textbook of complete dentures plummer 2009

C H A P T E R

introductionand Definitions

Dr. John Ivanhoe

Textbook of Complete Dentures

I. Introduction

The effect of new, well-fitting esthetic, functional complete dentures on a patient's sociallife, sense of well-being, and quality of life is often dxainatic. On post-insertion visits youmay note new hairstyles, makeup, a new Job, a change in dress and/or a personalitychange. CJhanges such as these justifiahly make clinicians proud of their work and skills.Many of these patients are reasonably simple straight-forward denture patients who areeasily managed. However, it must be remembered that every patient requiring opposingcomplete dentures is a "full-mouth rehabilitation" patient, and tlie treatment of some willbe very difficult.

Understanding these patients and providing the services necessary to achieve excel-lent results requires well-trained, capable, and caring experts. Unfortunately there is afeeling among some that, with the ad\'ances in the dental education of patients anddental materials and tt-chniques, complete denture patients \vill become rare in theimmediate future, and therefore complete denture prosthodontics is a dying art. Tliislack of appreciation has resulted in a decreased emphasis in this specialty' area within thecurriculum of dental schools to the point that some schools question the need forcomplete dentures in tiieir curriculum.

Contrary to those opinions, data indicates that the number of patients requiringcomplete dentures will continue to increase over at least the next fifteen years andthen stabilize for the foreseeable future. The number of patients in need of one or twocomplete dentures will increase from 33.6 million in 1991 to 37.9 million by 2020.Unfortunately these facts have been lost on some state legislatures and senior dentaleducators resulting in a decreased qualit) of health care in some areas allowing labora-tory technicians with no diagnostic skills or clinical experience to legally fabricatecomplete dentures.

The diagnosis and fabrication of complete dentures is often a very difficult area ofdentistry because of the uniqueness of the average denture patient's physical and mentalcondition. The dentist must attempt to restore, most often an elderly patient with physi-cal, mental and/or financial dilliculties, to an acceptable level of estlietics and function.This may be difficult because completely edentulous patients have lost all of the naturalteeth that would have provided raluable guidance on vertical and horiz<ïntal relation-ships, tooth size and color, and tooth position. They have lost the esthetics and functionof natural teeth anchored securely in strong bone. They may have lost large amounts ofridge structure, which might have pro\ided stability to their dentures. Many of thesepatients have lost muscular stiucture, which makes chewing food difficult. Most have losttissue elasticity resulting in poor muscular support of the lower face.

Mental stresses may also be devastating. Elderly patients are not as mobile as theyonce were; many can't drive themselves and are totally dependant on others for theirneeds. They are often on multiple medications, which may be creating a severe financialburden. Additionally these drugs often result in xerostomia, which often makes wciiringdentures verj' difficult. Some patients are seeking mates and they ieel that denturesmake them less of a person. Many are embarrassed over the possibilité' that their spouseswill see them without their dentures. Many are depressed over loss of a spouse or closelong-time friend. Otliers are depressed due to the loss of "feeling good and young." Someare concerned because they recognize that they have developed a significant loss ofshort-term memoiy. These mental stresses contribute to how cooperative these patientsmay be during the denture fabrication process.

Introduction and Definitions

•

Functionally these patients may also be quite compromised. Proprioception and astable occlusion have been losi with ihe removal ofthe lasi naiural teeth. Food may beunappetizing because of the lost taste buds and changes in salivary flow, perhaps result-ing in weight loss. Often these patients are debilitated and their tissues are abused fromwearing poorly fitting dentures or not wearitig dentures at all.

How did these patients reach this condition? The familial history of some will indi-cate neglect because dentistr\ wasn't important or perhaps the family simply couldn'tafford dentistry. Some are tlie resull of a hisioiA' of lack of concern for their own oralhygiene or the importance of preventive dentistry. Some may simply be facing üie effectsof adv'anced age and a combination of conditions leading to edentuHsm.

It becomes ver\ imporumt to differentiate between what can and can't be done forpatients with these physical, mental, and personal problems. Ob\iou.sly a dental profes-sional cannot reverse the age-related changes, however dentisLs are able to diminish theeffects of these changes in many patients. Patients cannol be restored to the estlietics andfunctional level of a dentate patient; however comprotnised function and esthetics canbe adequately addressed in most patients. Unrealistic expectations cannot be achievedand clinicians are on dangerous ground if they do not objectively recognize capabilitiesand ensure that the patient understands limitations. Even the most skillful and caring ofchnicians is doomed to failure if patients cannot be educated and made to understandthe degiee to which tlieir oral conditions have been compromised. It has been said thatsome patients with unrealistic expectations must be made to understand that completedentures are not a replacement for the missing natural dentition; they are a replacementfor having no dentition at all.

In reaching a prognosis a clinician often focuses in on the condition of the oralcavity and loses sight of the physical, mental, and financial difficulties of the patient.Because of compromised denttire stability, the use of a denture adhesive is often recom-mended—forgetting that the patient may not be able to afford the demure adhesive andalso how difficult it is for a ph 'sically challenged patient to apply and remove from boththe dentures and tlie ridges. To Increase the stability clinicians may recommend that thepatient attempt to chew food on both sides of the arch simultaneously forgetting thedifficulty in achieving such a feat for e\'en the physically capable patient with their natu-ral dentition. Satisfactory denture function is a combination of botli the fabrication ofexcellent prostheses and managing the emotional and physical conditions ofthe patient.

Yes, completely edentulous patients may be verv' difficult to manage, however, oncethe initial hesitancy of treating these patients is overcome and clinical skills developed,this is an extremely rewarding area of dentistry from both a financial and professionalstandpoint. Because many dentists never developed the skills and appreciation of treat-ing edentulous patients, those who do will become an importimt referral base for theircolleagues and other patients alike.

Definrtions

The editors have intentionally not been consistent in using the Glossary of ProsthodonticTerms for all terminology in this textbook. Wliilc tlie terminology, as defined in tileGlossary, is excellent for usage by specialists, it does not reflect many of the commonand accepted terms as practiced and understood by the average dentist or clinician.Tlierefore terms such as balanced occlusion, crossbite, and occlusal prematurities


continue to be used in place of balanced articulation, reverse articulation, and deflectiveocctusal contacts.

Articulator—A mechanical instrument that represents the temporo-mandibular joints and jaws, to which maxillary and mandibular casts maybe attached to simulate some or all mandibular movements.

Balanced occlusion—^The bilateral, simultaneous, anterior, and posteriorocclusal contact of teeth in the eccentric position and the bilateral simul-taneous occlusal contact of posterior teeth only in centric occlusion.

Centric occlusion—The occlusion ofthe opposing teeth when the mandibleis in centric relation.

Centric relation—The maxillomandibular relationship in which the con-dyles articulate with the thinnest avascular portion of their respectivedisks with the complex in the anterior-superior position against theshapes of the articular eminencies. This position is independent oftooth contact. This position is clinically discernible when the mandible isdirected superior and anteriorly. It is restricted to a purely rotary move-ment about the tiansverse horizontal axis. The clinician must be able tomanipulate the patient's mandible to tiiis position, as it is: 1) tiie startingreference point for complete denture fabrication, 2) repeatable and canbe verified, and 3) is a functional position for denture occlusion. The defi-nition pro\ided above is accurate but sometimes very difficult to deter-mine clinically. Remember, centric relation is located by detecting theonly retruded position of the mandible to the maxilla in which a cliniciancan obtain a purely vertical hinge movement of the mandible in relationto the maxilla.

. . Christensen's phenomena—Eponym for the space that occurs betweenopposing occlusal surfaces that occurs during mandibular protrusion.

Closest speaking space—The clearance between the anterior teeth when thepatient makes sibilant sounds. It is generally 1-2 mm.

Combination syndrome—The characteristic features that occur when anedentulous maxilla is opposed by natural mandibular anterior teeth,including loss of bone from the anterior portion of the maxillaryridge, overgrowth of the tuberosities, papillar\ hvperplasia of the hardpalate's mucosa, extrusion of the lower anterior teeth, and loss ofalveolar bone and ridge height beneath the mandibular removable dentalbases; also called anterior hyperfunctiou syndrome. Initially describedby KeUy.

Compensating cune—The anteroposterior curving and the mediolateralcurving within the alignment of the occluding surfaces and incisai edgesof artificial teeth that is used to develop balanced occlusion.

Crossbite—The relationship of the opposing posterior teeth when thebuccal surfaces of the mandibulai" teeth are more buccally positionedthan those of the maxillary teeth. The maxiUary buccal cusps are oftenoccluded with the central grooves of the mandibular teeth. {Reversearticulation)

Hinge axis—^An imaginary line between the two condyles around which themandible rotates when the patient is in centric relation. It is seen in thesagittal plane. (Transverse horizontal axis)

Introduction and Definitions

Immediate denture—^Any removable dental prosthesis fabricated for place-ment immediately following the removal of a natural tooth or multipleteeth.

Incisai guidance—1. The influence of the contacting surfaces of themandibular and maxillarv' anterior teeth on mandibular movements. 2.The influences of the contacdng surfaces of the guide pin and guide tableon articulator movements.

Interim complete denture—An immediate denture that is fabricated to seneonly during the healing phase following extractions. It will be replaced bya more définitive denture following healing. It is generally less costly thana conventional denture, and the master cast is often fabricated from anirreversible hydrocolloid impression.

Interocclusal clearance—The arrangement in which the opposing occlusalsurfaces may pass one another without any contact.

Interocclusal distance—The distance between the occluding surfaces ofthe maxillarv' and mandibular teeth when the mandible is in a specificposition.

Monoplane occlusion—An occlusal arrangement wherein the posteriorteeth have masticatoi7 surfaces thai lack any cusp height.

Nonworking side—That side of the mandible that moves toward the medialline in a lateral excursion.

Occlusal vertical dimension—The distance measured between two pointswhen the occluding members are in contact. (Vertical dimension ofocclusion)

Overdenture—Any removable dental prosthesis tbat covers and rests on oneor more remaining natural teeüi, the roots of natural teeth, and/or dentalimplants; a dental prosthesis that covers and is partially supported by natu-ral teeth, natural tooth roots, and/or dental implants.

Overextended—Being excessively long or deep. The term usually applies toan impression tray or impression, which may eventually lead to the finaldenture being overextended.

Physiologic resting position—1) The mandibular position assumed whenthe head is in an upright position and the involved muscles, particularlythe ele\'ator and depressor groups, are in equilibrium in tonic contrac-tion, and the condyles are in a neutral, unstrained position, 2) the posi-tion assumed by the mandible when the attached muscles are in a state oftonic equilibrium. The position is usually noted wben the head is heldupright, 3) the postuiul position of the mandible when an individual isresting comfortably in an upright position and the associated muscles arein a state of minimal contractual activity.

Protrusion—The position of the mandible anterior to centric relation.Rebase—The laboratory process of replacing the entire denture base mate-

rial on an existing prosthesis.Rehning—Tbe procedure used to resurface the tissue side of a removable

dental prosthesis with new base material, thus producing an accurateadaptation to the denture foundation area.

Resting vertical dimension—^The distance between two points (one of whichis on the middle of the face or nose and the other of which is on the lowerface or chin) measured when Üie mandible is in the physiologic restingposition. (Vertical dimension of rest)


Retention—The quality of a denture chat resists movement of the dentureaway fVoiii the tissue.

Stability—^The qualiiy of a denture that resists movement of the denture ina horizontal direction.

Support—The quahty of a denture that resists movement of a denturetoward ihe tissues.

Underextended—Being excessively short or shallow. This term usuallyapplies to an impression tray or impression. Being underextended mayresult in a denture with lack of stability or retention.

Working side—The side toward which the mandibles moves in a lateralexcursion.

References

Douglass. C.W., Shih, A., Osuy. L.: Will there be a need for complete dentures in the United Statesin 202{):-J Prosihei Denl.. 2002:87:5-8.

Tlie Noinenclauire Committee, Tlie Academy of Prosthodontics. The Glossary of ProsthodonticTerms. | Prosthet Dent. 200rï;94:]-92.

The Glossary of Proslhodontic Terms.J Prosthet Dent. 2005July;94(l):23.

PrefaceThe editors have felt for many years that there was no simple textbook designedfor the undergraduate dentaJ student or family dentist that explains the funda-mental treatment needs for completely edentulous patients. This textbook was noldesigned to contain all the informalion a graduate student or prosthodontistmight desire, but provides the basic information for consistent and quality treat-ment of the typica! denture patient seen in dentist's offices every day. It isan^anged in t\pical chapters with information in text and figure format. Theprimary chaptei-s relate to the second portion of the textbook, which is an Atlas offigures and legends to supplement the chapter information. The figures are allnew and in color, which supplements the text nicely. The material is easy to readand clinically related to place the fundamental steps in denture fabrication in aneasy-to-use reference. Our hope is that ihis textbook will help make the treatmentof denture patients a rewarding aspect of your clinical practice.

Kevin Plummer

XV

ContributorsPhiüp S. Baker, DDSAssociate ProfessorDepartnieni of Oral RehabilitationMediciU College oí GeorgiaSchool of DentistryAugusta, Geor"gia

Henry W. Ferguson, DNfD.Associate ProfessorVice Chair, Director of Post Graduate

TrainingDepartment of Oral and Maxillofacial

Surger)'Medical College of GeorgiaSchool of DendstryAugusta, Georgia

John R, Ivanhoe, DDS (Deceased)Professor EmeritusDepartment of Oral RehabilitadonMedical College of GeorgiaSchool of DentistryAugusta. Georgia

Dennis W. Kiernan, DMDProsthodontistPrivate PracticeAugusta, Georgia

Carol A. Lefebvre, DDS, MSProfessor; Associate Dean for Strategic

Initiatives and Faculty De\elopnientDepartment of Oral RehabilitationMedical CollegeSchool of DenusuyAugusta, Georgia

W. Jack Morris. DMD.Assistant ProfessorDepartment of Oral RehabilitationMedical College of CieorgiaSchool of DendstryAugusta, Georgia

Kevin D. Plummer, DDSAssociate ProfessorSection Director of Removable ProsthodonticsDepartment of Oral RehabilitationMedical College of GeorgiaSchool of DentistiyAugusta, Georgia

Arthur O. Rahn, DDSProfessor EmeritusDepartment of Oral RehabilitationMedical College of GeorgiaSchool of DentisliTAugusta, Georgia

Frederick A. Rueggeberg, DDS, MSProfessorSecdon Director of Dental MaterialsDepartment of Oral RehabilitationMedical College of GeorgiaSchool of DentistjyAugusta, Georgia

Mohamed Sbaraw>', DDS, PhDProfessorDepartments of Oral Bioiog)' and Oral

Maxillofacial Surgei7Medical College of CieorgiaSchool of Dentistr)'Augusta, Georgia

XVII

C H A P T E R

_f Dental Materials forComplete Dentures

Dr. Fred Rueggeberg


The fabrication of dentures involves a wide tange of materials and products. The v-ariedesof processing methods for the denture base and üie range of materials from whichdenture teeth are made provide the clinician with many decision-making steps.Knowledge of the underlying materials used for denture base constiaiction, the princi-ples of tlieir u.se, and the selection of ancillary products available help the clinicianprovide the most effective, appropriate treatment for each patient.

Denture Base Materials

WHien the natural teeth are extracted, the underlying, supporting bone tliat previouslysupported the tooth eventually disappears, leaving only a dense, "basement" type (alveo-lar) bone covered witii oral mucosa. The elevated contour of this tisstie that remains istermed the "edenuilous" or "residual" ridge. Previous to tooth extraction, the contoursofthe face were largely determined by tiie presence of alveolar bone and teeth beneatbthem. Loss of these tissue results in the typical "sunken" appearance of edentulouspatienLs. In addition, when teeth and boney stiaictures are in good healtii, tlieir positionsgreatiy aid in the ability ofthe patient to speak naturally, as well as to chew and appreci-ate textures and temperatures of food.

In considering replacing the missing natural teeth, not only do artificial teeth needto be provided, but ihey must also be positioned to provide for correct articulation andan esthetic facial contour. The bulk, form, and contour of missing hard, boney structuresalso need to be replaced to help hold the artificial teetli in these positions.

The purpose of the "denture base" then is to cover the existing residual ridge,provide facial contour, and hold the artificial denture teeth in the correct position, haaddition, the denture base must provide an iniimatc contact with the underKing mucosawitbout interfering with movements of the cheeks and tongue. The thin layer of salivathat exisLs between the tissue-bearing side of the denture base and tlie oral mucosa helpsform a hermetic seal, aiding in holding the denture to tissues through capillaiT action.Because the denture base leplaces mucosa-covered bone and will be visible to others, thispart of the prosthesis should also have life-like features, both in color and in contour.

Denture bases are fabricated of either polymeric materials or metal. The mostpopular material for denture base construction is a pohiiier. PoHmers are very easilyshaped and formed, and do not weigh as mtich as (are less dense than) the metallicmaterials. In most denture base materials, the same basic chemistr\' is involved.The liquid monomer (methyl nit'thacr)iate) is added with ground, powdered, pre-polymerized material. The resulting polymer consists of strands of newly polymerizedmaterial (polvTnethyl methacrylate) surrounding (but not chemically bonded to) tliepre-polymerized material originally added. The result is a very tajigled mass of polymerchains that provides sti'ength. Various types of monomers (resins) are used in difïerentproducts to control physical properties. Some products include a rtibber-like moleculethat provides elasticity to the denture and decreases the potential for fracture, should itbe dropped against a hard surface: high-impact denture base materials.

Resin-Based Bentures (Heat- and Auto-Poiymeriied Mataríais)

Denture ba.se materials are "processed" (polvTnerized) in a \-ariet\' of ways. The mostcommon method has been used for more than 60 years and includes a heat-polymerizedresin. In this method, the dentist initially constructs a denture tising wax as a base

Dental Materials for Complete Dentures

material to temporarily hold the artificial teeth. This assembly is made outside of thepatient's moutli, on stone casts that replicate the patient's oral mucosa (master casts).Using interocclusal records, these casts are positioned on an articulator. The artificialteeth are positioned in wax on the casts to have the angulation desired in the finaldenture. The wax is also sculpted to simulate the form and natural contours of thegingiva and mucosa that were present prior to tooth extraction. Once the teeth are intheir desired location and the wax denture base has been sculpted, the cast anddenture are invested in a large, brass flask (flasking), and the wax denture base isremoved by using boiling water. The base resin polymer and monomer are mixed to adough-like consistency, and packed into the void left when the wax was removed- Theflask halves are closed and pressed together, which forces the unpolymerized doughto flow into all the empty spaces within the stone mold. Pressing also helps to extrudeand eliminate excess, unpolymerized dough. The brass flask is placed into water andheated to a specific temperature at a specific rate. The warmth ofthe water eventuallyreaches the unpolymerized dough where it activates a setting mechanism of the polymer(heat-pohinerized resin).

The dough-like material could have been specially formulated so tliat the polymer-ization process would not require any heat to react, but instead, the components, whenadded and mixed, undergo a polymerization reaction at room temperature inside oftheflask (autopol)Tnerizing resin). After the material inside tiie flask has maximally poly-merized, the flask sections are separated, and the "processed" (cured, polymerized)denture is separated from the master cast, trimmed, polished, and stored in water.Because of resin shrinkage during polymerization (approximately 0.3 to 0.5%), dimen-sions of the denture are slightiy smaller than prior to polymerization. Fortunately, thedenture will absorb water from its storage fluid, and expand slighdy (0.1 to 0.2%),making its final dimensions almost exactly the same as those of the mouth. For thisreason, dentures must be kept wet when removed firom the mouth for soaking, cleaning,or storage.

A polymer denture base can also be made from different types of materials. In the"fluid-pour" technique, instead of mixing components into a dough-like consistency, thesame basic materials are mixed to pro\ide a mucli less \iscous (more water-like) product.This material is also formulated to undergo an autopolymerizatiou setting reaction. Thedenture is "Basked" in a similar manner, heated, and the wax is removed as mentionedpreviously (for the heat-polymerized and autopohinerized methods). Rather than press-ing the dough into tlie mold, the unpol>inerized, fluid-like uncured resin is pouredthrough a specially created hole in the flasking material, and the void is filled until thefluid flows out another hole. The flask is then allowed to sit at room temperature wherethe autopolymerizing reaction takes place, .\fter the denture base material has polymer-ized, the denture is recovered as described above, and finished.

Another type of denture base is also mixed into a dough and flasked like thosedentures mention above. Instead of being inserted into the conventional brass flask,however, the assembly is contained in a special flask material that does not interfere withmicrowave penetration. Pohmerization of the resin denture base inside the special flaskis caused by exposure to microwave radiation. A conventional, consumer microwave ovencan be used. This process is easy, requires no special equipment for processing, and hasbeen found to result in accurate, durable, clinically acceptable denture bases.

The final t\pe of polymeric denture base material comes in thin sheets of unpoly-merized material. The product is placed directly onto the master cast, molded, and teethare placed. The assembly is then placed into a large unit where it is exposed to ver)'intense light, causing the denture base to polymerize (a light-polymerized denture base).

10 Textbook of Complete Dentures

Metal-Based Dentures

A different type of denture base material is metal. Usually, only the side of the denturethat will be next to the oral mucosa (the tissue-bearing side) will be metal, and a polymermaterial will be added to stimulate gingiva and hold the demure teeth in place.The metal base is fabricated in a process that involves replacement of the wax form ofthe desired metal base with one tiial is made of metal using the lost wax technique.This technique is similar to that described previously for replacing wax \vith a materialthai is poljTnerized, but instead uses a special high-heat process that involves depositingmolten metal into the void. Advantages of the metallic base are that it provides a muchmore accurate fit to the underlying mucosa, and it also transfers heat from foods andfiuids to the palatal area (there is usually no polymer coating on this area). This addedsensation provides a great enhancement of the pleasure gained from eating for manyedentulous patients. An additii>nal advantage of a metal-based denture is its addedweigbt. For the mandibular denture, tliis weigbt helps to keep the denture in place.However, for metal-based maxillary dentures, the added weight may compromise theretention of the prosthesis.

I Denture Teeth

Tooth Retention

The function of an artificial loolh in a dennire is to provide esthetics, fimction. and artic-ulation diat were present in tbe natural state. The teeth are retained to the demure baseby either a mechanical undercut (with no chemical bonding), or by means of microme-chanical retention.

In mechanical bonding, the denture base flows into an internal void in the surfaceof the tooth. This void has small vent holes into which the unpolymeiized denture basematerial flows during packing, polymerizes, and becomes mechanically locked in place.Also, some denture teeth use pins with heads tliat will be covered by the unpoljTnerizeddenture base, and will be mechanically retained in place after polymerization.

There is no method to chemically bond any type of denture tootli to the denturebase. However, treatments of the underside of plastic teetii do allow a shallow infusion ofdenture base material into this surface, where it polymerizes around the existing polymernetwork of the denture tooth, and is this held in place micromechanically (mechanicalretention, but on a ver\' small, microscopic scale).

Porcelain Teeth

Denture teeth are made of either porcelain or plastic (a polymer). Within each type ofmaterial, there is a verv- wide range of shapes, colors, and compositions. Porcelain teethwere tbe first to be developed. These teeth are made of ceramic material and are quitehard and wear resistant. Disadvantages of porcelain denture teeth include their hard-ness, which can be a factor in excessive wear of any natural teeth to which they may artic-ulate. Porcelain teeth also tend to transmit impact forces from biting lo the underlying

Dental Matertals for Complete Dentures 11

mucosa, which helps to increase in the rate of bone résorption occuning in the under-lying residual ridge. Because these teeth are fabricated of ceramic material, they aresubject to fracture with minimal trauma. Again, because ofthe ceramic material, oppos-ing porcelain teeth that touch during speech often make a distinctive and disturbingclicking .sound. Being ceramic, these teeth are difficult to contour to fit ridges and toadjust when inserting. The hardness of the material can also be an ad\'antage becausepatients with porcelain denture teeth are less likely to demonstrate a loss of occlusal verti-cal dimension caused by wear of the denture teeth. However, one note of caution is inorder: The hardness ofthe porcelain teeth may direct forces to the underhing bone andcause a loss of occlusal vertical dimension because of bone loss. Many clinicians wouldprefer thai padents exhibit a loss of denture tooth material as opposed to loss of bone.

Polymer (Plastic) Teeth

The other type of denture teeth are made from polymers (called "plastic teeth"). Theseteeth are much softer than are their porcelain counterparts, and therefore do not impartas high an impact force to alveolar bone. Because of their comparative softness, plasticteeth are tliought to lessen the stresses to Lhe residual ridge resulting in less ridge résorp-tion. Being softer, plastic teeth are also less wear resistant than their porcelain equi\'alentsand therefore, when placed to occlude against natural dentition, plastic teeth will notcause the natural teeth to wear; instead the plastic tooth will bear most of the wearingprocess. Plastic teeth are easily contoured to fit the underlying ridges and are easy toadjust at insertion. They are less likely to fi"acture than porcelain teeth, but their occlusalsurfaces do wear more rapidly.

Plastic teeth can be classified into a N-ariety of types, based on their composition andmethod of polymerization: conventional plastic teeth and IPX (InterpenetratingPolymer Network). Conventional plastic teeth are homogeneous in their compositionand contain a polymer network that is basically only one type of resin. IPN teetli,however, are composed ofa unique combination of materials and oifer enhanced physi-cal properties (increased hardness and wear resistance) over their conventional analogs.In IPN teeth, two different pol\Tners do not chemically bond to one another, but insteadform totally independent polymer networks, where they become mechanically tangled.The combination of tlie different properties of these polymers as well as their mechani-cal entanglement help to enhance their properties compared with conventional teeth.

Plastic teeth are retained to the polymerizing denture base using a micromechani-cal interlocking of the new denture polymer enmeshing the polymer network of thedenture tooth in contact with the curing base.

E Denture Liners

Over time, the residual bone remaining after tooth extraction continues to slowly resorbresulting in a space between the tissue-bearing side of the denture and the residual ridge.Because of this space, the support, retention, and stability^ of the denture are all compro-mised. Excess movement of the denture base against the underlying mucosa (loose-fitting dentures) occurs, and the force delivered to the residual ridge is directed to only


small areas instead of being spread uniformly. Because of the high stresses and lateralmovements imposed ou the delicate oral mucosa, tlie patient experiences "sore spots,"which are localized areas of irritation that can cause extreme discomfort. Often, thesediscomforts are great enough to cause the patient not to wear the denture, exceptperhaps for social purposes.

To alleviate this ill-fitting condition, the clinician has two choices; making anentirely new denture, or adding only a small amount of new polymer that will take theplace of the voids and return intimate contact and stability of the denture base to a largearea of the underlying mucosa. The decision ultimately rests upon the amount of ridgeloss and resulting space. If the space is large and occlusal vertical dimension has beenlost, then making a new denture would seem appropriate. However, if the space is rela-tively small, a thin layer of new plastic can be added to the existing denture base. Thislater treatment is called a "rehne" and can be performed either direcdy on the existingdenture at chairside, or the denture can be sent to a laboratory where new material willbe added using more sophisticated polymerizing techniques.

Chairside Reiine Materiais

If performed chairside, the clinician again has a decision to make: whether to add eithera hard or a soft material to the existing denture. Both of these products consist of apowder and liquid that, when mixed, is ver\- similar in content to that used when makingthe autopolymerizing denture base material. The difference is tliat the hard material setsto a relatively inflexible consistency, and the softer type polymerizes to more flexiblemass. This fiexibility helps to decrease biting forces on the underlying tissues by creatinga soft cushion, while lessening tissue irritation and increasing overall patient comfort.

In this reiine process, the tissue-bearing side of the denture base is roughened toprovide a fresh, clean surface for die new material, and the product components aremixed and spread over the freshened denture surface. The denture is placed intodie patient's motith and held in position until tlie polymerization process has beencompleted. Extreme care must be taken because the heat released dtiring the polymer-ization reaction occurring immediately against the oral mucosa is high enough to causepain and scalding. Thus, it is not uncommon to remove and replace the denture severaltimes during its process of intraoral polymerizing. WHien polymerized, the excess mate-rial Cowing out of the denture is removed, and the jimcdon of tlie old denture to the newis polished. Even though the basic components and chemisüy of many of these types oflining agents are the same as those of tlie processed denture base, the extent of poly-merization of the reiine is not as thorough as that of the processed denture base. Thus,the reiine materials have inferior propt'iiies: weaker and more prone to absorb fluids,and to discolor over time.

Recendy, a new t -pe of deliveri.' sy-stem has been developed for extruding, mixing,and placing reiine materials directly onto the old denture base chairside. In this system,the components to be dispensed are present in a single cartridge that is placed into adeliver)' gun. When the trigger is pressed, a plunger moves and forces both materials tobe released, where they are directed into a nozzle that contains a special auguring deWcethat thoroughly mixes them prior to extrusion from tlie tip end. The mixed material isplaced direcdy onto the denture base, which is then inserted into the mouUi and allowedto polymerize as stated previously. Both hard and soft reiine materials are available usingthis type of delivery system.

Dental Materials for Complete Dentures 13

laboratory Refine Materiais

Denture reline materials that are sent to the laboratory for processing polymerize to ahigher degree than those that are used chairside. For the lab-processed relines, the olddenture surface is roughened as before, an impression material is placed directiy on thedenture base, and the denture is inserted into the patient's motitli. Thus, the old base isused much as an impression tray would be. The denture/impression is then sent to thelaboratory, where technicians encase the old denture in stone, much like in the conven-tional denture-making process previously described. Tlie new denttire base material isadded and polymerized directiy against the old base under heat and pressure. The result-ing polymer from this laboratorv* processing is much stronger, bonded more tenaciously,and is more resistant to fluid absorption and color change than are the ones polymerizeddirectiy in the patient's mouth: the chairside products.

Laborator)" metiiods are also used to process a "permanent," soft, silicone-basedreline material. For this process, a piece of fiexible liner is placed directly against thetissue-bearing side of the master cast, painted with an adhesive, and the case is thentreated like a conventional heat- or autopolymerized, fiasked denture. The resulting linerhas tiie advantage of staving flexible for considerably longer periods tliaii those madetotally of a modified methacrylate-based polymer. However, a silicone surface is fairlyporous and, over time, tends to accumulate bacteria and fungi; it must be treated toreduce tiiis potential. Instead of using silicone, a modified resin-based, soft polymer canbe placed on the tissue-bearing areas of the master cast in a similar manner as silicone.The conventional denture polymer is placed directly over tiiis soft material, and thetwo are polymerized together. In this manner, tiiere is a chemical bond formed betweenthe two materials. This bond is more durable than the adhesive bond upon which thesilicone material relies.

Benture Tissne Conditioners

It is not uncommon for a patient to present with a denture that has been in ser\ice for avery long time. As a result of this long-term use, the tissues ofthe residual ridge are oftenvery irritated and infiamed. If impressions were made for a new denture at this time, theresulting master casts would only duplicate infiamed and initated mucosa. A metliodmust be ttsed that allows these tissttes to heal, while also permitting the patient tocontintie to wear and use their existing dentures. This is the function of a "tissue condi-tioner." which may be thought of as a temporar) denture liner that pro\ides a ctishion-ing effect. The sponginess of this material absorbs loads to the underKing residual ridge,and allows those tissues to heal during function.

If tissue conditioner is allowed to remain on the patient's denttu"e for too long, it maybecome hardened, resulting in recreation of the initated state of the residual ridge seenprior to treatment. This loss of resiliency' is the result of dissolution (leaching) of a compo-nent (plasticizer) that helps to keep the material fiexible. Thus, it is typical that tissueconditioners must be frequentiy replaced during the course of a new denture fabrication.

