there are widely diverging implants, theremay be a problem in seating the impression trayover the impression copings and laboratory pins.Impressions will not be accurate if the hexagon ofthe abutments and the implants are not properlyaligned and tightened before the impression ismade. It may be prudent to confirm seating of thecomponents with periapical radiographs immedi-ately before making the impression. Radiographstaken by the surgeon after stage II surgery areinsufficient for this purpose because abutmentscrews may have loosened in the interim. Periapicalfilms are suggested because panoramic films willnot always reveal problems with the fit of the com-ponent parts due to variations of the angles of theimplants. If there is even a moderate labial or lin-gual inclination of the implant, an unseated abut-ment may not be noted in a panoramic film.

Even if the preceding precautions are taken,there are times when impressions will not be accu-rate. We recommend fabrication of a confirmationjig, which can be made by attaching impressioncopings to the abutment analogues on the mastercast and then luting them together with acrylicresin or a light-cured material. The jig must be rigidto allow its use in confirming accuracy. For thisreason there must be sufficient bulk of acrylic orcomposite material to ensure rigidity. This jig can

then be used to assess the accuracy of the mastermodel obtained from the original impression. If itdoes not go into place passively when screwed tothe implants in the mouth, the jig can be severed atthe offending connection, the sections seated andscrewed to the abutments in the mouth, and theparts luted together. The altered jig allows for cor-rection of the master model by drilling out the abut-ment analogue that was not in the proper place,attaching a new abutment analogue to the impres-sion coping in the jig, and adding new dental stoneto secure it. This resulting “altered cast” is thenused for fabricating the framework.

Try-in of Tooth Arrangement

At this stage of try-in of the tooth arrangement, theeffects of possible compromises made at stage Isurgery become evident. Unfortunate inclination orlocation of implants, whether due to anatomicaldeficits of the host bone or to operator misjudg-ment, may make it necessary either to revise theprosthodontic prescription or to use alternate hard-ware components. A frequent example in the max-illary arch is one or more labially angled implants.An angled abutment will have to be used to avoidhaving the gold alloy–retaining screw exiting fromthe labial surface of the prosthetic tooth. This cor-rects the esthetic concerns, but it does not correct


Figure 29-3 Six implants were inserted into this edentulous mandible where fiveimplants would have been ideal. The proximity of the implants results in a restriction ofspace for the prosthetic cylinders and difficulty and discomfort in carrying out hygieneprocedures (A). For the problem to be fixed, the implant marked by the arrow is scheduled tohave its abutment removed and to be re-covered with mucosa (B).

A B

for the nonaxial loading to which the implant willbe subjected during function.

As a result of trying to attain both an estheti-cally pleasing and functionally adequate tootharrangement, it may become evident that an origi-nally planned fixed prosthetic design will have tobe altered to a removable design (e.g., an overden-ture). Examples of such cases are implants thathave had to be placed in a straight line across thefront of the mandible and significant labiolingualdiscrepancies between the maxillary and mandibu-lar arches.

Framework Try-in

Producing a framework for a fixed implant pros-thesis involves several complex laboratory proce-dures, and occasionally the result is a frameworkthat does not fit passively in the mouth. Sometimesthis is visible to the operator; sometimes it is notedonly by a response from the patient. This responseis most often a small wincing response by thepatient or a report of tightness that is alleviatedwhen the “offending” screw(s) is loosened slightly.If either occurs, the framework is severed betweenthe segments that appear to fit passively but areclearly not doing so. Sometimes this will necessi-tate severing in more than one site to ensure thatthere is no stress on the components as they arescrewed into place. Once it is established that thecomponents fit completely and passively, they areluted together in the mouth with autopolymerizingresin or light-cured composite, and the mastermodel is altered accordingly, as previouslydescribed. Then the casting is reassembled throughcorrective soldering by the laboratory, and a secondtry-in appointment is scheduled.

Though a nonfitting framework is more likely tooccur when there are several abutments beingjoined together, there also can be discrepancies withbars joining as few as two abutments, especially ifthe implants diverge significantly from each other.

INSERTION OF PROSTHESISImplant-Supported Fixed Prosthesis

Some complications can occur either at the time ofor immediately after insertion of the fixed implant-

supported prosthesis. A few patients will note mas-ticatory muscle strain and fatigue during the firstweeks of wearing a mandibular prosthesis.Counseling the patient to avoid stressing the previ-ously relatively inactive muscles of mastication byinitially cutting food into smaller pieces and grad-ually working up to normal chewing usuallyresolves this problem. The presence of stable den-tal prostheses may encourage more rapid chewing,which could result in increased risk of cheek ortongue chewing. Just as counseling is needed toavoid stress to the musculature, patients may bene-fit from the suggestion that they chew slowly untilthey are accustomed to their new prostheses.

Potential esthetic problems are hopefully dealtwith at the tooth try-in stage of prosthesis con-struction. The situation is similar to the protocolfollowed in complete denture fabrication. It mustbe emphasized, however, that after final insertion,esthetic changes, although feasible, may be moreawkward and tedious to be carried out after finalprocessing is complete.

Initial difficulties with speech may be anticipatedwith a maxillary fixed prosthesis, especially if there isa large difference between the location of the implantsand the incisal edges of the prosthetic teeth. The bulkof the prosthesis necessary to reach forward from theimplant abutments to the prosthetic teeth can interferewith the tongue during normal speech. Though thisproblem usually resolves within a few days as thepatient’s tongue learns to cope, some patients find itnecessary to wear an obturator for several months,and very few will wear it indefinitely.

The incidence of speech problems also isincreased if the patient’s circumoral muscle activityeasily reveals maxillary gingival tissue. In these sit-uations, when the upper lip retracts during speech,it will not form an air seal, and there will be a result-ing “shshsh” when making the s sounds. Whenthere is a high lip line, it may be necessary to add aflange to the prosthesis for speech and esthetics aswell. Though the flange solves these problems, ithas the potential for creating other problemsbecause oral hygiene is made more difficult.

Implant-Supported Overdenture

Insertion of the implant-supported overdenture issometimes complicated by the necessity to accom-


modate both the soft tissue anatomy of the poste-rior part of the mouth and the implant abutmentand hardware connection in the anterior. It may benecessary to remove the otherwise useful exten-sions into the retromylohyoid space to completelyseat the overdenture.

Some patients with implant overdentures findthat food will collect under the anterior part of thedenture, whether it be retained by a bar and clipassembly or by ball attachments. This is due partly tothe relatively inaccurate impression of the anatomyhere (remember that the impression tray had to bemade wider than usual in this area to accommodatethe impression copings and was therefore too wideto achieve an accurate impression of mucosa) andpartly to the block-out around the retention hardwarethat was done before the final processing. A chair-side addition of an autopolymerizing acrylic resin tothe lingual and labial flanges in this area usuallysolves this problem.

If a bar and clip assembly is used, the clip maymake it very difficult to remove the overdenture,unless it is loosened slightly before the first inser-tion. It can easily be tightened after the other usualprocedures of insertion of a complete denture arecompleted.

In the first days after insertion of the overden-ture, the patient may experience minor denture irri-tations under the soft tissue–supported area of theprosthesis. This is corrected as the denture isrelieved and adjusted in the customary fashion.

POSTINSERTIONDuring the years of prosthesis wear, there are anumber of possible complications that may occur.Some of these are common to both fixed andremovable prostheses, whereas others are morespecific. The complications fall under the broadheadings of biological and prosthodontic mechani-cal ones (Table 29-2).

Biological complications include failure or lossof integration and soft and hard tissue complica-tions. Because osseointegration appears to resultfrom an induced and controlled healing response, itis not surprising that three fourths or more of allreported implant failures occur during the earlyhealing phase. The remaining failures occur afterocclusal loading takes place and are in all likeli-

hood caused by an inadequate healing responsebecoming compromised by subsequent loadingdemands. Meticulous treatment planning addressesthe remote possibility of the small, if inevitable,failures. This will ensure successful prosthodontictreatment outcomes even when fewer implants thanhoped for actually osseointegrated. The obviousexample would be the conversion of a proposed five-unit fixed prostheses to a two- or three-unit overden-ture if two or three implants should fail. Soft andhard tissue problems are also encountered and are asource of some controversy. A periodontic type ofmindset considers such changes as a version of peri-odontal diseaselike sequelae. On the other hand, sev-eral researchers, including this book’s editors, arguefor a mechanical and microbiological cause thatchallenges the implant’s surrounding gingival tissuesrather than its ankylotic-like attachment.

Structural

All of the three levels of components of the com-pleted implant-retained system are subjected torepeated stresses of occlusal and parafunctionalloading, and it is possible for these stresses to causefractures of any of these components: the prostheticretaining screw, the abutment screw, or the implantitself (Figure 29-4). Most common is the fracture ofthe gold alloy screw, usually at the base of the headof the screw. If the top of the threaded area is acces-sible, the screw fragment can be removed by care-fully touching the outside of the top of the fracturedpiece, which is remaining in the center screw of theabutment, with a tapered fissure bur in either aslow-speed handpiece or a high-speed handpiece


Table 29-2Prosthodontic Problems and Complications

Type Description

Structural Prosthesis fractureFracture of prosthesis retaining screwFracture of abutment screwFracture of implant

Cosmetic As perceived by patient and dentistFunctional Speech problems

Transient muscle discomfort or temporomandibular disorders


running at very low speed. Another approach is touse a hemostat to grasp the screw fragment and toturn it counterclockwise to remove the screw. If thescrew is fractured beneath the top of the abutment,it may be teased out by engaging the top of thescrew with an explorer and rotating the explorer tipin a counterclockwise direction. If this proves diffi-

cult or if the screw fragment cannot be reached, theentire abutment and center screw can be removed,and the gold alloy screw can then be retrieved on thebench rather than in the patient’s mouth.

Cementing a fixed prosthesis would of coursepreclude fracture of retaining screws, but looseningof the restoration can occur. Cementation is a pop-

Figure 29-4 Prostheses supported and retained by implants are subject to fracture withinthe metallic framework (A), or the esthetic facing (B), or both (C). Component fractures arepossible at each of the levels of the implant-retained system, whether it be with the originalregular tube-shaped abutments (D) or with the currently used conical abutments (E). The com-ponent most likely to fracture is the gold alloy prosthesis retaining screw a. The abutment-retaining screw can fail at the head of the screw b or at the level of the threaded area c, whichusually is well within the implant itself. Fracture of the implant d is rare, possibly because ofthe protective nature of the retaining components above it.

A

B C

D E

Continued

ular retentive approach in many clinical circlesbecause it is presumed to be more “user friendly.” It isargued that fixed prostheses can be easily recementedwhen natural teeth are used as abutments. However,screw-retained prostheses are electively and easilyremovable, which we regard as a plus from a long-term monitoring and maintenance point of view.

Fracture of the abutment screw can occur eitherat the level of the hexagonal top portion or at thespindle or threaded area deep within the implant. Inthe case of the fractured hexagonal top, removalcan be accomplished with a tapered fissure bur tocreate a slot into which a standard screwdriver isfitted. The center screw can then be easily reversedout of the implant.

Removal of an abutment screw that is fracturedfarther down its length is more difficult, and greatcare must be taken to avoid damaging the internalthreads of the implant. The use of an explorer totease the screw out of its seat is described in theprevious paragraph. An abutment screw retrieval orrescue kit is available to use in cases where removalis more difficult. The kit contains an end-cuttingtool that grasps the top of the fractured componentwhen pressure is applied. It is then rotated counter-

clockwise to remove the screw fragment from theimplant. Often this procedure is not as easilyaccomplished as this description suggests, espe-cially if the abutment screw fragment seems tohave bonded itself to the interior of the implant.Another approach is to very carefully prepare a“well” at the top of the screw fragment with a smallround bur (accompanied by generous irrigation)and then to use a larger round bur, held either in ahandheld torque driver or in the cutting tool holderprovided in the retrieval kit. The larger round bur ispressed onto the prepared top surface of the screwand turned counterclockwise to remove it.

Removal can be further complicated by soft tis-sue overgrowth or collapse into the space immedi-ately above the implant. Not only does this preventa clear view of the top of the fractured abutment,but also there is often some bleeding becausewith a fractured retaining component, the implant-supported bridge usually is mobile and pinches themucosa, causing it to become inflamed.

The instrumentation involved in an attempt toremove the broken abutment screw must be usedwith extreme care to avoid damage to the threads inthe interior of the implant. If the internal threads ofthe implant have been damaged, it will be difficultto insert the replacement abutment screw. In such acase, the fixture tap, also included in the kit, canthen be used to repair the threads.

The implant itself is also subject to fracture,though fortunately this is a very rare occurrence.The two upper levels of the system act as “fuses”and usually will fracture before damaging stressescan cause fracture of the implant. If an implantdoes fracture, it is usually at the level of the base ofthe abutment center screw, and, in most cases, ithappens when the bone level also has reached thispoint. The remaining implant fragment must beremoved by the surgeon using a trephine because italmost always remains osseointegrated.

Whenever component hardware fractures occur,the implant-supported bridge and its relationshipto the remaining dentition, the occlusal scheme, andthe presence and extent of cantilevers should beassessed very carefully to determine if it is prudentto make alterations to prevent further complications.Long cantilever extensions, especially when implantshave had to be placed in straight-line configurationsrather than in a semilunar arrangement, seem to be


Figure 29-4 cont’d The clinical photograph (F) shows two implants with attached abutments. Theabutment-retaining screw in the implant on the right isintact, whereas the head of the retaining screw in themiddle implant is fractured. On the left of this photo-graph, the abutment is off because its retaining screwhas fractured at the threaded area, thus illuminating theretaining function of the screw. Retrieval of an abutmentscrew that has fractured within an implant must be donewith great care to avoid damage to the interior threadedportion of the implant.

F


more frequently associated with component fracture.Even with the more desirable arch form implant dis-tribution, a heavy occlusal load on the cantileverportion of the bridge can cause fracture of the gold-retaining screw or even the abutment screw at themost anterior implant.