These materials do not tmdergo any type of polymerization when "curing." Theprocess by which they change from a fluid mass to a very viscous, flexible, and sponge-like solid is based on gelation of the components.


Denture Repair

Denture repair usually involves either replacement of a lost tooth or rejoining pieces ofa fractured denture base (or both). In each situation, the pieces are joined using anautopolymerizing resin.

When joining broken .sections, one must keep in mind that the success ofthe repairresults on formation of both marcomechanical and micromechanical retentive mecha-nisms. Macromechanical aspects involve the purposeful fabrication of mechanical inter-locks or undercuts, so that when the repair material is polymerized, it cannot bephysically separated from the joined sections. Micromechanical retention involves appli-cation of a liquid, usually the liquid monomer ofthe repair material, on ilie outer surfaceof the pieces to be joined. The liquid is spread on the broken sections to cause only theouter layers of polymerized denture polymer to absorb the fluid and then physicallyswell. Wlien tiie fluid repair resin comes into contact with this swollen surface, the poly-merization process will also involve the fluid monomer that had been absorbed into onlythe very outer portions ofthe broken surface. Once again, additional strength is given totlie repair at this site because of the formation of a new polymer network being formedaround that ofthe old denture base; an interpenetrating polymer network.

If the repair resin is allowed to polymerize under high pressure and heat, the phys-ical properties of the resulting joint will be greatly improved over one that is polymerizedunder ambient conditions. To create such conditions, the dental office laboratoiy willtypically have a "curing" pot into which hot water and the unpoKmerized repair resinare placed. Pressure is applied to the pot by asing the existing in-house compressed airsupply. This technique will produce a more dense, stronger polymer. The transversestrength of heat-polymerized repairs is approximately 80% of the unbroken material,whereas it is only 60% ofthe original strength for the chemically polymerized producL

Impression Materials

In Older to fabricate a denture, exact replicas of the patient's edentulous jaws must bemade. Basically, three different types of impression materials are used to capture thenegative image ofthe patient's ridge. The selection of each type material is based on thedegree of accuracy needed, as well as for the ability to mold tlie impression intraorally.

Alginate Hydrocolloid

Alginate hydrocolloid (an irreversible hydrocolloid) is usually packaged as pre-measured powder to which a specified volume of liquid (water) is added. Typically, room-temperature water is placed into a flexible, rubber mixing bowl, and the pre-packagedpowder contents are sprinkled into the i\*ater. The components are actively mixed, usinga wide-bladed spatula in a manner designed to eliminate incorporation of air bubbles.This mixed mass will have the consistency of very heavy dough, and is placed into a"stock" impression tray. Tliese trays are generally a\'ailable either in disposable plastic orreusable metal. Fach ira\ will have some method of retaining the impression material.


usually by the presence of small boles, tbrough which the unset pasle flows, hardens, andbecomes locked. In addition, prior to placing the impression material, tlie tray may besprayed with a special adhesive that further strengthens the bond between the impres-sion tray and set alginate.

The tray is seated on the ridge, and held in a stable position, while the material sets.This process usually takes a few minutes, and can be accelerated by using wann water, orit can be lengthened by using cold water. In addition, the powder packet is available inregular and fast^et v^arieties. Once set, the impression and tra) are removed by graspingthe front handle lifting the vestibular tissue, to break the seal around the impression andexerting a rapid, snapping motion. The alginate may be diificult to remove because ofexcellent adaptation to the ridges. Fast removal of the impression is necessar\' becausealginate is weak and may distort or tear if slowly pulled on the ridges during withdrawal.

The impression is examined to make sure that all desired areas were captured,rinsed to remove superficial debris and saliva, and is then sprayed with a solution ofwater-based disinfecting agent and placed into a sealed plastic bag as soon as possible.The impression should not be immersed in disinfectant because alginate can easilyabsorb water and swell, resulting in a distorted impression.

An alginate impression should be poured immediately. However, if the impressioncannot be poured for several minutes, the set material should he wrapped in a wet papertowel, which provides a 100% humidity environment. The major component of alginateis water, and if not protected, fluid may evaporate prior to stone being poured into theimpression. Even with good intentions, wdicr may be lost from the impression and there-fore, in all situations, an alginate impre.ssion should be poured widiin 10 minutes. Dentalstone is poured into the impression and vibrated to remove air bubbles and allow thestone to cover all impression surfaces. The impression should be immediately separatedfirom the set dental stone and not allowed to remain in contact with die stone. Alginatewill absorb water from the set stone, resulting in a weak, powdeiy, soft superficial castsurface. If left for too long, dried alginate will become very hard, and may actually breakthe fine, delicate stone reproductions when the two items are separated.

Polyviuyl Siloxane (PVS) and Poiyether <PE)

Most clinicians feel a more accurate Ímpre.ssion and master cast are required whenmaking complete dentures. These dentisLs will use the preliminary casts derived fromalginale impressions to fabricate plastic custom or final impression trays. The tray isadjusted intraorally and the borders are correcdy adapted to the ridges using .some typeof semi-solid impression material or a heaw-bodied polyvinyl siloxane or poiyether. Oncethe borders of the trays are conected, the tray is then removed and dried.

The tray is then painted with a specific adhesive material, which is allowed to dryfor a specified period. This waiting time is necessary to allow the volatile components ofdie adhesive to evaporate and to allow die adhesive to slighdy soften the surface of theimpression tray. This softening allows the adhesive to diffuse into the outer portions ofthe tray, allowing for a more tenacious bond.

A synthetic, elastomeric impression material (either a polyvinyl siloxane known asPVS or a polyether-based product) is often used for making final impressions. Thesemateriais are known for their high degree of accuraq, over die alginate products. PVSmaterials are available in a range of viscosities: hght-bodied (a more íluid-like material),medinm-bodied, heavy-bodied (much thicker consistency), or a putty (very dough-likeand nonfinid). The viscositv' to he used is based on the consistency of tlie tissues to be


captiued: the more unsupported and movable the tissue, the more fluid (the more light-bodied) the impression material desired so as to minimize distortion of the movabletissues. Polyether has an inherent hea\y consistency, although there are modifiers thatcan be used to make it more fluid. It is not, however, available in the range of viscositiesthat the PVS products are.

Each material is packaged as two different pastes that, once mixed uniformly, starta setting reaction. The pastes can be mixed by hand using a spatula, or they can beextruded from a gunlike device that dispenses the two different pastes and thoroughlymixes tliem when they flow through a delivery tip. In either case, the mixed componentsare placed as a thin layer into the adhesive-coated custom tray, which is then placed inthe patient's moutli. Once set, these tjpes of materials are removed witli a slow, teasingmotion, rather than a snapping one because they are strong and stiff when set, and ifremoved quickly, they might scratch or tear delicate oral tissues.

For disinfection, the PVS material may be soaked in any type of disinfectant for anylength of time, because it does not absorb water (is hydrophobic). Polyethers, however,do absorb water (are hydrophilic ), so they must be spray disinfected, and placed in a plas-tic bag (similar to alginate dishifection technique).

These materials do not need to be poured immediately, and may be shipped to alaboratory for pouring if necessary. Once poured, neither material should be separatedfrom the stone cast quickly, but instead a slow, steady force should be used. The PVSmaterial is strong enough to withstand multiple pours of stone, but the polyether mate-rial is relatively weak, and would tend to tear under such repeated stress.

Dental Stones

The major component in all types of dental stones (calcium sulfate hemihydrate) is actu-ally mined from the earth as the mineral g>psum. By treating the grotuid mineral in vari-ous manners (heating and application of pressure), different densities and hardness ofstone powders are formed. WTien dental stone sets, there is a volumetric expansion,depending greatiy on the type of stone tised. Thus, the different types of stones arisingfrom the rarious processing techniques vary in hardness, strength, surface detail repro-ducibilit), and setting expansion.

To obtain maximal properties of these g\-psum products, tlie proportioning ofwater and powder as well as the method of mixing are highlv influential. Manufacturersprovide detailed guidelines on the ratio of powder-to-water that shotild be present toprovide optimal stone quality. To help develop the proper consistency, manufacturersprovide dental stones in prepackaged, weighed, sealed bags, and also supply graduatedcylinders for water measurement.

Reduction of air incorporation is a goal when mixing the powder and liquidcomponents. For this purpose, special motor-driven mixing devices are available that alsosupply vacutim action during the mixing process: vacuum spauilation. The concept offilling the impression with stone is one that stresses displacement of trapped air andreplacement with the stone slurry mixture. Thus, the impression may need to be tiltedand the stone applied to the highest side, while the impression is placed in a vibratingtable and the stone is allow ed to fiow^ downward using gravit). To help the stone wet(cover) the impression material surface and to reduce the possibility of bubbles formingat this interface. P\ S materiais are sometimes painted with a surfactant (a t\pe of soap)prior to being poured.


Once the impression is filled, it needs to sit undisturbed while the chemistr) of Uiesetting reaction occurs. All t>pes of dental stones release heat (are exothermic) duringcuring. Once the heat maximum occurs, and the stone temperature has declined to nearroom temperature (no longer warm to the touch), the impression and stone cast can hesafely separated.

of Stones

Dental gypsum products range from a ver\' soft, weak "impression plaster" (Tvpe 1), toa very hard, strong, wear-resistant, and low expansion high-strength stone (Tipe IV).Most master casts for fabrication of indirect restorations {restorations not made direcdyin the patient's mouth, but instead, are made on stone reproduction casts) are madefrom one of tlie two hardest types of stone (Types III or I\0. T\pe III stone (dental stone)is less strong that Type IV, and also expands slighdy more. However, tliis t^pe stone is usedmost often to fabricate master casts as well as articulating (working) casts because it hasa relatively high strength, its surface reproduction is as good as that of the higherstrength stones, and costs less than the higher strength products. Type II products(model plaster, mounting stone), have tlie highest setting expansion, and are weakerthan T)'pes III and fV' materials. Model plasier is used mostly for stabilizing master castsin position to articulators.

interocciusai Registration Materials

It is essential not only to obtain exact replications of the oral tissues captured instone master casts, but also to have the opposing casts oriented in space precisely as theyare in the patient's head. The dentist has a wide variety of mechanical devices (articula-tors) to which these casts can he attached that will not only correctly orient the casts, butwill also allow the casts to veiy closely mimic the mandibular movements when in fimc-tion. In this manner, the artificial teeth can be properly placed into a denture when inthe wax-up stage, and they will ver\' closely match the location as well as fimctional posi-tion wben placed in the patient's moutli. However, for proper cast orientation, a facebowmust be used to attach the maxillary cast to the articulator and some t>pe interocclusalrecording material must be used to relate the opposing casts to each other. Tliis materialis also used to orient the completed dentures at in.sertion. A variety of materials are usedfor this purpose.

Registration Materiais

A variety of materials are used for the registration process. Generally the materials consistof either a moldable thermoplastic material or a pol>-\inyl siloxane. The thermoplasticmaterials are usually a fiber-reinforced, cloth-mesh encased, tough wax (Aluwax) or amixture of resins and waxes (impression compound). These materials may be softenedin wann water and harden readily when cooled in the mouth when a stream of air orcold water is directed at them. However, their abilit>' to retain dimension is related to notbeing heated again nor flexed. Thus care needs to be taken in handling these registra-tion materials once used. A light-bodied polj^inyl siloxane material (much hke the PVS


impression material previously mentioned) cau also be used to capture tiie registiationof the arches through their overlying appliances. Advantages of this material are that,once set, its dimensions are stable and not affected by temperature, and the material willnot distort or break with fiexure. A disadvantage is that the material is not rigid, and thecasts may not be properly oriented becau.se of this fiexibility.

Bentai Waxes

Among other uses, dental waxes serve as replacement for missing bone and mucosa priorto denture fabrication, are used tojoin casts together, hold the denture teeth in positionfollowing llie tooth arrangement, and for making specific type impressions. These mate-rials are mixtures of natural and synthetic hydrocarbons specifically designed to soften atpre-desired temperatures. Once cooled and hard, they also have a variety of flexibilitiesand hardness.

The most typical type of wax used for denture base fabrication is termed "baseplate"wax. This type of wax is available in three different levels of hardness, each having adifferent flowability at specific temperatures (room temperature, body temperature, andan elevated temperature). Type 1 wax is used mostly in denture base construction,appears moderately soft at room temperature, and has a moderate flow when heated.

The other type of wax commonly used in denture base fabrication is "sticky wax"and is knovm for its ability to adhere to casts. Thus, master casts can be temporally heldtogether using small pieces of tongue blade that have been attached to each cast usingsticky wax. At room temperature, this material is hard and brittle, but it readily flowswhen heated.

Lastly, a special, low-melting impression wax can be used to help capture sectionsof oral mucosa in a nonfunctional state. In the warm, fluid state, this material can bepainted over the impression tray to capture delicate, distortable tissues. When cooled,the material becomes hard and can be removed to provide a negative image ofthe tisstiesin their relaxed, unloaded state. These waxes are easily distorted, should be handled withgreat care, and the casLs poured immediately.

As is the case for all types of waxes used in denture fabrication, care must be exer-cised not to expose the completed wax setup to temperature extremes, as wax has tliehighest level of thermal expansion or contraction of all materials used. If warmed,stresses that had been locked into the "frozen" solid wax may be released, causing thewax to flow and allowing distortion of any impression or denture tooth movement.

Benture Gieansers

Proper denture cleaning is essential for maintaining denture base color and the generalhealth of the patient's moutii. If the dentures and underKing mucosa are not main-tained, tissue irritation, fungal infections, inflammatory papillary hyperplasia, and hali-tosis are possible. Often, patients clean only tlie visible, outside portion of the dentureand neglect cleaning the tissue-bearing side, or also ignore cleaning the tissues upon


which the denture rests. It is the clinician's responsibility to educate the patient in propercleansing methods as well to recommend specific types of ancillary cleaning products.Patients shouJd be warned to avoid use of high levels of heat to clean dentures becausethe dentures may waip irreversibly; resulting in a loss of correct fit.

Cleaning of the denture at ofïice check-up \isits should be used to reeducatethe patient to the procedures and products recommended by the office. Efforts to rein-force compliance with proper cleaning of all surfaces ofthe denture, as well as the oralmucosa should be made.

Denture bases retain plaque and accumulate debris that should be periodicallyremoved. Cleansing of the tissue-ljearing side of the denture is often overlooked. Fvenwith the unending list of denture cleansen tiiat are commercially available, patients canobtain excellent results with the use of an ordinaiy soft-bristle tooth brush and a mildsoap. This method of cleaning causes the least abrasion and discoloration ofthe denturebase aud pro\ides a much cleaner surface. Anotiier excellent method of cleaningdentures is through the use of an ultrasonic cleaner specifically made for denture clean-ing and home use. The use of an ultrasonic cleaner in conjunction with any of the follow-ing materials will yield excellent results. Denture cleansers can be divided into twogroups: abrasives and solutions.

Abrasive Cleansers

The abrasiveness of conventional toothpastes (especially the "whitening" formulations)is excessive for the relatively soft polymer of denture bases, and will easily scratch andcause excessive wear to the dentures. Thus, special formulations of paste-based cleansersare marketed specifically for cleaning these prostheses. Also, soft-bristied brushes arerecommended, as they help to decrease the potential for the cleansing process to abradethe relatively soft denture polymer.

Solution Cleaners: Hypechloriles, Dzygenating Agents, Mild Acids

Hypochlorites Stidium hypochlorite is a well-known antibacterial agent, and in mildconcentration, can be used to remo\e adherent proiein from the denture surface as wellas kill organisms present However, caution must be used, as this fluid is also highly corro-sive to the metal framework of removable partial dentures and therefore cannot be iLsedon these restorations. In additi()n, the color characteristics of the denture base (basic tintas well as inclusion of colored fibers to simulate blood vessels) may be irreversiblyoxidized, resulting in a loss of color and a general whitening.

A g e n t s Solutions of oxygenating agents (such as peroxides, perbo-rates, and peIXarbonates) are made by dissolving tablets or powders containing thesecompounds into water, in which the dentures are immersed for a period of time. Thebubbling activity developed from the tablet dissolution also creates a small agitation ttiathelps cleanse debris from tlie denture surface. However, the "cleaning power" of theseagents is really only superficial, and a denture base can only be tmly "cleaned" throughtlie mechanical action of a paste and baish or an ultrasonic cleaner. These oxygenatingagents should not be used if tiie denture base contains a soft liner, as ihe reaction of tliistype cleanser tends to irreversibly harden the liner.


Mild Acids The mecbanism of "cleaning" of some products relies on creation of mildlyacidic solutions: hydrochloric or phosphoric acids. These agents dissolve calculusdeposits, however they may also attack metals used in partial denture frameworks and aretherefore not recommended for routine use.

Denture Adhesives

If the tissue-bearing surface of the oral ca\it\ is not in intimate contact with the denturebase (through a thin layer of saliva), the denture becomes unstable and is easilydislodged. Increased space between the denture base and underlying tissues arises fromrésorption of underlying bone over time, or from improper denture construction.Relining the denture is often the best method of resolving this problem, however this isnot always possible. To alleviate this misfit, a variety of products are made that fill thesegaps as well as adhere to the denture and overlying mucosa. It should be mentioned, thatin the majorit) of cases, these adhesive materials are not needed if careful attention isgiven to the details of the entire denture fabrication process. However, these productsmay be of use in emergency situations where immediate denture stabilization is desired.

Denture adhesives are often "self-prescribed" by the patienl and are readily avail-able in a variety of over-the-counter formulations. Basically, these products will be eithera paste or a powder Tbere is no clear advantage to either type of product in their abilityto help stabilize a lose-fitting denture. Adbesives are also useful for those patients withlittle-to-no remaining residual ridge to help supply resistance to lateral denture move-ment (stability), for edentulous patients with cleft palates, and for patients wbo wear post-cancer treatment intraoral prosiheses.

Patients who use these t)'pes of supplementary products should be educated aboutthe need for frequent removal of the products from both the denture base as well as thetissues upon which they rest. It is not uncommon that patients continue to place addi-tional product to help "tighten their teeth," and the old material is never really elimi-nated. These products work best if used as a thin layer, and many times a patient willconsider "more is better," and place too much, which results in a denture even moreunstable than prior to the adhesive addition.

Two studies indicate that dentures adhesives may cause problems to a limitednumber of patients. First, sodium may leach from some of these materials and potentiallybe detrimental to those patients on sodium-free or reduced-sodium diets. Powder basedadhesives allow more sodium to be released into the saliva because of the increasedsurface area of the powdei"s: tiierefore a paste may be more appropriate for tbesepatients. Second, some denture cleaners may allow a mild acid buildup in the sali\'a andcould potentially etch (remove superficial enamel and dentin) the dentition in thosepatients witli retained natui"al teeth.

Powder-Based Products

Powder-based denture adhesives contain vegetable gums or special types of polymers thatbecome \iscous and form a mucin-Iike gel wben mixed with water. The resiilting stickinessto both tissues and denture material helps to retain the dentures. The powdered materialis sprinkled over the surface of a wet denture base and is then inserted into the mouth.


Paste-Based Products

Paste adhesives are based on a combination of natural tree-gums, a thick heavy organicgel, coloring, and flavoring agents. As opposed to the powdered products, these materi-als are water-resistant and attempt to displace surface water between the denture and thetissues and seal further water from seeping in. Paste is extruded directly onto the denturebase and is spread until it forms a thin layer, after which the denture is inserted.

References

Beaumont, A. J.. Tupui, L. M., Stuchell, R. N'.: Content and solubility of sodium in denuireadhesive.s. I IVosthel Dent. 1991; 63:536-40.

Craig, R. C. Powers, j . M., Wataha, J. C: Plasucs in Prosthetics. In: Craig, R. G., Powers, J. M.,Wataha, j . C, editors. Dental Materials, Properties and Manipulation. 8 ed, St. Louis: Mosby;2004, p. 270.

Garcia, L. T, Jones, J. D.: Soft Liners. In Agar, J. R., Taylor, T. D., eds. Removable Prosthodontics.Dental Clinics of Norül America. Philadelphia: W. B. Saiinders Company: 2004; 48:709-20.

Grasso, j . E.: Denture Adhesives. In Agai.J. R., Taylor, T. D., eds: Removable Prosthodontics. DentalClinics of North .America. Philadelphia: \V. B. Saunders Company; 2004; 48:721-33.

Koran, A., III.: Prosthetic Applications of PoIvTners. In Craig, R.G., Powers, M., editors: RestorativeDental Materials. 11''' ed. St. Louis. MO: Mosby; 2002, p. 6^0.

Love, W. B., Biswas. S.; Denture adhesives -pH and buííering capacity.J ProsLhet Dem 1991; 66:3.56-60.

Rahn, A. O,, Heartwell, C. M., Jr.: Complete Denture Impressions. In: Rahn, A. O., Heartvs'ell,C. M. Jr, editors: Textbook of Complete Dentures, 5" '' ed. Philadelphia: Lea & Febiger. 1993;p. 228-31.

1. List three of the four methods of polymerizing denture base resin.

2. What is the approximate shrinkage ofa denture base resin during polymer-ization (processing)?

3. Denture resin will absorb water from its storage fluid, and expand slightly(0.1 to 0.2%). WTiy is this important?

4. List four advantages of resin denture teeth over porcelain denture teetli.

5. What are some ofthe advantages ofa laboratory denture reline as opposed toa chair-side reline?

6. Why should a tissue conditioner be replaced reasonably frequently?

7. How does the strength ofa repaired denture compare to the original unbro-ken denture?

8. Why must an irreversible hydrocolloid (alginate) impression be pouredwithin 10 minutes?


9. Wliy should the adhesive for an impres.sion material be allowed to set for themanufacturers suggested time (oiten lU minutes), when visually it appealsilne after only 5 minutes?

10. Wiiat are two characteristics of denture adhe.sives that should be consideredwhen recommending one to a patient?

1. Heat, Chemical Reaction, Microwave Energy, Light

2. Approximately 0.3 to 0.5%

3. Absorption of water by the denture compensates for the shrinkage duringpolv-mcrization making the final dimensions almost exactly the same as thoseoí the mouth.

4. Better retention to the denture base, easier to adjust, less brittle, do notimpart as much occlusal impact to the underlying tissues, and less likely tofracture.

5. The resulting polymer from this laboratory polymerization is much stronger,bonded more tenaciously, and is more resistant to fluid absorption and colorchange than are the ones pohinerized directly in the patient's mouth: thechairside products.

6. If tissue conditioner is allowed to temain in the patient's mouth for too long,it may become hardened, resulting in recreation oí the irritated state of theresidual ridge seen prior to treatment.

7. The transverse strength of heat-polymerized repairs is approximately 80% ofthe unbroken material, whereas it is only 60% of the original strength for thechemically polymerized product.

8. An irreversible hydrocoiloid (alginate) impression should be potired immedi-ately. However, if the impression cannot be poured for several minutes, theset material should be wrapped in a wet paper towel, which provides a 100%humidity environment The major component of alginate is water, and ifnot protected, fluid may evaporate prior to stone being potired into theimpression. Even v\ith good intentions, water may he lost from the impressionand therefore, in all situations, an alginate impression should be pouredwithin 10 minutes.

9. This vraidng time is necessary- to allow the volatile components of the adhe-sive to ev-aporate and to allow the adhesive to slightly soften the surface ofthe impression tray. Tliis softening allows the adhesive to diffuse into theouter portions of the tray, allowing for a more tenacious bond.


10. Denture adhesives may cause problems to a limited number of patients.First, sodium may leach from some of these materials and potentially bedetrimental to those patients on sodium-free or reduced-sodium diets.Powder-based adhesives allow more sodium to be released into the sali\'abecause of the increased surface area of the powders; therefore a paste maybe more appropriate for these patients. Second, some denture cleaners mayallow a mild acid buildup in the saliva and could potentially etch (removesuperficial enamel and dentin) the dentition in those patients witli retainednatural teeth.

C H A P T E R

Anatomy of theEdentulous RidgesDr. Mohamed Sbarawy

25


Altiiough a thorough knowledge of all anatomical landmarks of the edentulous mouth isindispensable tor the .successliil treatment of dental patients, certain structures are espe-cially important wben fabricating complete denture.s. These structures, which affect tliefabrication of complete dentures, and the structures that underlie those important land-marks will be discussed in this chapter.

Accurate impressions of the maxillaiy and mandibular arches should reproducethe landmarks that do not cbange their position with function (Ex: alveolar ridges andhard palate) and the landmarks that change their shape v\ith function (Ex: freniila,vibrating line between soft and hard palate).

Identifying the anatomical landmarks in casts of the maxillary and mandibulararches and comparing them lo the same structures in a patient's mouth should help toprovide the clinician with the confidence that the impression procedure accuratelyreproduced the area to be covered with tiie denture.

E Extraoral Features

The following extraoral anatomical features should be noted when the patient hashis/her mouth closed (mandible in resting position) and his/her top and bottom lipslightly touching: phíltrum. labial tubercle, vermillion borders, nasolabial groove, andlabiomental groove (Eigure 3-1). The philtrum is a midline shallow depression of theupper Up, which starts at the labial tubercle and ends at the nose. The labial tubercle isa little swelling in the midportion of the vermillion border of the upper lip. Tbe lip iscovered by the skin at its facial surface and the mucous membrane at its inner surface.The transitional area between the skin and the mucous membrane of the upper andlower lips is a pink or red zone of thinner epithelium, which is called the vermillionborder. The nasolabial groove is a fuiTow of variable depth that extends from the wing(ala) of the nose to end at some distance from the comer of the mouth. The labiomen-

Fjgure 3-1 Note the Philtrum (P), Nasolabial groove (NL),Labial tubercle (T), Vermillion border (VB) and Labiomentalgroove (LM).

Anatomy of the Edentulous Ridges 27

tal groove is a sharp or deep groove that lies between the lower lip and the chin.Obliteration or filling of one of the above-mentioned normal grooves can occur from aswelling caused by trauma, infection, cyst, or neoplastic growth.

Structures of the Facial Vestibules

The maxillar)' and mandibular dental arches separate the oral cavity into a facialvestibule and an oral ca\it\' proper. With the patient in centric occlusion, the space thatis bound by the lips and cheeks facially and the teeth and gingiva internally is called thelabiobuccal, or facial, vestibule. The depth of the facia! vestibule and fornices changewit!) the way the cheek and lips aje manipulated during impression making. Horizontalpull or functional movements of the lips and cheek should moid the soft impressionmaterials and reproduce the position of the fornices.

The following facial vestibular anatomical landmarks should be idendfied onbotli arches: fomix of the vestibule; free gingiva; attached gingiva; unattached gingiva(alveolar mucosa); interdental papilla; median labial frenums; buccal frenums; andcanine eminences.

The fomix of the vestibule is the site where the mucous membrane lining of the lipsand cheeks reflects and joins the unattached gingiva, or alveolar mucosa. Some peoplecall the fornix the mucobuccal fold—a term tliat is inaccurate. The depth of the vestibulein the upper and lower Jaws is determined by tlie site of the fornix, which in turn is deter-mined by the muscle attachments to the bony Jaws. The muscle that limits the buccalvestibule in the upper and lower jaws is the buccinator- The muscle takes origin from thebase ofthe alveolar process, at the upper first, second, and diird tnolars and the externaloblique ridge opposite the lower molars. It also takes origin from the pterj'goid hamulusand the pter>gomandibular raphé. The latter joins the buccinator with the superiorconstrictor muscle of the pharynx. The fibers of the buccinator have to cross the retro-molar triangle (deep to retromolar pad) to join the pterygomandibular raphé medial tothe medial pteiygoid muscle.

The upper fornix is not supported by strong muscles but has small muscles oppo-site the region of lateral incisor called incisi\Tis muscle. In addition to the latter, obliquefibers of nasalis muscle fix the ala of the nose to underlying bone and septal muscle,which attaches to the septum of the nose. These little muscles do not form a barrier tothe subcutaneous tissue of the face. If, while taking an upper impression, the lips arepulled vertically instead of horizontally the action will artificially increase the depUi ofthe vestibule, and the flange of the denture will extend into tlie subcutaneous space,causing irritation of the mucosa and alteration of the facial appearance.

Following extraction oí teeth, the bone supporting the roots (alveolar process)undej^oes résorption and therefore the depth of the vestibule become shallower.Surgical creation ofa new fornix that would permit increase in the depth ofthe vestibitlemay be required before denture construction.

The free gingiva is the part ofthe gingiva that extends from the gingival margin tothe attached gingiva (approximately tlie level of the gingival sulcus). The attachedgingiva is the part of the gingi\a that is held fii miy to the underhing bone and cemen-tum (hard tissue that covers the root ofthe tooth). The unattached gingiva is tlie part ofthe gingiva that is loosely attached to the underlying bone. It is continuous witli the alve-olar mucosa. The interdental papilla is the part of the gingiva located in the interdental


Figure 3-2 Facial vestibule showing: Fornix (*), uppermedian labial frenum and lower median labial frenum (F),buccal frenum (BF), alveolar mucosa (AM), interdentalpapillae ÍIP) and marginal gingiva (MG).

space. In some patients, the marginal, or free, gingiva is demarcated from the attachedgingiva by the presence of a gingival groove (Figure 3-2).

The vipper medial labial frenum, or frenulum, is a fold of mucous membrane thatoverlies dense connective tissue (Figures 3-2 and 3-4). It does not contain muscle fibei-s,in contrast to die buccal írenula. It anchors the upper lip to the gingiva. The frenumvaries in size among individuals but it is usually more developed than other frenula foundin the vestibule. When it is ahnonnally large, it extends to the interdental papilla betweenthe two central incisors. An enlarged upper median labial frenum is frequently found inassociation with a diastema (large space between the two central incisors). In many eden-tulous patients, resoiption of Lhe alveolar bone brings tlie crest of the alveolar ridgecloser to the frenum. Therefore, a normal frenum may need surreal excision before

Figure 3-3frenums.

Buccal Vestibule. Note the prominent buccal


Figure 3-4 The upper medial labial frenum, or frenulum,is a fold of mucous membrane that overlies dense connec-tive tissue.

successftiï denture construction can be initiated. In all cases, the denmres should berelieved away from the frenula, to avoid iiTitation of these folds and to prevent futureinstability of the dentures. The upper buccal frenum is a mucotis membrane fold thatoverlies dense flbrous connective tissue and fibers of tiie caninus, or the levator angulioris muscle (elevator ofthe angle ofthe mouth). The latter is one ofthe muscles of facialexpression. The lower median labial frenum is morphologically similar to the uppermedian labial frenum but commonly less developed. The lower buccal labial frenum isalso morphologically similar to Uie upper bticcal labial frenum but again less developed.It contains muscle fibers from the depressor anguli oris, or triangularis (another muscleof facial expression) (Figure 3-3).

The canine eminence is a bony prominence in both the nieixilla and mandible thatdenotes the roots of the canine teeth. The eminences of the upper jaw raise the upperlip; its loss leads to the sagging of the lip associated with aging.

Alveolar (Residuai) Ridges

The roots of tlie teeth are supported by the alveolar process of the maxilla and themandible. Following full mouth extractions, the alveolar ridges undergo significantboney changes, with the largest changes seen on the mandibular arch. Studies indicatethat the mandibular ridge resorps approximately four times as much as the niaxillar\'arch. The direction of mandibular résorption is downward and outward, while maxillaryresolution is upward and inward. The results of this resorptive pattern often force a cross-bite ofthe posterior dentures in order to maintain the dentures over the residual ridges(Figures 3-5, 3-6).

The maxillarv" uiberosity is the most posterior part of tlie alveolar ridge; it lies distalto the position of the last molar. It is a bulbous mass of mucous membrane that overliesa bony tuberosity. The maxillary tuberosit)' is important from a denture standpoint


Figure 3 5 Mandibular alveolar ridge showing: crest ofthe ridge (*) and the retromolar pad areas (RP).

because it is considered a primary stress-bearing area and because surgery must beconsidered wben die tuberosity is extremely large and compromises the clearance neces-sary for opposing dentures. The most distal structure in the mandibular residual ridge isthe retromolar pad.

• Maxillary Arch

The anatomical landmarks of the maxillary arch, which may affect denture fabrication,include the incisive papilla, palatine rugae, torus palatinus. mid-palatine raphe. xnaila.

Figure 3-6 Maxillary arch showing: incisive papilla (IP),nnaxitlary tuberosity (MT) and the hamular notch (HM).


fovea palatini, hamuîar notches, posterior palatal seal area, and vibrating line (Figure 3-6through 3-8).

The incisive papilla is a small tubercle located on the palatal side between the twocenli"al incisors. It overlies the incisive foramen, through which the incisive nerve andblood vessels exit. Because of the sensitivitj of this structure, care must be taken wheninserting the maxillary denture to relieve almost all pressure in this area. The incisaipapilla is a good landmark wben contouring occlusion rims and positioning the denturesbecause studies indicate that tbe facial surfaces of the natural central incisors, whenpresent, were approximately &-10 mm anterior to the middle of the incisai papilla, andtlie tips of the canines were approximately in line with the middle of the incisai papilla(Figure 3-7).

The palatine rugae (Figure 3-7) are irregular mucous membranes that extend bilat-erally from the midline of the hard palate in relation to the upper six anterior and some-times bicuspid teeth. Many years ago it was felt dial these süuctures could potentially playa large role is speech and in helping the patient position the tongue. Dentures were fabri-cated with artificial rugae in an attempt to aid patients in these areas, however currentstudies do not indicate that tlie rugae play a significant role in speech or tongue position-ing, and they are no longer considered important when fabricating maxillarv' dentures.

Wien present, tbe torus palatinus (Eigiue 3-7) is a bonv prominence of variable sizeand shape, which is located in the middle of the hard palate. Because the tissue overlyinga palatal torus is usually very thin, and the torus is very rigid, any pressure caused by amaxillarv' denture during chewing and swallowing v\ill often u-aumatize ihe tissue and leadto irritation and ulcération. Care must be taken during insertion to relieve any pressureto the torus caused by the denture. Additionally, an enlarged torus palatinus could act asa fulcaim that can lead to Ínstabilit\ of a denture. Generally, any tonis thai has lateralundercuts or extends to the vibrating line should be considered for surgical removal.

The midpalatine raphé (Eigure 3-8, A) is a line in the middle of the mucosa of thehard palate that overlies the mid-palatine bony suture. The tissue in this area is very thin,and any pressure from a denture will not be tolerated in most patients. Care must betaken when inserting the denture to provide necessary relief.

The uvaila is a tongue-like projection extending from the distal extent of the softpalate. The uvula is muscular. Its exact function is unknown, however it helps in sealing

Figure 3-7 Note the palatine rugae (PR), incisive papilla(IP) and the torus palatines (T).


Figure 3-8 The midpalatine raphé (A) is a line ¡n themiddle ofthe mucosa ofthe hard palate, which overliesthe midpalatine bony suture.The fovea palatini (B) are twodepressions that lie bilateral to the midline of the palate,at the approximate junction between the soft and hardpalate, and denote the sites of opening of ducts of smallmucous glands of the palate.

the oral cavitj' from the nasal cavity during swallowing. Until recently, removing the uvulaand part of the soft palate (uvulopalatopharyngoplasty, UPPP) in an attempt to rehevethe symptoms of snoring and obsu uciive sleep apnea has been popular in the medicalcommunity. This procedure has lost favor, however, because of tiie reasonably low successrate, a certain amount of morbidity associated with the procedure, and the resultant diffi-culty in speech and swallowing in some patients. It is not involved in ttie constn.iction ofcomplete dentures.

The fovea palatini (Figure 3-8, B) are two depressions that lie bilateral to themidline of the palate, at the approximate junction between the soft and hard palate.They denote the sites of opening of ducts of small mucous glands of the palate. They areoften useful in the identification of the vibrating line because they generally occur within2 mm of the vibrating line.

The hamular process, or hamulus, is a bony projection of the medial plate of thepterygoid bone and is located distal to the maxillary tuberosity. Lying between the maxil-lar)- tuberosity and the hamulus is a groove called the hamular notch (Figure 3-9). Thisnotch is a key clinical landmark in maxillar) denture construction because the maxjmitmposterior extent of tlie denture is the vibrating line that runs bilaterally through tliehamular notches. The hamulus can be palpated clinically and it can be a possible site ofirritation in denture wearing patients, if the denture touches diis process. The tendon ofthe tensor velli palatini muscle runs across the hamulus to reach the soft palate. Underthe tendon is a small bursa (membrane between the moving tendon and the hamulus).Inilammation and pain can result from mechanical irritation by imstable dentures.

Although not a truly anatomical feature, tlie vibrating line is ver>' important tolocate for proper construction of tlie maxillarv complete denture (Figure 3-10).•Although not precisely true, tlie vibrating line can be considered as thejimction betweenthe hard and soft palates and is important because it is the maximum posterior limit tothe maxillarv denture. This line runs from about 2 mm buccal to the center ofthe hamu-


Figure 3-9 Lying between the maxillary tuberosity andthe hamulus is a groove called the hamular notch.Thisnotch is a key clinical landmark in maxillary dentureconstruction because the maximum posterior extent of thedenture is the vibrating line, which runs bilaterally throughthe hamular notches.

lar notch on one side ofthe arch, follows the junction ofthe hard and soft palates acrossthe palate, and ends about 2 mm buccal to the center of the opposite hamular notch.

Additionally the vibrating line is the distal extent of the posterior palatal seal area(Figure .3-11). The posterior palatal seal area is verv' important in maxillar> completedenture fabrication and must be identified and evaluated. It is the area of compressibletissue located anterioi" to the vibrating line and lateral to the midline in the posteriorthird of the hard palate. The distal extent of this area is tlie vibrating line, while the

Figure 3-10 The vibrating line is a very important featureto be located in the construction of the maxillary completedenture. It can be considered as the junction between thehard and soft palates and is important because it is themaximum posterior limit to the maxillary denture.


Figure 3-11 The posterior palatal seal area is very impor-tant in maxillary complete denture fabrication and must beidentified and evaluated. It is the area of compressibletissue located lateral to the midline and in the posteriorthird of the hard palate. The distal extent of this area isthe vibrating line, while the anterior border Is indistinct.

anterior border is indistinct. The redundancy of the tissue in this area is caused by thepresence of mucous glands surrounded by abundant loose connective tissue. The depthof compressible tissue is evaluated using palpation and noted for future reference. Thisinformation will be used following master cast fabrication and is important in maxillarv-denture retention.

Mandibular Arcii

In the lower jaw. a triangular area of thick mucosa is found distal to the last molar, basi-cally on the crest ofthe ridge, and is referred to as the letromolai pad (Figiue 3-12). Thispad is extremely important in denture construction from botii a denture extension andplane of occlusion standpoint. The retromolar pads should be covered by tJie denture,and Uie plane of occlusicm is generally located at the level ofthe middle to upper-thirdof this pad. Extending from the hamulus above to the area of the retromolar pad belowis the pterygomandibular raphé fold (Figure 3-13). The pteiygomandibular raphé, whichunderlies the fold, is tlie jtmction between the buccinator (cheek muscle) and the supe-rior constrictor muscle of the phar^'nx. It is often visible in the maxillary impression and,when present, is an excellent landmark for determining the distal extent of the maxillarydenture. It is usually insignificant when making the mandibular impression.

Just buccal to the crest of the mandibular ridge in the distal-buccal comer of thearch is an area known as tlie masseter notch, or groove area (Figtne 5-14). It is impor-tant in mandibular denture fabrication because of its influence on impression making. Itis a diagonal directed line that runs from the depth ofthe vestibule in the anterior to the

Anatomy ofthe Edentulous Ridges 35

Figure 3-12 In the lower jaw, a triangular area of thickmucosa is found distal to the last molar, basically on thecrest of the ridge, and is referred to as the retromolar pad.This pad is extremely important in denture constructionfrom both a denture extension and plane of occlusionstandpoint.

crest of the ridge in the posterior. It is formed by the actions of the masseter muscle.Because there is often a fatty roll of tissue overlying the buccinator muscle, medial to themasseter muscle, Lhis cheek area must often be lifted to eliminate the fatty roll, particu-larly when making the final impression (Figure 5-15). If clinicians do not properly eval-uate this area, the resultant completed mandibular denture is overextended. Thisoverextension will cause significant discomfort to the patient and/or the mandibulardenture will become dislodged on opening.

Figure 3-13 Extending from the hamulus above to thearea of the retromolar pad below is the pterygomandibu-lar raphé fold.


Figure 3-14 Just buccal to the crest of the mandibularridge in the distal-buccal corner of the arch is an areaknown as the masseter notch, or groove area (A). Themost distal extent of the inner surfaces of the mandibularridges ends in an area called the retromylohyoid area, orfossa (B).

The buccal shelf (Eigure 3-16) is located on the mandibular arch and is importantto mandibular denture fabrication because it is tbe primarv' stress-bearing area of tliemandibular arch. It is an area bounded on the medial side by the crest of the residualridge, on the lateral side by the external oblique ridge, in the mesial area by the buccalfrenulum, and on the distal side by the masseter muscle. It is just anterior to the pre-masseteric notch area. The buccal shelf consists primarily of thick cortical bone, incontrast to the crest of the ridge, which is fenestrated and consists of thin cortical boneoverlying more cancellotis bone.

Figure 3-15 Because there is often a fatty roll of tissueoverlying the buccinator muscle, this cheek area mustoften be lifted to eliminate the fatty roll, particularly whenmaking the final impression.


Figure 3-16 The buccal shelf (B) is located on themandibular arch and is important to mandibular denturefabrication because it is the primary stress-bearing areaof the mandibular arch.The residual ridge (A).

The tongue (Figure 3-17) is located in the floor of the mouth. It is important tobecome familiar v\ith the nomial features of the tongiie because many systemic diseaseprocesses, such as iron deficiency anemia and pernicious anemia, for example, can causechanges in the tongue. Early recognition of these changes may help in the discovery ofserious .systemic illness. The tongue is important in denture construction because of itssignificant mobility and because of its involvement with deglutition and speech. Its activ-ities must be accounted for when making impressions and when arranging the teeth onthe mandibular denture. The doi-sum of the anterior two-thirds of tlie tongue is roughbecause ofthe presence of projections known as lingual papillae. The junction between

Figure 3-17 The tongue is located in the floor ofthemouth. It is important to become familiar with the normalfeatures of the tongue because many systemic diseaseprocesses can cause changes in the tongue.


Figure 3-18 The ventral surface of the tongue isanchored to the floor by a mucous membrane foldknown as the lingual frenulum.

the anterior two-thirds and the posterior one-tliird of the tongue is denoted by a V-shaped sulcus called the sulcus limitans. Along this sulcus are 10-13 larger papillae knownas the circumvallate papillae. To observe these papillae, the tongue has to be pulledforward. In many patients, several normal fissures can be obsen'ed in the dorsum of thetongue. The ventral surface ofthe tongue (undersurface) is anchored to the floor by amucous membrane fold known as die lingual frenulum (Figures 3-18 & 3-19). Along thesides of the lingual frenulum slighdy tortuous vessels can be seen glistening through tliethin and smooth mucous membrane of the tongue. These vessels are branches of thelingual arteiT (linguae profundus) and the lingual vein (ranine vein). Branches ofthelingual nei-ve accompany these vessels. Careful handling of tlie dental instruments insidethe mouth is advisable as injury to the vessels and nerves could occur.

Figure 3-19 The ventral surface of the tongue showingveins on both sides of the lingual frenulum.


Figure 3-20 In the floor of the mouth, on both sides,prominent folds of mucous membrane called thesublingual folds are usually seen.

In tlie floor of the mouth, on both sides, prominent folds of mucous membranecalled the sublingual folds are usually seen (Figure 3-20). At Lhe medial end of each foldis a little swelling referred to as the sublingual canmcle, where the subniandibular sali-vary gland duct opens into tbe oral cavity (Figure 3-21, A). -Along the sublingual fold,one can see numerous tiny orifices for tiie ducts of the sublingual salivarv glands. Theorifice ofthe large parotid gland is found in the mucous membrane ofthe cheek oppo-site to the upper second molar. The parotid orifice is gtiarded by a mucous membraneswelling called tiie parotid papilla (Figure 3-22). The orifice of tlie parotid has been

Figure 3-21 At the medial end of each fold is a tittleswelling referred to as the sublingual caruncle; this is wherethe subnnandibular salivary gland duct opens into the oralcavity (A). Some patients exhibit bilateral bony promi-nences of the inner surface of the mandible in the regionof the premolar teeth called the torus mandibularis (B).


Figure 3-22 The parotid orifice is guarded by a mucousmembrane swelling called the parotid papilla.

used as a landmark to help determine the level ofthe plane of occlusion. Because of itsposition, however, il is veiT diñiciilt to visualize in many patients without mo\'ing thecheek to an unnatural position.

Along the inner surfaces of the middle to posterior one-third of the mandible, bonyridges knowTi as the niylohyoid, or internal oblique ridges (site for attachment of themylohyoid muscles) can be palpated. Occasionally prominent sharp, bony ridges musl besurgically reduced prior to making complete dentures to minimize patient discomfort.These are important structures because ofthe attachment ofthe mylohyoid muscles andthe influence of tliese muscles on the denture flanges.

Some patients will exhibit bilateral bony prominences of the inner surface oftlie mandible in the region ofthe premolar teeth called the torus mandibularis (Figure3-21, B). These prominences must usually be removed prior to denture fabrication.

Figure 3-23 In patients suffering from atrophiedmandibles, the residual ridge resorbs to the level of thegenial tubercles, which can easily be palpated. (A) residualridge, (B) genial tubercles


TTie most distal extent of the inner surfaces of the mandibular ridges ends in anarea called the retromylohyoid area, or fossa (Eigure 3-14, B). The fossa is bound later-ally by the mandible and the most anterior border of the medial pterygoid muscle andmedially by tbe tongue. Tlie fossa is distal to the most posterior fibei-s of the mylohyoidmuscle. The impression materia! may extend into the fossa. The opposing retromylohy-oid areas are usually undercut, in relation to each other. One difficulty encounteredwhen fabricating tbe mandibular denture is that these bilateral undercuts may greatlycompHcaie the process of making preliminai^ and final impressions. The dentures mayalso reqtiire significant adjustments in these areas at the time of insertion.

In patients suffering from atrophied mandibles, the residual ridge resorbs to thelevel of the genial tubercles, which can be easily palpated (Eigure 3-23). Tliese bonymidline lingual projections offer attachment to genioglossi and geniohyoid muscles. Thedentures should be trimmed around the genial tubercles in those cases.

1. What is the name of the site where the mucous membrane lining of thelips and cheeks reflects and joins the unaltached gingira or alveolar mucosa?Some people call tiiis the muct>buccal fold—a term that is inaccurate.

2. Besides location, what is one major difference between the upper mediallabial frenum, or frenulum, and the buccal frenuia?

3. Eollowing full mouth extractions, the alveolar ridges undergo significantbone loss in most patients. Compare the amount of bone loss of themandibular and maxillary arches.

4. Why is the incisai papilla a good landmark to note when contouring occlu-sion rims and positioning tlie denture teeth?

5. Why is the location of the fovea palatini important to note in the edentulouspatient?

6. The maxillary complete denture should not cover the hamular process, orhamulus; why then is the location of the hamular process important?

7. \Miat structure is located distal to the last mandibular molar and why is itimportant in the making of complete dentures?

8. JiLSt buccal to the crest of the mandibular ridge in the distal-buccal comerof the arch is an area known as the masseter notch, or groove area. Why isthis area of interest when fabricating a mandibular denture?

9. WTiat and where is the buccal shelf and why is it important in the fabricationand wearing of mandibular complete dentures?

10. What is the area that determines the most distal lingual extent of amandibular complete denture and what difficulties may the clinicianhave with this area?


1. The fornix of tlie vestibule is the site where the mucous membrane liningof the lips and cheeks reflects and joins the tmattached gingiva, or alveolarmucosa.

2. The upper medial labial frenum, or frenulum, does not contain musclefibers, in contrast to the buccal frenula.

3. Studies indicate that the mandibuiar ridge resorps approximately four timesas much as the maxillary arch.

4. The incisai papilla is a good landmark when contouring occlusion rims andpositioning tlie dentures because studies indicate that the facial surfacesol the natural central incisors, when present, are approximately 8-10 mmanterior to the middle of tlie incisai papilla, and the tips of the canines areapproximately in line with the middle of the incisai papilla.

5. The fovea palatini are two depressions that lie bilateral to the midline of thepalate, at the approximate junction between the soft and hard palate, anddenote the sites of opening of ducts of stiiall mucous glands of the palate.They are often useful in the identification of tlie vibrating line because theygenerally occur within 2 mm of the vibrating line.

6. The hamular process, or hamtiltis, is a bony projection ofthe medial plateofthe pter\goid bone and is located distal to tbe maxillarv' tuberosity. L>ingbetween the maxillary tuberositv' and the hamulus is a groove called thehamular notch. This notch is a key clinical landmark in maxillar)' dentureconstruction because the maximum posterior extent of tlie denture is thevibrating line, which runs bilaterally through the hamular notches.

7. In the lower jaw, a triangular area of thick mucosa is found distal to the lastmolar, basically on the crest of the ridge, and is referred to as tlie retromolarpad. This pad is extremely important in denture construction from both adenture extension and plane of occlusion standpoint. This pad should becovered by the denture, and the plane of occlusion is generally located at thelevel of the middle to upper one-third of this pad.

8. This area is important in mandibular denture fabrication because of its influ-ence on impression making. Becau.se there is often a fatty roll of tissue overly-ing the masseter muscle, this cheek area tnust often be lifted to eliminate thefatty roll, particularly when making the final impression. Clinicians may notproperly evaluate this area and the resultant completed mandibular dentureis overextended, causing dentute instability and tissue initation.

9. The buccal shelf is located on the mandibular arch and is important to man-dibulai" denture fabrication because it is the primary stress-bearing area of themandibuiar aich. It is an area bounded on the medial side by the crest of theresidual ridge, on the lateral side by the external oblique ridge, in the mesialarea by the buccal frenulum, and on the distal side by the masseter muscle.It is just anterior to the masseter notch area.


10. The most distal extent of the inner surfaces of the mandibular ridges endsin an area called the retromylohyoid area, or fossa. This area is the mostdistal extension of the mandibular denture, and the opposing retromylohy-oid areas are usually undercut in relation to each other. One difficulu-encoimtered when fabricating the mandibular denture is tliat these bilateralundercuts may greatly complicate the process of making the preliminar}-and final impressions. The dentures may also require significant adjustmentsin these areas at the time of insertion.

C H A P T E R

Diagnosisand TreatmentPlanning

Dr. Jack Morris

45


To have an excellent prognosis for any dental treatment requires proper preplanning,which will inciude at least a thorough examination, diagnosis, and a treatment plan.After the examination is complete and all diagnostic information has been evaluated,only then should a final diagnosis, treatment plan, and prognosis be formalized anddiscussed with the patient. Patients may require pre-prosthetic surger)-, antifungal ther-apy, or soft relines to obtain better tissue health before definitive treatment can be initi-ated. Prior to forming a treatment plan, all reasonable patient treatment options.should be discussed with the paüent to include implant-retained or supported prostlie-ses. The final treatment plan should be the best treatment for the patient based on hisor her chief complaint, medical history', clinical exam, financial resources, and the timerequired to complete the planned treatnient. Dentists must realize that, just as dentatepatients \'ary in their dental treatment complexity, edentulous patients also vary in thediíTicultv' of their treatment plan. This occasionally means thai, based on the dentist'sevaluation ofthe patient and the patient's desire to have a complex implant restoration,a patient should be referred to a specialist for treatment. To successfully treat edentulouspatienis, the clinician must develop good diagnosis and treatment planning skills tobetter identif)' the complexity ofthe patient. Once these skills are developed, both thesuccess rate of the dentist when treating edentulous patients, and the niunber of refer-rals to a prosthodontist will rise.

A great deal of iniormation is required to complete a proper diagnosis, includingpatient attitude, past and present medical conditions, past and present dental condition,and extraoral and intraoral examinations.

Diagnosis

M. M. Devan said "we must meet the mind of the patient before we meet the mouth ofthe patient." Edentulous patients come to us looking for solutions to their problems, andoften these problems are botli physical and psychological. A good initial inter\iew is verycritical to the diagnostic process. Clinicians musl allow patients to communicate theirchief complaint in their own words and take note of how patients present themselves.This might include how patienLs dress, tlieir concern for their physical appearance, andtheir overall attitude and expectations concerning treatment. It is important as a healthcare provider never to treat a stranger. Taking time to allow the patients to voice theirconcerns and expectations will contribute to their trust and confidence in their dentist'sability to diagnose and successfully Lreat iheir oral condition.

Medicai History

Acquiring a thorough medical history must be one of the very fim steps in successfullytreating any dental patient. A good medical history questionnaire combined withverbal qualification by the patient is essential to any dental treatment plan. .Any medicalor psychological condition that is a deviation from "the norm" must be noted and evalu-ated for its potential effect on patient treatment. Uncontrolled diabetics, padents with

Diagnosis andTreatment Planning 47

cardiovascular disease and subsequent treatment wilh blood thinners, and immunocom-promised patients may be excellent denture patients but might not be considered goodsurgical risks and therefore, pre-prosthetic surgery may be contraindicated. The date ofthe patient's liist physical exam is important because the medical condition of the patientmay have changed dramatically if the last exam was several years ago. A history of move-ment disorders such as Parkinson's Disease could affect one's ability to treat the patientas well as the patient's abilitv^ to successfully wear the complete denture. Patients witli ahistory of psychological and cognitive impairment diseases might have unreasonableexpectations of complete denture treatnjent and may be unable to significantly cooper-ate in their own care. One condition that could alter routine treatment is a history ofhead and neck radiation which could comphcate any need for pre-prosthetic surgei^ andalso result in xerostomia for the patient.

Present Medical Condition

It is essential to update the patient's medical historv' at each follow-up appointment toensure that the patient is truly being appropriately followed for their medical conditionsand that they are correctly taking any prescribed medications. Witb tbe aging denturepopulation, many patienLs are taking nimierons medications, many times prescribed inan uncoordinated fasbion by multiple physicians. If ihe clinician has any concerns abouta particular medication or possible confiicting medications that a patient is taking, areferral to the patient's primai^ care provider is appropriate. Consults should be writtento appropriate physicians to evaluate any questionable medical conditions. Many eideriypatients must he accompanied to their appointments by friends or family members whoalso might be questioned concerning the patient's health.

Vital signs to include blood pressure and pulse are important to establish an initialbase line; patients could require a referral if ihey are not within normal limits. Baselinevital signs may be critical information in any future medical emergency. Many of today'smedications can cause xerostomia, wbich can affect the patient's oral health and abilityto wear complete denlures successfully. Patients taking antihistamines as well as medica-tions for depression, anxiet), high blood pressure, muscle relaxation, urinary inconti-nence and Parkinson's disease can have dry mouth as a side effect. Any allergies shouldbe identified and noted in the patient's record. Knowing that a patient has allergies toantibiotics and pain medications is extremely important because it is occasionally neces-sar\' to treat dental infection and pain following any pre-prostbetic surgery.

A greater number of patients are being recognized as allergic to latex and metals,particularly nickel. These allergies must be considered for even routine care of tbepatient and when contemplating die metal to be used in a removable partial denUire.

A medical bistor)' must include vital signs, medications being taken, allergies, pastmedical history, and present medical condition. Sufficient information is essentialto allow the dentist to make an assessment of the patient's general overall healtli. Willthe patient be able to tolerate long appointments or, due to their failing healih,should appointments be as short as possible? A good written medical questionnaire andverbal interview is essential for the dentist to help determine the patient's diagnosis andsubsequent treaunent plan as well as the projected prognosis for tbe complete denturepatient.


I

I

Dentai History

A complete denture exam should incltule a thorough dental liistory of the padent, whichincludes at least the following: What is the patient's chief dental complaint? Were theirteeth lost due to caries, periodontal disease, or trauma? Has periodontal disea.se or traumacompromised the residual ridges? How long has the patient been edentulous? If tiiepatient has been edentulous for some time and has never worn dentures, why not? Howlong has the patient worn complete dentures, and were tlie dentures fabricated alter somehealing time or inserted imtTiediately? A patient with recent extractions will be expectedto experience more imtnediate changes to the residual ridge than a patient who has beenmissing teetli for many years. Has the patient had good follow-up care to include relinesand remakes as needed? If not, why not? Are the dentures properly extended, stable, andretentive? Are tbe esthetics and phonetics of tlie present dentures acceptable? (-an signif-icant improvements be made? Are the patient's expectations reiisouable? How much toothdisplay is visible at rest and when .smiling? Is the occluding vertical dimension (OVD)acceptable with the existing prosthesis? Are the denture teeth porcelain or plastic, andwhat type occlusal scheme exists? Will tlie patient tolerate a change if indicated? Overall,is the patient pleased with his or her present prosthesis? Wliat are the patient's likes anddislikes with any exisdng prostlieses? Wliat are tlie patient's expectations for tlie newdentures? Can you as the clinician meet those expectations? Are the patient's concernswith the present denturesjtistified? How many dentures has the patient had in the last fiveyears? A patient presenting with two or more sets of recently fabricated dentures oftenindicates a padent who may have an exacting or unreasonable mental attitude.

CiiDicai Extraoral Examination

Good physical diagnostic skills involve observation, palpation, and auscultation andshould be utilized when performing the clinical head and neck exam. WTien examininga patient, it is important to be thorough and sequential. A good clinical exam form ishelpful in accomplishing this (Figure 4—1 ). The patient's range of mandibular movementshould be obsened for any t)pe of irregular tiiovement or deviation. Tlie muscles ofmastication and facial expression should be ohsened during movement and conversa-tion as well as palpated to locate any muscle tenderness or dysfunction. Uncoordinatedmandibuiar movement or temporomandibular disorder/pain could certainly complicateany attempt to obtain accurate interocc!u.sal records and might help detennine that asimple occlusal scheme should be selected for this patient. The temporomandibular jointshould be palpated as well as auscultated and any pain, tenderness, popping, or clickingshould be noted.

The neck should be palpated for any lumps, masses, or enlarged lymph nodes.The lips and skin should be evaluated for any type of nonhealing lesions or untisual nevi.The commissures of the lips should be examined and any evidence of angular cheilitis(Figure 4-2) noted. The lip length, thickness, and curvature .should be noted with thepatient's existing prosthesis in place. The face should be observed and noted in frontaland profile facial form. The patient's facial midline should be noted. Does the middle ofthe philtrum of the lip and the patient's midline on their e.visfing maxillary prosthesiscoincide?

Diagnosis and Treatment Planning 49

Complete Denture Examination, Diagnosis and Treatment Planning Form

Patient: Date:

1. Chief complaint (patient's own words):

2. Past Dental History:a. Date of last visit to dentist:b. Reason for last \isit and treatment received:c. Date of last extraction:d. Pre\ious prosthesis t\pe(s):e. Number of previous complete dentures:f. Ability to adjust to previous dentures:g. Patient reaction to previous treatment:

3. Evaluation of Present Dentures:a. Esthetics:b. Phonetics:c. \T>O:d. Base extension:e. Stability and retention:f. Occlusion:g. B-L tooth position:h. Occlusal plane height:i. Pattern of tooth wear:

j . Denture hygiene:k. Evidence of self-adjustment:1. Patient criticism of previous denture (own words):m. Patient expectations of new denture:n. Compare your observations witli the patient's comments:o. Problems noted:p. Can improvemeiiLs be made?

4. Soft Tissue Examination: (note areas of potential patliology):

5. Hard Tissue Examination (Radiographic exam): pre-pros surgery required? ( )

6. Saliva: amount: excessive ( ) scant}' ( ) average ( )consistency: thick ( ) thin ( ) average ( )

7. Facial Appearance: frontal: square ( ) tapering ( ) ovoid ( ) combination ( )profile: straight ( ) curved( ) combination ( )muscle tone: good ( ) fair ( ) poor ( )

8. lip form: length: long ( ) short ( ) average ( )thickness: thick ( ) thin ( ) average ( )curvature: curved upward ( ) curved downward ( )

9. Maxillary Ridge Form: Mandibular Ridge Fonm:a. shape a. shape shape: square, tapering, ovoid, combo.b. size b. size ï^rge, medium, smallc. width c. width broad, narrow, averaged. cross section , c. cross section square, trapezoid, triangular, flat

{Continued)


10. Ridge relationship:a. An te ropos te ri orb. Medio-lateralc. Parallelism

CI I (normal), CI II (retro), CI III (prog)normal, unilat cross-bite, bilat cross-biteparallel, divergent, convergent

11. Tuberosities RL

(bone/soft tissue) large, meditim, small, undercut(bone/soft tissue) large, medium, small, undercut

12. Inter-ridge spaee: large ( ) small ( ) average ( )

13. Tongue: size: large ( ) small ( ) averageposition; retracted ( ) normal ( )controi: can move to follow directions ( ) can not ( )

14. Hard Palate Form: high vault ( ) shallow vault ( ) average ( ) v-shaped ( )

15. Soft Palate Form: CI I (gradual) ( ) CI U (moderate) ( ) CI UI (steep) ( )

16. Floor of mouth: location: high ( )mobility: mobile ( )

low ( )immobile ( )

average ( )average ( )

easy ( ) hard ( ) may be impossible ( )

indifferent ( ) senile ( )

17. Ability of patíent to repeat CR position:

18. Patients Mental Attitude:

philosophical ( ) exacting ( ) hysterical ( )

19. Patients Adaptive Potential: good ( ) poor ( )

Treatment Prognosis: good ( ) fair ( ) poor ( )

Summary of Special Procedures Needed: Additional Radiographs ( )Biops)' ( )Pre-pros surgery ( ) Stirgical tetnplate ( )Tissue conditioning ( ) Anti-fungal therapy ( )

Treatment Plan and Sequence:

Figure 4-1 Complete denture examination, diagnosis, and treatment planning form.

Figure 4-2 Angular chelltis


Intraorai Examination

Tlie intraorai exam should begin first with a general evaluation of the patient's oralmucosa (Figure 4-3). Note the condition of the mucosa—specifically whether it is fiabbyor bound down, pink and healthy, or red and edeniatous. Excessively thick or ihin areasof oral mucosa should also be noted. The mueosa should be evaluated as it relates to theridge. For example, are there large areas of keratinized attached tissue on the ridge or isthere mostly mo\'able mueosa on the ridge? .-MI areas of the oral cavic)" should be gener-ally inspected for any type of patholog)' to include the soft palate and the lateral bordersof the tongue.