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Chow J, Hui E, Liu J et al: The Hong Kong Bridge Protocol.Immediate loading of mandibular Branemark fixtures usinga fixed provisional prosthesis: preliminary results, ClinImplant Dent Relat Res 3:166-174, 2001.

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Eckert SE, Wollan PC: Retrospective review of 1170endosseous implants placed in partially edentulous jaws,J Prosthet Dent 79:415-421, 1998.

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of implant restorations, Pract Periodontics Aesthet Dent10:737-746; quiz 748, 1998.

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Hemmings KW, Schmitt A, Zarb GA: Complications and main-tenance requirements for fixed prostheses and overdenturesin the edentulous mandible: a 5-year report, Int J OralMaxillofac Implants 9:191-196, 1994.

Jemt T: Failures and complications in 391 consecutivelyinserted fixed prostheses supported by Branemark implantsin edentulous jaws: a study of treatment from the time ofprosthesis placement to the first annual checkup, Int J OralMaxillofac Implants 6:270-276, 1991.

Levine RA, Clem DS III, Wilson TG Jr et al: Multicenter retro-spective analysis of the ITI implant system used for single-tooth replacements: results of loading for 2 or more years,Int J Oral Maxillofac Implants 14:516-520, 1999.

Piattelli A, Piattelli M, Scarano A et al: Light and scanning elec-tron microscopic report of four fractured implants, Int JOral Maxillofacial Implants 13:561-564, 1998.

Pilliar RM, Lee JM, Maniatopoulos C: Observations on theeffect of movement on bone ingrowth into porous-surfacedimplants, Clin Orthop (208): 108-113, 1986.

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Rangert B, Krogh PH, Langer B et al: Bending overload andimplant fracture: a retrospective clinical analysis, Int J OralMaxillofac Implants 10:326-334, 1995.

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C H A P T E R 30Implant Prosthodontics for EdentulousPatients: Current and Future DirectionsEmad S. Elsubeihi, Nikolai Attard, George A. Zarb

528

Osseointegration has had a dramatic influence onprosthodontic practice. With its emphasis on scien-tific rigor, osseointegration now provides expandedtreatment management strategies for virtually allpartially and completely edentulous patients(Plates 30-1 through 30-5). The clinical yield fromosseointegration as summed up in Box 30-1reflects the results of numerous studies on its effi-cacy and effectiveness.

In 1990 we reported the results of the firstNorth American long-term prospective implantstudy in prosthetically maladaptive edentulouspatients (Zarb and Schmitt, 1990). One particularlycompelling finding was that successful prostho-dontic treatment outcomes exceeded individualimplant survival ones, and all of the treated patientsdemonstrated ongoing long-term comfortable andsuccessful prostheses wear. This study and subse-quent ones strongly suggested that the provision ofa fixed or quasi-fixed (overdenture) prosthesis wasthe optimal solution to complete denture problemsof a functional nature (prosthetic maladaptation). Itwas concluded that the major determinant of suc-cess in wearing removable prostheses was patient-perceived comfort and stability. The latter objectivewould be readily achieved irrespective of the numberof successfully osseointegrated fixtures and under-scored the merits of diverse applications of a tech-nique that has arguably revolutionized prosthodontictreatment.

Furthermore, evidence now continues the con-tribution of osseointegration to a slowing down, orreduction, in the bone resorptive process that wouldotherwise be likely to occur in the edentulous site(s)of proposed implant placement. Additionally, thedocumented virtual absence of even minimal mor-

bidity has also become a significant considerationwhen prescribed surgical and prostho-dontic protocols are followed. This encouragesthe conclusion, albeit a largely anecdotal but veryfrequently encountered one, that a patient’s lifequality is significantly enhanced by implantprosthodontics.

Brånemark’s pioneering work in osseointegra-tion catalyzed the conclusions in Box 30-1 andquite understandably led to several developmentaland research initiatives, which are summed up inBox 30-2. Regrettably, very few of the availablesystems have been validated in the literature(Eckert, Parein, Myshin et al., 1997), and claimsfor predictably safe site development tend toremain long on anecdote, if somewhat short on sci-entifically documented outcomes. As a result bothpatients and dentists cannot readily answer thebasic question that must be asked about any sys-tem’s or surgical technique’s effectiveness evaluation:Do the proposed biotechnology and interventionslead to more good than harm in those people to whomit is offered? This has become a dilemma in clinicalpractice where advertised hype risks outweighingthe quality of required long-term evidence, whichled to the compelling documented outcomes foundin Box 30-1. It is hoped that continued efforts atscientific validation will evolve into the yardstickthat dentists and patients will routinely use whenmaking clinical decisions on prescribing implant-supported/retained prostheses and the associatedprotocols.

It is encouraging to note that significant clini-cal research initiatives continue to provide a betterunderstanding of treatment outcomes with our pre-ferred implant systems, along with systemic and

local determinants of successful osseointegration(see Table 25-1).

HOST BONE RESPONSELong-term studies on the success/survival of dentalimplants reveal an impressive prosthodontic treat-ment outcome (Table 30-1). Because osseointegra-tion is essentially a wound healing process, it ispresumed that factors that interfere with the healingprocess may contribute to implant failure. As a result,in some studies investigators attempted to relateimplant failure to the status of changes in bone qual-ity or quantity. In other clinical studies researchersattempted to investigate the success rate of dentalimplants in different systemic conditions that havebeen shown to adversely affect wound healing andmay therefore compromise successful osseointegra-tion (Elsubeihi and Zarb, 2002). Although the resultsof some of these studies have provided some indica-tions on conditions that can influence osseointegra-tion (Table 30-2), most did not provide conclusiveevidence on the impact of systemic conditions ondental implant success. The reason is that most of thereported studies were either case reports or retro-spective case series studies of small sample size. Thisis further complicated by the fact that little is knownabout local hormonal, metabolic, and cellularprocesses in the jawbone. The reference section pro-vides more sources of information (Elsubeihi andZarb, 2002; Sennerby and Roos, 1998; Esposito,Hirsch, Lekholm, et al., 1998).

Smoking

It is estimated that implant failure is about twice ascommon in smokers as compared with nonsmok-

Chapter 30 Implant Prosthodontics for Edentulous Patients: Current and Future Directions 529

Clinical Yield from Long-TermProspective Clinical Studies in

Osseointegration

1. Enhancement or guarantee of prosthesisretention/stability

2. Retardation in bone reduction3. Minimal treatment outcome morbidity4. Enrichment of patients’ life quality

Box 30-1

Table 30-1Rate and Distribution of Early and Late Implant Failures in Two Studies

Meta-analysis Study* University of Toronto†

Total number of implants 2812 1852Early failure 3.6% 4.21%Late failure 4.1% 3.66%Overall failure 7.7% 7.9%

*Meta-analysis of 73 published studies over a 5-year period (Esposito, Hirsch, Lekholm, Thomsen, 1998).†Data from prospective follow-up studies at the University of Toronto since 1979.

Research Developments

Developments in Implants/ImplantComponentsImplant material biocompatibilityImplant and component designsImplant surface characteristics

Developments in Surgical/ProsthodonticTechniquesSurgical techniqueImplant placement techniqueSite developmentTiming of loading protocols

Understanding Patient-Mediated ConcernsLocal factorsBehavioral and systemic conditionsQuality of lifeHealth economic benefits of treatments

Box 30-2

ers. Substantial evidence exists to support the con-clusion that cigarette smoking is associated withincreased risk of implant failure, increased mar-ginal bone loss, and poor periimplant soft tissuehealth. In general, cigarette smoking has beenshown to impair soft tissue wound healing by affect-ing the circulatory and immune systems and byimpairing normal cellular function. Furthermore, itappears that cigarette smoking during adulthood isassociated with decreased hip and vertebral bonedensity later in life in both women and men.However, the exact mechanism by which smokingexerts its negative effect on bone is not yet fullyunderstood. Bone loss occurs if there is an imbal-

ance between the amount of bone resorbed and theamount of bone formed. The available evidenceexamining whether one or both of these mecha-nisms contribute to the bone loss associated withsmoking is limited. It has been demonstrated thatlower bone density at the lumbar spine in smokerswas associated with higher serum calcium andurine pyrdinoline levels, which is consistent withincreased bone resorption. Furthermore, it was alsosuggested that increased bone resorption associ-ated with smoking is in part due to decreased pro-duction and acceleration of degradation of estrogenleading to early menopause and higher rate ofbone loss. On the other hand, histomorphometric


Table 30-2Summary of Influence of Various Factors on Implant Prosthodontic Treatment Outcomes

Patient-Related Factors

Local Systemic/Behavioral Prosthodontic/Surgical Technique Implant-Related Factors

No Demonstrable Age and gender Incision techniqueNegative Effect* Controlled diabetes mellitus Immediate loading

Controlled cardiovascular Exposed threadsdisease Lack of bicortical stabilization

Controlled hypothyroidism Number of supporting implantsHereditary ectodermal diseaseHIV/AIDSSystemic corticosteroid

therapy

Possible Risk ofFailureJaw site Maxilla in postmenopausal Clinician’s skill and experience Implant diameter

women not receiving HRT Compromised infection control Implant design†Vitamin D–dependent rickets Lack of initial stabilizationSjögren’s syndrome Immediate placement in infected Diphosphonate therapy extraction sockets

Distribution of implants

Increased Risk of Failure*

Compromised Cigarette smoking Lack of antibiotic prophylaxis Implant lengthbone quantity Irradiated maxilla

Compromised Recent chemotherapy Implant material†

bone quality

*Note that with the exception of smoking and diabetes mellitus, the influence of other systemic conditions on implant failure is based on casereports and retrospective studies with small sample sizes.

†Implant microscopic and macroscopic characteristics are discussed in Chapter 26.HRT, Hormone replacement therapy.

investigations suggested that reduced bone forma-tion is responsible for the deficit in bone volumeseen in smokers. In vitro and animal studies haveshown that several components of cigarette smoke,such as nicotine and aryl-hydrocarbons, can depressosteoblast activity, reduce collagen synthesis, andinhibit osteodifferentation and osteogenesis. Othercomponents of cigarette smoke, such as carbonmonoxide (which binds to hemoglobin to form car-boxyhemoglobin) and hydrogen cyanide (whichinhibits cellular respiratory enzymes), result in tis-sue hypoxia and alter tissue healing. The effect ofthese components on jawbone behavior at the tis-sue and cellular levels needs to be fully explored.

Irradiation Therapy

Irradiation therapy in which more than 55 gray (Gy)was used has been associated with increased risk ofimplant failure and soft tissue complications duringhealing, particularly in the maxilla. It has been sug-gested that the use of hyperbaric oxygen in thesepatients can improve success rates, particularly inthe maxilla. In addition to the known risk of osteo-radionecrosis, experimental evidence suggests thatradiation induces cellular changes in bone whereosteocytes in the direct pathway of irradiation arekilled and the regenerative potential of the perios-teum is compromised because of reduced cellular-ity, vascularity, and osteoid formation potential.Furthermore, blood vessels’ patency is reducedleading to diminished hematopoietic turnover.

Osteoporosis

The term osteoporosis has been somewhat looselyused in the dental literature and often to implypostmenopausal osteoporosis. Several reports sug-gest that osteoporosis is not a risk factor forimplant failure in the jaws; however, these werelimited to case reports and case series studieswhere the diagnosis of osteoporosis was not con-firmed. Interestingly, biochemical analysis of bonederived from human osteoporotic femoral headshowed evidence of overhydroxylation of lysineand a consequent reduction in the stabilizing cross-links of the collagenous framework that has beensuggested to contribute to increased fragility ofbone. Indeed, mechanical testing of healing femoral

fractures in rats indicated that ovariectomy impairsfracture healing up to 4 weeks after fracture. Thisreturned to normal levels 6 weeks after fracture.The administration of 17-β estradiol during frac-ture repair also resulted in a dose-dependentincrease in the peak force required to break thefracture. These observations may explain the recentfindings of increased risk of maxillary implant fail-ure when tested with the reverse-torque method atstage II surgery in osteoporotic patients not receiv-ing hormone replacement therapy. Interestingly, nocorrelation was found between changes in bonemass in different parts of the skeleton and dentalimplant failure. This observation underscores theneed for a better understanding of the effects ofsystemic factors on jawbone changes at both thetissue and cellular levels.

Experimental evidence has shown that estrogendepletion leads to a significant loss of bone mass inthe edentulous mandible, but not in the dentatemandible, possibly because of the protective effectof masticatory forces (Elsubeihi and Zarb, 2002).The reduction in bone mass of the edentulousmandible of estrogen-depleted animals was associ-ated with an increase in bone turnover where bothbone resorption and bone formation rates areincreased, with the former exceeding the latter,resulting in bone loss. Evidence at the gene expres-sion, cellular level, and tissue level in other parts ofthe skeleton further supports these findings.

Several authorities maintain that a clinical diag-nosis of osteoporosis per se is not a contraindica-tion for dental implant placement. However, inpatients with a diagnosis of osteoporosis and wherethe local jaw bone quality is judged to be of infe-rior quality (e.g., Type IV bone, particularly in themaxilla), clinical prudence suggests the followingclinical strategy: self-threading implants should beplaced with meticulous surgical technique, and anappropriately longer healing period should beallowed before subjecting the implants to highocclusal stresses. The recent introduction of surface-modified self-threading implants may also prove tobe of value in these situations. Interestingly, func-tional loading of healed dental implants in patientsmay increase the bone mass in the jaws, an obser-vation that is consistent with lack of effect ofestrogen depletion on the dentate mandibles ofanimals.



Other Systemic Conditions

Case reports and retrospective studies with a smallpatient sample size indicate that there is an increasedrisk of implant failure in patients with Sjögren’ssyndrome, patients with vitamin D–dependent rick-ets, and in patients receiving active chemotherapyand diphosphonate therapy. On the other hand, noevidence of increased risk of implant failure hasbeen demonstrated in patients with controlled dia-betes mellitus, controlled cardiovascular disease,controlled hypothyroidism, HIV/AIDS, hypophos-phatasia, scleroderma, Erdheim-Chester disease,and hereditary ectodermal dysplasia. It should beemphasized, however, that with the exception of thestudies on smoking, diabetes mellitus, and irradi-ated maxillae, the quality of most reports does notallow for firm conclusions, and further studies areneeded.