Some complete denture patients refuse to remove or clean their prosthesesfor prolonged periods (Figure 4-4) and as a result might have extremely initated and

Figure 4-3 Hyperkeratotic lesion in cheek oral mueosa

Figure 4-4 Denture of patient who failed to remove anddean denture


Figure 4-5 Denture stomatitis. Note the highly inflamedtissues of a patient who rarely removed the maxillarycomplete denture.

traumatized tissues (Figure 4-5). These patients are much more susceptible to fungalovergrovvth and colonization of the prosiheses and subsequent inflammatoi-y papillaryhyperpUisia—especially in Uie palate (Figure 4-6). .\ieas of redundant tissue adjacent todenture borders, called epulis fissuratum (Figure 4-7), are usually quite painful and arecaused by excessive denture fiange length. These areas should also be noted andappointed for surgical excision if the condition does not resolve following the removal ofthe overextended denture border.

The saliva should be evaluated both in amount and consistency. A normal amountand thickness of saliva is paramount in the ability of most patients to comfortably weardentures. The saliva acts as a lubricant and also serves as the interface between thedenture base and tbe tissue allowing for denture retention. A patient with xerostomia orexcessive saliva containing much mucous can have difficulty obtaining an adequate seal

Figure 4-6 Inflammatory papillary hyperplasia.Thiscondition must be addressed prior to fabrication of anew denture.


Figure 4-7 Epulls fissuratum. Usually caused by anoverextended denture flange.

for their prosthesis. A patient with normal salivar\ flow will benefit from its adhesive andcohesive qualities. Patients with diy mouth not only have poor prostliesis retention butalso a greater tendency for oral mucosa tenderness. During the oral exam, the salivarygland orifice should be inspected for proper opening and salivary flow'. Ideally tbe salivawould be ofa thin, serous type as compared to thick, ropy saliva.

During the course of the examination it is helpful to note whether the patient hasa problem with gagging. A hypersensitive gag reflex can complicate successful fabricationof a complete denture. Often patients will volunteer their gagging problems whilediscus,sing their dental history or this could be detected while performing a routine hardand soft tissue exam with an intraoral mirror. Most of these patients can be successfullytreated by the dentist using proper impression techniques. However, a ven' small percent-age of patients have a truly hypersensitive gag reflex and might be best treated by aprosthodontist.

A cuiTent panoramic radiograph reflecting the patient's present condition must beevaluated. Conditions to especially note are the mandibular bone height, the position ofthe mental foramen, retained root tips, unerupted teeth, residual cv'sts, bony pathology,maxillaiy sinus position and healtli, and any unusual TMJ anatomy. Retained root tipsand impacted teeth should be evaluated for any pathology' and whether they arecompletely retained in bone. Teeth and root tips that are only covered by soft tissue orare exposed to the oral cavity should be considered for removal. The removal of deeplyimpacted teeth and root tips may cause excessive bone to be lost and cause more harmto tbe denture bearing surface by removing than just leaving and follov ing them peri-odically with radiographs—especially in patients who are in poor health. In every case thepatient shotild be informed of the risk and benefit of the removal of the impacted teethand root tips, and a decision should be agreed upon by the dentist and the patient.

The maxillarv^ ridge should be evaluated for size, shape, and cross-sectional fonn.Generally speaking, a larger ridge will have more surfece area for better retention andstabilitv' as compared to a small ridge. The residual ridge shape is cla.ssified as square,tapering, or ovoid. The shape is probably most important as it relates to the opposingarch because mismatched arch shapes can make tooth arrangement challenging. Nextcross-sectional form should be noted. Ridges are generally U-shaped. V-shaped, knifeedged, or flat. The worst type of ridge is a knife edged or Oat ridge, which does not


provide a good foimdation base for the denture. The most ideal ridge would be aU-shaped ridge—almost Hat at the crest of the ridge witli tall non-undercut approximat-ing buccal and palatal walls. These ridges provide maximum retention, stability, andsupport. Tlie ridge should also be evaluated for any exostoses or bilateral posteriorundercut. Bulbous tuberosities can result in bilateral posterior undercuts and insufficientinterocclusal space. In these situations, preprosthetic surgery' is usually indicated.

The form of the hard palate should be determined. Any pedimculated torus(Figure 4—8) or a torus that extends into tlie posterior palatal seal atea should beremoved if possible. The hard palate is tisually classified as a high, average, shallow, orV-shaped. An average U-shaped palate is ideal. A V-shaped palate or high vault cancompromise the seal of tlie denture.

The soft palate is classified as Class I, Class II, or Class III depending upon theamount of movement or slope of the soft palate relative to the hard palate. Genei"ally themore severe the angular change from the hard to the soft palate, the easiei' and yet morecritical the exact location of the vibrating line becomes. A denture cannot extend ontothe movable soft palate without signiftcantly increasing the possibility of loss of dentureretention and causing tissue irritation and discomibrt to the patient. Generally, a softpalate that moves slightly and slopes little is considered a Class I palate. One that dropsabnipdy at the junction of the hard and soft palate is considered a Class III palate. ACla.ss II palate would fall between tihe above mentioned examples.

Similar to the maxillary ridge, the mandibular ridge is evaluated for size, shape, andcross-sectional form. A larger ridge can provide more surface area for stability, support,and retention, and again the shape of the arch is most important in its relationship tothe opposing arch. As with the maxilla, a U-«haped ridge in cross-section is much morefavorable than a V-shaped, knife edged, or flat ridge. The ridge should be evaluated forany tori (Figiu e 4-9), exostoses, and bilateral undercuts. Diagnostic casts are often neces-sary to adequately evaluate the residual ridges.

Maxillary and mandibular ridges should be evaluated for how much space theborder tissues allow for complete denture fabrication. If frenula attachments are close tothe crest of the residual ridge then denture borders must necessarily be short, which

Figure 4-8 Maxillary pedunculated torus. Must beremoved if it is so large that it will interfere with space forthe tongue, is undercut, or extends so far posteriorly thatit prevents the placement of a posterior patatal seal.

Diagnosis and Treatment Planning 55

Figure 4-9 Mandibular tori. Must generally be removed.

could compromise the retention of Lhe denture. As the lips and cheeks are simulatingmuscle movement, the dentist should note whether the attachments are near the crest oftlie ridge or whether the muscle and tissue attachments are away from the crest of theridge to allow for a more substantial denture foundation. It is especially impoitant tonote the muscle attachments on the lingual side of the mandibular ridge. Is the anteriorlingual flange ofthe mandibular denture going to be compromised becatise the genialtubercles are near tlie crest of tlie ridge? A patient with sh(irt lingtial flanges because ofhigh lingual attachments (often referred to as high floor of the mouth) can havecompromised lateral stability ofthe denture. Palpate the mylohyoid ridge. Is it extremelylarge or sharp? Evaluate the reuomylohyoid aiea, space, or fossa. As the patient toucheshis lips with tlie tongue is the retromylohyoid space obliterated or is tiiere space thatcould be occupied by the lingual flanges of the denture base? Once again, for mostpatients, the longer the flanges of the dentures, the more support, stability, and reten-tion will be obtained with the denture.

How do the opposing residual ridges relate to each other? The occluding verticaldimension can be approximated in most patients by having them Ughtiy close on a fingerplaced between the anterior ridges; thereafter some statement can be made about therelationship of the residual ridges. Another method is to e\aluate the ridges when thepatient closes into a position where the ridges are approximate!) parallel to each other.In some patients this is almost impossible and diese notations must be made after castsare mounted on an articulator at the appropriate occluding vertical dimension. Theanterior-posterior relationship of tlie residual ridges of the complete denture patient canbe misleading. As the residual ridge resorbs, the maxillary ridge resorbs upward andinward, and the mandibular ridge resorbs downward and outward. The crest ofthe ante-rior mandibular ridge resorbs four times more than the anterior crest of the maxilla inthe first seven years after teeth are extracted, therefore significant changes should beexpected particularly when contemplating immediate dentures. Essentially the maxilla isgetting more narrow and shorter, and the mandible is getting longer and wider tendingto make the patient appear prognathic in the anterior and to have a crossbite ridge rela-tionship in the posterior. In observing the anterior posterior position of the ridges, itis important to note tlie location of tlie incisive papilla and realize tliat the incisai edgesof the maxillary natural teeth were, on average, 7-8 mm anterior to that position. Manypatients will exhibit significant bone loss in this area, witii the incisive papilla literally


being on the anterior slope of the ridge. Is the patient's antero-posterior relationshipprognatliic (Ciiass III). retrognaUiic (Class II), or a normal (Class I) relationship?Generally speaking a Class I patient is an easier complete denture patient than a Class IIIpatient, and a Class II patient is the most difficult of all. Severe Class II patients shouldhe considered for referral to a prosthodontist.

The medio-lateral relationship of the opposing ridges should also be evaluated. Dothe arches coordinate? Is one arch shaped difíerently ihan the other? Will teeth have tobe set in a crossbite relationship? Are the ridges generally parallel at the proper occlud-ing vertical dimension? Ridges tend to be parallel at the proper occluding vertical dimen-sion unless there has heen some t)'pe of irregular resorptive pattern (Figure 4-10). Ridgesthat are not parallel at the proper occluding vertical dimension can make the completeddentures quite unstable during function. Learning to use such dentures may present asignificant challenge for the patient. Evaluation ofthe patient's inter-ridge space at theestimated OVD is necessaiy. Excessive inter-ridge space or too little inter-ridge space cangreatly compromise proper denture fabrication. Tuberosities should also be evaluated atthe estimated OVT). A mouth mirror, which is usually ^ to 2.5 mm thick, can be used toevaluate if enough space is available for each denture bases to be at least 1 mm thick.

The tongue size and position should be noted. A ver>' large tongue can be seen inpatients who have been edentulous wiili no replacement prosthesis for an extendedperiod (Figure 4-11), An enlarged or oversized tongue can greatly compromise apatient's ability to successfully wear a complete denture. According to Dr. C. Wright, theposition ofthe tongue greatly affects the ability of a patient to successfully wear completedentures. He reported that 35% of people had a retracted tongue, which could compro-mise a denture patient's ability to seal the lingual border of the mandibular denture.Additionally he felt that the ideal position of the tongue was with Uie apex (jf the tongueslightiy below the incisai edges of the mandihular incisors and with the dorsmn of thetongue visible above the teeth in all parts of the mouth. The control or coordination ofthe tongue should also be noted. Is there any neuromuscular condition that affectsthe patient's speech, .swallowing, or general muscle coordination? If so, tins may compro-mise the ability of a patient who is a first time denture wearer, to satisfactorily adjust tothe dentures.

Figure 4-10 An irregular bony resorptive pattern maymake complete dentures unstable.


Figure 4-11 Example of a very large tongue, which maycause great difficulty in wearing a complete denture espe-cially for a first time denture wearer.

Mental Attitude of Patient

Successfully wearing a complete denture is a learned skill for most patients and especiallyfor new denture patients. Therefore, the mental attitude of the patient may play a veryimportant role in die edentulous patient's abilitv' to adapt and can be vei-y valuable infor-mation for a dentist to help evaluate the ultimate prognosis of denture patients.Dr. House has classified complete denture patients into four mental attitude categories—philosophical, exacting, indifferent, and hysterical.

The philosophical patient exliibits an attitude that is optimistic, cooperative,rational, and sensible. The patient is veiling to accept advice and desires the properrestoration to return himself/herself to an excellent state of oral health. This is the idealpatient type. The exacting patient is precise, meticulous, and could make extreme andunreasonable demands of the dentist. This tvpe of patient often questions even minutedetails of the denture, including the alignment of a single posterior tooth, and whetherthe new dentures will ever look right or function well. These patients can often requireexcessive amounts of the practitioner's time to satisfy their demands. These patients canbe far less than ideal. The hysterical patient is often excitable, nervous, excessively b)per-sensitive, and often very pessimistic. This patienl might dread dentistry and feel that heor she may never be able to wear the new dentures. This patient may require professionalpsychological counseling in order to be treated successfully. Some have suggested thatdentists are fully justified in charging increased fees to this patient because of the extratreatment time required. The indifferent patient is likely to lack motiv-adon and might beunwilling to follow instructions regarding bis or her oral health. Many times diis patientis seeking treatment not because of concern for his or her dental health but because aspouse or family member has encouraged them to care about oral health. Patients in thiscategorv' are less likely to persevere and learn to function witii their complele dentures.These patients can be the most difficult categor)' of patient to treat because of their lackof motivation.


Additionai Diagnostic Iníormatíon

Diagnostic casts are very helpful to further evaluate the anatomy and condition of theresidual ridges. Generally diagnostic casts are made from preliminary impressions madewiüi irreversible hydrocolloid (alginate) in stock trays (Figure 4-12). Good diagnosticcasts should include the retromolar pads and border tissues as well as tlie pterygomaxil-lary notch and the posterior palatal seal area (Figure 4-13). See Chapter 6 on Prelimi-nary Impressions and Custom Impression Trays for further infomiation.

Another tool to help the dentist identify' the complexity of their denturepatient is called the Prosthodontic Diagnostic Index (PDI). The American College ofProsthodontists has recommended that practioners use the PDI to classify edentulouspatients. This system is said to help better identify difficult denture patients and help

Figure 4-12 Examples of nicely made preliminaryimpressions

Figure 4-13 Examples of excellent diagnostic casts


dentists better tmdei^tand when to refer a patient. The PD! could also help dentists withreimbursement if insurance companies are willing to qualify that all denture patients arenot the same difficulty. This classification system uses four general diagnostic assessmentcriteria: mandibular bone height, maxillomandihular ridge relationship, residual ridgemorpholog); and muscle attachments. The system also idendfies several other criteriaand diagnostic modifiers that can be expected to increase complete denture difficulty.These modifiers include systemic considerations, psychosocial considerations, tongueanatomy/activity, temporomandibular disorders, condidons requiring preprostheticsui^ery, interarch space, refractory patients, patients vrith a history of paresthesia ordyTsesthesia, maxillomandibiilar ataxia, and maxillofaclal defects.

After all the PDI diagnostic criteria and modifiei s have been identified, the patientis categorized from Class I to Class IV (Figure 4—14). A Class I patient is uncomplicatedand should be able to be treated by a general dentist vsith limited complete denture expe-rience. The prognosis for tliis patient should be good to excellent. A ( lass II patient hassome moderately complicating factors, such as systemic disease or residuid ridge anatomy,and should be successfully treated hy a gener.il dentist with experience treating patientswith complete dentures. For the experienced general dentist or prosthodontist, die prog-nosis for this patient should be good. A Class III patient has additional complicatingprohlems, such as TMD symptoms, limited or excessive interarch distance, and possibly aneed for pre-pros the tic surgeiy. This t)pe of padent is best treated by a prosthodontist ora general dentist v\'ith addidonal training in advanced prosthodontic techniques. The

Complete Edentulism Checklist

Bone Heighf-Mandibular21 mm or greater16-20 mm] l-15mm10 mm or less

Residual Ridge Morphology-MaxillaType A-resists vertical & horizontal, hamular noten, na toriType B-no buccal vest., paar hamular notch, na foriType C-no ont vest, min suppari, mabile ant ridgeType D-na ant/post vest, tari, redundont tissue

Muscle Attachments-MandibularType A-adequate attached mucosaType B-no b attach mucosa (22-27). +mentalis mType C-no ant b&i vesi (22-27), +genio & mentolis mType D-att mucasa in past aniyType E-na att mucasa, cheek/lip moves tongue

Maxillomandibular Relotionships

Class 1

Class tl

Class 111

Conditions Requiring Preprosthetic Surgery

Minor soft tissue procedures

Class 1 Class II Class III Class tV

[Continued)


Minor hard tissue proceduresImplants - simpleImplants with bone graft - camplexCorrection of dentotacial deformitiesHard tissue augmentalfonMajor soft tissue revisions

Limited Interarch Space

18-20 mmSurgicol correction needed

Tongue Anatomy

Large (occludes interdental space)Hyperactive- with retracted position

Modifíers

Oral manifestation af systemic diseasemildmoderatesevere

Psychosacialmoderatemajor

TMD SymptomsHx of paresthesia or dysesthesiaMoxillofaciai defectsAtaxioRefractory Pafient

Figure 4-14 Prosthodontic Diagnostic Index (PDI)

prognosis for this patient is guarded tcj good for the experienced general dentist orprosthodontist. At the final end of the spectrtim is the Class IV patient, the most compli-cated and debilitated patient. This patient might be characterized by ver)' poor edentu-lous arches that are indicated for pre-prosthetic surgery but this may not be possiblebecause of the patient's health, finances, or preference. This patient is best treated by asurgical specialist and a prosthodontist. The prognosis for this patient would be poor ifbeing tieated by an experienced general dentist and only guarded for the prosthodontist.

Treatment Planning

The proper treatment planning for a patient requires that all information gathered on apatient be considered when determining the treatment to be completed and thesequence of this treatment. Lab test results and referral recommendations as well asresults of any soft or hard tissue biopsies should be reviewed before a final diagnosis andtreatment plan are fonnalized. Once all information has been obtained, a formal treat-ment plan should be discussed with the patient. This would inchide how treatment willbe sequenced as well as an estimate of the length of time to complete the treatment. Anestimate of cost for the treatment should also be disctissed and approved by the patient.


Generallya patient should be free of dental pain to include TMD pain before defin-itive prostheses are fabricated. Any needed preprosthetic surger\' should be accom-plished early in tiie treatment plan to include extractions, alveoloplastj', tori remov"al,frenectomies, exostoses, and tuberosit\- reductions. If the patient has existing dentures,these will need to be modified after the surger) and managed during the healing periodwith soft reline material. If preprosthetic surgery will render the patient edentulous,immediate dentures may need to be fabricated. Tlie patient's esthetic requirementsduring this healing period will need to be e\aluated by the dentist and completelyexplained to the patient. Depending on the number of teeth being removed, this mightrequire that two sets of complete dentures be fabricated—an immediate set and (afierhealing) a definitive set.

Ifa patient has TMD pain, every effort should be made to have the patient pain freebefore fabricating definitive prostheses. This might be as simple as modifying the exist-ing worn prostheses with acrylic resin to a more a appropriate vertical dimension ofocclusion or fabricating an acrylic TMD splint that fits over the existing prosthesis. If thisdoes not resolve the problem then it might be necessary to refer the patient to an oraland facial pain specialist before definitive prostheses are fabricated.

Once the patient is pain free and appropriate healing has taken place, only then isthe patient readv to have definitive prostheses fahricated. After lhe prostlieses are fabri-cated and initially foUowed-up to ensure proper fit, function, and homecare. the patientshould return for periodic exams at least annually to e\'altiate tlie prostheses as well astlie patient's general oral health.

Prognosis

After reviewing the Complete Denture Evaluation, Diagnosis, and Treatment PlanningForm as well as tlie Prostiiodontic Diagnostic Index (PDI) the practitioner should be ableto make some judgment about the prognosis of their patient. A patient who has a Class1 antero-posterior ridge relationship, has proper size and fimction of the tongue, hasnormal qualit\' and quantity of saÜN-a, has U-shaped (cross-section) edentulous ridges thaiapproximate the opposing arch, has successfully worn complete dentures in the past, andis a philosophical patient (PDI I) will have a good prognosis. A patient who is in ver\ pot)rhealth, has a CUss II antero-posterior ridge relationship, a retracted tongue, maxillaiTposterior bilateral undercuts in need of pre-prosthetic surgery; ropy saliva, and an indif-ferent attitude (PDI TV) will have a poor prognosis. Many times the greatest predictor ofsuccess for complete denture patients is whether they have successfully worn completedentures in the past.

ReferencesAppleby, R. C. Ludwig T. F.: Patient evaluation for complete denture therapy. J Prosthet Dent.

1970; 1:11-17.CJiaytor, D. V.: Di^nosis and treatment planning for edentulous or potentially edentulous

patients, hi Zarb, G. A., Bolemler, C. L., editors. Prostliodondc treatment for edentulouspadenis. 12th ed. St. Louis, MO: Mosby; 2004. pp. 73-99,

DeVan, M: Physical, biological, and ps)'chologic¿ factors to be considered in lhe construction ofdenuires. J ,\m Dent .Assoc. 1951; 42:290-3.


Heartwell, C. M.; Psychologic considerations in complete denture prosthodontics. J Prosthet Dent1970; 1:5-10.

House, M. M.: The relationship of oral examination lo dental diagnosis. ] Prosthet Dent. 1958;2:208-219.

Ivanliof. J. R.. Cibirka. R. M., Parr. G.R.: Treating the modern denture patient: a review of theliterature. 1 Prosthcl Dent. 2002;6:631-635.

MacEiitee, M. I.: Tlie complete denture a clinical pathway. Carol Stream, IL: QuintessencePublishing Co. Inc.; 1999. p. 1-7,

McGarry, T. J.. Niinmo. A.. Skiba.J.: Classification system for complete edentulism. J Prosth 1999;1:27-39.

Parr. G. R.; Complete denture examination, diagnosis and treatment planning form. In: Ivanhoe,]. R,, Rahn, A. O., editors. Clinical Guide for Complete Dentures. 2006 ed. Medical College ofGeorgia School of Dentistix 2006. p. 38.

Rahn. A. O.: Diagnosis. In: Ryhn, A. O., Heartwell, C. M., editors. Textbook of complete dentures.Dih ed. Philadelphia: Lea & Febiger; 1993. pp. 131-67.

W'inkler, S.: Essentials of complete denture prosthodontics. 2nd ed. Littleton, MA:PSG PublishingC;o, Inc.; 1988. pp.1-7.

Wright. C: A study of the tongue and its relation todenturestability.J Am Dent Assoc. 1949;39:269-7.5.

Zarh, G. A.: The edentulous milieu. J Prosthet Dent. 1983; 6:825-3L

1. List four classifications of patients* mental attitudes.

2. Name four classes, or categories, of medications that cause xerostomia.

3. What types of examination techniques should be utilized when performinga head and neck exam?

4. What type of soft palate, as classified by House, turns down abruptly asrelated to tlie hard palate and requires tlie most precision when determin-ing the location of the vibrating line?

5. Name four anatomic structures that, when present, complicate the fabrica-tion of a complete denture?

6. Wniich cross-sectional ridge form is the least desirable?

7. According to Tallgren, at what rate does the mandible resorb cotnpared tothe maxilla during the seven-yeai" period following extraction of all remain-ing teeth?

8. Which anteio-posterior ridge relationship is the easiest, or most ideal, fortlie fabrication of complete dentiues?

9. Too litde or excessive interarch space can complicate the construction ofcomplete denture? True or False.

10. According to Wright, what percentage of the population has a retractedtongue?

Diagnosis andTreatment Pianning 63

1. Hysterical, exacting, indifferent, and philosophical.

2. High blood pressure medication, antihistamines, muscle relaxants, andmany drugs used to treat anxiety and depression.

3. Observation, auscultation, and palpation (look, listen, and feel).

4. Class III

5. Mandibular tori/maxillary torus, high frenula attachments, large bulboustuberosities, and inflammatory papillarv' hv-perjilasia.

6. Knife edged or flat.

7. Mandible four times greater than the maxilla.

8. Class 1

9. True

10. 35 %

C H A P T E R

Pre-prostheticSurgiealConsiderations

Dr. Henry Ferguson

65


Surgical goals for treamit-nt of patients should address the folk)v\ing faciois: providingthe patient with the best possible tissue contoui"s for prosthesis support, function, andcomfort; maintaining as much bone and soft tissue as possible; and doing this in thesafest, most predictable manner for the patient. With these goals in mind, we can thenwork backward, with a concept of the final result, sequencing the ueaunent(s) that willrealize these goals. These goals can he reached through the achievement of specificobjectives, which include creating a broad ridge form, providing an adequate amount offixed tissue over the denture bearing areas, establishing adequate vestibular depth forprosthetic flange extension, establishing proper inter-arch relationships and spacing,supporting arch integrity, providing adequate palatal vault form, and when required, toprovide proper ridge dimensions for implant placement.

I Patient Evaluation anil Expectations

Prior to the performance of any procedure, several key steps must be performed. Theobjective of a thorough patient evaluation, review of the past medical histoiy, and physi-cal évaluation is to identify treatment-modifying factors required for the safe anduneventful treatment of the patient.

The physical examination includes thorough evaluation of the oral hard and softtissues and radiographs. This examination will reveal the difticult)' of performing thedesired preprosthetic surgical procedures or even whether they are possible. Forinstance, the refening dentist may desire that the patient receive a reduction of thetuberosities but radiographie evaluation by the surgeon may reveal that tbis procedure isnot possible because of the position of the maxillary sinus.

Radiographically, the panoramic radiograph is the workhorse image for prepros-thetic surgeiy. With this radiograph one can visualize many of the important anatotnicand structural relationships necessary to accurately create a treatment plan for prepros-thetic procedures. For the mandible and maxilla in general, pathologic lesions, retainedroots, impacted teetii, and overall ridge morphology can be seen. For Uie mandible, rela-tionships between the inferior alveolar canal and the ridge crest, and position of themental foramina to the ridge crest can be obsei-ved. For the maxilla, relationshipsbetween the íloor ofthe maxillai^ sinus and the alveolar crest, anterior nasal spine, andthe anterior maxillary alveolar crest can be determined. Additionally, the hard tissuecontribution versus soft tissue component of hv-perplasic tuberosities can be determined.Other radiographie images may be required when specific anatomic relationships needto be observed.

For preprosthcdc procedures and treatment plans, which may include implantplacement, more sophisticated, radiographie studies may be required. Tomograpbicstudies and computerized tomography (CT scans) may be used. The CT scan can providecross-sectional detail of the maxilla in both the axial and coronal views. This providesexcellent information regarding such important planning factors as alveolar height andwidth, facial, lingual, and palatal alveolar contours, relationships between the maxillarycrests and the sinus fioor and nasal fioor, and the mandibular inferior alveolar canal andmental foramina to the crestal bone.

Pre-prosthetic Surgical Considerations 67

Treatment Pianning

With the desired preproslhetic surgery identified, and the physical evaluation andradiographie examinations completed, a problem list is made. Treatment planningnow becomes the next critical step. No procedures should be performed without atreatment plan designed to sequence and address the patient's problem list. Based onstate of health, complexity of treatment plan, and level of anxiety, referral may be madeto place the patient in an ennronment where all of these important factors can be safelyaddressed.

Goals for treatment should address the following factors: providing the patientwith the best possible tissue contours for prosthesis suppon, (unction, and conübrt;maintaining as much bone and soft tissue as possible; and doing this iti the safest mostpredictable manner for the patient. With these goals in mind we can sequence the treat-ment(s) that will achieve these goals.

Review of Fiaps

Access to and exposure of the surgical site is critical. The clinician's tool for adequateexposure is the full thickness mucoperiosteal fiap. This aggressive surgical approach withits greater visibility, protection of adjacent tissues, time efficiency, and more routine post-operative course is far more valuable and less traumatic to the patient than other lesseffective techniques. Diagnostic casts are excellent aids in outiining areas of surgicalfocus and for flap design.

For most ofthe procedures a midline crestal incision is recommended. In edemu-lous areas, there is usually a dense scar band on the crest of the ridge (Figin e 5-Î ). Thistissue is stronger, more resistant to tears, and holds sutures well. WTien teeth are present

Figure 5-1 Midline crestal incision is recommended formost flap procedures.


and the surrounding soft tissues are to be included in the flap, a stdcular inci.sion sharplyto bone is recommended. The reflection should be subperiosteal and deliberate. Whenworking around teeth, the papillae should be gendy reflected, then tlie remainingattached tissues in a uniform plane before attempting to teflcct more apically. Beingdeliberate, precise, and having patience vAW reward tlie clinician with a clean subpe-riosteal dissection. The dissection should proceed apically as far as needed to visualizethe area of concern. Dissection antero-posteriorly should be made as necessary toallow for elevation of the flap and appropriate exposure without placing tension on theflap. Althottgh envelope flaps are usually adequate for most procedures, if access isa problem, both anterior and posterior releasing incisions are recommended. The baseof the flap niitst be wider than the crestal aspect so tiiat blood supply to the flap will notbe compromised.

When the procedure is completed and the flap is repositioned. tlie clinician mustfeel the utiderlying bony contours through the flap to enstire that the intended goal hasbeen reached. Then the flap is reelevated and copiously irrigated along the entire lengthof the flap to remove all debris. Once the flap is anatomically repositioned, a suture isused to secure the Haps p(,)sition. Sutures are placed to approximate and not strangulatethe tissues.

Commoniy Usetl Preprosthetic Procedures

Common preprosthetic procedures include ridge alveoloplasty \vith extraction (s):ridge alveoloplasty without extractions for recontotiring of the knife edged ridge orother ridge deformity or contour problems; intraseptal alveoloplasty; maxillary tuberos-ity reductions; recontouring of palatal and lateral exostosis and contour problems;mandibular tori remo\'al; maxillaiy toti remoral; myloliyoid ridge reduction; and genialtubercle reduction. Soft tissue procedures might include maxillary tuberosity soft tissuereduction, maxillary labial frenectomy, mandibular lingual frenectomy, and excision ofredtmdant tissue.

Ridge Aiueoioplasty with Extraction

After extraction of a tooth or teeth, the clinician must make a determination about tbeappropriateness of the remaining ridge contour{s) to fit into the preprosthetic plan, andif the recontouring will be made at the time of the extraction{s) or at a later time. If morethan finger compression is needed, a full thickness flap should be elevated to a pointapical to the area in need of recotitotiring. Depending on the amount of recontouringneeded, a bone flle may be sufficient to produce tlie desired contours. For greater recon-touring, a side cutting rongeur or handpiece and acrylic resin bur can be used (Figure5-2). WTien using these burs, always use copious irrigation to avoid overheating the boneand subsequent bony necrosis. Irrigation also cleans tiie flutes of the btir and carries awaydebris. After bulk recontouring, a bone file is uses to "fme tune" tiie recontouring. Bonefiles or rasps give the clitiician a great tactile sense and good control. Wiien finished, theflap is repositioned, contours palpated to verify that a desired endpoint has beenreached, and is approximated primarily (Figure 5-3). Wiien soft tissue recontouring isneeded, reposition the flap; observe where the adjustments are needed, and tLse a sharp


Figure 5-2 Bone rongeur used to accomplish bone reduc-tion during a ridge alveoplasty along with extractions.

pair of scissors or surgical blade to make the cuts. It is usually more prudent to sequen-tially remove small amounts of tissue than to remove too much at one time.Consideration must also be given to maintenance of vestibular deptb and form whentrimming and approximating the flap.

Intraseptal Alveoloplasty

When the ridge has acceptable contour and height but presents an unacceptableundercut, which extends to the base of the labial vestibule, the intraseptal alveoloplastymight be considered. This procedure is best accomplished at tlie time of extractionor early in the postoperative healing period, .\fter extraction of the teeth, the crestaltissue is slightiy elevated to fully expose the extraction sockeLs. Using a small rongeuror handpiece and bur, the inti'aseptal bone is removed to the depth of the socket

Figure 5-3 Primary closure ofthe flap following extrac-tions and ridge alveoplasty.


Figure 5-4 Interseptal alveoplasty during extractionprocedures.

(Figure 5-4). After adequate removal of bone, finger pressure is applied in a constant,controlled manner unlil the labiocorticiil plate is greensiick fracuned and can be posi-tioned palatally, narrowing üie cresi and eliminating lhe undercut. If significant resist-ance is encountered, a verdcal cut in the bone can be made using osteoLome or bur frominside Lhe most distal .sockets outward, carefully scoring the bone. Periosteum and softtissue should not be violated. Finger pressure should be applied to the area of the verti-cal bone cut to achieve mobility of the segment and guide its repositioning. A bone filecan be used to smooth rougbened edges, and the site can be irrigated. The crestal softtissue can now be approximated and closed witb interrupted or continuous sutures.Ideally, a surgical stent or soft-tissue-lined immediate denture can be inserted to main-tain the reposidoned bony segment until the initial stages of healing have taken place, atabout two weeks aiter the procedure.