THE SURGICAL PROTOCOLSurgical technique and the healing potential of thepatient are local determinants of implant success. Theaims of the surgical technique are to place and locatethe required number of implants (prosthodonticallydriven) in host sites as atraumatically as possible andto obtain primary stability or implant immobility. Thisstability is dependent on the surgical technique used,plus the bone quality and quantity of the host site,which in turn determines the length of implant used.

An empirically based classification of bonequality and quantity was proposed by Lekholm andZarb (1985) and describes commonly encounteredvariations in jaw morphology or quantity, as deter-mined by clinical examination and radiographicimaging. Bone quality is also described subjec-tively by the surgeon during the surgical procedure(Figure 30-1).

Bone Quality

Bone quality in the mandible is typically cortical innature anteriorly and more trabecular posteriorly.Likewise, the maxilla is generally trabecular withminimal cortical bone present in the alveolarprocess. However, alveolar bone is highly variable,and the transition between anterior and posterior isgradual. Bone quality appears to influence treat-ment outcomes, with high success rates described

in the anterior mandible and somewhat lower onesobserved in the maxilla. This clinical observationcatalyzed research to improve success rates forclinical situations where poor bone quality isencountered. Examples include the following:

1. Modification of the surgical technique:underpreparation of host sites and the use ofosteotomes. The presumed advantages ofsuch techniques are bone preservation andlocalized increase in bone density of theosteotomy site.

2. Modification of the implant design: widerdiameters, changes in thread design, andintroduction of self-tapping implants.

3. Modification of implant topography byintroducing roughened surfaces to increasebone to implant contact.

However, the long-term benefits of such modifica-tions, especially those related to surface modifi-cation, are still to be determined clinically. To date,long-term prospective studies have revealed pre-dictable prognoses for machined surface implants,even when the implant surface was exposed to oralflora as a result of bone resorption. On the otherhand, a rough surface, although reported to inducemore initial bone formation, may in the long-termbe prone to infection-related problems due to therisk of more enhanced bacterial adhesion. Furtherresearch is clearly required to better understand theeffects of implant surface topography in situ.

There are currently no specific tools that con-clusively determine bone quality before the implantsurgical intervention. Although computed tomog-raphy remains a helpful diagnostic imaging tech-nique that provides insight into the architecture ofthe bone, this does not necessarily guarantee suc-cessful osseointegration. Further research at thecellular level is also required to determine the var-ious steps of the healing phenomenon and to devisemethods of harnessing and improving it (Watzekand Gruber, 2002). Numerous attempts to coatimplant surfaces with organic factors (bone mor-phogenetic proteins [BMPs]) and inorganic materials(such as hydroxyapatite) that stimulate mesenchymalprogenitor cell migration and differentiation havealso been proposed. Regrettably, published resultsare still inconclusive. Clinical experience indicated


that implant failure is a localized phenomenon.Site-specific healing potential is yet to be deter-mined both at a morphological and cellular level.Furthermore, if this ability to do so was possi-ble, this does not necessarily guarantee that suchparameters would be useful predictors of osseointe-gration.

Bone Quantity

Ridge reduction is an ongoing and cumulativeprocess, and the resultant residual bone quantitycan compromise implant placement. Consequently,several patients who are most in need of implants fre-quently have compromised bone anatomy. Varioussurgical endeavors in the edentulous patient have

been suggested for compensatory ridge augmenta-tion, with the gold standard for bone grafting beingautogenous bone.

Research has established that a healing phase forthe graft is required before implant placement.However, the time required for this intermediatephase before implant placement is yet to be deter-mined conclusively. Currently, the suggested interme-diate healing phase is approximately 6 months.Moreover, the impact of these surgical interventionsand associated morbidity still needs to be investigatedin elderly patients. This is a significant concernbecause this age cohort will likely be the main recip-ient of implants.

The need to find alternatives to autogenousbone harvesting has also led to various research ini-

1

A B

Maxilla

Mandible

C D E

2 3 4

Figure 30-1 Lekholm-Zarb classification of edentulous anterior jawbone quantity andquality. Types A through E reflect a range of resorptive patterns relative to the presumeddemarcation of the alveolar and basal jawbone (dotted line). Quality (Types 1 through 4)reflects a range of cortical and cancellous patterns, which have been consistently used inplanning oral implant treatment.


tiatives. Basic science research in various animalmodels demonstrated the bone regeneration capac-ity of various growth factors such as BMPs, tumorgrowth factor-β (TGF-β), platelet-derived growthfactor (PDGF), and the maintenance of de novobone under functional loading. A dearth of infor-mation remains on the use of these regenerativematerials in clinical studies, although short-termresults appear to hold promise. The need for mini-mally invasive preprosthetic surgical techniques tocreate better host sites for implants remains a seri-ous research priority.

PROSTHODONTIC LOADINGOcclusal forces are the major source of loading ondental implants. The basic tenets of a therapeuticocclusion were originally described by Beyron andunderscore the standard determinants of a physio-logical occlusion in prosthodontic patients (Box30-3) (Mohl, Zarb, Carlsson, et al., 1988).

These objectives are easily achieved in settingup teeth for complete denture fabrication (seeChapters 16 and 17). However, their effectivenessis also dependent on the quality of available resid-ual ridge support. Occlusal loading potential in theedentulous patient is limited by the health andnature of the oral mucosa and the morphology ofthe denture-bearing area. As a result, patient suc-cessful acceptance of conventional prostheses,notably lower complete dentures, remains a serioustreatment challenge and in the past led to numerousingenious surgical techniques to enlarge the den-ture load-bearing area.

Initially, patients seeking implant-supportedprostheses were treated with a minimum of five tosix implants in the anterior mandible and maxilla,respectively. These locations were selected becauseof likely favorable host site dimensions. Theimplants’distribution followed the residual arch formso that they were better able to provide mechanicalsupport for the prosthesis, and after a suitable heal-ing period (4 to 6 months), the implants were thenrestored with a fixed prosthesis.

Efficacy and effectiveness studies on patientswith maladaptive prosthetics who were treatedwith fixed restorations show that these patientswere significantly helped with this technique (seeChapter 28). However, it should be realized thatthis treatment modality is time-consuming andexpensive. Therefore we reiterate our convictionthat the dramatic impact of osseointegration treat-ment should include a simpler, less dramatic appli-cation of the technique. Since many experiencedprosthodontists have long recognized that mostpatients’ denture difficulties can be easily rectifiedif denture stability is improved, it appears logicalthat these patients do not necessarily need a con-version of their unstable complete denture into afixed osseointegrated one. All they appear to needis a source of prostheses stability that can be read-ily achieved with the presence of two or moreoverdenture abutments. It is therefore tempting forthe prosthodontist to include such an “abbrevi-ated” use of osseointegration in the form ofimplant-supported overdentures. Such an applica-tion offers both practical clinical and financialadvantages. The surgical operation becomes areduced one, both time and money wise, and theapproach is kinder to the patient particularly in thecontext of the patient’s state of health or age.Considerable evidence now endorses the functionalbenefits obtained by patients who wear implant-retained overdentures. These benefits includeimproved denture stability, expanded scope foraesthetic solutions, enhanced patient confidenceand comfort, and retardation of loss of the residualbony ridge height (see Chapter 27).

The initial proposed healing periods for theburied implants were an outgrowth of early trialsbased on extrapolated observations from orthopedicresearch. The original Brånemark osseointegrationtechnique required a two-stage surgical approach

Beyron’s Determinants of aPhysiological/Therapeutic

Occlusion

1. Acceptable interocclusal distance2. Stable jaw relationship with bilateral contacts

in retruded closure3. Freedom in retrusive range of contact4. Multidirectional freedom of contact movement

Box 30-3


with a minimum healing period proposed to obtaindurable direct bone to implant contact. This periodwas suggested to be at least 4 months in themandible and 6 months in the maxilla.

In the last decade, clinical research has ques-tioned this timing protocol and led to altered imme-diate or early loading treatment protocols, mainlyin site-specific areas. It should be understood thatif implants are loaded early, we are not dealing withthe biological phenomena of osseointegration perse, but rather with primary mechanical implant sta-bility. The time-dependent secondary implant sta-bility is achieved when bone formation andremodeling at the bone/implant interface is com-pleted. The presumed advantages of the changein time-related loading protocols include thefollowing:

1. Treatment for routine patients with variousimplant designs, most particularly in theparasymphyseal region of the mandible. Thisarea has the highest reported clinical successrates when compared with the conventionaldelayed surgical approach.

2. A reduction or elimination of the healingphase before loading of the implants with aresultant reduced time commitment by thepatient.

3. One-stage surgery in an effort to reduce thesurgical morbidity.

Several published studies suggest that immediateor early loading with fixed or overdentureimplant-supported prosthesis is a viable option, atleast in the short term. However, the results arefar from conclusive, and a number of concernsstill need to be investigated to determine thefollowing:

1. The biological implications of reducing thehealing time.

2. The true impact of such an approach on thepatient’s quality of life.

3. The specific protocol of immediate loadingto be followed, specifically, the minimumhealing time required, the number ofimplants needed to support fixed or over-denture prostheses, and also the prostheticdesign.

4. The long-term success and economic bene-fits of immediate loading in the context ofpublished treatment outcome criteria thatjustified use of traditional surgical and load-ing protocols.

The biomechanics of the healing implant boneinterface remains a fascinating if complex concernfor various researchers, from tissue engineers toclinical specialists. It appears that time-dependentstress-strain states in mesenchymal tissue influenceall differentiation in the various stages of bonehealing. This occurs in fractures, in implant-relatedosteotomies, and in distraction osteogenesis. Itmust therefore be emphasized that current clinicalexperiences with different implant-loading proto-cols (though ingenious and exciting) are based onscrupulous observation exclusively and not on afull understanding of the biomechanics of implant-bone interfaces.

Oral Ecology and Implant Prosthodontics

Ecology is described as that branch of biologydealing with relations of microorganisms to oneanother and to their physical surroundings. In abroader sense it also includes the relationshipbetween changes in a particular environment andthe resulting impact on specific presences or par-ticipants. Oral ecological responses to prosthodon-tic interventions can therefore be regarded as abalance between the implicit invasiveness of anyprocedure (making crown preparations with sub-gingival margins, using edentulous ridges forocclusal support, implanting tooth root substitutes)and the host tissue site responses. Consequently,treatment techniques such as the ones mentionedmay elicit changes that lead to specific ecologicalupsets manifested as clinical complications. Theseinclude recurrent caries and periodontal diseasearound a crowned tooth or inflammatory and mor-phological changes in residual ridges under com-plete dentures. The development of such adverseecological shifts are time dependent but alsoreflect patient- and dentist-mediated judgment andskills. It is therefore quite remarkable to note thevery minimal local or systemic morbidity recor-ded in long-term prospective studies in implantprosthodontics.


One fascinating fact has been the well-recordedobservation that osseointegrated implants are veryrarely associated with postloading failure. Althoughclinical skill and judgment, plus optimal patientselection and operating protocols, appear to virtu-ally guarantee favorable long-term treatment out-comes, the choice of implant per se also appears tocontribute to clinical success.

When encountered, implant failure afterprosthodontic loading has often been attributed toa so-called periimplantitis. This is described as aninflammatory process affecting the tissue around animplant, which results in loss of supporting boneand which has been reported in particular withrough-surface implants. The latter observationmay therefore suggest a greater vulnerability forimplants with roughened as opposed to machinedsurfaces extending to their cervical regions, withan analogy with periodontal disease a long-stand-ing temptation. This in turn has led to severalhypotheses regarding the etiology of implant fail-ure and a regrettable rigid insistence on a similarperiodontitis and pathogenic etiology. It has evenled to treatment for periimplantitis based on peri-

odontal therapy protocols. A recent literaturereview (Esposito, Hirsch, Lekholm, et al., 1999)concluded that the treatment of failing implants isstill based on empirical considerations oftenderived from periodontal experiments, from dataextrapolated from in vitro findings, or from anec-dotal case reports performed on a trial-and-errorbasis. To date, no compelling data have been pre-sented to justify treating teeth and implants asidentical clinical entities. Their attachment mecha-nisms are different because the tooth’s haveresulted from an evolutionary process, whereas theimplant’s is an induced healing response (Figure30-2). As a result, functional differences betweenimplant and tooth are quite obvious (Table 30-3),yet numerous articles in the periodontal literatureand in some microbiological reviews haveattempted to advance an argument favoring peri-odontitis-related bacteria as the cause of implantfailure. It appears that the most serious conclu-sions from such reviews are that the microflora ofperiimplantitis resemble those of adult or refrac-tory periodontitis and that potential periodontalpathogens that are present in the mouth do not

AFigure 30-2 A, In natural teeth, the structural continuity of tooth and periodontaltissues is the product of a well-integrated series of developmental events.

necessarily act as periimplant pathogens. Weregard available evidence as circumstantial at best,more particularly because it appears to ignore thelikelihood of a compromised healing or osseointe-grated response, which could eventually succumbto the diverse and unpredictable magnitudes, fre-

quencies, and durations of occlusal loading. In thiscontext, interfacial cracks may result, and thesemay eventually coalesce and lead to implantmotion and in time a separation at the interface.Secondary infection is then the likely outcome,with complete loss of bony support the inevitable


Figure 30-2 cont’d B, In contrast to natural teeth, the structural continuity between anosseointegrated implant and its host site is the result of a wound-healing process and not adevelopmental one.

B

Table 30-3Differences between Teeth and Implants

Teeth Implants

Attachment mechanism (periodontal ligament) is Interfacial osteogenesis (ankylotic-like) is an induced healing the result of evolution and has not been response that is readily replicatedreplicated

Variable mobility is present; increased mobility Immobile (ankylotic-like)may be reversible

Can be intruded, extruded, or moved Cannot be intruded, extruded, or moved (ankylotic-like)In young patients, teeth continue to erupt In young patients, implants are “left behind” while

surrounding tissues changeProprioception So-called osseoperceptionHas a rich plexus of blood vessels and nerves A relative absence of such a sophisticated circulation and

in the periodontal ligament probably innervationData present to show progress of mucosal Similar data are not present

inflammation to periodontal disease


consequence. It is not surprising therefore thatfailing implants demonstrate a microorganismenvironment usually associated with periodontaldisease. At this stage of our knowledge base itmay even be tempting to conclude that the causeof implant failure is multifactorial and perhapsthat even genetic factors may play a role.However, our perception is that a reconciliationof the healing process around an implant with thetime-dependent nature of the load it is subjectedto remains the major determinant of implant suc-cess or failure. This conviction does not ignorethe fact that pathogenic microorganisms inplaque around teeth or implants may have sys-temic health implications and that plaque shouldtherefore be controlled.

SUMMARYScientifically acceptable treatment outcome timeframes for implant loading cover a spectrum ofpossibilities. This spectrum ranges from over 20years for machined commercially pure titaniumimplants and traditional surgical protocols withdelayed loading, to virtually immediate loadingones using various surgical methods of host siteimprovement and implants with roughened sur-faces. Time, and even better research that includeseconomic benefits, will ultimately determine towhat extent the complete denture will be eclipsedby the implant-supported prosthesis. In the mean-

time, there is little doubt that both techniques canaddress the edentulous individual’s needs. Bothpatients and dentists have already benefited enor-mously from this enriched spectrum of treatmentpossibilities.

ReferencesEckert SE, Parein A, Myshin HL et al: Validation of dental

implant systems through a review of literature supplied bysystem manufacturers, J Prosthet Dent 77:271-279, 1997.

Elsubeihi ES, Zarb GA: Implant prosthodontics in medicallychallenged patients: the University of Toronto experience,J Can Dent Assoc 68:103-108, 2002.

Esposito M, Hirsch JM, Lekholm U et al: Biological factorscontributing to failures of osseointegrated oral implants. II.Etiopathogensis, Eur J Oral Sci 106:721-764, 1998.

Esposito M, Hirsch J, Lekholm U et al: Differential diagnosisand treatment strategies for biologic complications and fail-ing oral implants: a review of the literature, Int J OralMaxillofac Implants 14:473-490, 1999.

Lekholm U, Zarb GA: Patient selection and preparation. InBrånemark PI, Albrektsson T, Zarb GA, editors: Tissue-inte-grated prostheses: osseointegration in clinical dentistry,Chicago, 1985, Quintessence.

Mohl ND, Zarb GA, Carlsson GE et al editors: A textbook ofocclusion, Chicago, 1988, Quintessence.

Sennerby L, Roos J: Surgical determinants of clinical success ofosseiointegrated oral implants: a review of the literature, IntJ Prosthodont 11:408-420, 1998.

Watzek G, Gruber R: Morphological and cellular parametersof bone quality, Applied Osseointegration Research, 3:3-10,2002.

Zarb GA, Schmitt A: The longitudinal clinical effectiveness ofosseointegrated dental implants: the Toronto Study. Part II:The prosthetic results, J Prosthet Dent 64:53-61, 1990.

Index

539

AAbutments

immediate denturedescription of, 132reduction of, 151, 152ftrimming, 146-147

implantcomplications of, 520height of, 520-521

loosening of, 520overdenture

attachment mechanisms, 172f, 172-173caries associated with, 46-47, 162, 174coronal reduction of tooth, 169, 171, 175endodontic status of, 168gingivitis around, 174fgold copings for retention of, 171f, 171-172hygiene of, 173location of, 167-168long-term monitoring of, 173-174loss of, 172-174maxillary teeth as, 169tperiodontal status of, 166-167preparation of, 168-173selection of, 166-173telescopic crowns for retention of, 173tooth mobility considerations, 167

Acrylic resin. See also Polymethylmethacrylatedenture base, 195denture teeth

anterior, 303description of, 19t, 195, 197-198posterior, 306

hollow obturator prosthesis capped using, 469-470shrinkage of, 404trial denture base, 254water absorption by, 425

Actinomyces, 46Adhesion, 438Adhesives

components of, 443

Adhesives (Continued)contraindications, 444-445cream vs. powder, 445definition of, 442description of, 442indications, 444-445limitations of, 447objective responses to, 443-444patient education regarding, 445-447professional attitudes toward, 447subjective responses to, 443-444

Age. See also Older adultsconcealment of, 30coordination declines associated with, 21depression incidence based on, 22harmony considerations based on, 373-375, 374fpersonal appearance concerns, 30-31

Aging. See also Older adultsbone loss associated with, 61concealment of, 30edentulism and, 25energy needs, 59global changes in, 24, 25tincome levels, 24jaw movement changes, 27-28life expectancy changes, 24natural appearance changes, 343-344nutrition changes, 28personal appearance concerns, 30-31population changes, 24, 25tpremature, 343smell sense decreases, 28, 58taste sense decreases, 28, 58teeth color changes, 30

Ala nasi, 348fAla-tragus line, 262, 262fAlcohol abuse, 60-61Alginate, 221Alkaline hypochlorites, for denture cleaning, 204, 205tAluwax, 339-340, 406Alveolar bone loss, 61Alveolar groove, 237fAlveolar process

description of, 11Page numbers followed by “f ” denote figures, “b” denote boxes, and“t” denote tables.

Alveolar process (Continued)direction of, 352

Alveolar ridgeaugmentation of, 116hamular notch obliteration, 116hyperplastic, 102-103integrity of

existing teeth for maintaining, 160periodontal ligament effects, 12, 160

residual. See Residual ridgeresorption of. See Residual ridge, resorption ofvestibuloplasty of, 110-111, 113, 116, 118f-119f

Alveolingual sulcus, 91, 237f, 241, 243Amylase, 15Angular cheilitis

Candida-associated stomatitis and, 38clinical features of, 28, 29f, 36, 37f

Angulus oris, 348f-349fAnterior teeth

artificialanteroposterior positioning of, 309f, 351-356arch form of, 363-364articulator programming for, 294incisal wear and age, 368-369, 369f-370finclination of, 361f, 361-362long axes of central incisors, 364-365, 366fmandibular, 311-313maxillary

description of, 310-311labiolingual inclination of, 369, 371f

observation of, after removal of trial denture base, 354,358f

placement of, 306-307, 310frepositioning of, 350rotational positions of, 370selection of

characterization of selected teeth, 303-304, 304f-307fcolor, 301-302, 351considerations for, 351description of, 298environmental setting, 301gingiva considerations, 303mold for, 302, 302fpatient preference considerations, 303patient’s involvement in, 299-303photographs used for, 300, 300fshade guides, 298, 299f, 302size, 302timing of, 302-303

trial denture base, 359vertical orientation of, 356-361, 359f-360f

immediate denturedecoronation of, 153setting of, 144, 146-147

naturalirregularities of, 370, 372labiolingual inclinations of, 371f

Anteroposterior compensating curvefor balanced articulation, 318, 318ffor lingualized articulation, 322

Archanteroposterior position of, 309description of, 258-259harmony of, 362-364, 363f-364fmandibular, 259-260, 260f, 365maxillary, 260-261, 261fmidline of, 310f, 365ovoid, 363, 363f-364fsingle edentulous, 427soft tissue considerations, 259square, 362, 363f-364ftapering, 362, 363f-364f

Articulating paper, 410f-411fArticulator

centric relation verification using, 331-335definition of, 291Dentatus, 339-342, 401ferrors in, 295hinge, 291, 292fjaw movements recorded using, 265jaw relation records transferred to, 284-285mandibular relation to, 291, 291fmaxillary relation to, 289-290, 290focclusal errors corrected on, 404-405, 405fprogramming of

arbitrary settings, 295-296condylar elements, 294description of, 294incisal elements, 294-295, 295f

protrusive interocclusal records, 338-342remounting on

cast for, 399, 400finterocclusal records for, 405-406

selection of, 292-294semiadjustable, 293ftypes of, 291-292Whip Mix, 338-339

Artificial teeth. See Denture teethAsymmetrical symmetry, 366, 368f

BBalanced occlusion, 414Basal seat

changes in, 473irritation in, 425modifications in, 476

Basal surface errors, in denture, 402-404, 403f-404fBase, denture. See Denture baseBasocellular carcinoma, 42fBeeswax occlusion rim, 331, 331fBilabial speech sounds, 381-383, 382tBiological price, 100Biomaterials

copolymers, 190-191denture-lining

description of, 198long-term soft liners, 200, 200bplasticized acrylics, 200-201, 203bself-administered home relines, 200short-term soft liners, 198-200, 199b

540 Index

Biomaterials (Continued)silicone soft liners, 201

denture teethacrylic resin, 195, 197-198, 198tcomposite resin, 197description of, 195porcelain, 197, 198t, 306requirements of, 197b

requirements, 191bBite force

adhesives effect on, 444age-related declines in, 47amount of, 10denture effects, 417teeth effects, 9

Boil-out, 149, 150fBoley gauge, 277, 280f, 302fBone

calcium for, 61-62characteristics of, 87health assessments of, 87-89Lekholm-Zarb classification of, 533fmetabolic diseases of, 87-88older adult changes in, 26-27, 61quality of, effect on implants, 532-533quantity of, effect on implants, 533-534radiographic assessments of, 80remodeling of, 45turnover of, 27vitamin D for, 62

Bone graftingautogenous, 533-534healing phase before implant

placement, 533mandible, prostheses for, 466-467, 467f

Bone morphogenetic proteins, 532Border molding

mandibular dentures, 246-248maxillary dentures, 225-227, 228f

Boxingmandibular impressions, 249, 249fmaxillary impressions, 229, 230fmaxillofacial prostheses, 468

Branemark, Per Ingvar, 4, 484, 528Bruxism, 16Buccal flange, 237f-238f, 421Buccal frenum, 216, 217f, 237fBuccal notch, mandibular, 237f-238fBuccal shelf, 232-233, 234f, 237fBuccal vestibule

anatomy of, 217, 237f-238f, 238-239impression taking of, 223

Buccinator, 216, 239, 261, 348Burlew foil, 152Burning mouth syndrome

description of, 42-43etiologic factors of, 43b, 43-44management of, 44psychogenic factors, 43b, 43-44

CCalcium

absorption reductions, 61-62bone health and, 61-62dietary reference intake recommendations for, 61, 62tfood sources of, 62supplementation, 62woman’s intake of, 61

Candida infectionssigns of, 86stomatitis, 35-40

Caninesmandibular, 311, 371fmaxillary, 311, 371f

Caninus, 352fCarborundum paste, 412Caries

fluoride prophylaxis, 174overdenture-related, 46, 162, 174

Castdiagnostic

description of, 83immediate denture uses of, 130, 132focclusion evaluations, 130, 132fvertical dimension of occlusion determined using, 275,

276fmandibular denture, 256fmaxillary denture, 229, 230f, 255fremounting, 399, 400f

Cast metal alloys, for denture base, 205-207, 206, 206fCemento-enamel junction, 391Central incisors

long axes of, 364-365, 366fmandibular, 371fmaxillary, 309-311, 369mesial rotation of, 373fsquare arch, 362, 364f

Central pattern generators, 380Centric occlusion

correction of errors in, 410fdescription of, 19, 90, 283

Centric relationcorrection of, 331, 331fdefinition of, 18-19, 92, 283errors in, 330, 331finterocclusal record of, 406-407record of, 265-266, 288-289significance of, 284verification of

description of, 408-409extraoral articulator method for, 331-335intraoral observation of intercuspation, 330-331

Characterization, of denture teeth, 303-304, 304f-307fCheeks, muscular evaluations of, 93Chemically activated resins, for denture base, 191b, 193-194,

196tChewing

adhesives effect on, 444age-related changes in, 28

Index 541

Chewing (Continued) denture-wearing effects on efficiency of, 47, 57, 416-417teeth primarily used for, 16

Chlorhexidine, 47Choking, 59Christensen phenomenon, 284Cigarette smoking, 496, 529-531Cleansers, denture. See Denture cleansersCobalt-chromium alloys, for denture base, 205-206Coble device, 282fCohesion, 438-439Color of teeth

age-related changes, 30anterior teeth selection, 301-302, 351

Communicationdoctor/patient, 183-184effective, 181-183environment effects, 180functions of, 180-181history of, 178-179importance of, 180-181model of, 178-180nonverbal language, 182overview of, 177-178physical reactions, 182physiology of, 179f, 179-180schematic diagram of, 179fscope of, 178self-awareness and, 181

Complete dentureadaptive responses, 20-22, 386adjustments

denture base, 420-424occlusal, 420

advantages of, 514banterior teeth for. See Anterior teetharticulator for, 292-294basal seat

changes in, 473irritation in, 425modifications in, 476

base of. See Denture basebehavioral responses, 20-22bone loss associated with, 12border tissues for, 90-91centric relation for, 18-19contraindications, 486bdentists’ evaluation of, 400-401disadvantages of, 514bdiscomfort associated with, 16-17follow-up care, 419-426friends’ evaluation of, 401-402inaccuracies in, 402loosening of, 420, 423, 473maintenance of, 471maladaptive, 3-4malnutrition risk factors, 64bmandibular. See Mandibular denturemandibular process height changes, 18