Edentulous Ridge Alueoloplasty

For routine eliminadon of sharp (knife-edged) ridges and removal of undesirablecontours, undercuts, or prominences, direct vision and frequent palpation until tliedesired endpoint is reached will be sufficient. When tlie mandibular or maxillary eden-ttilous ridges require multifocal, moderate, or greater amounts of recontouring, use ofdiagnostic casts tc) identify areas oí" concern, and fabrication of surgical guides, arerecommended. In this way, the cUnician has a model with the specific areas outlined toassist in the exAcl orientation once tissues are reflected and. if necessary, a surgical guideto assist with the detailed removal and recontouring of the bone.

The edentulous ridge alveoloplasty begins with idendfication of the areas ofconcern. A full thickness flap is designed and implemented to fully expose the targetedareas. Using bone files/rasps, rongeurs handpiece, and burs or combinations, thetargeted areas are recontoured. Digital palpation with tlie flap in place is done until thedesired endpoint is achieved. The site is irrigated and close primarily with an interruptedor continuous suture technique.


Figure 5-5 Marking Uie midline crestal incision to beused for access to remove buccal exostosis on themandibular ridge.

Buccal Exostosis

This approach can be used on either arch and for irregularities on the palatal aspect oftbe maxillaiy alveolus. A crestal incision is made to extend beyond the margins of theareas reqtiiring recontouring (Figure 5-5). A full thickness flap is elevated to completelyexpose the involved area (Figure 5-6). When an envelope fiap will not provide the neces-sary exposure without placing tension on the flap, a releasing incision, as describedearlier, may be incorporated into the flap design. For gaining assess to a palatal exosto-sis, make the incision longer and reflect more tissue to gain enough relaxation in theflap. Because of the greater palatine and incisive branch anastomosis, vertical releases in

Figure &-6 Elevation of full thickness flap to exposebuccal exostosis, which will be recontoured prior toprosthodontic procedures.


Figure 5-7 Exposed exostosis demonstrating the use of arotary instrument for recontouring. Note retractor provid-ing exposure of operating site and protecting adjacent softtissue.

the palate area not recommended. Once the iiTegularity is exposed, the tissue is elevatedand protected, and the appropriate instrument is used to recontour the bone to thedesired endpoint (Figure 3-7). The area is palpated throtigh the flap to confirmadequate reduction or recontouring. When completed, the area is irrigated and closed.

Maxiiiary Tuberosity Reductions

Maxillary hyperplasic tuberosities present real problems for gaining appropriate inter-arch distance posteriorly. The tuberosities can be hypcqïlastic in the horizontal or verti-cal planes, and may involve osseous hj-perplasia, soft tissue hyperplasia, or both. Toidentift- the hard tissue and soft tissue component that requires recontouring, apanoramic radiograph will usually suffice. This will provide infonnation about the hardand soft tisstie contributions and the overall contoiu^ of the tuberosity and proximity tothe maxillary sinus. It is important to remember that maxillary sinuses may pneiunatizeinto the tuberosity areas. A crestal incision is made from a poiiu anterior to where therecontouring will start, over and up behind the tuberosity. Tissue must be elevated onboth the buccal and palatal aspects to fully expose the tuberosity (Figure 5-8). Aftermaking sure that all soft tissue is protected, instrumentation can start (Figure 5-9). Thetuberosit)' can be recontoured with bone file, rongeur, or bur (Figures 5-30 and 5-11).If a great deal of bone needs to be removed, again as in other procedures, a surgicalguide may be necessary. If tlie maxillar)- sinus has pneumatized, care must be taketi whenremoving the bone, and the sinus membrane may become exposed. However, this is nota problem as long as the membrane is intact.

Mandibuiar Tori

In the dentate arch, tori pose few, if any, problems. Occasionally tori can be large enoughto interfere with tongtie mobility and speech, and tlie thin mueosa overhing the torimaybe chronically irritated or injured when eating certain foods. In the edenLulous arch,tori may pose significant interference when wearing a remo\'able prosthesis and oftenmust be removed.


Figure 5-8 Arrow indicates a bony undercut on the lateralsurface of the maxillary tuberosity.

Figure 5-9 Tissue flap is elevated to expose bony under-cut (arrow) that requires recontouring.

Figure 5-10 Arrow indicates recontoured buccal bonewith the undercut eliminated.


Figure 5-11 Before (/n, añü oiier (B) recontouring thebuccal bone to eliminate an undercut on the lateral aspectof the maxillary tuberosity.

A midline crestal incision is made to extend about 1.0 -1.5 cm distal to the mostposterior tori, to decrease tension and tearing of the flap. A full thickness lingualmucosal flap is slowly elevated. Because the tori may be pedimculated. dissection of thevery thin mucosa located in the undercuts may be tenuous. However, like other proce-dures discussed, patience and a steady hand will prevail. ..Mter elevating all mucosa off ofthe tori{s) to a point below the tori where normal lingual cortical anatomy is found, atissue retractor must be placed to maintain exposure and protect tbe flap. If anosteotome slips, it should hit the retractor and not perforate the floor of the mouth.Similarly, the tissue must be out ofthe way when using a rotary instrument and bur. Forsmaller tori, bone file and rongeur or rotary instrument and bur may be used for bonereduction (Figure 5-12).

Figure 5-12 Removal cf a mandibular tori.The(A) indicates the reflected tissue flap and the arrow (B)indicates the bony projection to be removed with theosteotome.


After all tori have been removed and bone smoothed, the flap is repositíoned andthe lingual plate palpated to confirm achieving tlie desired contours. Use tbe suturetechnique of choice, but because of the length of the incision, a continuous suturingtechnique with good margin inversion is recommended. To minimize hematoma forma-tion 4x4 gauze is rolled into tlie appearance of a cigar, the tongue is elevated to the roofofthe mouth, and the gauzed is placed under tlie anterior aspect ofthe tongue over therepositioned siuured fiap. Have tlie padent lower die tongue. The weight ofthe tonguewill push the gauze down and forward, pushing the gauze against tlie fiap and the flapagainst the bone. These will tamponade any smali oozing and eliminate dead space.

Maxillary Tori

A maxillarv' tori may pose a significant problem in the fabrication and wearing of a maxil-lary complete denture. The tori may be especially problematic when it is positioned moreposteriorly, creating problems with posterior palatal seal of die prosthesis (Figure 5-13).A midline incision is placed over die torus \vith oblique releasing incisions at each end.WTien tbe tori are multilobulated and pedunculated, elevation of the thin mucosa maybe difficult. After the tonis is exposed, adequate flap contiol for best \isualizatioti isimportant (Figure 5-14A). An excellent method of keeping the fiaps open is to suturethe margin of the fiap to tlie crest of tlie ridge on the same side. For some larger pedun-culated multilobulated tori, a midcrestal incision with elevation of the entire palatalmucosa is recommended. This dissecdon must stay subperiosteal to avoid injuiy to tliepalatal blood supply. The desirable end point is for the palatal vault to be smooth andconfiuent with no undercuts or elevations (Figure 5-14B).

The margins of the llap are digitally positioned and pressed against the bone.Removal of redundant dssue can now be performed, keeping in mind that all bone mustbe covered with tension-free closure. Also keep in tnind that the tbin mucosa overKingthe torus does not bold a suture well, so margin uimming should be consei^ative or notat all (Figure 5-15). Hematoma formation in the palate under the fiap is a great concern.Excellent methods of applying pressure are with the placement of a temporary denture

Figure 5-13 Maxillary tori extending into the posteriorpalatal seat area.


Figure 5-14 Pedunculated bony tori exposed by elevatingsubperiosteal flaps (A) Smooth palate created by the toriremoval (B)

with soft reline material over the surgical site or with a well-fitting, surgical guide with softreline placed over the area. The pressure should be maintained for several days. Thepatient can remove the appliances for local wound care and oral rinsing.

Myiohyoid Ridge Reduction

In the mandibular post-extraction ridge remodeling sequencing, the alveolar bone andexternal oblique ridge resorb because of lack of stressing and functional remodeling.The myiohyoid ridge, which supports the attachment ofthe mylohyoid muscle, remainsrelatively intact, and becomes a prominent feature in the posterior mandible.

After providing profound anesthesia, a midcresta! incision is made anterior to tliesite of ridge reduction and carried posteriorly gradually deviating toward the buccal, to

Figure 5-15 Primary closure achieved after bony recon-touring is complete.


avoid potential injury to the lingual nerve. The flap is elevated to expose the mylohyoidridge and attached muscle. Using sharp dissection, the tendenous attachments of tiiemylohyoid muscle are stripped. The muscle will retract into the floor of the mouth andreattach during healing. A bone bur can be used to reduce the ridge to the desiredheight. A bone file can be used to fine-tune the contouring. When completed, the areashould be copiously irrigated and closed primarily with interrupted or continuoussutures. Once the fiap has been closed, ideally a denture with a soft reline is placed toallow for the lingual fiange to help with displacement of the detached mylohyoid muscle.

Genial Tubercie Reduction

In the post-extraction ridge remodeling of the anterior mandible, the alveolar ridge andtooih-bearing areas resorb because of lack of stressing and functional loading. The supe-rior pair of genial tubercles provides insertion for the paired genioglossus muscles, whilethe lower paired tubercles provide insertion for tlie paired geniohyoid mtiscles. Becauseofthe constant movement ofthe tongue and stressing ofthe tubeicles once the alveolushas resorbed and remodeled, the genial tubercles can become very prominent structuresin the anterior mandible and impede proper seating of the denture.

The clinician must be aware that thi.s surgical site lies between two movingstructures—the tongue and the lip. Therefore this is an area that may be prone to wounddehiscence. making this a very difficult surgery.

A full thickness fiap is elevated to expose the genial tuhercle and genioglossusmuscle attachments. The tendenous muscular attachments are sharply detached fromthe bone to randomly reattach more inferiorly. With exposure of the bone and protec-tion of the fiap, the bone height can be reduced witii die instnament of choice to thedesired level. The wound is copiously irrigated and closed primarily.

Sot! Tissue Procedures

With loss of teeth, bony résorption, and remodeling, soft tissue relationships that existedwith teeth and were not problematic may become concerns. With reduction of ridgeheight and contour, soft tissue and muscular attachments change. These muscular andsoft tissue changes are often deleterious to prostliesis stahility and function, and requireremoval or alteration. Additionally, witii the potential trauma and chronic irritationcaused by ill-fitting prostheses, the development of hypei-plastic tissues in the denture-bearing and peripheral tissue areas may occur These hvperplastic tissues contribute tolack of denture fit and stability, and can contribute to patient discomfort.

Because it is very difficult to replace oral mueosa after it has been removed, thetreatment plan must detail the sequence in which the sofi tissue abnormalities will beaddressed. Treauneni will usually address the bony abnormalities first, to achieve nonnalbone healing with good soft tissue coverage. Additionally, if implant placement is part ofthe treatment plan, bone augmentation may be required. Preserving redundant softtissue to provide coverage for bone augmentation should be considered. The soft tissuei^ues may be addressed after the gralting and or implants have healed. In general,excised, redundant hvperplastic soft tissues are the result of chronic irritation from an ill-fitting prosthesi.s. However, because of tlie chronic irritation, pathologic changes within


the tissues can occur. Therefore, as a rule, a portion of all excised hyperplastic tissuesshould be submitted for histopathologic examination.

Maxillary Soft Tissue Tuberosity Reduction

Interarch distance is a critical element for proper fabrication of denture bases, andhyperplastic maxillar)- tuberosit)' tissues often impinge on adequate interarch distance.To determine if the reduction will be primarily bone or soft tissue, a panoramic radi-ogi'aph that can discriminate the soft tissue shadow from bone is required. If not avail-able, sounding of the soft tissue with the anesthesia needle after the region isanesthetized will provide the clinician with detail of the tissue thickness. If a great dealof tissue removal is anticipated, a surgical guide is recommended.

A midline elliptical incision is made sharply to bone with the widest part of theellipse direcfly over the area where tiie most tissue is to be removed. The anterior andposterior portions of the ellipse should taper into the normal portions of the ridge ante-riorly and to the posterior tuberosity posteriorly. The ellipsed portion is elevated andremoved. The clinician can now look into the area made by the removed section of tissueand evaluate tlie tissue height above the bone. Directing attention to tlie buccal andpalatal edges of Uie incision, tlie clinician will thin the tissue by removing a uniformthickness—staying an even distance from üie surface and remembering to adjust theangle while thinning around the curve. Buccally, there are no structures of concern totlie clinician as he/she makes contact with the bony lateral aspect of the ridge. Palatally,the clinician needs to be caieful not to extend the thinning too deep into the palataliispect of the ridge because of the greater palatine neurovascular bimdle. Once theexcess tissue has been removed and there is a uniform thickness of mucosa, digital pres-sure will approximate the buccal and palatal flap margins to evaluate the amount of verti-cal reduction that has been accomplished. Having the patient close down gently on theclinician's fingers will allow for evaluation of tlie change in interarch distance. If the verti-cal reduction is acceptable, the wound margins are approximated and trimmed to get atension-free butt Joint closure. The wound is closed with an inteiTtipted, or continuous,suture technique.

If the tissue has been thinned and no additional vertical change is possible withinthe soft ti.ssue, and yet more is needed, then the flaps will need to be reflected buccaliyand palatally. Bony reduction wiil need to be done to achieve the desired vertical change.(Refer back to bony tuberosity reduction).

MaMiliary Labiai Frenectomy

Labial frenal attachments are thin bands of fibrous tissue/mtiscle covered with mucosathat extend from the lip or cheek and attach into the periosteum on tlie sides of, or thecrest of, the alveolar ridge. Except for frenal attachments, which attach at the incisivepapillae and contribute to tlie midline diastema, most frenal attachments—like othersoft tissue structures—are of litde consequence when teeth are present. On the edentu-lous ridge, which has experienced résorption and remodeling, the muscular and softtissue attachments may direcdy aííect the seating, stabilization, and construction of theprosthesis, as well as subject the patient to reduced function and discomfort. Althoughthis is a simple technique, it yields great benefit.

Although other techniques exist, the following is recommended for a simplefrenectomy. Infiltration anesthesia to the lip around the frenum is usually adequate.


Injecting directly into the frenum may distort the anatomy. After achieving good anes-thesia, two small, curved hemostats are placed witii the curved sides against the tissuesover the superior aspect of the frenum and the inferior aspect of the frenum. The tips ofthe hemostats will touch in the deep aspect near the vestibtile. A surgical assistant shouldsuction and retract the tip superiorly. Holding tlie top hemoslat, tiie clinician will use asurgical blade and follow the curvature of the upper hemostat, cutting through theupper aspect ofthe frenum (Figiue .T-I6). This is repeated for the lower hemostat. Thefrenum will now be excised, leaving a diamond-shaped wound (Figure 5-17). Exploringthe wound, any frenal remnants should be excised directiy to periosteum. A suture isplaced through tlie wound margin engaging the periosteum in the depth ofthe vestibuleright below Uie anterior nasal spine. A knot is tied and the margins will be drawntogether and pulled down to the periosteum in the depth of the vestibule. Additionalsutures are placed in a similar manner so that the dianiond-shaped wound now closes ina linear manner (Figure 5-18). If tlie frenum extended to Uie crest ofthe ridge and was

Figure 5-16 Maxillary labial frenectomy using two curvedhemostats as guides for tissue excision.

Figure 5-17 Maxillary labial frenectomy after tissueexcision prior to primary closure.


Figure 5-18 Maxillary labial frenectomy primary closurewith sutures.

excised thorough attached tissue, all parts of the wound v\ill close primarily except thatpart in the attached tissue. No attempt should be made to close that area and it shouldbe left to granulate and heal by secondary intention.

Excision of Redundanl/Hypermobiie Tissue Overlying the Tnberosities

Redundant h>-permobile dssue is often the result of ill-fitting dentures, ridge resoiption,or both. After identifying the area to be excised, parallel incisions on the buccal andlingual or palatal aspects of the tissue are made sharply to bone. Tbe incisions will taperinto each other posterior to the area to be incised. The excised piece of tissue will bedissected from the bone and removed. Digital pressure is applied to check for primaryclosure of the wound margins. If additional tissue needs to be removed, tangential inci-sions on the buccal and palatal, or lingual, sides of the wound are made to remove andthin out additional tissue. Tbis is done carefully until the wound margins approximateprimarily. The wound is irrigated and closed primarily. Care should be taken to avoidsignificant undermining of the buccal/facial aspects of the flaps, and loss of vesdbulardepth when closing the wound.

Excision ot inliammatory Fibrous Hyperpiasia (Epuiis Fissuratum)

Infiammatory fibrous hyperplasia is a generalized hyperplastic enlargement of themucosa and fibrous dssue in the alveolar ridge and vestibular area. The etiology is mostclosely associated witli chronic trauma to the involved areas from ill-fitting prosthesis.Infiammatory fibrous h\perplasia progresses in stages, and the surgical procedure indi-cated varies with the stage. For those lesions in the early stages, there is not a significantdegree of fibrosis of the involved tissues, and nonsurgical therapies may be effecdve.In the later stages where there is significant fibrosis and hyperplastic changes, excision ofdie hyperplastic mass of tissue is the treatment of choice (Figure 5-19).

Se\'eral treatment options exist based on the size of he hyperpiasdc mass of tissueto be removed. If the d.ssue mass is not extensive, use of lasers or electrosurgery


Figure 5-19 Inflammatory fiberous hyperplasia in themaxillary labial vestibule.

techniques provides good results for tissue excision. For more extensive tissue masses,the margins of the tissue ma.ss are elevated using tissue forceps, and an incision is madeat the base of the mass, but not tiirough the periosteum. A suprapcriosteal dissection ismade under the entire mass ofthe hyperplastic tissue, and the mass is removed.

The normal mucosal margins are sutured in place, and the superior margins aresutured to the depth of the vestibule. In order to minimize soft tissue creeping and lossof vestibular height with secondarv' intension healing, a surgical stent with an extendedanterior Cange lined v\ith soft tissue conditioner, or the existing denture with the flangeextended to engage the height of the vestibule. A soft tissue conditioner should beplaced, and the prosthesis should only be removed for wound care and rinsing, andcleansing of tbe intaglio surface of the prosthesis. Secondary epithelialization v\ill takefour to six weeks.

Infiammatory Papiiiary Hyperpiasia ot the Paiate

Inflammatory- papillarv' hvpeiplasia of the palate is a condition affectitig the palatalmucosa, tliought to be caused by ill-fitting prosthesis, poor hygiene, or fungal infectionsand the as.sociated inflammation. Its clinical presentation appears as multiple nodularprojections in die palatal mucosa. The lesions may be ervthematous or may have normalpalatal mucosal coloration (Figure 5-20).

Early treatment consists of prosthesis adjustments, tissue conditioner, and properoral hygiene. In more advanced presentations, several treatment options have beensuggested. Because this is primarily an inflammatory disorder, there is no need to excisethe full thickness of the palatal tissue. In any of the described treatment options, thesuperficial infiamed layers of the palatal mticosa are removed leaving the palatal perios-teum intact to heal by secondary intension. These techniques include removal of tiieinflamed mucosa with electrosurgery loops, laser ablation of the superficial layers, sharpdissection, use of coarse fluted burs, or dennabi^asion brushes to bur or abrade this layer,and cryotherapy {Figure 5-21 ). As mentioned earlier, no matter which technique ts used,care should be taken to ensure that the periosteum is not violated and the underl)ingbone is not involved. The palate is covered with a surgical stent or denture witii a soft


Figure 5-20palate.

Inflammatory papillary hyperplasia of the

Figure 5-21 Inflammatory papillary hyperplasia removedusing cryotherapy.

tissue conditioner to assist with patient comfort and provide coverage while secondaryepithelialization takes place in the following four to six weeks.

I Surgicai Guides (Tompiates)

When moderate amoimts of bone recontouring are required and the treatment planrequires a degree of precision in the amount and location of bone to be removed, surgi-cal guides are excellent adjuncts. Using a duplicated diagnostic cast, the areas of concernare modified to achieve the ideal ridge fomi. A clear rigid guide is then fabricated usinga vacinim-formed technique. During the surgical procedure, after recontouring has beenaccomplished, the surgical guide is placed over the area witli the flap repositioned, and


areas of soft tissue blanching are obser\'ed. These blanching areas represent areas whereadditional remo\al of bone and recontouring are still required. This procedure isrepeated until no blanching exists and the surgical guide is stable when seated. Soft tissuetrimming, if necessary, can now be done.

References

Miloro, M., Ghali, G-E., Larsen, RE-, Waile, P.D.; Peter's Principles of Oral and MaxofiUial Surgery,Hamilton, Ontario: BC Decker Inc., pp. 157-188.

Ochs, M.W., Tucker. M.R.: Preprosthetic Surgery- In: Coniemporary Oral and Maxillofacial Surgery,4th Ed, St. Louis, MO: .Mosby Publishing pp. '248-304.

Peterson, L. J., Indresano, A.T, Marciani. R-L., Roser, S.M.: Principles of Oral and MaxillofacialSurgery, Volume 2, Philadelphia, P.-\: Lippcucott Oimpany, pp. 110.^1132.

Spagnoli, D.B.. Gollehon, S.G., Misiek. D.J.: Preprcsthetic and Reconstructive SurgeryIn: Principles of Oral and Maxillofacial Surgery 2ed., Hamilton, Ontario: B.C. Decker, Inc.,pp. 157-187

Tucker, M.R,: .^mbulatoiy Prepro.stheUc Reconstructive Surgery In: Oral and MaxillofacialVolume 3, St Louis, MO.: Mosby PubUshing. pp. 1103-1132.

1. WTiat other diagnostic imaging might be used for preprosthetic surgery treat-ment planning besides typical panographic radiographs?

2. Surgical access is often gained through the use of full thickness mucope-riosteal flaps. \Miai are the advantages to this surgical approach over otherflap techniques?

3. \\Tiat three instruments are commonly used for recontouring bone duringpreprosthetic surgery?

4. True or False: Maxillar)' tori may present more of a problem for a completedenture patient if it extends past the vibrating line where the posteriorpalatal seal is usually placed.

5. What techniques can be tised to remove inflammatory papular)' hypeqîlasiaafter controlling the causative factors?


ANSWERS

1. Tomographie studies and computerized tomography (CT Scans) may beused. The ( T scan can provide cross-sectional detail of tlie maxilla in boththe axial and coronal views.

2. This aggressive surgical approach with its greater visibility, protection of adja-cent tissues, time efficiency, and more routine post-operative course is farmore valuable and less traumatic to the patient than other less effectivetechniques.

3. a. bone file

4. TRUE

b. side-cutting rongeur c. handpiece and bur

5. a. electrosurgery loops b. laser ablation c. sharp dissection to periosteumd. dermabrasion brushes e. cryotherapy

C H A P T E R

'Ô PreliminaryImpressions,Diagnostic Casts,and Custom (Final)Impression Trays

Dr John R. IvanhoeDr. Kevin D. Plummer

85


Dental paiicnts require a thorough examination, diagnosis, and treatment plan prior toinitiating any definitive treatment—which, for m(»st patients, requires the use of maxil-lary and mandibular diagnostic casts (Figure 6-1). Diagnostic casts allow for the evalua-tion of haicl and soft tissue anatomy without the presence of the patient. They also allowfor determination of necessarv- preproslhetic surgery, can be mounted on an articulattjr,and the interocclusal space can be evaluated. Perhaps most important, for a completedenture patient, diagnostic casts provide the base from which custom impression traysaie fabricated.

Diagnostic casts are made from preliminary impressions and are often very accuraterepresentations of the hard and soft tissues of the ridges, bui with p<tor detail of thedepth and width of the vestibules and sut rounding mtiscular attachments. This lack ofdetail is often the result of the impression trays and materials required when makingthe impressions rather than poor clinical techniques. Becatise custom impression trayscannot yet be fabricated for Uie patient, stock impression ti-ays must be used. Thesetrays are made to lit the average patient and therefore lack the accuracy requiredfor making detiiiled master casts. Because of low cost and ease of use, irreversible hydro-colloid impression materials are the materials of choice for making the preliminaryimpressions. Because of their high viscosities, however, these impression materials willoften displace the soft tissues ofthe vestibules, resulting in an overextended impressionand resulting casi. This vestibular inaccuracy in the diagnostic cast is not important fordiagnosing and creating treatment plans for most patients, but is unacceptable in eitherthe diagnostic or master cast for a complete denture patient. Fabricating completedentures requires master casts with extreme acciuacy of the vestibules and thereforerequires the use of accurate custom impression trays and specific lower viscosity impres-sion materials.

Figure 6-1 Examples of well-made diagnostic casts.Note that the casts demonstrate all desirable anatomicalfeatures ofthe patient, including the vestibules, yet theimpressions were not overextended onto movable muscleand frenulum attachments.

Preliminary Impressions, Diagnostic Casts, and Custom (Final) Impression Trays 87

Mailing the Preiiminary impressions

Stock impression trays are selected for both tlic maxillarv and mandibular arches.Because of the limited selection of stock tray sizes, shapes, and extensions, the clinicianmust examine the trays intraorally and select the most accurately fitting tray (Figures 6-2and &-3). VVlien available, a tray is selected that will pro\ide about 5~ö mm (1/4 inch)even spacing between the tray and the tissues. For the right-handed dentist, the correct

Figure 6-2 The clinician must examine the tray intraorallyto ensure that adequate space exists between the impres-sion tray and the tissues, and that the tray flanges areadequately extended.

Figure 6-3 This mandibular stock tray fits appropriatelyand provides adequate space for the impression material.Note that, although the flanges of the tray extend into thevestibules, the surrounding soft tissues are not beingdisplaced.


body position is to the right and in front of the patient, and the tray is inserted by distend-ing the left corner of the patient's moutli with the left index linger or a mouth mirror,placing the posterior two-thirds of the right side of the tray into the right comer of themouth, and rotating the tray into position inside of the mouth.

The clinician should place the posterior border of the tray slightly beyond thehamular notches for the maxillary arch and over the retromolar pads for the mandibu-lar arch. With the lips being held outward, the front part of die tray is rotated into posi-tion while retaining the proper posterior alignment of the trays over the hamularnotches or retromolar pads. The impression tray is the correct size if it provides coverageof all desired tissues and provides a uniform space of approximately 5-6 mm {1/4 inch)between the tissues and itnpression tray. The buccal flanges of the tray, in relation tobuccal slopes of the residual ridges, are also evaluated to ensure that adequate spaceexists for the impression material (Figure 6-4).

The clinician should note the position of the tray when it is correcdy located in themouth. The relation of the handle of the tray should be aligned with the middle of ihepatient's face; tliis will be the desired alignment wben the preliminary impression isbeing made.

The tray is refined, as necessary, with "periphery wax" to reshape the tray to assureproper spacing between the tray and tlie tissues and gain additional flange extension(Figure 6-5). For example, periphery wax is often tiecessaty iti the palatal area of the trayfor those patients with a high palatal vaults. The purpose of the periphery wax is to create5-6 mm (1/4 inch) spacing between the tray and tlie tissues, which will support theimpression material and minimize slunipitig of the material away from the tissues. A filmof impression material adhesive should be sprayed or painted to the tissue side of the trayand to any peripher\- wax that was placed on the tray. It should be allowed to dry as perthe manufacturer's recotnmendations.

Prior to making the impression, the patient is instructed to rinse his or her mouthwith water to reduce the \iscosit\' of the saliva. Usitig the proper water/powder ratio, theirreversible hydrocolloid tnaterial is mixed according to the manufacturer's instructions,and the impression ü"ay is loaded approximately one-half to three-quarters full. Do not

Figure 6-4 This stock tray fits well in the anterior area.It extends into the vestibule but it is not overextendedand will not distort the soft tissues during the impression-making procedure.

Preliminary Impressions, Diagnostic Casts, and Custom {Final} Impression Trays 89

Figure 6-5 Periphery wax has been added to these traysto gain additional extension. Periphery wax may also benecessary to minimize large voids between the stock trayand the underlying tissues. A well-fitting tray shouldexhibit approximately 6 mm (1/4 Inch) of space betweenthe tray and the tissues.This proper fit will adequatelysupport the impression material and minimize potentialslumping of the material away from the tissues.

overfill tJie tiay because excess material will be expelled as the tray is seated and oftenlead to severe gagging, which will often compromise die patient's ability to breath.

Prior to inserting the impression tray, the patient should be asked to swallow to elim-inate excess saliva. Impression material should be placed, by finger, into any areas that theclinician feels may not be adequately reached by the impression tray. These areas ofteninclude the palatal vault, retromylohyoid spaces, and/or buccal vestibules (Figure 6-6).

Figure 6-6 Prior to inserting a tray with the impressionmaterial loaded, additional material may be placed inareas that may be difficult to record. In this example,reversible hydrocolloid material has been placed in theretromylohyoid area prior to inserting the tray.


Figure 6-7 The clinician should lift the cheek upward andaway from the ridge to ensure that the impression trayhas been adequately seated and to allow impressionmaterial to record this area.This procedure also allowstrapped air bubbles to be expelled so as not to becaptured in the impression.

To minimize gagging, continually remind the pafient to take short breaths throughdie nose and not to swallow. The loaded tray is placed in the mouth and centered overthe residua] ridges, hamular notches, and/or retromolar pads. Wiien making themandibular impression, instruct the patient to raise the tongue while the impression isbeing seated. While seating the tray, the cheeks should be lifted beyond their normalrelaxed position to allow impression material to completed fill tJie vestibules and to allowair bubbles to be expressed (Figure 6-7). It is important to lift the cheeks outward in themandibular notch areas so tbat the commonly seen roll of fatty tissue will not be trappedin the impression (Figures 6-8 and 6-9).

The tray is seated from the posterior to tlie anterior so that the material fiowstoward the anterior rather than toward the posterior. It is important to note Uieposition of tbe anterior flange of the impression tray. It should be seated in the middleof tbe labial vestibule. In many instances, an impression will be unaccepuble becauseeither the tongue forced the impression tray too far forward and important posterioranatomy was not captured in the impression or the vestibule was not captured becausethe tray was not fully seated. Seat with the index finger of both hands on each side of tbetray in approximately the region of the first molar. The tray is positioned as duringpracticing by noting the location of the handle in reladon to the middle of the face.The clinician must condnuously monitor the padent and ensure tliat excess impressionmaterial is not pennitted to fiow posteriorly, which would compromise the patient'sabilit\- to breath. If tbis happens, the excess can often be removed with a mouth mirror.The clinician may never leave an impression in a patient's mouth and tum away fromthe patient. The cänician must always have control of the impression tray in case of asudden complication.

Once seated, all soft tissues surrounding the vesdbular borders should be manipu-lated (border molded) to minimize overextension of the impression material (Figure6-10). (See Chapter 7 on Final Impressions for the proper border molding technique.)This tissue manipulation is accomplished while the impression material is still very ilowable.

Preliminary Impressions, Diagnostic Casts, and Custom (Final) ImpressionTrays 91

Figure 6-8 Note that a "fatty" pad of tissue (A) is oftenpresent in the distobuccal area of the mandibular arch andmay fold over the retromolar pad (B) and become trappedin an impression.This fold can be minimized by lifting thistissue upward and away from the retromolar pad whileseating the impression.

The tray is held steadily in position until the impression material has set, as deter-mined by the manufacturer. Althotigh the tray must be held securely in the mouth withthe fingers, the clinician should be able to direct only minimal pressure to the trays. Thepurpose of the fingers is to maintain the position of the impression tray and prevent itirom dislodging vertically away from the ridge and distorting the impression.