Complete denture (Continued)mastication effects, 15-16masticatory movements, 16maxillary. See Maxillary denturemucosal support for, 10-11muscle activity effects, 21natural teeth vs., 16neurological diseases and, 444nutrition care for. See Nutritionocclusal surface of, 252, 253f, 440focclusion for

balancing contacts, 324-325, 326fdescription of, 19, 269maximum intercuspation, 324, 324fmodifications, 324-327protrusive contact prevention, 325-327, 327fschemes, 313-323working contacts, 324-325, 326f

older adult use of, 25oral environment, 34parafunctional habits, 16patient instructions regarding

appearance, 416educational materials, 418-419individual differences, 416mastication, 416-417oral hygiene, 417-418overview of, 414, 416residual ridge preservation, 418speech changes, 417

patients’ evaluation of, 401periodic recalls to evaluate, 426polished surface of

anatomical portion, 390-391art portion, 390description of, 252, 254f, 439fwaxing of, 390-392

posterior teeth for. See Posterior teethpresumptions regarding use of, 484fresidual ridge. See also Residual ridge

description of, 11-13reduction of, 17-18

retention ofadhesion, 438adhesives for. See Denture adhesivesatmospheric pressure, 441cohesion, 438-439description of, 12-13factors that affect, 437-442gravity, 442interfacial force effects, 437-438oral and facial musculature effects, 439-441parallel walls for, 442psychological effects on, 14rotational insertion paths for, 441surface tension effects, 437tongue base, 441undercuts, 441

rotary movement of, 473

542 Index

Complete denture (Continued)sequelae caused by

burning mouth syndrome. See Burning mouth syndromecaries, 46control of, 49denture irritation hyperplasia, 40, 41f, 418flabby ridge, 40, 41fgagging, 44masticatory muscle atrophy, 47-48nutritional deficiencies, 48-49oral cancer, 42residual ridge resorption, 44-45, 45bstomatitis. See Stomatitistraumatic ulcers, 41, 42f

speech adaptation to, 386stability of, 389surfaces of, 252, 253f, 439f-440ftissue support for, 12tooth-supported, 174-175

Composite resin posterior denture teeth, 306Concrete expression, 183Condyles

articulator programming for, 294guidance mechanisms for, 337-338movement of, 269, 284registering of path of, 337

Coronal reduction of abutment tooth, 169, 171, 175Counseling, nutrition, 64-68Cross-linked polymers, 191Custom impression trays

immediate denturessectional, 134-137, 139f-143fsingle full arch, 133-134, 137f-138ftwo-tray, 134-137, 139f-143f

maxillary dentures, 223, 225-230

DData collection and recording techniques

description of, 77-78diagnostic casts, 83intraoral videography, 80measurements, 83palpation, 82-83preextraction radiographs, 79questions, 78radiography, 80-82, 81frecords, 78-79visual observations, 79-80

Deflasking, 398Deglutition

description of, 9occlusion and, 19reflex, 19

Dehydration, 58Dental arch

anteroposterior position of, 309description of, 258-259harmony of, 362-364, 363f-364fmandibular, 259-260, 260f, 365

Dental arch (Continued)maxillary, 260-261, 261fmidline of, 310f, 365ovoid, 363, 363f-364fsoft tissue considerations, 259square, 362, 363f-364ftapering, 362, 363f-364f

Dentatus articulator, protrusive interocclusal records for,339-342

Dentist. See DoctorDentition. See also Teeth; specific teeth

adaptive mechanisms, 15development of, 14, 14f

Denturecomplete. See Complete denturedentists’ evaluation of, 400-401errors in, 402-405existing

evaluation and examination of, 84, 502implant-supported overdenture-related evaluations of, 502inadequate, tooth loss secondary to, 260-261vertical dimension of occlusion determined from

measurements of, 277, 280ffriends’ evaluation of, 401-402immediate. See Immediate denturesmaladaptive behavior, 483-484mandibular. See Mandibular denturemaxillary. See Maxillary denturepatients’ evaluation of, 401patient’s reaction to, 183single. See Single denturessurfaces of, 252, 253f

Denture adhesivescomponents of, 443contraindications, 444-445cream vs. powder, 445definition of, 442description of, 442indications, 444-445limitations of, 447mechanism of action, 443objective responses to, 443-444patient education regarding, 445-447professional attitudes toward, 447subjective responses to, 443-444

Denture baseadhesion, 438adjustment of, 420-424biomaterials for

cast metal alloys, 205-207, 206b, 206fcopolymers, 190-191requirements, 191bresins. See Denture base, resinstitanium, 206-207

cured, shaping and polishing of, 398-399description of, 13evaluation of, 472fracture of, 434ideal, 191b

Index 543

Denture base (Continued)labial considerations, 94resins

characteristics of, 191bchemically activated, 191b, 193-194, 196tlight-activated, 194-195, 196tmicrowave-activated, 194, 196tmodified acrylic, 195polymethylmethacrylate

description of, 190heat-activated, 191-193polymerization of, 190, 192rubber-reinforced, 195

stresses on, 192-193visible-light-activated, 190, 194-195

tissue displacement beneath, 16trial

acrylic, 254characteristics of, 252resin, 252, 256fsize of, 358“sprinkle-on” method for, 252, 256fwax template for, 252, 255f

Denture-bearing areasmandible

anatomic considerationsalveololingual sulcus, 241, 243buccal shelf, 232-233, 234f, 237fbuccal vestibule, 237f-238f, 238-239genial tubercles, 234, 236labial vestibule, 236-238, 237fmental foramen, 233f, 234mylohyoid muscle, 239-241, 240fmylohyoid ridge, 234, 236fresidual ridge crest, 232, 233fretromylohyoid fossa, 237f-238f, 241sublingual glands, 241, 242fsupporting structures, 232-236torus mandibularis, 236, 237f

description of, 232distal extension, 239, 240fexisting denture effects on, 436fimpressions

border molding, 246-248boxing, 249, 249fcustom tray for, 245-248, 246ffinal, 248-250preliminary, 243-245, 244fremaking of, 249-250stock tray for, 243, 245f

limiting structures, 236-243peripheral structures, 236-243supporting structures

anatomy of, 232-236shape of, 234-236

maxillaryanatomic considerations

buccal vestibule, 217, 223hard palate, 211-212, 212f

Denture-bearing areas (Continued)incisive foramen, 214labial vestibule, 215-216, 216f, 223maxillary tuberosity, 214, 214fpterygomandibular raphe, 217, 220fresidual ridge, 212-214sharp, spiny processes, 214supporting structures, 211-214torus palatinus, 214, 215fvibrating line, 217, 219f

description of, 211impressions

border molding, 225-227, 228fboxing, 229cast created from, 229, 230fcustom tray for, 223, 225-230elastomeric materials for, 225final, 225-230irreversible hydrocolloid for, 221, 224fmetallic oxide pastes for, 225mouth preparation for, 219mucostatic, 220preliminary, 221-225principles of, 218-219procedures, 219-221silicone putty for, 221stock tray for, 221, 222ftechnique for, 222-225, 224f-225ftrays for, 220-222

limiting structures, 214-217peripheral structures, 214-217supporting structures for, 211-214

nonsurgical preparations ofjaw exercises, 102nutrition, 102occlusal correction of old prosthesis, 102rest, 100-102tissue-conditioning materials, 100

surgical preparations ofcorrection of function-precluding conditions, 102-110description of, 102enlargement of areas, 110-111, 113, 116exostoses, 107, 110f-111fgenial tubercles, 107, 112fjaw size discrepancies, 107, 114f-115fmental foramen pressure, 108-110objectives, 102bridge augmentation, 116tooth roots replaced with osseointegrated implants, 117,

120f-121ftori removal, 104, 107, 108f-109fvestibuloplasty, 110-111, 113, 116, 118f-119f

Denture cleanserschemical, 204commercially available materials, 203description of, 202-203dilute acids, 205tdisadvantages of, 205thypochlorite solutions, 204, 205t

544 Index

Denture cleansers (Continued)mechanical techniques, 203-204oxygenating, 204, 205tpowder/paste, 205trequirements of, 203b

Denture-lining materialsdescription of, 198plasticized acrylics, 200-201, 203bself-administered home relines, 200soft liners

bacterial colonization prevention, 201-202chemically activated acrylic resin, 200-201long-term, 200, 200bpermanent, 201-202, 202fshort-term, 198-200, 199bsilicone, 201

Denture teethacrylic resin, 195, 197-198, 198t, 303anterior

anteroposterior positioning of, 309f, 351-356arch form of, 363-364articulator programming for, 294characterization of selected teeth, 303-304, 304f-307fcolor, 301-302, 351correct positioning of, 354, 356fdescription of, 298environmental setting, 301gingiva considerations, 303horizontal orientation of, 351-356incisal wear and age, 368-369, 369f-370finclination of, 361f, 361-362lip support by, 352-354, 355flong axes of central incisors, 364-365, 366fmandibular, 311-313maxillary

description of, 310-311labiolingual inclination of, 369, 371f

mold for, 302, 302fobservation of, after removal of trial denture base, 354, 358fpatient preference considerations, 303patient’s involvement in, 299-303photographs used for, 300, 300fplacement of, 306-307, 310frepositioning of, 350rotational positions of, 370selection of

characterization of selected teeth, 303-304, 304f-307fcolor, 301-302, 351considerations for, 351description of, 298environmental setting, 301gingiva considerations, 303mold for, 302, 302fpatient preference considerations, 303patient’s involvement in, 299-303photographs used for, 300, 300fshade guides, 298, 299f, 302size, 302timing of, 302-303

Denture teeth (Continued)shade guides, 298, 299f, 302size, 302timing of, 302-303trial denture base, 359vertical orientation of, 356-361, 359f-360f

arrangement ofbalanced articulation

mandibular teeth, 318-320maxillary teeth, 320

description of, 313-314lingualized articulation, 321-323monoplane articulation, 320-321patient’s acceptance of, 377-378

buccolingual width of, 304composite resin, 197description of, 195mesiodistal length of, 304-305molds for

anterior teeth, 302, 302f, 308tposterior teeth, 321-322

overdenture considerations, 303porcelain, 197, 198t, 303posterior

acrylic resin, 306arranging of

anatomical, 315-318bilateral balanced articulation evaluations after, 317-318description of, 313, 314flingualized articulation, 321-323number of teeth, 314

buccolingual position of, 313buccolingual width, 304criteria, 304description of, 304mandibular

balanced articulation arranging of, 318-320first molar, 319first premolar, 319lingualized articulation arranging of, 321-323second molar, 319-320setting of, 315-317

maxillarybalanced articulation arranging of, 320first molar, 320first premolar, 320lingualized articulation arranging of, 321-323second molar, 320setting of, 317

mesiodistal length, 304-305molds for, 321-322occlusal forms for, 314porcelain, 306premolars, 315-317, 316fsetting of, 314vertical height of the facial surfaces, 306

requirements of, 197bselection of, 351

Depression, 22

Index 545

Depressor septi nasi, 349fDiagnosis

biomechanical considerations, 89-92border tissue evaluations, 90-91data collection and recording techniques

description of, 77-78diagnostic casts, 83intraoral videography, 80measurements, 83palpation, 82-83preextraction radiographs, 79questions, 78radiography, 80-82, 81frecords, 78-79visual observations, 79-80

findingsinterpreting of, 94problem list created using, 98

health assessments. See Health assessmentshistory-taking for. See History-takingidentification of pathoses, 77muscle tone assessments, 92muscular development assessments, 92-94patient familiarity, 73problem identification, 73-74saliva assessments, 91-92setting for, 73specific observations

existing dentures, 84soft tissue health, 84-87

summary of, 94, 95bvisual perception for, 73, 79-80

Diagnostic casts. See also Castdescription of, 83immediate denture uses of, 130, 132focclusion evaluations, 130, 132fvertical dimension of occlusion determined using, 275, 276f

Dietassessment of, 65counseling regarding, 64-68evaluative form for, 67ffat intake in, 59protein intake in, 59-60for tooth extraction patients, 68-69

Diffuse atrophic glossitis, 37fDilator naris, 349fDiscontinuity mandibulectomy, 464-466, 466f

EEccentric relation records

description of, 284, 337interocclusal, 338protrusive

for Dentatus articulator, 339-342for Whip Mix articulator, 338-339

recording of, 289Ecology, oral, 535-536Edentulism

behavioral responses, 20-22

Edentulism (Continued)decreases in, 25dentist’s view of, 6description of, 3distribution of, 25esthetic changes, 20etiology of, 6facial skeleton changes secondary to, 6-8, 7f-8ffacts regarding, 6food intake effects, 56-58gastrointestinal functioning effects of, 58-59morphological changes associated with, 20bobturator prosthesis in, 454, 454fin older adults

bone mass changes, 26-27distribution of, 25impact of, 25mucosal effects, 25-26salivary changes, 27

oral cancer and, 26perceptions associated with, 6, 8, 485-486prevalence of, 25temporomandibular disorders in. See Temporomandibular

disordersElastomeric impression materials, 225Electropalatography, 386, 386fEmotional factors, 21-22Endosseous dental implants, 483Environment

communication affected by, 180internal, 180

Epulis fissuratum, 77, 86, 103Errors

basal surface, 402-404, 403f-404focclusal

in anatomical teeth, 409-412articulator correction of, 404-405elimination of, 409-414, 472mesiodistal relationship, 412in nonanatomical teeth, 412-414

treatment of, at insertion, 402Esthetics

edentulism effects on, 20existing denture, 84

Estrogen, 531Existing dentures

evaluation and examination of, 84, 502implant-supported overdenture-related evaluations of, 502inadequate, tooth loss secondary to, 260-261vertical dimension of occlusion determined from

measurements of, 277, 280fExostoses, 107, 110f-111f

FFace bow

description of, 285-287, 286fmandible technique, 288maxilla technique, 287-288

Face height, 17, 18f

546 Index

Facial and functional harmonyanterior teeth

arch form of, 363-364harmony in composition of, 362-369horizontal orientation of, 351-356inclination of, 361f, 361-362patient’s acceptance of arrangement of, 377-378vertical orientation of, 356-361, 359f-360fvertical overlap reductions, 375-376, 377f

denture teeth selectionanterior teeth. See Facial and functional harmony, anterior

teethdescription of, 351

description of, 343facial landmarks, 345-347, 348f-350ffacial support considerations, 347-348, 350, 352f-353fguidelines for developing, 350-377incisal guidance and esthetics, 375-377muscles involved in, 347-348, 350, 352f-353fnatural appearance, 343-345tooth position refinement

anterior teeth variations, 369-370description of, 369harmony, 372-373irregularity of teeth, 370, 372spatial harmony, 372-373

Facial landmarks, 345-347, 348f-350fFacial profile line, 367-368, 368fFeedback, 380Fixed prostheses, implant-supported

abutment considerations, 510-511advantages of, 514bbone quality considerations, 511, 513cementation of, 525-526complications of

insertion-related, 523structural-related, 525f

contraindications, 511bdesign considerations for, 510-513disadvantages of, 514binsertion-related complications, 523local considerations for, 511blocation of, 511patient selection for, 510presurgical treatment, 513prosthetic considerations for, 511bprosthodontic protocol, 513-514radiographic evaluations, 510, 512fsmile line considerations, 513speech effects, 511bsurgical stages for, 513

Flabby ridge, 40, 41fFlasking, 149, 392-393Food intake

assessment of, 65dental status effects on, 56-58denture-wearing influences on, 57implant effects on, 57-58

Fordyce’s granules, 85

Fracturedenture base, 434implant, 526

Frenectomy, 104Frenum

anatomy of, 103-104buccal, 216, 217f, 237flabial, 216f, 236, 237f, 238lingual, 237f, 241

Functional impression technique, for relining or rebasing,478-480

GGagging, 44, 93, 422Gastrointestinal system, edentulism effects on functioning

of, 58-59Genial tubercles, 107, 112f, 234, 236Gingival disease, 162Gingival irritation, 174Gingival line, 391fGingivitis, 174fGold copings, for overdenture abutment retention, 171f,

171-172Graphic records, 287

HHamular notches

anatomy of, 91, 116, 217, 218flesions of, 420

Hard palateanatomy of, 211, 212f, 449border molding of, 452-453evaluation of, 85maxillary obturator prosthesis for defects of

anterior teeth positioning, 458definitive, 457-459edentulous, 454, 454fhypernasality associated with, 460impressions, 457, 457findications, 453interim, 455-457nasal reflux, 459-460palatal contour evaluations, 458retention problems, 459, 459fsurgical, 453-454

Harmonyage of patient and, 373-375, 374farch form, 363-364incisal wear and age, 368-369, 369f-370flong axes of central incisors, 364-365, 366fopposing lines of labial and buccal surfaces, 365-367, 368fpersonality factors, 373profile line of face, 367-368, 368fsex-based variations, 373smile line, 365, 367fspace between teeth, 372-373tooth position, 372-373

Health assessments, 85-89Heat-activated polymethylmethacrylate, 191-193

Index 547

Herbal supplementation, 64Hierarchy of needs, 180Hinge axis

description of, 283records of, 285

History-taking, 74-77Hollow obturator prosthesis, 469-470, 470fHydroxyapatite, 493Hygiene, oral

overdenture abutments, 173patient instructions regarding, 417-418

Hypernasalitymaxillary obturator prosthesis, 460soft palate obturator prosthesis, 461

Hyperplastic ridge, 102-104Hypochlorite solutions, for denture cleaning, 204, 205tHyposalivation, 27

IIatrosedative interview

description of, 184elements of

exploring the problem, 185-187interpreting and explaining the problem, 187offering solution to problem, 187-188recognizing and acknowledging of problem, 184-185

Immediate denturesadjunctive care, 130-131advantages of, 124-125anterior ridge undercut, 124anterior teeth

decoronation of, 153setting of, 144, 146-147

candidate for, 126f-127fclinical and laboratory procedures for

anterior teeth setting, 144, 146-147boil-out, 149, 150fcustom impression trays

sectional, 134-137, 139f-143fsingle full arch, 133-134, 137f-138ftwo-tray, 134-137, 139f-143f

description of, 132diagnostic casts, 145ffinishing, 151flasking, 149impressions, 133, 134f-136fjaw relation

record of, 137, 139-140, 145fverifying of, 141

loose teeth, 133posterior limit records, 137, 139-140, 145fprocessing, 151setting the denture teeth, 141-147surgical templates, 151, 152ftooth extractions, 132-133try-in, 141, 146f, 148fwax contouring, 148-149

contraindications, 125conventional

Immediate dentures (Continued)advantages and disadvantages of, 125definition of, 123diagnostic casts, 145fimpressions for, 133, 136findications for, 125-126, 128tinterim denture vs., 128trelining, 155restorations completed before, 131sectional custom impression tray for, 134-137, 139f-143fsingle full arch custom impression tray for, 133-134,

137f-138fdefinition of, 123, 130bdisadvantages of, 124-125endodontic consultations, 131imperfect results, 155implant-retained overdentures placed under

case study of, 157f-158fdescription of, 158

informed consent for, 130binsertion of

follow-up care after, 153, 155patient instructions after, 153postoperative care, 153, 154fridge resorption after, 155surgical technique for, 151-153, 152fsutures, 151, 152f

interimadvantages and disadvantages of, 125conventional denture vs., 128tdefinition of, 123diagnostic casts, 145fimpressions for, 133, 135findications for, 126, 128treplacement denture for, 155restorations completed after, 131

mandibularcasts for, 136f-137f, 143ffull-arch custom impression trays for, 138fpreliminary impressions for, 135frecord base for, 144fsectional custom impression tray for, 140f

maxillarycasts for, 136f-137f, 143ffull-arch custom impression trays for, 138fpreliminary impressions for, 135frecord base for, 144fsectional custom impression tray for, 140f

overdenture abutments, 132overdenture attachment, 155, 156f, 161prognosis, 130referrals, 130-131restorations completed before, 131selection considerations, 125-126tooth-supported, 175treatment planning for

existing teeth evaluations, 129explanation to patient, 127, 129blip evaluations, 129

548 Index

Immediate dentures (Continued)occlusion analysis, 130oral examination, 127, 129oral prophylaxis, 131tooth modifications, 130, 131f

well-being benefits, 124Immediate load implants, 516Immune system, wound healing and, 68Implant(s)

complications and problems associated withabutment loosening, 520abutment screw fracture, 526bleeding, 517-518dehiscence, 519description of, 516-517framework try-in, 523impressions, 521-522infection, 518postinsertion, 524-527prosthodontic-related, 520-523screw fractures, 524-525structural, 524-527surgically related, 517-520suture removal, 518try-in, 522-523

factors that affect success and failure ofbed, 496biocompatibility, 492-493bone quality, 532-533bone quantity, 533-534description of, 492design, 493host bone response. See Implants, host bone responseloading conditions, 496-497smoking, 496, 529-531surface, 493-495surgical technique, 496

failure ofpostloading, 536study findings, 529t

fracture of, 526framework try-in, 523host bone response to

description of, 529irradiation therapy effects, 531smoking effects, 530-531systemic conditions that affect, 532

immediate loading of, 516loading of, 496-497, 516, 534-536long-term studies of, 528osteoporosis considerations, 531roughness of surface, 493-495surface of, 493-495teeth vs., 538t

Implant prosthodonticsadvances in, 484-485description of, 4-5reasons for popularity of, 485treatment outcome determinants in, 487t, 487-488, 530t

Implant-supported fixed prosthesesabutment considerations, 510-511advantages of, 514bbone quality considerations, 511, 513cementation of, 525-526complications of

insertion-related, 523structural-related, 525f

contraindications, 511bdesign considerations for, 510-513disadvantages of, 514binsertion-related complications, 523local considerations for, 511blocation of, 511patient selection for, 510presurgical treatment, 513prosthetic considerations for, 511bprosthodontic protocol, 513-514radiographic evaluations, 510, 512fsmile line considerations, 513speech effects, 511bsurgical stages for, 513

Implant-supported overdenturesadvantages of, 514banchorage devices for, 504, 506, 506bbars for, 506, 507fcase study of, 157f-158fcomplications of

insertion-related, 523-524structural-related, 525f

considerations for, 499denture design, 504description of, 158disadvantages of, 514bexclusion criteria for, 499-500, 500bimpression techniques, 504inclusion criteria for, 499b, 499-500insertion-related complications, 523-524maintenance of, 506-508mandibular, 502, 503fosseointegration phase, 502-503presurgical evaluation, 500-503prosthodontic procedures, 503-506radiographic evaluations, 500-502retentive devices for, 504, 506, 506bsingle-attachment retentive system for, 506, 507fsurgical procedure for, 502-503treatment goals, 498-499treatment planning, 500b, 500-503

Implant-supported prosthesisadvantages of, 49case study of, 157f-158fdescription of, 4-5, 5t, 483fixed prosthesis. See Implant-supported fixed prosthesesillustration of, 120fmaxillofacial, for edentulous patient, 467, 468f-469fobjectives of, 486patient considerations, 485-487periodontal ligament considerations, 486

Index 549

Impressionschairside, 480complications of, 521-522functional, 478-480immediate denture, 133, 134fimplant-supported overdentures, 504mandibular denture-bearing areas

border molding, 246-248boxing, 249, 249fcustom tray for, 245-248, 246ffinal, 248-250preliminary, 243-245, 244fremaking of, 249-250stock tray for, 243, 245f

materials for making, 133maxillary denture-bearing areas


objectives of, 218obturator prosthesis, 457, 457fprinciples of, 218-219relining, 476-480static, 476-478

Incisal guide table, for articulator programming, 294-295, 295f

Incisal wear and age, 368-369, 369f-370fIncisive foramen, 213f, 214Incisive papilla

anatomy of, 260, 261fanterior teeth placement guided by, 306-307, 310fvertical dimension of occlusion measurements, 276

Incisorscentral

long axes of, 364-365, 366fmandibular, 371fmaxillary, 309-311, 369mesial rotation of, 373fsquare arch, 362, 364f

lateralharmony of, 375, 375fmandibular, 311, 371fmaxillary, 311, 370

Inflammatory papillary hyperplasia, 86Inner dialogue, 182

Intercuspationintraoral observation of, for centric relation verification,

330-331maximum, 324, 324f

Interfacial force, 437-438Interocclusal distance insufficiencies, 425-426Interocclusal records

centric relation, 406-407description of, 287eccentric, 338lateral, 338plaster, 338protrusive


remounting of denture using, 405-406Intraoral radiography, 82Irradiation, effects on osseointegration, 496, 531Irreversible hydrocolloid, 221, 224fIrritation hyperplasia, denture-related, 40, 41f, 418

JJaw movement. See also Mandible, movement of

age-related changes in, 27-28articulator for recording, 265condylar, 269, 284description of, 268-269envelope of motion, 271-272, 272f-273ffactors that regulate, 269muscles involved in, 270neuromuscular regulation, 270-271opposing tooth contact influences on, 269rotational, 269sagittal plane, 269, 269ftemporomandibular joint effects on, 269-270tracing of, 271ftranslatory, 269

Jaw relationsarticulator for recording, 265assessments of, 89-92horizontal

centric relation. See Centric relationdescription of, 283terminology associated with, 283-284

maxillomandibular, 274-283record of, 137, 139-140, 145frecords of

centric relation records, 265-266, 288-289face bow, 285-287graphic records, 287hinge axis, 285horizontal, 283-284interocclusal, 287mandibular movement. See Mandible, movement ofmaxillomandibular relations, 274-283transfer to articulator, 284-285vertical dimension of occlusion. See Vertical dimension of

occlusionrest position

550 Index

Jaw relations (Continued)description of, 272-274, 274fphysiological, 277-278, 281fregistration of, 277-278

size discrepancies in, 107, 114f-115fin swallowing cycle, 280vertical. See Vertical dimension of occlusion

“Jiffy” denture, 123-124

KKinematic analysis of speech, 386

LLabial flange, 238fLabial frenum, 216f, 236, 237f, 238Labial notch, 237fLabial sulci, 90Labial vestibule

anatomy of, 215-216, 216f, 236-238, 237fimpression taking of, 223

Labiodental speech sounds, 382t, 383Lamina propria, 211Lateral incisors

harmony of, 375, 375fmandibular, 311, 371fmaxillary, 311, 370

Lateral relations, 335-336Lekholm-Zarb classification, 533fLevator anguli oris, 216Light-activated resins, for denture base, 194-195, 196tLiners, soft

bacterial colonization prevention, 201-202chemically activated acrylic resin, 200-201long-term, 200, 200bpermanent, 201-202, 202fshort-term, 198-200, 199bsilicone, 201tissue tolerance to, 202

Lingual flange, 440Lingual frenum, 237f, 241Lingualized occlusion, 412-413Lingual notch, 238fLinguoalveolar speech sounds, 382t, 384-385Linguodental speech sounds, 382t, 383-384Linguopalatal speech sounds, 382t, 385Linguovelar speech sounds, 382t, 385Lips

age-related changes, 28, 30f, 261, 261f, 343-344anatomic variations in, 346, 348fanterior teeth support of

correct positioning, 355fdescription of, 352-354excessive support, 354, 357fvertical orientation determinations, 357-358

contours of, 345immediate denture evaluations, 129incorrect contouring of, 353flower

smile line of, 365, 367f

Lips (Continued)vertical orientation determinations, 357-358

muscles ofanatomy of, 216, 238evaluation of, 93-94

orbicularis oris, 216, 236, 309-310, 347-348, 349fspeech-related movement of, 354f, 356upper

estimating length of, in relation to residual ridge, 357, 359fincline of, 347, 351f

vertical dimension of occlusion increases for, 279Listening, 182Loading

effects of, 9implant, 496-497, 516, 534-536masticatory, 10occlusal forces, 534prosthodontic, 534-536responses to, 101f

MMagnesium, 60Malnutrition. See also Nutrition

causes of, 48in older adults, 28, 56risk factors, in denture wearers, 64bsigns and symptoms of, 56xerostomia and, 48b, 58