The patient is instructed to relax die lips while tiie clinician removes the impres-sion. This allows air under the impression, which breaks the seal and releases the impres-sion from tbe arch. Because irreversible hydrocolloid impression material may tear ifexposed to continuous slow stretching forces, a sudden snapping movement is used toremove the impression.

Figure 6-9 The fatty pad (A) was trapped in this impres-sion. This impression must be remade.


Figure 6-10 While maintaining the position ofthe impres-sion tray, the soft tissues beyond the vestibular areasshould be manipulated (border molded) to prevent grossoverextension ofthe impression. Grossly overextendedborders in preliminary impressions will cause inaccurate,overextended vestibules in the diagnostic casts, resultingin overextended custom impression trays. An inordinateamount of time is often wasted correcting the flangelength of custom impression trays because the preliminaryimpression was not properly formed.The more closely apreliminary impression resembles a final impression, theeasier almost all following clinical procedures will be.

Tlie impression is examined to assure acceptability (Figures 6-11 and 6-12). At aminimum, preliminary impressions and diagnostic casts for complete denture patientsmust include all hard and soft tissues of the ridges, the entire vestihules, retromylohyoidareas, entire hard and initial 3-^ mm (1/4 inch) ofthe soft palate, and hamular notches.If the decision is made to remake an impression, the initial impression should be care-fully evaluated to dctemiine the cause of tiie initial pioblem in order to minimize thelikelihood of having the same problem occur a second time. An impression must beremade for matiy reasons including;

1. Incorrect tray position in the mouth, which has caused one or moreanatomical areas not to he captured in the impression.

2. Excessive areas of the impression tray showing through the impressionmaterial indicating pressure that may have resulted in a distortedimpression.

3. ,\ny void or discrepancy too large to accurately correct on the cast.4. Incorrect border fonnation as a result of incorrect border length of t:he

tray. A sliaip border usually indicates that the impression is under-extended in that area.

5. Obviously distorted impression because of movement of the tray duringthe setting ofthe final impression material.

6. Poor detail in the impression because of a poor mixing technique orbecause the material had begun to set before the impression was fullyseated-


Figure 6-11 A well-made maxillary preliminary impres-sion. Note that all anatomical areas of the ridge have beenaccurately recorded and, even though the border thicknessis a little excessive, the border length is excellent.Thisimpression closely resembles a final impression and assuch will allow the fabrication of an excellent diagnosticcast and eventual custom impression tray.

Once deemed acceptable, the impression is thoroughly rinsed to remove excesssaliva, disinfected, and immediately Uken to tiie laboratoiT and poured. If any delay isencountered in pouritig tlie impression, the impression must be wrapped in wet papertowels or placed in a humidor to minimize the loss of water from the impression. Loss ofwater will cause the impression to unacceptably and irreversibly become distorted. Anirreversible hydrocolloid impression should be poured in dental .stone within 10 minutes.

Figure 6-12 This mandibular preliminary impression notonly records all desired anatomical areas but also exhibitsexcellent border extensions.


Ponring the Diagnostic Casts

A mix of dental stone is prepared using the water/powder ratio provided by the manu-facturer's instructions. A clean mixing bowl and spatula should be used, and the powderis gently added to the water to minimize the trapping of air \vithin the mixture. Amechanical spatula and vacuum mix are generally not necessai7 when mixing the dentiilstone for a diiignostic cast, although a more den.se stone will be formed if this techniqueis used. All excess water is carefully removed from the impression by gently blowing withan air pressure hose. However, the impression material must not be allowed to becomedried. Mix the material thoroughly as.suring that all dry stone is wet, and a smoothmixture with minimal bubbles is achieved.

A vibrator set to a medium to low speed sbould be used when pouring the impres-sion. High speed vibration will often trap air bubbles in the cast in critical areas. The.stone is carefully and slowly \ibrated into the anatomical areas of the impressionin small increments until the impression is completely filled and borders covered(Figure 6-13). Avoid locking stone around any portion of exposed impression tray. Thisproblem could make removal ofthe cast difficult after the stone is sei if it is locked ontothe tray. After the stone has reached its initial set and is hard enough to handle, a secondmix of artificial stone is made and a base of approximately 15-17 mm (3/4 inch) inheight and slightiy wider than the initial pour of the impression is formed. .Allowingthe initial pour of stone to achieve its preliminary set before inverting the impressionwill help minimize the slumping of stone away from the impression, which would resultin an inaccurate impression. Inverting the poured impression before the initial set alsolets air and water rise to tbe critical tissue detail area resulting in a weaker and possiblydistorted casi. The cast is inverted onto this mound of stone and the width of the futureland areas are extended to 5 - 6 mm (1/4 inch) beyond the impression (Figure 6-14).Although the ridge crests cannot be visualized at this time, an attempt should be made

Figure 6-13 The initial pour of a preliminary impression.Note that small nodules have been placed on the surfaceof the material. Once this initial pour of stone has achievedits initial set, it Is inverted into a second pour of stone toform the completed diagnostic cast. These nodules willhelp provide additional strength to the two-pour cast.

Preliminary Impressions, Diagnostic Casts, and Custom (Final) Impression Trays 95

Figure 6-14A These maxillary and mandibularpreliminary impressions have been inverted into asecond pour of stone to form a base for the diagnos-tic cast. Note that the stone on the maxillary cast hasbeen allowed to harden while in direct contact withthe impression tray.This is incorrect, and this tray willbe difficult to separate from the cast.

Figure 6-14B Trimming the retentionnodules flat will stabilize the initial pourwhen inverted into the second pour ofstone.

to make the ridge crests parallel to the table top. Trimming the retention nodules fiatand as parallel to the ridge crests as possible will give a stabile platform to rest the initialpour on while forming tbe base (Figure 6-14B). This will aid in shaping the cast at thenext laboraton- step. The stone should be allowed to set imdisturbed as per the manu-facturer's recommendation, generally for about 45 minutes.

r Shaping the Diagnostic Casts

The impression tray and material sbould be carefully removed from the casts; breakage ofthecast at this step may necessitate the remaking of the impression. .Ml debris and impres-sion material is removed fi'om the cast. The cast should be carefully examined to ensuretbat all desired tissues have been captured. A successfully formed diagnosdc cast shouldexhibit all ridge and vestibular areas and all desired anatomical structures. Wlicn properlyshaped, the cast sbould also exhibit land areas around the vestibules and a base of approx-imately 12-13 mm (1/2 inch) in tliickness. This base thickness provides for sufficientstrength while minimizing excessive thickness.

Excess stone is removed from tlie casts with a cast or model trimmere and runningwater. A slurry mixture of water and stone will be Formed by the model trimmer as tbecast is being trimmed. Tbe slurrv' mixture should not be allowed to touch a dry castsurface because it will quickly stick to tbe dry surface and become almost impossible toremove. Therefore, prior to trimming, always wet all cast .surfaces. .\11 slurrv' and residueshould be continuoasly and tliorouglily rinsed off casts immediately as trimmingproceeds; if allowed to drs; the slurr\' mixture will compromise tbe accuracy of the diag-nostic cast. AVhile the slurr)' must be removed with clean water, tbe casts should not beleft under running water for extended periods because the stone surface can be unac-ceptably dissolved. Dry trimmers eliminate tiiis potential problem.

The bottom of tbe base of tlie cast is initially trimmed so tliat the crests of the ridgesare parallel to the base, and tbe thinnest areas of the casts are approximately 12-13 mm


Figure 6-15 The bottom of the cast is the initial surfacetrimmed using a model trimmer.The bottom should betrimmed so that the ridge crests are parallel to the bottom,or bench top, and the thinnest portion of the base of thecast is approximately 12 mm (1/2 inch) thick.

in thickness (Figure 6-15). The sides of the cast are not trimmed until the ridges areparallel to the bottom of the cast and the base is the proper tliickness. The sides of thebase ofthe cast can now be trimmed and will be perpendicular to the ridges. When trim-ming the sides, enough excess is left to provide the land area beyond the anatomicalsurface of the cast. The land area shotild be approximately 2-3 mm (1/8 inch) wide onthe buccal and labial sides and 5-6 mm (1/4 inch) wide in the posterior (Figure 6-16).The vestibular depths should be approximately 2-3 mm in depth where possible and aknife, arbor band, or acrylic bur may he used to fiatten the land area on the cast and

] 10 20 30

AT MARK INDICATINGEFT CUSPID

Figure 6-16 Once the base of the cast is properly formed,the sides of the cast can be trimmed to create land areasapproximately 3 mm (1/8 inch) in width in the labial andbuccal areas and 6 mm (1/4 inch) posterior to the retromo-lar pads and hamular notches.The land areas will later betrimmed vertically to create vestibules no deeper than3 mm (1/8 inch).

Preliminary impressions, Diagnostic Casts, and Custom (Final) Impression Trays 97

reduce the depih of tlie vestibule as necessarv. It is important to reduce the depths ofthe vestibules of the casts so that the entire vestibules are easily accessible for adaptationof custom tray material in future procedures. The trimmed casts can be finished withwet-or-dry fine sandpaper, 320 grit. The casts are allowed to thoroughly dry beforeproceeding to the fabrication of custom impression trays.

Custom (Finai) impression Trays

There is general agreement among dentists that an impression made using a customtray is necessary to achieve the desired goals of a final impression and master cast. Thisis because, for most patients, it is difficult to make an acceptable master cast with theproper extension and tissue detail from an impression made using an irreversible hydro-colloid impression material and a stock impression tray.

\\1ien making a final impression, the goal is to make as exact a replica of the softand hard tissues as possible. v\ith maximum coverage of supporting tissues and minimalextension onto movable tissues and muscle attachments. The impression must be ableto be used to create a master cast that v\ill exhibit these same characteristics. An exactreplica of the tissues is necessar)' to create a denture/tissue interface v\itli intimatecontact tiiroughout, which will result in excellent retention, stability, and support of thedenture. Wiien completed and inserted, an acceptable dentiu-e base should cover basi-cally all immovable tissues on an arch. The base v\ill also lightly contact the surroundingsoft displaceable tissues but not be allowed to restrict the movement of underlyingmuscles and frenulum. Restricting these movements could adversely alfect the functionofthe patient and will usuall) result in tissue irritation and pain to the patient.

A correctly formed tray must be fabricated so that the clinician's desired impressionphilosophy and technique can be achieved. It must be fabricated of a material thai isrigid and stable, and easily adjusted as necessaiy, while not bulky. This tiay material isoften some type of autopolymerizing or light-activated acrylic resin.

Custom impression Tray Extensions

The ideal coverage of a maxillarv final impres.sion tray, when e\:a1uated intraorally, is thatthe tray extends to the vibi"ating line in tiie posterior and ends 2 mm away from tiie depthof the vestibule in the buccal and labial flange areas of the tiay (Figure 6-17). Amandibular tray ends 2 mm above the depth of the vestibules in the buccal, labial, andlingual areas, and a 2 mm horizontal space would separate the tray from tbe tissues in themasseter notch area. It would also end 2 mm short of the extent of the retromylohyoidarea. Having trap's fahricated to these measurements is important because they will mini-mize the amount of "chair time" lost by tlie clinician due to tray adjustments.

Creating impression trays with these characteristics requires acceptable diagnosticcasts made from excellent preliminary' irreversible hydrocolloid impressions (Figure6-18) Because the technician only has the diagnostic casts to work from, he/she mustassume that the vestibular depths and extensions present on the diagnostic casts are accu-rate, and fabricate the trays using these measurements. Overextended or underextendedpreliminar) impressions lead to diagnostic casts with overextended or underextended


Figure 6-17 The desired 2 mm of space exists betweenthe custom impression tray and the depth of the vestibuleson this maxillary arch.

Figure 6-18 The mushroom-shaped nonstress-bearingarea of the maxillary arch has been outlined. Note that thearea also includes the median palatal suture area.

vestibular extensions. This results in overextended or underextended final impressiontrays, which often cause significant clinical delays during the final impressions appoint-ment because of the need to excessively reduce or add to the impression trays.

I Impression Philosophies as Related to Tray Fahrication

Impression philosophies differ concerning the amount and placement of pressureapplied to the underlying hard and soft tissues during the impression-making proce-dtire. Generally a clinician's impression philosophy will be "mucostadc," "functional," or

I


"selective pressure." With the mucosutic philosophy, the clinician attempts to make tlieimpression with minimal to no pressure to any of the underlying structures. With theselective pressure philosophy, an attempt is made to place light to moderate pressure onspecific areas ofthe arches and minimal to no pressure on other areas.

With the functional philosophy, tiie clinician attempts to place mild to moderatepressure over the entire usable ridges when making the impression. This technique isgenerally limited tí» those patients with an existing denture, and the denture becomestbe impression u-ay. The denture is lined with some lype of soft ilowable impression mate-rial, and the patient is allowed to wear the denture for a specific period of time. The softlining material adapts to the underlying tissues and is used as the final impression.

Ob\iously the impression trav's for the diftering philosophies must van in design.Therefore, the laboratory- technician must know the technique to be used by the clini-cian when making the custom impression tray! Because it is probably the most commonphilosophy used, tlie selective pressure impression uay will be described here.

The Selective Pressure Impression Tray and Stress-Bearing Areas

This philosophy requires that the impression tray be fabricated so that, during themaking of the impression, light pressure is applied to those areas of the arch tliat canbest tolerate the anticipated fimctional loads, and yet minimal to no pressure is appliedto those areas of the arch that are not suited to accept these loads. Those areas of thearches that can best tolerate the functional loads are called "primarv" and "secondary"süess-bearing areas, while those that do not tolerate functional loads are called nonstress-bearing areas.

While opinion of the exact position of these areas may vary slightly with theindividual clinician, they are reasonably well described. Generally the crest and slopes ofthe maxillary arch are described as "primary" and "secondar)'" stress-bearing areas, whilethe rugae and incisive foramen areas are considered nonstress bearing. The buccalshelves and slopes of the mandibular arch are generally considered to be primar)- andsecondary areas. Because of the degree of bone loss on the mandibular arch and theresultant knife-edged ridge, the crest of tlie ridge on the mandibular arch will not acceptfunctional loads on many patients and is therefore generally considered a nonstress-bearing area.

Block Out and Belief Wax

To minimize tray and cast breakage and to allow the clinician to make the impressionusing his/her impression philosophy, the diagnostic cast must be modified with waxprior to fabrication of the custom impression tray.

To achieve an acceptable selective pressure impression, tiie impression tray mustbe fabricated so that only those areas of the tray that overlie primary and secondarystress-beaiing areas are in physical contact with those tissues during tlie impressionprocedure. The primary and secondarystress-bearing areas should be outlined on thediagnostic cast.s as an aid to the laboratory technician (Figures 6-18 and &-I9). Ideally;


Figure 6-19 The nonstress-bearing area of the mandibu-lar arch, primarily the crest of the residual ridge, has beenoutlined.

when making the impression, tliere should be no tray/tissue contact in those areas thatoverlie nonstress-bearing tissues. To create this effect, a relief chamber should bepresent in the tray in these areas. The relief chamber is created by applying onethickness of baseplate wax over all nonstress-bearing areas of the diagnostic cast priorto fabricating the impression tray (Figures 6-20 and 6-21), This wax is commonly called"relief wax."

Additionally, to allow tray removal from tbe diagnostic cast, all excessive undercmsand tissue irregularities present on the diagnostic cast are minimally relieved or blockedout using a baseplate wax. Tbis is often referred to as "block out" wax.

Figure 6-20 Relief wax has been properly positioned overthe nonstress-bearing areas and attached to the maxillaryarch. It is one thickness of baseplate wax that is attachedto the cast with melted wax approximately every 12-16mm (1/2 inch).


Figure 6-21 Relief wax attached to the mandibular archover the nonstress-bearing areas.

Fabrication o( the impression Tray

The impression tray is usually fabricated of autopolymerizing or light-activated acr\Iicresin. When using light-activated resin, a sheet of resin is simply adapted to the diagnos-tic cast, which has been modified with relief and block out wax. Tray handles are fonnedusing excess material, and tlie tray is polymerized following the manufacturer's recom-mendations. If autopolymerizing resin is used, genei-ally a 3 to 1 ratio of polymer to

Figure 6-22 The mandibular tray has been trimmed andfinished by the laboratory technician. A 2 mm space hasbeen created between the depth of the vestibule and theflange of the tray.This same spacing should exist intrao-ratly if the preliminary impression and diagnostic castswere not over- or underextended.


Figure 6-23 The maxillary tray has been trimmed andfinished and its posterior extension ends at the vibratingline. Note that the handle projects from the tray at approx-imately the angulation of the natural central incisors.

monomer is mixed, formed into a resin paddy, adapted to the diagnostic cast, andallowed to polymerize. Handles can be added as desired by using additional material.The pol)ineri7.ed impression trays are then Lrimmed to tlie desired extent—as marked onthe diagnostic cast—smoothed, and finished (Figures 6-22 & 6-23).

Figure 6-24 Following the border molding procedure, therelief wax is removed from the impression tray. This wiilprovide a void (relief chamber) between the impressiontray and the nonstress-bearing tissues.This spacing mini-mizes the possibility of physical contact between the trayand underlying tissues during the impression-makingprocedure. Note that multiple holes have been createdin the tray to aid in the escape of the impression materialand reduction of hydraulic pressure during the impres-sion-making procedure. Although these holes may providesome retention of the impression material, that is not theirprimary purpose.


Clinically, following the border molding procedure, the relief wax is removedimmediately prior to making the final impression, which creates a pressure-fi ee reliefchamber over the nonstress-bearing tissues (Figure 6-24) and results in pressure beingprimarily applied only to the primary and secondary stress-bearing areas.

References

Davis, D. M.: Developing an analogue/substitule for the maxillary denture-hearing area.hi Zarb, G. A., Bolander, C. L., eds.. Prosth odontic Treatment for Edentulous Patients. 12 th ed.St. Louis: Mosby Inc; 2004. pp. 221-225, pp. 243-246.

Felton, D. A.. Cooper, L. F- Scurria. M. S.: Predictable impression procedures for completedentures. In Engelmeier, R. L.. ed.. Complele Dentures. Dent Clin Noith .\m. Philadelphia:W. B., Saunders. 1996; 40:43-46.

Hayakavva. I.: Piintiples and Practice of Complete Dentrues. Tokyo: Quintessence Publishing Co;2m)l. pp. 41-42.

Rahn, A. O.: Developing complete denture impressions. In Rahn, A. O., Heartwell, C M,, editors.:Textbook of complete dentures. 5th ed. Philadelphia: Lea & Febiger; 1993. pp. 236-37.

Sowter, J. B.: Custom impression irays. In Barton R. E., ed. Removable Piosthodondc Techniques.Re\ised edition. Chapel Hill: University of North Carolina Press; 1986. pp. 16-22.

1. What is the primarv' difference in requirements between an acceptablediagnostic cast used for treatment plarming for tiie average patienL andone used for complete denture patients?

2. How does the clinician know if a partictUar stock impression tray is thecorrect size for a patient?

3. What is the puipose of periphery wax?

4. In what situation can a clinician leave an impres.sion unattended in apatient's mouth?

5. How quickly should an irreversible hydrocolloid impression be poured?

6. Wliat are the goals when making a final impression?

7. What are the physical characteristics of a correctiy formed impression tray?

8. What are three final impressions techniques?

9. How does the selective pressure technique differ from the other two tech-niques?

10. What are primary, secondary, and nonstres.s-bearing areas?


1. Diagnostic casts with inaccurate or partially missing vestibules are oftenacceptable when creating a treatment plan for the routine dental patient.Diagnostic casts for the complete denture patient should have all vestibulespresent and have accurate extensions. Accurate vestibular extensions ai-enecessary for the creation of acceptable custom impression trays.

2. The impression tray is the correct size if it provides coverage of all desiredtissues without being overextended and provides a uniform space of approx-imately 5-6 mm (1/4 inch) between the tissues and impression tray.

3. Periphery wax is used to change the internal contour of an impre.ssion tiayas necessary to ensure proper spacing between the tray and the tissues andalso to gain additional flange extension. Occasionally it may be placed onthe borders ofa stock tray if the flanges have shai'p edges. Periphery waxshould not automatically be placed on all stock trays; it should be used onlywben necessaiy

4. Never.

5. W'ithin 10 minutes. Once removed from the mouth, the impression isquickly rinsed, di.sinfected, and wrapped in wet paper towels until it canbe poured.

6. The goal when making a final impression is to make as exact a replica ofthe soft and hard tissues as possible, bave maximum acceptable coverageof supporting tissues, and have minimal extension onto the surroundingmovable tissues and muscle attachments.

7. Il must be fabricated ofa material that is rigid and stable, easily adjusted asnecessary, and not bulky.

8. Mucostatic, functional, and selective pressure.

9. With the selective pressure technique, the clinician attempts to place light-to-moderate pressure on speciik areas of the arches and minimal-to-no pres-sure on other areas. With the mucostatic technique, an attempt is made toplace minimal-to-no pressure on the supporting structures. With the func-tional technique, pressure to the supporting suiictures is desirable.

10. The primary and secondary stress-bearing areas ofthe arches are those areasthat are best able to withstand the functional forces that are applied to adenture. The nonstress-bearing areas are those that are least able to with-stand tiiose forces. With the selective pressure technique, an effort is madeto direct these functional forces to the primar)' and secondary stress-bearingareas and eliminate them from the nonstress-bearing areas.

C H A P T E R

Final Impressionsand Creating theMaster Casts

Dr John Ivanhoe

105


While the final impression üppointment Is important, it is essentially no more importantthan any other appointments. Inattention to detail on any visit will usually lead to anunsatisfactory' completed denture and an unhappy patient. The goals of the clinicianwhen making a final impression arc to capture an exact likeness of the hard and softtissues ofthe arches, have maximum possible extension ofthe impression over all tissuecapable of supporting the denture, especially during function, and not to impinge onmovable tissues that will be irritated by the denture during normal functional move-ments. .Additional goals include not having pressure areas or voids witliin the impression(Figure 7-1). Several acceptable techniques exist for making final impressions forcomplete dentures that will meet these goals.

Factors that affect denture retention have been listed as atmospheric pressure,adhesion, cohesion, mechanical locks, muscle control, and patient tolerance.Additionally, intimate contact ofthe denture with the supporting tissues is a major factorof retention, which also dramatically improves the stability and support ofthe denture.Almost all of these factors are improved by maximum tissue coverage of the completeddenture. However, overextension of the denture base onto movable tissue and muscleattachments will adversely affect the fit, comfort, and ability of the patient to wear diedenture and therefore should be avoided.

A necessit) that is often ignored or overlooked is that of the patient removing anyexisting dentures for a minimum of 24 hours, with 48 or 72 hours being more desirable,prior to making final impressions. Removing existing dentures prior to making finalimpressions is necessary to allow the underlying tissues to assume their most healthy andnormal physiologic shape. Additionally, lissue irritation or indication that tlie patient hasbeen wearing dentures (tissue abuse, inflamed papillary hyperplasia, or imprint of theold denture in tissue) must be eliminated prior to making the impression. This is oftencompleted by adjusting the existing dentures, educating the patient about properhygiene, having the patient leave the existing dentures out for at least eight hours a day,and/or relining tlie dentures with a tissue conditioner or interim soft liner. Once thepatient has allowed tissue recovery, by leaving the dentures out for at least 24 hours, ifthe patient inserts a denture for even five minutes the tissues may be quickly distorted,and proper tissue recovery may require two or more additional hours of not wearing the

Figure 7-1 A completed maxillary final impressionshowing minimal pressure areas and voids

Final Impressions and Creating the Master Casts 107

denture. TTierefore patient should not "just wear their dentures into the dentist's office."When possible, impressions appointmenLs should be scheduled early in the morning sopatients do not have to go throughout the day without their dentures.

Proper Custom Impression Tray Extension

Because it is difficult to make an acceptable master cast with the proper extensionsusing a stock impression üay, custom impression ti-ays become necessary. Ii is theresponsibility of the clinician to determine which impression technique is to be used—functional, mucostatic. or selective pressure—and to outline the desired extent of theimpression tray on the diagnostic cast. The desired extent ofthe tray should be drawn asan outline approximately 2 mm above the depth of the vestibules or obvioiLs muscle orfrenulum attachments on the labial, buccal, and lingual, and should extend posteriorlyto the vibrating line on the maxillar)' arch and to the full extend to tlie retromylohyoidspace on the mandibular arch. For casts indicating high muscle attachments, the trayoutline may be several millimeters aho\e the depth ofthe \estihnle (Figure 7-2).

The laboratory' technician should fabricate the custom tray so that tlie fiangesfollow the outline on the diagnostic cast (Figure 7-3), It would seem that having theimpression tray 2-3 mm above tlic depüi of ihe vestibule or ob\ious tissue attachmentson the diagnostic cast would result in the tray being 2-3 mm above these areas intiao-rally, however this is usually not the case. Why would correcdy fabricated trays on thediagnostic casts be excessively long when checked intraorally? This results from the useof an ineversible hydrocolloid impression material and stock impression uay. Becausethe stock trays were not properly extended custom trays, and it is difficult to properlyborder mold irreversible hydrocolloid impression material, the .soft tissues around theborders of the impression were displaced in multiple areas. Displacement of the soft

Figure 7-2 Maxillary diagnostic cast with the desiredtray outline marked. Note the outline indicating the borderofthe tray is several millimeters above the depth of thevestibule in the anterior area because of very high frenu-lum and tissue attachments.


Figure 7-3 Custom impression tray fabricated with thelabial and buccal borders of the tray approximately 2 mmabove the depth of the vestibule. Although not visible, theposterior extent of the tray is the vibrating line.

tissues is usually in the form of the depth and width of the impression being deeperand wider tlian the actual useable vestibules, and the distal extent of the impressionbeing excessively long. Hence the depth and width of tlie vestibules of the diagnosticcast are excessively deep and wide and often called "overextended." This would usuallyapply to the distal extension of the diagnostic cast as well. Therefore, even if the labora-tory technician fabricates a u-ay tiiat is 2-3 mm short of the depth of the vestibtiles,it will often impinge on the movable tissues intraorally (Figure 7-4). One of the goalsm making a custom tray is to have the flanges of the tray 2-3 mm short of the actualvestibules and tissue attachments, and only visual examination intraorally by the clinician

Figure 7-4 Even though the impression tray was cut backby 2 mnn from the depth of the vestibule on the diagnosticcast, the borders of the tray are impinging on the movabletissues intraorally and must be shortened.


Figure 7-5 The buccal and labial flanges of the impres-sion tray have been shortened sufficiently to createadequate space for the border molding material.

can determine if that goal was achieved. Careful attention should be paid to muscleand frenal attachment areas because the tray may require significant correction intliose areas. The clinician is responsible for properly evaluating and adjusting theborders of die custom impression tray prior to initiating ihe border molding procedure(Figure 7-5).

In correcting the distal extension of the maxillary custom tray, one importantfeature to locate is tiie vibrating line (Figure 7-6). .\ltiiough not exactly true, for clinicalpurposes it may be thought of as the Junction between the more stable, almost immov-able, hard palatal tissue and the movable tissues of the soft palate. This imaginary line

Figure 7-6 The vibrating line has been identified at themidline and Is marked with an indelible marker. Note theobvious angular difference between the rather flat, hardpalate and significant slope of the soft palate at the vibrat-ing line. A noticeable change in tissue color is also presentat that point.


crosses the palate, generally with an anterior curvature, and extends through the hamu-lar notches bilaterally. Exact location of this line is important because it is the distallimit of the maxillary denture and also the distal limit of the posterior palatal sealarea, which will be discussed later Several tet hni(¡ues, or features, will aid the clinicianin locating the vibrating Une. The clinician v ill often visuali/.c- ihe position of this lineby having the patient say "Ahh" and noting that the soft palatal tissues will usually liftwhile the hard palatal tissues remain immobile. Another technique to help locate theline is called the Valsalva maneuver in which ttic patient is asked attempt to blow airthrough their nose while the nostrils are gently pinched closed. While gently holding thetongue down with a mouth mirror, the clinician will often easily \'isuaUze the line becausethe soft palate will drop dramatically at the vibrating line using tliis tecbnique. Otherfeatures indicating the position of this line may include a rather sharp color changebetween the hard and soft palatal tissues at die \ibrating line and/or tbe presence of thefovea near the line. Lastly, and often the easiest to visualize, may be the rather significantangular change between the rather flat hard palate and the moderately to severely slop-ing soft palate. This jiuiction indicates the vibrating line. Extension of the denturebeyond the vibrating line will result in the denture terminating on excessively movabletissue and often cause lack of retention or irritation to the tissue. The vibrating line islocated and marked using an indelible pencil or marker, and the impression tray istrimmed to this line (Figure 7-7).

The same general procedures are followed for the mandibular impression tray withthe exception being that there is no vibrating line to be located. Unique difficulties asso-ciated with correcting the Hange length of tlie mandibular tray include difficulty in visu-alizing the lingual border of the impression tray and the presence of a fatty roll of tissueoften present in the masseter muscle areas (Figure 7-8). Extra care is necessar\' whenreducing the tray in the masseter/buccinator muscles area because impinging on tliesetissues will cause irritation and discomfort to the patient and dislodgement of thecompleted denture when the patient opens his or her mouth. A properly shapedmandibular impression tray will most often exhibit the following three features: First the

Figure 7-7 The posterior extent of the impression trayis shortened to coincide with the vibrating iine.The trayis shortened to the proper length at the midline area andthen a smooth curve is created, in most patients, whichflows through the hamuiar notches.


Figure 7-8 The fatty roll of tissue in the masseter musclearea must be removed from beneath the impressiontray when evaluating the extension of the tray. Note thesmooth slope ofthe impression tray from the vestibulararea to the retromolar pad area. See Figure 10. Patients donot exhibit any sharp corners in the tissues in this area.

labial and lingual fianges in the anterior area will be approximately the same lengthunless the patient has had some type vestibular extension surgical procedure or severeloss of the residual ridge (Figure 7-9). Second, the distal-buccal Hange will gi-aduallytaper from the vestibule to the crest of the residual ridge, often at approximately a 45to 60** angle, (Figure 7-10) and continuously flow into the retromylohyoid area(Figure 7-11 ), The longest part of the tray shotild be just lingual to the crest of the ridgewith a smooth ciu^ature mimicking the shape of the retromylohyoid curtain. .•Vnd lastly,

Figure 7-9 For most patients, the labial and lingualflange lengths will be of equal length unless the patienthas had a surgical extension of the vestibular notch orsevere bone loss resulting In the genial tubercle beingelevated.


Figure 7-10 The impression tray should show a smoothcontinuous decrease in flange length as it continues fromthe buccal shelf area to the crest of the ridge. Patients donot exhibit sharp corners in this area intraorally.

Figure 7-11 The border of the impression tray shouldcontinue as a smooth, continuous line from the massetermuscle area to the retromylohyoid area with the longestpart of the tray located just lingual to the retromolar pad.This flange area should be gently rounded to mimic theshape ofthe retromytohyoid curtain.

the lingual flange will begin at the level of the labial fiange in the anterior area andgradually become longer than the buccal flange as it approaches the retromylohyoid area(Figure 7—12). It generally exhibits a smooth continuous form, not an irregular shape, asit progresses from the anterior to the posterior. Once all extensions have been corrected,the impression trays are ready for border molding.


Figure 7-12 The lingual flange of the tray should resem-ble a smooth continuous line beginning at the level of thelabial flange in the anterior and gradually increasing inlength, as compared to the buccal flange, as it approachesand enters the retromylohyoid area.