Malocclusion, 86Mandible. See also Jaw movement

anatomy of, 232-236, 233farticulator relation of, 291, 291fbone-grafted, prostheses for, 466-467, 467fbone mass in, 61bone quality in, 532bone resorption, 86face bow technique, 288movement of

alterations in, 451-452description of, 268-269envelope of motion, 271-272, 272f-273ffactors that regulate, 269muscles involved in, 270neuromuscular regulation, 270-271opposing tooth contact influences on, 269rotational, 269sagittal plane, 269, 269ftemporomandibular joint effects on, 269-270tracing of, 271ftranslatory, 269types of, 269

resection ofdescription of, 451-452prostheses for, 463-467

residual ridge ofparallelism of, 276-277resorption of, 235f

rest position ofdescription of, 272-274, 274f

Index 551

Mandible (Continued)physiological, 277-278, 281fregistration of, 277-278

retromolar pad of, 220f, 237f-238f, 239, 240f, 263, 264fridge resorption, 90

Mandibular arch, occlusion rim designed for, 259-260, 260fMandibular dentures

immediatecasts for, 136f-137f, 143ffull-arch custom impression trays for, 138fpreliminary impressions for, 135frecord base for, 144fsectional custom impression tray for, 140f

impressionsborder molding, 246-248boxing, 249, 249fcustom tray for, 245-248, 246ffinal, 248-250preliminary, 243-245, 244fremaking of, 249-250stock tray for, 243, 245f

loss of bone structure effects on, 473-474, 475fremounting of, 407-408, 408frotational movement of, 473-474, 475fsingle, 434-435

Mandibular molars, 317, 319-320, 322-323, 431fMandibular overdentures, 162, 167fMandibular tori

definition of, 88surgical removal of, 104, 108f

Mandibulectomydiscontinuity, prostheses for, 464-466, 466fedentulous, 466marginal, prostheses for, 463f-464f, 463-464

Marginal mandibulectomy, 463f-464f, 463-464Maslow, Abraham

hierarchy of needs, 180human nature as viewed by, 181self as defined by, 181

Masticationchoking caused by inadequacies in, 59denture effects on, 15-16, 48, 416-417denture movements during, 16digestion functions of, 15factors that affect, 57forces generated during, 10, 17tfunctions of, 15, 59occlusal movements during, 15-16physiology of, 15, 450regulation of, 270-271, 271fteeth position during, 16tongue movement during, 450

Masticatory mucosa, 85, 211Masticatory muscle atrophy, 47-48Masticatory system, 8-10, 258Maxilla

anterior denture teeth placement, 310-311articulator relation of, 289-290, 290fbone resorption, 86

Maxilla (Continued)denture-bearing areas. See Denture-bearing areas, maxillaryface bow technique for, 287-288mucous membrane of, 211palatine processes of, 211, 212fresidual ridge of

parallelism of, 276-277resorption of, 235f

sharp, spiny processes on, 214vertical or horizontal deficits of, 165f-166f

Maxillary arch, occlusion rim designed for, 260-261, 261fMaxillary denture

anatomic considerationsbuccal vestibule, 217, 223hard palate, 211-212, 212fincisive foramen, 214labial vestibule, 215-216, 216f, 223maxillary tuberosity, 214, 214fpterygomandibular raphe, 217, 220fresidual ridge, 212-214sharp, spiny processes, 214supporting structures, 211-214torus palatinus, 214, 215fvibrating line, 217, 219f

description of, 211flange of, 424impressions


limiting structures, 214-217palatal alveolar surface in, 390peripheral structures, 214-217single

description of, 430, 432rationale for, 434, 435f

speech considerations, 390supporting structures for, 211-214

Maxillary teethmolars, 320natural irregularities of, 372premolars, 320

Maxillary toridescription of, 104surgical removal of, 104, 107, 109f

552 Index

Maxillary tuberositiesanatomy of, 214, 214f, 220fdescription of, 90pendulous, 104, 104fsurgical reduction of, 104f-106f, 104-107vertical height of, 105f

Maxillofacial prosthodonticsanatomical and physiological considerations, 449-450bone-grafted mandible prostheses, 466-467, 467fborder molding

hard palate, 452-453velopharyngeal area, 452

facial form changes, 451focus of, 449implant-supported prosthesis, 467, 468f-469flaboratory procedures for, 468mandible movement alterations, 451-452mandibulectomy prostheses

discontinuity, 464-466, 466fedentulous, 466marginal, 463f-464f, 463-464

obturator prosthesishollow, 469-470, 470fmaxillary


soft palate, 460-461palatal augmentation prosthesis

clinical examination for, 462description of, 461-462patient adjustment to, 462-463

processed bases, 452, 452f, 468prosthetic seal testing, 453vertical opening losses, 451

Maximum contact mold, 321, 323Maximum intercuspation, 324, 324fMedial pterygoid muscle, 241, 242fMedian rhomboid glossitis, 37fMediolateral compensating curve

for balanced articulation, 318-319, 319ffor lingualized articulation, 322

Mental foramenanatomy of, 233f, 234pressure on, 108-110

Mental health assessments, 75-76Mentalis, 236Mental nerve, 88Mentolabial sulcus, 346, 348f-349fMentum, 348fMetabolic bone diseases, 87-88

4-Methacryloxyethyl trimellitic anhydride, 197Microwave-activated resins, for denture base, 194, 196tModified acrylic resin, 195Modiolus, 262-263, 263fMolars

mandibular, 317, 319-320, 322-323, 431fmaxillary, 320

Monomer, 396Monoplane articulation, 320-321Mouth, 85-86Mucosa

abnormalities of, 85color of, 86complete denture requirements, 10-11edentulism effects on, in older adults, 25-26fibrous tissue excesses beneath, 86-87health assessments, 85keratinization of, 213masticatory, 85, 211maxillary, 211

Mucostatic impressions, 220Mucous membrane

attached vs. unattached, 213fbuccal shelf, 233labial vestibule, 215residual ridge

crest, 232description of, 213, 213f

Muscle toneage-related changes in, 27assessment of, 92

Muscular skill, 21Myerson Lingualized Integration molds, 321Mylohyoid muscle, 239-241, 240fMylohyoid ridge, 234, 236f

NNares, 348fNasalis, 349fNasal reflux, from obturator prosthesis, 459-460Nasolabial fold, 261, 261f, 346Nasolabial sulcus, 346, 348f-349fNeuromuscular control and coordination, 76, 92Neurosis, 75Neutral zone

definition of, 252, 439determination of, 260illustration of, 254fimportance of, 259-260

Nickel-chromium alloys, for denture base, 206Noise, communication affected by, 180Nonverbal language, 182Nutrition. See also Malnutrition

age-related declines in, 28, 48calcium intake, 61-62counseling regarding, 64-68deficiencies

description of, 48-49in older adults, 60

Index 553

Nutrition (Continued)signs of, 60t

dental status effects on, 56-58description of, 56factors that affect, 56, 57fgoals for, 65-66herbal supplementation, 64history-taking questionnaire, 66folder adult

deficiencies in, 60food selections, 59-60

vitamin supplementation, 62-64

OObturator prosthesis

hollow, 469-470, 470fmaxillary


Occlusal force, 9, 106Occlusal index, 401f, 409Occlusal plane

anterior, 313height of, posterior teeth placement and, 313inclination of, 313irregularity of, 430, 431flevel of, 262-263

Occlusionadjustments, 420balanced, 414Beyron’s determinants of physiological/therapeutic, 534bcentric, 19, 90, 283complete denture, 19components of, 14deglutition and, 19development and adaptation of, 14fdiagnostic cast evaluation of, 130, 132ferrors in

in anatomical teeth, 409-412articulator correction of, 404-405elimination of, 409-414, 472mesiodistal relationship, 412in nonanatomical teeth, 412-414

follow-up examinations, 420historical studies of, 15immediate denture evaluations, 130lingualized, 412-413mutually protected, 283vertical dimension of. See Vertical dimension

of occlusion

Occlusion rimsanterior portion of, 259anteroposterior tooth positioning using, 310arch form

description of, 258-259mandibular, 259-260, 260fmaxillary, 260-261, 261fsoft tissue considerations, 259

beeswax, 331, 331fcentric relation record, 265-266contouring of, 262fdescription of, 252indications for, 254level of occlusal plane, 262-263mandibular, 264fsequences for, 257-258single denture, 430vertical dimension of occlusion determinations, 263, 265,

282-283Older adults. See also Age; Aging

alcohol abuse by, 60-61bite force in, 47dehydration in, 58dietary modifications for, 49edentulism in, 25, 26tenergy consumption by, 59jaw movements in, 27-28malnutrition in, 28, 56muscle tone decreases in, 27nutrition for

caloric intake, 59changes in, 28deficiencies, 60food changes, 59recommendations, 59-61

personal appearance concerns, 30-31saliva production in, 27skin changes, 28, 30smell sense decreases, 28, 58taste sense decreases in, 28, 58teeth color changes, 30xerostomia in, 27, 58

Oral cancerdenture-related tissue irritation and, 42edentulism and, 25racial predilection of, 25risk factors for, 42

Oral cavity, 449-450. See also specific anatomyOral ecology, 535-536Oral environment

complete denture in, 34prosthetic material interactions in, 34b

Oral hygieneoverdenture abutments, 173patient instructions regarding, 417-418

Orbicularis oculi, 349fOrbicularis oris

anatomy of, 216, 236, 309-310, 347-348, 349frepositioning of, 348, 350

554 Index

Orofacial dyskinesia, 444Osseointegration

age of patient considerations, 496benefits of, 528, 529bcontraindications, 496definition of, 489description of, 4-5failure of, 519, 520f, 524implants, factors that affect success and failure of

bed, 496biocompatibility, 492-493description of, 492design, 493loading conditions, 496-497smoking, 496surface, 493-495surgical technique, 496

implant-supported overdentures, 502-503interface created by, 489-492irradiation effects, 496, 531long-term studies of, 529bmechanism of action, 490-492principles of, 485success rates with, 489timing of, 516, 534-535tooth roots replaced with implants, 117, 120f-121f

Osteomalacia, 87Osteoporosis

definition of, 87description of, 27, 531implant placement considerations, 531residual ridge resorption as indicator of, 45risk factors for, 61

Osteosclerosis, 87Overdentures

abutmentsattachment mechanisms, 172f, 172-173caries associated with, 46-47, 162, 174coronal reduction of tooth, 169, 171, 175endodontic status of, 168gingivitis around, 174fgold copings for retention of, 171f, 171-172hygiene of, 173location of, 167-168long-term monitoring of, 173-174loss of, 172-174maxillary teeth as, 169tperiodontal status of, 166-167preparation of, 168-173selection of, 166-173telescopic crowns for retention of, 173tooth mobility considerations, 167

advantages of, 161-162anterior teeth selection, 303caries associated with, 46description of, 46designing of, 160disadvantages of, 162historical uses of, 160, 163f-164fillustration of, 121f

Overdentures (Continued)immediate, 155, 156fimmediate complete dentures vs., 161implant-supported

advantages of, 514banchorage devices for, 504, 506, 506bbars for, 506, 507fcase study of, 157f-158fcomplications of

insertion-related, 523-524structural-related, 525f

considerations for, 499denture design, 504description of, 158disadvantages of, 514bexclusion criteria for, 499-500, 500bimpression techniques, 504inclusion criteria for, 499b, 499-500insertion-related complications, 523-524maintenance of, 506-508mandibular, 502, 503fosseointegration phase, 502-503presurgical evaluation, 500-503prosthodontic procedures, 503-506radiographic evaluations, 500-502retentive devices for, 504, 506, 506bsingle-attachment retentive system for,

506, 507fsurgical procedure for, 502-503treatment goals, 498-499treatment planning, 500b, 500-503

indications, 164, 166mandibular

description of, 162, 167fimplant-supported, 502, 503f

monitoring programs for, 49objectives of, 160, 162foral hygiene for, 47outcome studies of, 175treatment planning, 164, 166versatility of, 160, 163f-170f

Ovoid dental arch, 363, 363f-364fOxidized implants, 491Oxygenating denture cleansers, 204

PPalatal vault, 363Palate

augmentation prosthesisclinical examination for, 462description of, 461-462patient adjustment to, 462-463

evaluation of, 85hard. See Hard palatesoft

anatomy of, 91, 449evaluation of, 85obturator prosthesis for, 460-461swallowing physiology, 449vibrating line, 217, 219f, 342, 342f

Index 555

Palatine bone, 211, 212fPalpation

salivary glands, 85submucosal structure, 82

Papilla, incisive, 260, 261fPapillary hyperplasia, 86Papillomatosis, 103Parafunction

forces generated during, 17thabits associated with, 16-17mandibular movements in, 269

Passavant’s ridge, 461fPatient

anterior teeth arrangement accepted by, 377-378denture evaluated by, 401education of, 22, 98f, 99expectations by, 74, 76history-taking information about. See

History-takinginterview with, 22maladaptive reactions

description of, 183iatrosedative interview for dealing with. See Iatrosedative

interviewmotivation of, 21-22, 77preparation of, 99psychological preparation for treatment, 77reaction to denture, 183referral of, 78

Periimplantitis, 536Periodontal disease, 162Periodontal ligament

alveolar bone integrity and, 12, 160description of, 9implant-supported prostheses considerations, 486natural dentition support area, 10, 11f

Periodontiumanatomy of, 8-9functions of, 9

Person centeredness, 183Philtrum, 346, 348f-349fPhonetic tests, for vertical dimension of occlusion

determinations, 278-279Pinpoint hyperemia, 36fPlaque, overdenture-related accumulation of, 46-47Plasticized acrylics, 200-201, 203bPlatysma, 349f, 352fPolishing surfaces

overview of, 389-390waxing of, 390-392

Polymethylmethacrylate. See also Acrylic resincharacteristics of, 196tchemically activated

denture base fabricated from, 191b, 193-194, 196t

soft liners, 200-201denture teeth fabricated from, 195, 197-198description of, 190disadvantages of, 205fiber-reinforced, 195, 196t

Polymethylmethacrylate (Continued)heat-activated, 191-193, 196tmicrowave-activated, 194, 196tpolymerization of, 190, 192rubber-reinforced, 195, 196t