Border Molding

Border molding is the techniqtie for correcdy extending the flanges of a custom impres-sion tray. The flanges were intentionally adjusted intraorally to be 2-3 mm short of tiieactual desired final extent of the final impression to allow room for the border-moldingmaterial. The correction is completed using a soft but slightly \iscous impressionmaterial that becomes at least semi-rigid as it cools, or polymerizes. This material isslightly overextended on the tray beyond the 3-4 mm the tray was shortened, tlierebyassuring at least complete coverage of all usable tissues (Figure 7-13). Once insertedand prior to the impression material becoming rigid, tlie son tissues are manipulateduntil the desired extensions are recorded in this soft material (Figure 7-14). The tech-nique is continued until the correct extension of the entire impression tray is captured(Figure 7-15).

Several materials have been used to border mold an impression tray, includingmodeling compound, hea\y bodied \inyl polysiloxane and poiyether materials. Greenmodeling cotnpound is an excellent material with advantages atid disadvantages. Oneadvantage of modeling compound is tliat, if the final impression must be remade, oftenthe impression material can be removed from the impression tray and the modelingcompouiid border molding can be reused. .Ajiother advantage is that, because of its rigid-ity, it can be used to extend custom impression trays whose borders have become exces-sively short, more than 3-4 mm, of the desired final extension. Once chilled in ice water,this rigidity also allows tiie trimming of the material without fear of distortion, -\notheradvantage is that, even when acceptably soft for border molding purposes, it is generallysufliciently \iscous to retain its form. Tbis often provides an ideal width (2-.S mm) tothe tray flange. A disadvantage of modeling compound is that the need for planned


Figure 7-13 Only sufficient border molding material isadded to the impression tray to slightly overfill the spacecreated when the tray was shortened 2 mm from thedepth of the vestibule.Therefore only approximately 3 mmof border molding material is required to assure completefill ofthe vestibule. Excess material will overextend theflange length.

preparation and the use of several pieces of equipment and materials, including a waterbath, a Bunsen burner, petrolatum jelly, sharp trimming knife, and an alcohol torch.Modeling compound is acceptably soft and yet not uncomfortably hot, between approx-imately 49"C (120 * F) and 60" C (140' F). Setting the hot water bath to the upper limitof Ulis range provides an acceptable but minimal working time. Therefore only reason-ably small areas of the borders can be corrected before the material cools and becomes

Figure 7-14 While the material is still softened, the bordermolding nnovements are completed. When removed fromthe mouth, if the impression tray shows through theborder molding material, the tray was insufficientlyreduced. Any border molding material should be removed,the tray further reduced, and the border molding proce-dure repeated.


Figure 7-15 The border molding is completed, and allexcess material has been removed.The material shouldbe no more than 2-3 mm In height above the tray flangeand only as thick as the desired flanges of the completeddenture (2-3 mm). Additionally there should be no areas inwhich the impression tray has shown through the material.

too rigid to be useful. The material must be very soft to be used effectively and thereforemust remain in the mouth for approximately 15 seconds to be sufficient!)' rigid not todistort when being removed from the mouth. It must immediately be immersed in icewater and become rigid before attempting to trim any excess material. A sharp knifeblade must be used to allow for trimming of the material rather than breakiige. Anotherdisadvantage is that, once cooled, because of its rigidity it is often difFicult to place andremove from bilateral undercut areas, particularly the retromylohyoid areas, withoutcausing trauma to tiie tissues and discomfort to the patient.

Heavy bodied vinyl polysiloxane (VPS) is anotlier excellent material for bordermolding. An advantage of tbis material is that it is a simple material to work with thatrequires minimal equipment. AddititJiially, because tbe working times of varieties of VPSvaiy, from approximately two to eight minutes, the clinician can select the one that bestfits his/her impression tecbnique. Generally a material witb a working time of about twoor three minutes in the mouth provides plenty of time to border mold and is ideal.Anotber advantage to using VPS is that, even when polymerized, it remains reasonablysoft and yet accept;ibly rigid, and can be removed from undercut areas witb minimaldiscomfort to the patient. An additional advantage of VPS is tJiat, because of theextended working time :LS compared to modeling compoimd, it is often possible toborder mold an extended border of an impression tray at one time as opposed to havingto complete it one smaller section at a time, as is necessary widi modeling compound. Ifan area of the border molding must be redone, it is quite simple to add additional mate-rial and repeat tbe procedure. A disadvantage to border molding and making tiie finalimpression with VPS is that tbe border molding and impression materials bond duringpolymerization and cannot be separated when desired. Therefore, if the final impressionis not acceptable and must be remade, tbe border molding material v>ill often be lostduring the process of removing the impression material from the tray, resulting in thenecessity of repeating tbe border molding procedure. Another disadvantage is tbat \TSadhesive must be used to bond the material to the impression ti"ay requiring severalminutes to set. This time may simply be lost to the clinician if the impression procedures


art- noi pntperly planned. VPS does not have the viscosity or rigidity of modelingcompound and therefore cannot be used to correct borders that are underextendedby more than 4-5 mm. Also if not supported by the impression tray, VPS cannot bedepended on to form tray fianges 2-3 mm in thickness. This is especially noticeable inthe reuomylohyoid areas, where the distal extent of the border molding and finalimpression is often tJiinned by the tongue to a "knife edge." This may result in a mastercast with an indistinct shape in this area, which could result in a completed denture withan inacctirate border length and thickness.

Border Molding with Modeiing Compound

Because of its minimal working time, border molding using modeling compound mustbe completed in multiple reasonably small areas (Figures 7-16 and 7-17). Once thecompound is added to a fiange area of the impression ti ay, the material is tempered inthe hot water bath for approximately 5 to 8 seconds, placed in the mouth, bordermolded, atid allowed to stay in the mouth for approximately 15 seconds following theborder molding procedure. The impression tray is removed and immediately placed inice water until rigid. It then must be examined and trimmed as necessary. The materialhas a dull, matte, surface when properiy formed. The completed border should beapproximately 2-3 mm in width in order to approximate the desired thickness ofthe fiange of the completed denture. The material is then rechecked intraorally toensure complete fill oí tlie border and yet show no evidence of overextension. If the softtissues are being displaced more tlian a slight amount, the material is overextended andthe border molding technique must be repeated. If the impression tray is showing

Figure 7-16 Because ofthe limited working time whenusing modeling compound to border mold, the bordermolding must be done In reasonably small sections.This is not necessary when using vinyl polysiloxane.Thesuggested sequence for border molding the maxillaryarch, when using modeling compound, is illustrated.


I

Figure 7-17 The suggested sequence for border moldingthe mandibular arch when using modeling compound. It ispossible to border mold the longer segments of themandibular tray with VPS, however, the material in theretromylohyoid area will almost always be "knife-edge"thin, if not manipulated correctly.

through the material, the material must be removed, tlie tray shortened, and tliehorder molding repeated. Once one section is lotally completed, a second section canbe border molded. Wlien completed, the material should smooLhly ilow from one areato the next without visible lines of demarcation. Each area must be totally completedprior to starting another area. Remember, once completed, lhe height of the bordermolding material above the tray should be no more than 2-3 mm because that wasthe amount of space created between the soft tissue and the impression tray prior toborder molding.

Border Molding the Maxiiiary Arch

The initial border molding oí the maxillary arch should begin with eitlier tlie left or rightbuccal flange area. The modeling compound is added, and this area and border aremolded by grasping the cheek bet veen the thumb and fingers and manipulating thetissue outward, downward, and inward. The opposite area is then completed.

Obsen'e the attachment ofthe buccal frenum. WTien border molding the frenulumarea, move the check out, down, in, backward, and forwaid. This movement is necessaryas the tissue in the region of the buccal frenum moves anteroposteriorly. Repeat for theopposite side.

Next, observe the space in the labial vestibule and the size of the labial frenum.During border molding of this region, the contour of the impression must be adjustedso that the lip is not over-supported. The labial flange should not be thinner than 2 mmat tiie completion of the border molding procedure, or it will not adequately supportthe final impression material. It should also not be more than 4 mm thick. Modelingcompound is placed from tlie canine region on one side around to the midline, and this


area is border molded by pulling the upper lip otttward, downward, and inward. Aside-ti)^ide movement is not indicated hecaiisc the labial frenum does not function inthis manner. Rej)eat for the opposite side.

The final area to be border molded is the posterior extent of the tray. Impressioncompound is placed across the posterior portion of the tray from just buccal to thehamular notch on one side to the same position on the other side. Because the tray hasbeen trimmed to the proper lengtli, to the \ibrating line, the compound shotild beplaced within the tray and not extended beyond the posterior extent of the tray. Thecompound should be no more than 1-2 mm in thickness and 3-4 mm in width. Have thepatient open his or her mouth wide, Uien protrude and move the mandible to the rightand to the left. This action develops the distal extent of the dentine in the hamularnotch and also develops the space between die anterior border of the ramus coronoidprocess and tJic luberosity. WTien using \TS, the entire border may be completed in onestep using the same border-molding techniques as listed previously. Many clinicians lindborder molding half tlie tray at one time a much more controllable procedure.Depending on the complexity of the impression and the experience of tbe clinician,even smaller segments may be done with tbe VPS material.

H^Border Molding the Mandibular Arch

Wiien border molding v\ith modeling compound, have the tongue slightiy elevatedwhenever the heated compound impression is placed in the patient's mouth. This willfacilitate the placing of the impression and will minimize distortion of the impressioncompound.

The buccal shelf areas are initially border molded and must be completed individ-ually. Do not attempt to complete them simultaneously because the useful softness of thecompound is only approximately 10 .seconds. Add modeling compound to the right orleft buccal shelf areas of tJie tray from the distal of tJic buccal frenum to the anterior partof the retromolar pad regions. Place die tray in the patient's mouth and border mold bymanipulating the cheek outward, upward, and inward. Remove and chill. Repeat for theopposite side.

Border molding of the buccal and labial borders and frenulum are completed in amanner similar to what is done on the niaxillaiy arch, with the exception of the lips orcheeks being manipulated outward, upward, and inward. The buccal notches will almostalways be shorter and narrower than the adjacent borders.

Next add compound through the retromolar pad regions (doing each separately)and while inserting making sure to pull any fatt\- roll of tissue in the nia.sseter area frombeneath the impression material prior to final placement. The patient is asked to closeonto the clinician's fingei-s while the clinician resists the closure movement and gentlypresses downward on the tray. This procedure forces the nia.sseter muscle into action; themasseter, in turn, forces the buccinator in the direction of the distal buccal comer of theretromolar pad, creating the masseter groove.

The distolingual and postniylohyoid areas should be developed nexi by having thepatient forcefully protrude the tongue and move it from side to side. This proceduredevelops the slope of the lingual Hange in the molar region as well as the remaininglength of the flange. If modeling compound excessively builds up inside of the lingual


flange, it should be reduced, the material should be reheated, and the border moldingprocedure repeated.

Add modeling compotmd to the anterior region of the lingual flange if necessaryand instruct the patient tí) push the tongue against the front part of Üie hard palate. Tlïisprocedure develops the width of and length ofthe anterior lingual flange.

Border molding of the retromylohyoid areas are left until last because of the areasbeing bilaterally undercut in relation to each other. Wlien using modeling compound,especially once chilled, it is often physically difficult to get an impression U"ay into andout of these areas. Also, if these aieas are completed early on in the border moldingsequence, it may make the remainder of the border molding quite uncomfortable tothe patient. Add modeling compound to one distal-lingual flange area and insiructthe patient to "open and protrude the tongue" to activate the retromylohyoid curtainand then to "close down on my fingers" to activate tlie medial pterygoid muscles, whichfunction posteriorly to the curuiu and tend to displace it forwaid. As tlie patient closes,resist the closure by downward pressure of the fingers to cause the medial pterygoidmuscles to contract. If a formed border is not present or if the border is knile edged, theflange is usually loo short. This procedure may have to be repeated several times toachieve the desired results. These areas are difiBcult to properly form and take skill tocomplete.

Lastiy, heat the compound in the retromolar pad areas, temper, place the impres-sion tray in the mouth, and instruct the patient to "open wide." This procedure reducespressure over the retromolar pad areas. If the border is too long, a notch will be fomiedat the posterior medial border indicating tiie upwai d passage of tiie pterygomandibuiarraphe. Border molding of the mandibular impression is completed.

It is not possible to border mold the entire mandibular arch at one time usingVPS material. The tray should be stabilized by border molding the buccal shelf ajeas andthen completed as the clinician's experience level dictates. The retromylohyoid areasmay require more than one insertion to develop the proper border thickness. On subse-quent insertions v\ith additional border molding material added, the area can be moreeasily thickened if the patient closes slightiy as the tray is positioned and asked to mois-ten their lips gently to accomplish the border molding.

Preparing the Tray for the Impression

Any "relief wax" is removed from the tray. For the selective pressure technique, thiscreates a void or chamber between the nonprimary stress-bearing tissues of the archesand impression trays. This chamber minimizes the possibility of physical pressure fromthe tray to the tissues during the impression-making procedure. Any sharp ridges at theresin/wax interface are smoothed with an acrylic bur. Additionally, approximately five #8round bur sized holes are cut through tiie tray in the chamber areas (Figure 7-18). Theseholes allow the relief of hydraulic pressures that will build hecause of tlie viscous impres-sion material being squeezed between the tissues and tiie impression tray. No relief of theborder molding material is normally required because most impression materials will beminimally viscous and therefore no extra space is required for tlie material. If a viscousimpression material is selected, then approximately 0.5 millimeter of the border mold-ing material should be removed. Adhesive specific to the particular impression material


Figure 7-18 The relief wax has been removed from theimpression tray creating a relief chamber in the area. Allsharp edges have been rounded, and five relief holes havebeen prepared using a #8 round bur.

being used is applied to the entire tissue side of the tray and extends onto the labial andbuccal surfaces approximately 4 mm. AH impression compound border molding materialsbould be coated with tbe adbesive.

Making the Final Impression

The final impression is made using the desired impression material. Some of the char-acteristics of an ideal material include being minimally viscous, polymerizing (setting)intraorally within 2-3 minutes, being hydrophyllic, being thixotropic, not ilowing onceremoved from the mouth, nqt being excessively rigid, not being excessively expensive,being well tolerated by the tissues, being exacting in recording and maintaining tissuedetails, and the ability to be poured in a dental stone more tban once.

The selected impression material is mixed according to the manufacturer's direc-tions and applied evenly to the tray to a thickness of approximately 3 mm, being carefulto avoid capturing air bubbles within the material. Only this minimal thickness of impres-sion material is needed because a custom impression tray, rather than a stock tray, isbeing used and was fabricated to closely fit the underlying tissues. Because most impres-sion materials are hydrophobic, while the impression tray is being loaded, tbe tissues tobe captured in the impression should be freed of moisture. The patient should swallowall excess saliva, and the tissues sbould be carefully dried with 2x2 sponge gauze.

When inserting the impression tray, the clinician mast carefully observe the seatingofthe tray onto the tissues. Before completely seating the impression, the clinician mustproperly position the impression tray over the ridge so that the anterior flange of the traywill seat properly and completely into the labial vestibule. AVhen seating the mandibularimpression tray, the clinician must take special care to not capture any fattj' roll of tissue


in the masseter muscle area as part of the impression. This can be accomplished bypulling this roll of tissue from beneath the tray on one side of die arch, slightly seatingthat side of the tray, ptilling the opposing roll of tissue fi^om beneath that side of the tray,and tlien partially seating tliis side ofthe tray. For the final seating, the patient should beasked to lift the tongue and, as the impression is being seated, tlie patient should bedirected to relax the tongue. This procedure will minimize capturing the tongue, salivary-glands, and other nondesirable areas within the impression. A similar procedure isaccomplished when making the maxillary impression with the addition of having thepatient move the mandible in extreme lateral motions as part of the impression proce-dtire. This movement will cause the coronoid processes to help contotxr the lateralborders of the impression in the ttiberosity areas.

Border molding of the impression must be initiated before the impression materialbegins to polymeri/e and must continue until the material begins to pohmerize. If tissuemanipulation is stopped prior to the initial polymerization, the material may again fiowbeyond the desired extensions, causing excessive thinning of the borders and overex-tension ofthe impression. Manufacturer's directions are followed for mixing and settingtimes of all materials.

Care is often required to minimize patient discomfort when removing an impre.s-sion. On the maxillarv^ arch this discomfort may be caused by excessive retention of theimpression within the mouth. Generally an index finger can be used to lift the tissuesaway from one ofthe fiange areas, which breaks the border seal by allowing air under theimpression. On the mandibular aicli tliis discomfort may be caused by the impressionextending into bilatei"al undercuts in the retromylohyoid areas.

The impressions shotild be rinsed and then disiniected before further handling.The niaxillarv' impression is trimmed back to within 1 mm of the vibrating line. Evervimpression must be objectively evaluated by the clinician to iissure its accuracy andremade when necessary. {Table 7-1 ).

le 7-1 REASONS FOR REMAKING IMPRESSIONS

1. Incorrect tray position in the mouth- A thick border on one side with a corresponding thin border onthe opposite side is a good indication that the tray was out of position in the direction of the thickborder. Pressure spots on the lingual surface of the maxillary labial flange usually indicate that thetray was not fully seated. Pressure spots on the anterior part of the mandibular lingual flange indicatethat the mandibular iray is too far forward in the mouth, in many instances as a result of action ofthe tongue,

2. Pressure areas in secondary stress bearing areas, e.g.. the region of the crest of the ridge of themandibular tray or the rugae region of the maxillary tray.

3. Any void or discrepancy too large to accurately correct. Some voids may be corrected by adding newimpression material to the impression and reinserting however any impression with a void this largegenerally should be remade in its entirety. Small voids may be correciable on the master cast sincethey will result in positive bubbles that can be removed with a cleoid/discoid instrument.

4. Incorrect border formation as a resuft of incorrect border length of the tray—a sharp border mayindicate that the impression is too short in that area.

5. incorrect consistency of the final impression material when the tray was positioned in the mouth.6. Distortion of the impression material because of movement of the tray during the setting of the final

impression material.


Posterior Palatal Seal Areaè

Probably the most critical of the retention factors listed earlier is that of atmosphericpressure. When the pressure of the air between the denture base and the underlyingdssues is less that tJiat of the atmospheric air pressure, excellent retention of the dentureis expected, and patients often refer to this retendon as suction. This retention is lost,most noticeably from the maxillary arch, if the denture/tissue contact (seal) around thedenture borders has been lost and air is freely allowed between the denture and theunderlying tissues. A loss of this seal is often caitsed by resin shrinkage during polymer-izadon. Acrylic resin shrinks toward the area of greatest bulk of the denture, which isgenerally around the denture teeth. On the maxillary arch, this shrinkage usually resultsin the creation of a good seal around the labial and buccal sides of the denture andloss of seal at distal extent of the denture as it crosses the palate. In this area, as theresin shrinks toward the denture teeth, it tends to lift away from the cast resulting in afuture loss of the seal and hence loss of denture retendon. This shrinkage must beanticipated and steps taken to help ensure that resin/tissue contact will exist followingprocessing. Some newer injection molding techniques minimize this problem. Besure to check with the material manufacturer regarding recommendations concerningpalatal seal areas.

This technique is called the placement of a posterior palatal seal within thedenture. The procedure consists of an initial identification of compressible tissue in theposterior of the hard palate and the determination of the depth to which this tissue couldbe comfortably compressed by the denture base. The posterior limit of the posteriorpalatal seal area is the vibrating line, which extends from just buccal (2 mm) to onehamular notch area across the palate to just buccal to the opposite hamular notch(Figure 7-19). At the vibrating line, the tissue in the posterior palatal seal area can becompressed approximately 0.5 mm deep in the hamular notches and midline areas and1 mm deep in other areas however the exact depth for a specific patient is determinedhy palpation. Intraorai identification of this area is eventually followed by a laboratoryprocedure, which consists ofthe removal of an area of stone from the master cast thatcorresponds to the amount of displaceable tissue palpated intraorally. The depth of stoneto be removed from the cast is genei"ally deepest toward the vibrating line and feathersto an indistinct anterior border.

When acceptable, the impression should be disinfected, prior to removing it fromthe operator^; and the posterior palatal seal area should be di awai on the impression witlian indelible pencil (Figure 7-20), Ii can then be taken to the laboratoiT, beaded, boxed,and poured using an ADA-approved dental cast stone of choice following manufacturer'sdirections.

Creating the Master Cast

Acceptable master casts should be of the proper thickness, bubble and void free, andinclude an accurate representation of all impressed tissue surfaces and surroundingfinished borders, often called land areas.

H


Figure 7-19 The shape of the average posterior palatalseal area is indicated in blue. Note tbat the black line, indi-cating the vibrating line, is the most distal extent of boththe posterior palatal seal area and the completed denture.The green area represents an area of the hard palate thatoften has soft tissue than can be compressed approxi-mately .5 mm.The orange area indicates the tissue thatcan generally be compressed approximately 1 mm.Thisdegree of compressible tissue varies with each patient andmust be determined intraorally. Stone will be removedfrom the master cast in this shape and depth as a labora-tory procedure ending in a "feather edge" in the anterior.

Figure 7-20 The completed maxillary final impressionwith the outline of the posterior palatal seal drawn onthe impression with an indelible marker. Note that, eventhough not indicated on the impression, the posteriorpalatal seal will extend approximately 2 mm through thehamular notch areas.


Figure 7-21 Play-doh '" is used to form the beading/basefor this mandibular impression. Note that the borders ofthe impression are at least 2 mm above the Play-doh'".

Prior to attempting to pour the final impressions, a fonn should be created aroundtiie impressions to simplify the procedure and to give the proper size and shape to themaster casts by confining the dental stone while the impressions are poured. The proce-dure for developing this form is called "beading and boxing" the impressions. Thepurpose of beading impressions is to define the impression surfaces and also to aid insupporting the impressions during pouring. The impression surface is defined by creat-ing shouldei"s outside the impressed tissue surfaces of the impression (Figure 7-21).Boxing is the process of enclosing the impression and beading material to confine thedental stone to both the desired shape and thickness, to minimize trimming the cast andexcess use of the dental stone (Figure 7-22). Boxing is routinely completed with a waxmade especially for this puipose, while beading is often done viith a rope-t>'pe wax, Play-

Figure 7-22 Boxing wax has been positioned around thebeading/base material and is sealed to minimize loss ofdental stone during the pouring of the impression.


Figure 7-23 The initial pour of the stone into the impres-sion is shown here.The stone is added in small incrementsand is slowly moved posteriorly using a vibrator set to amoderate to low vibration rate. Note the position of thethumbs and fingers.Tbey are positioned to minimize thepossibility of collapsing the boxing wax during the pouringofthe impression.

irreversible hydrocoiloid, or a mixture of stone and pumice. Both the beadingand boxing materials must be inexpensive, easily handled by die technician, and suffi-ciently strong to retain size and shape while the impressions are poured (Figure 7-23).Wiien the stone sets, it should then be reasonably easy to remove from both the mastercasts and impressions.

Once the stone has set and the beading and boxing materials have been separatedfrom the master casts, the casts are trimmed to the final size and shape using model trim-mer, acrylic burs, and laboratoiy knives. Tbe bottom and sides of tbe base of tlie castshould be trimmed in a specific sequence to ensure an acceptable final result. Wbencompleted, the casts should be trimmed so that the ridges are parallel to the bottom oftlie base, and the base is ofthe proper thickness. Because most casts are often not pouredwitb the proper thickness and ridge/bottom parallelism (Figure 7-24), die bottom of tbecast should be trimmed first (Figure 7-25) until the crests ofthe residual ridges are paral-lel to the bottom ol' tbe cast and the cast is approximately the correct thickness. Thethinnest portion of the master cast should be approximately 12-15 mm in thickness,which results in the cast being thick enough to resist breakage and yet thin enough toeventually fit into a processing lîask (Figure 7-26). Remember, die tliinnest portion of acast is generally going to be between the deptb of the vestibule and tlie bottom of thecast. The sides of tbe base ofthe cast can then be trimmed on a model trimmer until theHidth ofthe land areas is approximately 2-3 mm on the buccal and labial (Figure 7-27),and approximately 5-6 mm distal to the hamular notches and retromolar pads. Once thecast is dry, the level of the land areas and tongue area can be contoured and smoothedwith an arbor band or aco'lit bui until the vestibules are approximately 2-3 mm in deptband the land areas are parallel with the bottom of tbe cast (Figure 7-28). .\n excellentfinish can be placed on the cast using silicon carbide wet/drv' 320 sandpaper. Whencompleted the master casts (Figures 7-28 and 7-29) are ready for the fabrication ofrecord bases and occlusion rims.


Figure 7-24 Note that the crests ofthe residual ridges are not parallel tothe bottom of the base of the castfoilovtfing the initial pour of themaster cast.

Figure 7-25 Prior to trimming thesides of the base of the cast, thebottom is trimmed in order toachieve an acceptable thickness andto make the ridges parallel to thebottom of the base.

Figure 7-26 The thinnest portion ofthis cast is in the vestibule. (X)Theminimum thickness of a master castshould be 12-15 mm in the thinnestarea.


Figure 7-27 Once alt trimming hasbeen completed on the model trim-mer and the cast has been allowedto dry, the land areas can be prop-erly trimmed.The land areas shouldbe trimmed so that the vestibulesare no more than 3 mm In depth.Also see Z in Figure 7-26.

Figure 7-28 An example of a well-shaped and finished maxillarymaster cast.

Figure 7-29 An example of a well-shaped and finished mandibularmaster cast.


References

Avant, W.: A comparison of the retention of complete denture bases having different types ofposterior piilatal seal.J Prosthet Dent. I973:48'1-9. .

Duncan, J. P., Taylor, T. D.: Simpliiied complele dentures. Dent Clin North .\m. 2004;48:625-i0.Felton, D. A., Cooper, L. F., Scurria, M. S.: Predictable impression procedures for complete

dentures, In Engelmeier, R.L., ed. Complete Dentures. Dent Clin North Am. Philadelphia: W.B.Saunders, 1996;40:39-51.

Kolb, H.: Variable denture-limiting strutiures of the edentulous muuth. Part 1: Maxillary- borderareas.J Prosthet Dent. 1966;16:194-201, pp. 202-212.

Pctrie, C. S., Walker, M. P., Williams, K.; A suiTcy of U.S. prosthodontists and dental schools on thecurrent materials and rneihods for final impressions for complete denture prosthodontics.J Prosthodont. 20()5;14:2ri3-2t}2.

Petropoulo.s, V. C;., Rashedi, B.: (;ompkte denture edtication in U.S. dental schools.J Prosthodont. 2005:14:191-7.

Rahn. A. O.: Developing Complete denture impressions, in: Rahn, A. Ü., Heartwell, C. M., editors.Textbook oí complete dentures. 5lh ed. Philadelphia: Lea & Febiger: 199ÍÍ. pp. 221-247.

1. What feature of a cotnpleted denture routinelv increases the factorsof retention?

2. What is the distal extent of a maxillary complete denture?

3. What is border molding?

4. Why is the "relief wax" removed from an impression tray just before makingthe final impression?

5. Why are multiple #6 or #8 round but r-sized holes cut into the impression trayjust prior to making the fmaJ impression?

6. What is the location of the posterior palatal seal area, and what is its ante-rior and posterior limits?

7. How does the clinician minimize the capturing of the roll of tissue, seen inmany paüents in the masseter muscle areas, within the impression?

8. What are some of the characteristics of a good impression material?

9. What are some of the disadvrantages of itsing modeling compound as abotder-molding material?

10. Why should a maxillary denture not be extended onto the movable softpalate?


1. Maximum tissue co\erage

2. Vibrating line

S. Border molding is the technique of properly extending the fiange lengthof an impression tray prior to making the final impression.

4. Removal ofthe relief wax creates a chamber, or relief area, within theimpression tray that reduces the chance of physical pressure from theimpression tray to the underhing nonsuess-beaiSng tissues.

5. To reduce the hydraulic pressure that builds up within the impressioncaused by the viscous impression material being trapped between theimpression tray and the underlying tissues.

(). Anterior limit is nonspecific and depends upon the available displaceabletissue. The posterior limit is the \ibrating line.

7. By pulling the tissue from beneath the impression tray while seating the tray.

8. Is minimally viscous, polymerized intraorally within 2-3 minutes, ishydrophyllic, is thixotropic, will not fiow once removed from the mouth,is not excessively rigid, is not excessively expensive, is well tolerated by thetissues, is very exacting in recording and maintaining tissue detaiis, and canbe poured in a dental stone more than once.

9. Planned preparation and the usage of several pieces of equipment andmaterials are required. Only rea.sonably small areas of the horders can becorrected at a time before the material cools and becomes too rigid to beused properly. Once cooled, because of its rigidity, it is very difficult to placeand remove from bilateral undercut areas—particularly the retromylobyoidareas—^without causing trauma to the tissues and discomfort to tlie patient.

10. Retention of the denture may be compromised, and the denture may causeirritation and trauma to the soft movable dssues.

C H A P T E R

URecord Basesand OcclusionRims

Dr Arthur D, RahnDr John R. Ivanhoe

131


At this time the clinician has completed making the final impression and fabricationof tlie ma.ster casts for the maxillary and mandibular arches. 1 hese casts will be usedthroughout the remainder of the denture construction, and the dentures will beprocessed on them. Prior to that time, jaw relation records will be made, the casts willbe placed on an articulator, and denture teeth will be arranged on tliese casts. Thereforea method becomes necessary to accurately attach the opposing maxillary and mandibu-lar casts to an articulator. This requires the use of record bases and occlusion rims{Figures 8-1 and 8-2).

The record base and occlusion rim are necessary for (1) establishing facia!contours, (2) an aid in tootb selection, (3) establishing and maintaining the verticaldimension of occlusion during records making, (4) making interocclusal records, (5) tliearrangement of the denture teeth, (6) the verification of the correct master cast mount-ing on the articulator, at the estlietic trial insertion appointment, and (7) a waxed-upmold for the external surface ofthe complete denture.

Record Base Fabrication

A satisfactory record base must be stable on both the master casts and intraoraily. Itshould be rigid, accurately adapted to the casts, fully cover the entire supporting tissuesof tlie arches, and also esthetic and comfortable to the patient. For strength, rigidity, andgood adaptation of the bases on the cast and intraorally, autopolymerizing acrylic resinis generally the material of choice for their construction.

To protect the master casts, tissue undercuts and irregularities are blocked out withbaseplate wax (Figures 8-3). This blocking out of the undercuts is particularly importantwhen initially separating the record base from the master cast, which may result in abroken cast and the need for new final impressions and casts to be made. The commonlocations for undercuts or irregularities on the maxillary casts are on the labial of the

Rgure 8-1 Well-formed maxillary record base and occlu-sion rim.

Record Bases and Occlusion Rims 133

Figure 8-2 Well-formed mandibular record base andocclusion rim.

anterior ridge, in the rugae areas, and sometimes in the tuberosity areas laterally. On tliemandibular cast, the retromylohyoid areas often must be rather heavily blocked out, andin many situations the posterior inferior portion of the record base is not ever extendedinto these areas. This is because these areas are often severely undercut in relation toeach other, and the master cast may be damaged or the record base broken during itsplacement and removal from the cast.

Wax used in blocking out buccal and lingual undercuts should be applied in suffi-cient thickness to almost completely block out most undercuts. An exception is the

Figure 8-3 On this mandibular cast, note that undercutson the labial and lingual side of the thin ridge have beenblocked out with thin layers of baseplate wax (arrows),whereas in the more severely undercut retromylohyoidareas, the area has been entirely blocked out with redutility wax. The record base will not completely extendinto the retromylohyoid area.


undercut on tlie labial or anterior portion of the maxillary cast, which need not becompletely eliminated: the completed record ba.se and occlusion rim can be placed andremoved in an anterior direction. The adequacy of the block out may be evaluated bylooking down on the cast from the direction that the lecord base will be placed andremoved from tbe cast.