Porcelain denture teethanterior, 197, 303posterior, 306

Posterior limit records, 137, 139-140, 145fPosterior palatal seal, 342f-346f, 342-343Posterior teeth, of denture

acrylic resin, 306arranging of

anatomical, 315-318bilateral balanced articulation evaluations after,

317-318description of, 313, 314fmandibular, 315-317, 316fmaxillary teeth, 317number of teeth, 314

buccolingual position of, 313buccolingual width, 304criteria, 304description of, 304mandibular, 318-323maxillary, 320, 323mesiodistal length, 304-305molds for, 321-322occlusal forms for, 314porcelain, 306premolars, 315-317, 316fsetting of, 314vertical height of the facial surfaces, 306

Poverty, 24Premolars

maxillary, 320posterior, 315-317, 316fsetting of, 315-317, 316f

Premylohyoid eminence, 237f-238fPressure indicator paste, 421Pressure spots, 403f, 421Procerus, 349fProcessed bases, for maxillofacial prosthodontics, 452, 452f,

468Profile line of face, 367-368, 368fProsthodontics

implantadvances in, 484-485description of, 4-5reasons for popularity of, 485treatment outcome determinants in, 487t,

487-488, 530tmaxillofacial. See Maxillofacial prosthodontics

Protein deficiency, 60tProtrusive contacts, 325-327, 327fProtrusive interocclusal records


Protrusive relations, 335-336Proxemics, 182

556 Index

Pterygomandibular notch, 237f, 342fPterygomandibular raphe, 217, 220f, 237f, 261

QQuadratus labii inferioris, 349f, 352fQuadratus labii superioris, 349f, 352f

RRadiographs

bone quality assessments, 80diagnostic and evaluative uses of, 80-82, 81fextraoral, 80implant-supported fixed prosthesis

evaluations, 510, 512fimplant-supported overdenture evaluations, 500-502intraoral, 82preextraction, 79profile, vertical dimension of occlusion determined from,

275, 275fRebasing

description of, 472impression techniques for

chairside, 480functional, 478-480static, 476-478

Referral of patient, 78Relining

closed-mouth, steps involved in, 477bconventional immediate dentures, 155description of, 471impression techniques for

chairside, 480functional, 478-480static, 476-478

maxillary denture, 223need for, 223open-mouth, 477preliminary treatment before, 476rationale for, 471-472reasons for, 472-476tissue conditioners for, 476, 479f

Remodeling of bone, 45Remounting

cast for, 399, 400finterocclusal records for, 405-406mandibular dentures, 407-408, 408f

Residual ridgeanatomy of, 212-214complete denture support by, 11-13crest of, 213, 232, 233f, 235fdefinition of, 11harmony of form of, 362-364, 363f-364fmandibular

parallelism of, 276-277resorption of, 235f

maxillaryparallelism of, 276-277resorption of, 235f

mucous membrane of, 213, 213foverdenture benefits for, 161-162

Residual ridge (Continued)parallelism discrepancies, 109patient instructions regarding, 418periodontal ligament health and, 12rate of reduction, 12f-13fresorption of

anterior mandibular alveolar ridge susceptibility to, 167characteristics of, 44-45, 89control of, 49denture movement secondary to, 473, 475fdescription of, 25, 27, 61, 160, 212-213, 471factors associated with, 45gender predilection, 61implant-supported overdenture considerations, 502mandibular ridge, 235fmaxillary ridge, 235fmental foramen pressure caused by, 108-110pathogenesis of, 45, 45bpatient satisfaction and, 45

undercuts ondescription of, 88-89illustration of, 113fremoval of, 107, 113fstability uses of, 107, 113f

upper lip length in relation to, 357, 359fResins

characteristics of, 191b, 196tchemically activated, 191b, 193-194, 196tlight-activated, 194-195, 196tmicrowave-activated, 194, 196tmodified acrylic, 195polymethylmethacrylate. See Polymethylmethacrylatestresses on, 192-193visible-light-activated, 190, 194-195, 479-480

Respiration, 449Retention

complete dentureadhesion, 438adhesives for. See Denture adhesivesatmospheric pressure, 441cohesion, 438-439description of, 12-13factors that affect, 437-442gravity, 442interfacial force effects, 437-438oral and facial musculature effects, 439-441parallel walls for, 442psychological effects on, 14rotational insertion paths for, 441surface tension effects, 437tongue base, 441undercuts, 441

implant-supported overdentures, 504, 506, 506bobturator prosthesis, 459, 459f

Retinol, 63Retromolar pad of mandible, 220f, 237f-238f, 239, 240f,

263, 264fRetromylohyoid fossa, 91, 237f-238f, 241Rima oris, 348f-349fRisorius, 349f, 352f

Index 557

Root indication lines, 392f-393fRubber-reinforced polymethylmethacrylate, 195, 196t

SSaliva

cohesive properties of, 438-439factors that affect, 91-92high-mucin, 439medications that affect, 27normal flow rate, 91in older adults, 27pretreatment evaluations of, 76, 91-92sialogogues for increasing production of, 58

Salivary glands, 85Self-awareness, 181Self-disclosure, 182Shingles, 31Sialogogues, 58Silicone soft liners, 201Single dentures

adverse outcomes ofdenture base fracture, 434natural tooth wear, 432f-434f, 432-434

clinical and laboratory procedures for, 430, 432description of, 427diagnosis, 428-430displaceable tissue considerations, 429-430edentulous arch, 427mandibular, 434-435maxillary

description of, 430, 432rationale for, 434, 435f

occlusal plane irregularity, 430, 431fsupport variations, 427-428treatment planning, 428-430

Sinus lift, 88Skin, 28, 30Smell, age-related declines in, 28, 58Smile line, 365, 367f, 513Smoking, 496, 529-531Soft liners

bacterial colonization prevention, 201-202chemically activated acrylic resin, 200-201long-term, 200, 200bpermanent, 201-202, 202fshort-term, 198-200, 199bsilicone, 201tissue tolerance to, 202

Soft palateanatomy of, 91, 449evaluation of, 85obturator prosthesis for, 460-461swallowing physiology, 449vibrating line, 217, 219f, 342, 342f

Soft palate erythema, 37fSoft tissue

health assessments of, 84-87mucosa. See Mucosa

Solar lentigines, 28

Speechanalysis of, 385-386anatomy of, 379, 380fcomplete denture adaptation, 386, 417control of, 380description of, 93, 379electropalatography evaluations, 386, 386ffunctional deficits of, 450-451hearing loss effects on, 380implant-supported fixed prosthesis effects, 511blip movement during, 354f, 356neurophysiological background of, 380physiology of, 379, 380fprosthetic considerations, 386-387teeth effects on, 380-385vertical dimension of occlusion evaluations, 387

Speech soundsbilabial, 381-383, 382tlabiodental, 382t, 383linguoalveolar, 382t, 384-385linguodental, 382t, 383-384linguopalatal, 382t, 385linguovelar, 382t, 385overview of, 381

Square dental arch, 362, 363f-364fStaphylococcus aureus, 38Static impression technique, for relining or rebasing, 476-478Stefan’s law, 438Stellite alloys, 205Stock tray

mandible impressions, 243, 245fmaxillary impressions, 221, 222f

StomatitisCandida-associated

angular cheilitis and, 37f, 38antifungal drugs, 39clinical features of, 36, 37fmanagement of, 39-40predisposing factors, 38bpreventive measures, 39-40

classification of, 35-36description of, 25-26diagnosis of, 36etiology of, 36, 38-39illustration of, 29fmanagement of, 39-40predisposing factors, 36, 38b, 38-39preventive measures, 39-40type I, 36ftype II, 36ftype III, 37f, 40f

Streptococcus, 46Sublingual glands, 241, 242fSubmandibular gland, 27Submucosa

anatomy of, 211maxillary, 211palpation of, 82radiographic evaluation of, 80-82, 81f

558 Index

Surgical template, 151, 152fSwallowing

functional deficits of, 450-451physiology of, 449vertical dimension of occlusion determinations from, 280-

281, 282f

TTactile sense, vertical dimension of occlusion determinations

using, 281-282, 282fTapering dental arch, 362, 363f-364fTardive dyskinesia, 445Taste, age-related declines in, 28, 58Teeth. See also specific teeth

age-related changes, 30asymmetrical symmetry of, 366, 368fbiting forces on, 9buccal lines of, 365-367, 368fcomplete denture vs., 16deglutition effects on, 9denture. See Denture teethdevelopment of, 14, 14fextractions of. See Tooth extractionshealth assessments of, 87labial lines of, 365-367, 368floading of, 9natural

implants vs., 538tocclusal vertical dimension, 274structural continuity of, 537fzone of equilibrium, 259

natural irregularities of, 370, 372occlusal forces on, 9-10, 10bshade of, 129

Telescopic crowns, for overdenture abutment retention, 173Temporomandibular disorders

age-related increases in, 51-52arthritic conditions associated with, 53definition of, 51in edentulous populations, 51-54management of, 52-53pain associated with

description of, 52pharmacotherapy for, 53

symptoms of, 92Temporomandibular joint

edentulism-related changes, 19-20mandible movement influenced by, 269-270morphological face height changes secondary to, 17vertical height of, 19

Terminal hinge axisdescription of, 283records of, 285

Tissue conditioner, 198-199, 199b, 476, 479f, 519bTissue hyperplasia

denture-related, 40, 41fevaluation of, 86

Titanium, for denture base, 206-207Titanium implants, 484-485, 492-493

Tonguecomplete denture retention and, 441denture-related discomforts, 17denture-related effects, 17, 21diffuse atrophic glossitis, 37fhealth assessments, 85masticatory positioning of, 450median rhomboid glossitis, 37fmuscular development assessments, 92-93palpation of, 82retruded position of, 92-93stability of denture and, 417

Tooth contacts, effect on mandible movement, 269Tooth extractions

dietary management for, 68-69indications for, 87

Tooth positionrefinement of, for functional harmony

anterior teeth variations, 369-370description of, 369harmony, 372-373irregularity of teeth, 370, 372single maxillary denture, 430spatial harmony, 372-373

speech production effects, 380-381Tori, 88

mandibularsurgical removal of, 104, 108f

maxillarydescription of, 104surgical removal of, 104, 107, 109f

Torus mandibularis, 236, 237fTorus palatinus, 214, 215fTrays. see Custom impression trays; Stock traysTreatment planning

definition of, 76, 94description of, 74elements of, 94-95financial considerations, 77immediate dentures

existing teeth evaluations, 129explanation to patient, 127, 129blip evaluations, 129occlusion analysis, 130oral examination, 127, 129oral prophylaxis, 131tooth modifications, 130, 131f

implant-supported overdentures, 500b, 500-503overdenture, 164, 166problem-solving uses of, 95reasons for, 95, 96fschematic diagram of, 97fsingle dentures, 428-430treatment options developed by, 95, 96b

Trial denture baseacrylic, 254characteristics of, 252resin, 252, 256fsize of, 358

Index 559

Trial denture base (Continued)“sprinkle-on” method for, 252, 256fwax template for, 252, 255f

Triangularis, 349f, 352fTry-in appointment

centric relation verificationextraoral articulator method for, 331-335intraoral observation of intercuspation, 330-331

description of, 329environmental factors, 336-337facial and functional harmony. See Facial and functional

harmonyimmediate dentures, 141, 146f, 148fimplant, complications during, 522-523lateral relations, 335-336posterior palatal seal, 342f-346f, 342-343protrusive interocclusal records


protrusive relations, 335-336vertical dimension of occlusion verification, 329-330

Tuberosities, 90

UUlcers, denture-related, 41, 42fUndercuts

complete denture retention and, 441remounting cast, 399, 400fresidual ridge

description of, 88-89illustration of, 113fremoval of, 107, 113fstability uses of, 107, 113f

VVelopharyngeal closure

definition of, 449-450, 450fdisruption of, 450

Vertical dimension of occlusiondetermination of

description of, 274-275, 465diagnostic casts, 275, 276ffacial measurements, 275-276, 276fformer denture measurements, 277, 280fjaw rest position, 277-278, 281fmechanical methods, 275-277parallelism of ridges, 276-277, 278f-279fphonetic tests, 278-279, 387profile radiographs for, 275, 275fridge relations, 276-277speech patterns, 387swallowing threshold, 280-281, 282ftactile sense, 281-282, 282f

esthetic considerations, 279-280illustration of, 31fmeasurement of, 83occlusion rim for determining, 263, 265, 282-283restoration of, 102supporting structure loss effects on, 473

Vertical dimension of occlusion (Continued)temporomandibular disorders and, 51tests to determine, 263, 265try-in appointment verification of, 329-330verification of, 329-330

Vestibulebuccal

anatomy of, 217, 237f-238f, 238-239impression taking of, 223

impression taking of, 223labial

anatomy of, 215-216, 216f, 236-238, 237fimpression taking of, 223

Vestibuloplasty, 110-111, 113, 116, 118f-119fVibrating line, 217, 219f, 342, 342fVisible-light-activated resins, 190, 194-195, 479-480Vitamin E, 60Vitamin supplementation, 62-64

WWater-soluble vitamins, 64Wax contouring, 148-149Waxing

gingival line, 391fmold

formation and preparation of, 392-396packing of, 396-397root indication lines, 392f-393f

orientation relations, 398overview of, 389-390polished surfaces, 390-392

Wax record, 335fWax spacer, 245Wettability, 437Whip Mix articulator, protrusive interocclusal records for,

338-339“Witch’s chin,” 113Women

calcium intake by, 61osteoporosis risks, 87-88

Working contacts, 324-325, 326fWound healing, immune system functioning and, 68

XXerostomia

burning mouth syndrome and, 43definition of, 58denture base adhesion and, 438malnutrition and, 48b, 58management of, 58medication-induced, 58in older adults, 27, 58

ZZygoma, 217, 218fZygomatic head, 349fZygomaticus, 346, 349fZygomaticus major, 352f

560 Index

prosthodontic treatment for edentulous patients: complete dentures and implant-supported prostheses

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