Following the block out of the master cast, the cast is soaked in room-temperaturewater for five tninutes in order to expel air from within the stone, which will help mini-mize the formation of bubble-like deiccts in the completed record base. Air bubblesfrequently will rise to the stu-face from within tbe master casts when separating mediumand/or monomer is applied to the casts unless they have been soaked. Tbe soaking ofthe cast must be completed after the cast has been blocked out with wax because the waxwill not stick to a wet surface.

A tinfoil substitute is then tised as a separating mediittn to protect tlie cast andallow the separation of the record bast- from the cast following the application ol" themonomer and polymer. The tinfoil substitute is applied twice, allowing llie firet applica-tion to dry prior to applying a second coat. Each application is applied as a thin film toall surfaces of the cast, including land areas and the sides of base that may come incontact with the resin (Figures 8-4). No pooling of the tinfoil sttbstitute on tlie castsshould remain. Brush only long enough to distribute tiie tinfoil evenly. Excess brushingcauses the material to "ball up." Allow the secotid application of the tinfoil substitute todry completely. When dry, the tinfoil substitute will have the appearance of a thin layerof cellophane. Therefore, do not attempt to expedite the drxing time by blowing itdry with air under pressure. Doing so may cause tlie separating tiiedium to be blown offthe cast.

The record base is fabricated with autopolymerizing acryîic resin using a "spinkle-on" technique (Figures 8-5). This technique uses a material that can be completedquickly and provides an accurate and rigid final product.

Wben cartying out this technique, a small area of the vestibtile is initially wettedwith monomer (liquid). Then a thin layer of polymer (powder) is sprinkled onto themonomer until there is no visible liquid remaining and the mixture is reasonably

Figure 8-4 Tinfoil substitute is applied in two thin layers,allowing the first layer to dry prior to adding the second.


Figure 8-5 The initial placement of the monomer followedby the polymer. Although both the eyedropper with themonomer and the container with the polymer are showntogether, the monomer is always placed first, followedby the polymer.

dense while having no dry polymer remaining. Continue the sprinkling and saturatingprocess until the refiections of the casts are filled and tlie palatal portion of the max-illarj' and lingual, labial, and buccal slopes of both rims are approximately 2-3 mm inthickness.

The record base should be thinner on the crest of the ridges and buccal to thecrest of the ridges because space may be limited when the denture teeth ate beingarranged at a fiiture date. Once this sprinkle-on procedure is started, it must be totallycompleted. The application of the polymer just to the stone cast followed by themonomer, or allowing the i esin to begin to polyinerize, if more thickness of the recordbase is required, should he avoided. Either one of these situations will create porositywithin the record ba.se. .Also, in order to prevent porosit)' caused by the rapid e\'aporationol the monomer, the casts and record bases should be placed into a humidifier orcovered with a damp paper towel and a rubber plaster bowl inverted over the top untilthe resin has polyTnerized.

The resin should be allowed to poK-merize for 1.5 minutes. Then the resin base canbe carefully removed from the cast. Be careful removing the record base because exces-sive force may fi"acture the master cast. .\lso, do not remove the wax relief from inside ofthe baseplate unless it prevents the proper seating of the record base back on the cast. Ifleft in place, it will enhance stabilit)' both on the cast and within the mouth.

On a lathe or with a handpiece, trim away any excess resin at the borders of tiie baseand in tlie areas where artificial teeth will be set with an arbor band or acrylic bur.Smooth the base and recontour any areas that are too thick (more than 3 mm) (FiguresSS). Because the record base may warp if beated. care must be taken not to apply exces-sive pressure when trimming the resin. The finished resin base must be sufficientiy tiiickfor strength and accuracy, yet it should not interfere with the arrangement of artificialteeth or in making interocclusal records. Replace the resin base back onto the cast. Ifthere is a rocking of the base on the cast, the base must be remade.


Figure 8-6 Note that the record base is rigid and accu-rately fits the master cast.The record base should fill thevestibules, which were border molded during the impres-sion procedure in the mouth.

I Occlusion Rim Fabrication

The occlusion rim is generally fabricated from pink baseplate or set-up wax, which iseasily manipulated in the laborator)'. easily contoured intraorally for proper shape, isesthetically pleasing, and can be shaped to tlie approximate size and shape of the teethalong with being comfortable to the patient. Although the occhision rim can becompletely fabricated from a sheet of baseplate wax, a "preformed" wax occlusion rim isoften used (Figures 8-7). If a sheet of baseplate wax is used, it is warmed and rolled into

Figure 8-7 A preformed occlusion rim in its initial posi-tion before being properly aligned and attached to therecord base.


Figure 8-8 The maxillary occlusion rim, as viewed fromthe anterior, has been completed.

a cigar shape that is shaped to mimic the crest of the ridge of the cast before the teethwere extracted.

The occlusion rim is placed over the ridges of the previously made record base andgently pressed down until the occlusion rim is parallel to the base of the correctlytrimmed master cast. The rim is sealed to the base, and all labiaJ and lingual voids areeliminated with additional wax. The occlusion rim is smootlied (Figures 8-8).

The external size and shape of the occlusion rims is of utmost importance. Theocclusion rims should be approximately the sanie size and shape as the natural teethbeing replaced. When completed, the plane of occlusion on the maxillary arch shouldbe approximately 22 mm in height, as measured from the bottom ofthe notch createdby the labial frenulum, and approximately 18 mm in height on tlie mandibular arch. Itshould gradually taper toward the occlusal plane and be approximately 8-10 mm inwidth in the posterior, and 6-8 mm in width in the anterior region. The maxillary occlu-sion rim should be approximately 12 mtn in heiglit from the record base at tlie crest ofthe ridge in the tuberosity areas. The mandibular occltision rim should be at the heightof the top of the retromolar pad. Studies indicate that the labial surface of the naturalcentral incisors averages 6-8 mm anterior to the middle of the incisai papilla. This shouldbe kept in mind when fonning the maxillary occlusion rim. Therefore, from canine tocanine, the rims incline at approximately a 15" angle labially to pro\ide adequate supportfor the lip (Figures 8-9 & 8-10).

The record bases and occlusion rims must be neatly constructed because patientsoften begin to form opinions about their new dentures based on the appearance and feelofthe record bases and occlusion rims. In fact, may patients assume the record bases andocclusion rims are part of the completed dentures and become concerned about theappearance and fit. For tliese patients, it becomes important to continuously informthem that the record bases and occlusion rims are not part of the completed dentures,and that tliey may feel a little loose becatise of the required blocked-out undercuts.Speech difficulties are catised primarily because the occlusion rims are not completelycontoured, and mav be a little thick.


Figure 8-9 A properly contoured maxillary record baseand occlusion rim along \«ith the desired dimensions. Notethat the plane of occlusion is parallel with the base of thecast, and the labial inclination of the anterior portion of theocclusion rim is at approximately a 15° angle to offer lipsupport.The numbers provided (22 mm and 12 mm) areaverages that will generally provide slightly more wax thannecessary.This rim will be contoured intraorally to estab-lish the final plane of occlusion and lip support.The poste-rior ofthe maxillary occlusion rim should slope occlusallyat approximately a 45 degree angle from the record base,beginning approximately 8 mm from the posterior extentof the record base. This will generally provide space forthe mandibular record base once placed intraorally.

Figure 8-10 A properly contoured mandibular recordbase and occlusion rim along with desired dimensions.Note that the plane of occiusion runs parallel with thebase ofthe cast, which was trimmed to be parallel withthe residual ridges. Also the plane of occlusion is approxi-mately at the level of the middle-to upper-third of theretromolar pad.


References

Rahn, A. O.: Record bases and occlusion rims. In: Rahn, A. O., Heartwell, C. M., editors: Textbookof complete dentures. 5th ed. Philadelphia: Ixa & Febiger; 1993. pp. 26.T-268.

Sowter, J. B., Baseplates. In Bantui, R. E., ed.: Reniov-able Prosiliodoniic Techniques. Revisededition. Chapel Hill: University of i\onh Carolina Press: 1986. pp. 32-39.

Zarb, G. A., Finer, Y.: Identification of shape and location ol" arch form: The occltision rim andrecording of trial denture base. In: Zarb, C. A., Bolander. C. L-, eds. Prosthodontic Treatmentfor Edentulous Paüents. 12th ed. St. Louis: Mo.sby Inc: 2004. pp. 252-261.

1. Wiiat are some of the procedures that require the use of a record base andan occlusion rim?

2. List some of the characteristics of a satisfactory record base.

3. Why is it important to properly block out undercuts on the master cast priorto fabricating the record base?

4. What area is a possible exception to complete block out of an undercutprior to record base fabrication, and why is this area an exception?

5. WTiy is tiie blocked-out master cast soaked in water for five minutes prior tofabricating the record base?

6. Can the drying time of the titifoil substitute be expedited by drying with airtuider pressure?

7. What material and laboratory technique is itsed to create the record base?

8. Other than over-reduction, why must care be taken when trimming the poly-merized record base with an arbor band or acrylic burr?

9. Can any average position of the natural central incisor be used as a guide infabricating ihe maxillan' occlusion rim?

10. The record bases and occlusion rims will eventually be destroyed. So, whyshould the laboratory technician spend time properly shaping them andmaking them neat and clean?


1. The record base and occltision rim are necessary for establishing facialcontours; as an aid in tooth selection, in establishing and maintaining thevertical dimension of occlusion during record making; for making interoc-clusal records; for tiae arrangement of the denture teeth; for the verificationof the collect master cast mounting on the articulator; at the esthetic trialinsertion appoinmient; and as a wax-up mold for the external surface of thecomplete denture.

2. A satisfactory record base must be stable on both the master casts andintraorally, be rigid; be accurately adapted to the casts; be comfortable tothe patient and esthetic; and fully cover the entire supporting tissues ofthe arches.

3. Because of the possibility of cast breakage when initially separating therecord base from tlie master cast, which usually necessitates making a newfinal impression and creating a new master cast.

4. An exception is the undercut on the labial or anterior portion of tlie maxil-lary cast. It need not be completely eliminated because the completedrecord base and occlusion rim can be placed and removed at an angle froman anterior direction.

5. The cast is soaked in room temperature water for five minutes to minimizethe foiTnation of bubbles in llie completed record base.

6. Do not attempt to expedite the drying time by blowing it dry with air underpressure because the separating medium may be blown off the cast

7. The record base is fabricated with an autopolymerizing acrylic resin using a"spinkle-on" technique.

8. Because the record base may warp if excessively heated, care must be takenwhen trimming the resin.

9. Studies indicate that the labial surface of the natural central incisors average6-8 mm anterior to the middle of the incisai papilla. This should be kept inmind when forming tlie occlusion rim.

10. The record bases and occlusion rims must be neatly constioicted becausepatients often begin to fonn opinions about their new dentures based onthe appearance and feel of these record bases and occliision rims.

C H A P T E R

Occlusal Concepts

Dr. John R. Ivanhoe

141


The concept of denture occlusion is confti.sing to many clinicians. This confusion tnayresult from tiie myriad of occlusal decisions that the clinician must make for each patient.Questions that must be addressed include but are not limited to the following: What typeof pijsterior denture teeth are indicated? WTiat type of articulator is required?, Is abalanced occlusion necessarv for this patient?, and is a protrusive record necessary?

To simplify occlusal concepts, the following principles of occlusion for completedentures are generally accepted:

1. Complete denture patients mtist make initial and complete occlusalcontact while in centric relation. This is called cenuic occlusion.

2. All anterior and posterior denture teeth inclines and surfaces must func-tion as a "imit" during excursive movements.

3. Any prematurity preventing the movements described in principles1 and/or 2 must be eliminated.

4. Significant disclusion of tbe po.sterior denture teeth when a patientproti'udcs is contraindicated.

5. Anterior tooth contact is contraindicated in centric occlusion.

Posterior Occiusal Schomes

Posterior occlusion can be cia.ssified as either nonhahinced (monoplane) or balanced.Differing tooth morphologies are used, depending upon the type of occlusion beingdeveloped (Figures 9-1 and 9-2). A monoplane occlusion is considered one in whichnonanatoniic denture teeth are used at least on the mandibular arch and are arrangedso that the occlusa! surfaces lay on a fiat (mono) plane (Figure 9-3). This fiat plane is notnecessarily paralk-I to ihe upper and lower members of the articulator. A balanced occlu-sion generally has anatomic or semi-anatomic denture teeth on both die maxillary andmandibular arches (Figure 9-4). Both occlusal schemes have simultaneousbilateral posterior occlusal contacts when the patient is in the centric relatioti position.In complete denture patients, this is called centric occlusion. It is desirable to have

Figure 9-1 Teeth with 33°, 20°, and 0° toothmorphologies.

Occlusal Concepts 143

33 degreeAnaiomk:

20 degree 0 degreeSemi -anatomic Non -anatomk

Figure 9-2 Teeth with 33°, 20^ and 0^ tooth morpholo-gies as viewed from the mesial.

Monoplane Occlusion

Oppo^ng AnaiMnicOpposing

Non-matomic

Figure 9-3 Two different monoplane occlusions. On theleft are opposing 0° teeth set for a traditional monoplaneocclusion. Imagine the potential poor esthetics, especiallyof the monoplane maxillary first premolar. On the right isa nonbaianced lingualized occlusion tooth arrangement.A maxillary anatomic tooth was selected to improveesthetics and possibly masticatory efficiency. Notethere are no cuspal inclines to direct lateral forces to theresidual ridges during excursive movements. This is oneof the advantages to a monoplane occlusion.

simultaneous anterior and posterior bilateral contacLs in all excursive movements,although tbis is often not achievable in a monoplane type occlusion. This will bediscussed in further detail later.

As stated in Principle #5, anterior tooth contact is not indicated in centric occlusionfor either type of occlusal scheme. Loss of tlie occluding vertical dimension becau.se ofsurface wear of the posterior teeth may result in excessive force on the anterior denture


Figure 9-4 Opposing semi-anatomic (20") denture teetharranged for a traditional balanced occlusion.

teeth and hence the residual ridges. This is especially true if the dentures were fabricatedwith contact of the anterior teeth. It mu.st be remembered that tiie anterior bone in eden-tulous patients is not itsually cortical hone tiiat can withstand strong occlusal forces.Therefore every attempt should he made to eliminate vertical and horizontal stresses onthese ridges, including the elimination of anterior contacts while the patient is in centricocclusion.

As stated in Principle #1, to prevent denture instability and potential tissue abusewith either occlusion, a patient must make initial and complete occlusal contact while incentric occlusion. Therefore, per Principle #3, premature deflective occiusal contacts oninclined surfaces during closure, with either occlusal scheme, must be eliminated. Ideallyall centric occlusion contacts would occur on horizontal surfaces. However, contacts oninclined surfaces are usually caused by tooth morphology and cannot always be avoided.Therefore, the clinician must assure that those occlusal contacts that occur on inclinedsurfaces are not prematurities. Because nonanatomic denttire teeth are used on atleast the mandibular arch for a monoplane occlusion and are ctispless, thereis minimal chance that a patient will make initial contact on any inclined surface withthis type of occlusion. The reverse is trvte for a balanced occlusioti because thereare many opposing inclined surfaces that may make deflective occktsal contactsduring closure. This is especially significant if it was not possible for the clinician to makeaccurate interocclusal records.

Traditional Baianced Occiusion

Although several methods of achieving a balanced occlusion have been vised in the past,the most common and traditional method is to use anatomic or semi-anatomic dentureteeth on both the maxillary and mandibular arches and arrange the teeth to a compen-sating curve.


The denture teeth must be arranged and/or adjusted to eliminate prematuritiesso that all anterior and posterior inclined surfaces act as a "unit" in centric occlusion andduring excursive movements. This is discussed in greater detail later in this chapterThe steepness of these movements is dictated by the incisai guidance and the condylarinclination. This is a complex occlusion that pro\ides multiple "cross tooth" and "crossarch" contacts on most if not all the posterior teeth (Figure 9-5). Although a balancedocclusal scheme may be desired or required for several reasons, it is a difficult occltisionto achieve and maintain from both a laboratory' and clinical standpoint.

To accurately mimic the mandibular movements of the patient and create an occlu-sion in which all anterior and posterior inclines can be arranged or adjusted to act as aunit in excursive movements, a Class III (semi-adjustable) aiticulator with tiie maxillarycast positioned using a facebow is required. Additionally, to accurately matcb the excur-sive movements of the patient, the horizontal condylar inclinations on the articuiatormust closely mimic tlie movement of the heads of the condyles down the articulareminencies. Therefore accurate protrusive and/or lateral records must be made toprogram the condylar inclinations. This is an additional procedure that is not requiredwhen a monoplane occlusion is selected.

It is important that the clinician make an accurate repeatable centric relationrecording when articulating the mandibular master cast. Tbis is imperative for a patientreceiving a balanced occlusion. Therefore, clinicians must carefully evaluate tiie repeata-bility of centric relation on all patients prior to selecting posterior denture teeth and theocclasal scheme. If the centric relation position cannot be accurately repeated, interoc-clusal recoi ds cannot be accui'ately made, the alignment of tlie opposing denture teethwill be inaccurate. Therefore, it may be almost impossible for the clinician to eliminateocclusal prematurities at insertion. This is a minimal problem with a monoplane occlu-sion becau.se there are no opposing occlusal inclines to become prematurities. Almost allocclusal contacts occur on flat surfaces. Therefore, because being able to repeat centric

Balanced OcclusionOpposing Semi-anatonnic Teeth

Right SideBilateral oi

Cross Arch Contacts

Unilateral Cross Tooth Contact

Patiem in Left Working Movement

Figure 9-5 Opposing semi-anatomic denture teeth set ina traditional balanced occlusion and moved into the leftworking movement, Note the cross-arch occlusal contactsand cross-tooth contacts that occur on the left side. Thiscross-tooth contact is not seen in a lingualized occlusion,which is one of the advantages of a lingualized occlusion.


relation foj- many patienLs is difficult if not impossible, a balanced occlusion requiringopposing anatomic denture teeth is often contraindicated. For these patients, it váW bediiricult to make accurate the protrusive or lateral recordings necessary to properlyprogram the articulator.

A balanced occlusion is primaiily indicated for patients having good anteriorand posterior residual ridge alignment This is important because of the necessity forachie\ing good occlusion of the opposing anatomic or semi-anatomic posterior teethwhile still arranging tlie teetli over the ridges. For patients with a normal buccal-lingualalignment of tJie posterior ridge or a total cross-bite ridge alignment, arranging the poste-rior tooth arrangement is reasonably easy. The difficult)' arises when a patient has anormal buccolingual ridge alignment in the premolar areas and a complete reverse artic-ulation (crossbite) alignment in the second molar area. For ttiese patients, to maintain theteeth over the ridges, the first premolars must be in a normal buccolingual alignment andyet the second molars must be in a reverse articulation (crossbite). One oi" more teeth,usually in the first molar area, become the cross-over teeth. To have the teeth remain overthe ridges means that Lhe opposing buccal and lingual cusps cannot be set in a cusp-fossaalignment. Tlie opposing cusp tips become end-Lo-end. It becomes impossible to positionthe teeth, while retaining good occlasion and reasonable esthetics. When arranged to thebest occlusion possible, equilibration Lo eliminate excursive prematurities often destroysall semblances of normal tooth morphology. Therefore, from both a laboratory and clin-ical standpoint, the use of opposing anatomic denture teeth may not be realistic forpatients without good ridge alignments. This includes those requiring a unilateral or bilat-eral posterior reverse articulation (crossbite) and prognathic and retrognatliic patients.Once again, this is a minimal problem with a monoplane occlusion.

It must be remembered that creating a balanced occlusion requires a fairly signifi-cant commitment for botli the technician and clinician, and therefore must provide sufñ-cient benefits to be selected over a monoplane occlusion. One potential benefit may bedie reduction of lateral forces during functional and parafunctional movements. Onestudy indicated that a balanced occlusion might ofíér the benefits of improved lateraldenture stability because of the bilateral posterior contacts. However Kydd found that thetise of anatomic teeth, necessary- for a balanced occlusion, actually increased the lateralforces to the ridges. Therefore some still question whether a balanced occlusion actuallyreduces the lateral forces on ridges.

Creating a balanced occlusion while the teeth are in acttial functional contact?It was once believed that when food or anything else was placed between any of theopposing teeth, all opposing tooth contact (balance) was lost, so any potential advantageof a balanced occlusion would also be lost. The following question arises: Are functionalcontacts a significant issue, and what is the amount of time that the opposing teethwill actually contact in a 24-hour period? Functional contact of the opposing teethhas been estimated at only 17.5 minutes per day, therefore many clinicians believe thatthe effort necessary to create a balanced occlusion is not justified by this minimaldaily occlusal contact time. However parafunctional, poientially destructive, occlusalcontact time has been estimated at 2-4 hours per day. Therefore, even though themaximum occlusal force of complete denture patients only averages 35 pounds, func-tional and parafuntional contacts should be considered when selecting a posteriorocclusal scheme.

Others believe that the opposing anatomic denttire teeth used in a balanced occlu-sion may offer improved masticator\- efficiency over the non-anatomic denture teeth usedin a monoplane occlusion. However studies in this area have also been inconclusive.Esthetics are certainly improved for many patients with anatomic denture teeth.


More recently a .simplified occlusion called a lingualized occlusion, which will bediscussed later, has become popular and successful. It may be used to replace bothconventional balanced and monoplane occlusions.

Conventionai iVIonopiane Occlusion

For most clinicians and laboratory technicians, a satisfactory monoplane occlusion is amuch simpler occlusion to achieve and maintain iniraorally. Many clinicians successfullyuse a fixed or nonadjtistable articulator and arbitrarily position the maxillary cast ontothe articulator when creating a monoplane occlusion. Tliis technique is not recom-mended. It may be determined at the trial insertion appointment that, for phonetic oresthetic reasons, a vertical overlap of the anterior teeth and hence balanced occlusion isnecessary. Then a semi-adjustable articulator with the maxillarv- cast positioned using afacebow and tiie condylar inclination set with protnisive or lateral records is necessary. Afixed artictilator does not allow the altering of the condylar inclination. Therefore theuse of at least a semi-adjustable articulator with the maxillar)' cast positioned tising a face-bow is recommended for all patients.

Since there are few, if any, ctispal inclines to be concerned with, achieving an exactcentric relation recording, while desirable for all patients and required for patientsreceiving a balanced occlusion, may not be a necessity for all monoplane occlusionpatients. Because of the non-anatomic mandibular denture teeth, a specificcusp/marginal ridge alignment ofthe opposing denture teeth is unnecessar\-. Thereforethis type occlusion is useful for prognathic, rctrognathic, and reverse articulation (cross-bite) patients. It is not necessary to program the condylar inclination of the articulatorwith excursive records for a monoplane occlusion because no attempt is made to balancethis occlusion. Generally the condylar inclination and incisai guidance are arranged tobe parallel to the plane of occlusion.

Since opposing non-anatomic denture teeth arc traditionally used for thesepatients, poor esthetics and compromised masticator)' efficiency must be considered.Esthetics is compromised. However, suidies have been inconclusive when comparing themasticatory efficiencies of patients with balanced and monoplane occlusions.

Because patients witii a monoplane occltision have no vertical overlap of theanterior dennire teeth, when the patient protrudes, a mild disclusion (Christensen'sPhenomena) of tlie most distal teeth often occurs. Clinicians must recognize andaccept this condition and imdei'stand Uiat this disclusion may not be as significant as thatseen in a balanced occhision patient. This will be discussed in greater detail later in thischapter.

W Baianced Occlusion or Not

A question tJiat has been discussed for decades is whetlier a balanced occlusion isrequired for most complete denture patients. A balanced occlusion is not requiredand, because of its complexity; not indicated for many patients. A balanced occlusionis required for two specific groups of patients. Those are, patients with a steep, vertical


overlap of the anterior denture teeth (steep incisai guidance) and patients who requireopposing anatomic or semi-anatomic denttire teeth ior estlietics or other reasons.

Why is a Balanced Occlusion Required in Patients Exhibiting a Significant Degreeof Incisai GuidanceP

As stated in Principle of Occlusion #4, significant posterior disclusion, which is caused bya moderate-to-steep vertical overlap of the anterior teeth, is contraindicated in completedenttire patients.

Many patients with remaining natural anterior teeth exhibit significantdisclusion of the posterior teeth (Christensen's phenomena) when tbey move fromcentric occlusion into excursive positions. Tbis disclusion is caused by a combination oftbe incisai guidance (vertical overlap) of the anterior leeth and tbe movement of thehead ofthe condyle down the articular eminence. Often only two or three anterior teethaie involved in this incisai guidance. If they are strong, natural teeth well anchored inbone, this is called an anterior disclusion and usually is considered a favorable type ofnatural occlusion. This occlusion reduces potentially destructive lateral forces from theposterior teeth.

Complete denture patients are different. Because of esibetic and/or functionalrequirements, some complete denture padents must have their anterior denture teetharranged with a steep vertical overlap (incisai guidance). Unfortunately, because allcontact occurs on the anterior denture teeth, the resultant forces are transferred to tiieanterior portion of the opposing ridges. These forces are usually excessive, cause traumato tlie underlying hard and soft tissues, and may lead to excessive soft tissue abuse andeventual bone loss. To eliminate the effects of this posterior disclusion, it becomes neces-sary to attempt to distribute tlie occlusal forces over both anterior and posterior teeth,tliereby gaining maximum anterior and bilateral posterior ridge support. Tbis occlusion,by definition, is a balanced occlusion and is tberefore indicated when there is a moder-ate-to-steep vertical overlap of the anterior teeth. Therefore, one primary indication fora balanced occlusion is for those patients witb a moderate-to-steep \'ertical o erlap of theanterior teetli and who make reasonably frequent conmct of the anterior teeth leadingto posterior disclusion.

Additionally, the steep vertical overlap of tbe anterior teeth often causes denturedislodgement tliroughout the day because oí repeated paralunctional contact. A balancedocclusion is required for tbese patients to distribute the occlusal contact to at least someofthe posterior lectb. thereby increasing denture stability.

Patients with a monoplane occlusion have no vertical overlap of tlie anterior teeth,and therefore have an incisai guidance of zero degrees. When these patients move intoa protruded position, there is generally only a minimal separation of just tlie molars.Multiple anterior and posterior occlusai contacts are usually present tliat may extend tothe second premolars. The extended area of these contacts, as opposed to the limitedarea of contacts \\ith a steep incisai guidance patient, provides distribution of tbese forcesover a broad enough area tliat excessive forces to any specific area of the ridges areusually eliminated. Also, with no vertical overlap of the anterior teeth, denture dislodge-ment because of parafunctional contacts is also iLsually eliminated. Denture instabilitycaused by tlie occlusion is an unusual problem for these patients.

Therefore the clinician or the patit-nt may desire a balanced occlusion because ofthe perceived functional or actual esthetic advantages of anatomic denture teeth. It is not


required, however, except when desiring to spread functional or dislodging forces over alarger area or over a greater number of denture teeth.

From the previous comments it may be a.ssumed by some that a balanced occlusionis necessar\' for all patients requiring a vertical overlap of the anterior teeLh. Tbere is anexception to this general as.sumption. Many patients \vi\h a significant vertical overlapalso exhibit a significant degree of horizontal overlap of the anterior denture teeth. Thisoften results in a mild-to-moderate incisai guidance that may not be a concern. Althoughthere isa vertical overlap of the teeth, because of the significant horizontal overlap, manyof these patients almost never have functional or parafunctional contact of the anteriorteeth. Therefore almost no chance of uauma to the underUing anterior soft and hardtissues exists. Again, because of its simplicity, a monoplane occlusion is often acceptablefor tiiese patients.

A balanced occlusion is necessary for some patients, but because of the simplicity forboth the clinician and laboratoiy technician and because patients' acceptance is high, amonoplane occlusion should be considered as the occlusion of choice for most patients.

Why is a Balanced Occlusion Required In Patients with Opposing AnatomicOenture Teeth?

A second primary indication for a balanced occlusion is for those patients requiring theuse of opposing anatomic or semi-anatomic denture teeth. Principle #3 states that prema-turities that prevent ;ill anterior and posterior denture teeth inclines and surfaces fromfiinctioning as a unit must be eliminated. Therefore, v ith opposing anatotnic or semi-anatomic denture teeth, the only way to eliminate excursive premattirities is through thecreation of a balanced occlu.sion.

Lingualized Occlusion

Lingualized occlusion was developed in an attempt to simplify denture occlusion whileniainiaining the adrantages and eliminating the disadvantages of both balanced andmonoplane type occlusions. .-Vmong other disadvantages, a balanced denture occlusionis difficult to achieve because of the multiple opposing inclined surfaces that must beadjusted, the necessity of a good opposing residual ridge alignment, and the requirementfor a repeatable centric relation position. A monoplane occlusion on both archesexhibits poor esthetics and the potential for a decreased efficiency when masticatingfood, A balanced or monoplane occlusion can be achieved while using the lingualizedconcept, which minimizes or eliminates most of tbe potential disadvantages listed earlier.

Opposing anatomic or semi-anatomic denture teeth are selected when creating abalanced lingualized occlusion, and anatomic teeth opposing non-anatomic teeth areselected for a nonbalanced lingualized occlu.sion. The niaxillaiT teeth for both occlusionsare arranged so that the lingual cusps are in contact with the mandibular teeth, and thetooth angled so that the buccal cusps lie slightly above the occiusal plane (Figure 9-6).This means that, in both centric occlusion and during excursive movements, the maxil-lary lingual cusps are the only cusps occluding witli the opposing teeth and therefore arethe functional cusps.


Unguailzed Occiuüon

Balance! Lingualized Non-balancd Lingualized

Figure 9-6 Examples of lingualized occlusion. A balancediingualized tooth arrangement is seen on the left side.The arrangement of the opposing teeth for a nonbalancedlingualized occlusion is seen on the right side. Note thatthe buccal cusps are set above the occlusal plane toachieve no contact between the buccal cusp and theopposing teeth in the working movement.There areno cross-tooth prematurities to be concerned with inexcursive movements.

There is a significant clinical advantage lo having otily the maxillai-\ lingual cuspscontact the opposing teetli in a balanced lingualized occltision. WTiile cross-arch contactsmust be maintained, cross-tooth contacts are not present and not desired in the balancedlingualized occlusion. Because the maxillary buccal cusps never contact the mandibtilarteeth, prematurities seen in a traditional balanced occlusion are dramatically reduced.The advantages of a conventional balanced occlusion are still achieved while beinggreatiy simplified with a lingualized occlusion.

To improve tiie esthetics and potential masticaton' efficiency ofa monoplane occlu-sion, a monoplane or nonbalanced lingualized type occlusion has also been developed.A monoplane lingualized occlusion is easily achieved and yet only slightly differeni froma conventioniU tiiuiioplane occlusion. Non-anaLomic teeth arranged on a fiat occlusalplane continue to be used on tiie mandibular arch, while anatomic denture teeth areselected for the maxillar)' arch. The non-anatomic teeth on the mandibular archcontinue to provide the benefits of a monoplane occlusion, while the anatomic teethused on the maxillary arch overcome the esthetics concerns of a conventional mono-plane occlusion. Additionally, the selection of anatomic maxillarv- teetli may also addressthe potential loss of masticator)' efficiency reported by some when using opposing mono-plane teeth. This type of occlusion seems to eliminate the disad\'antages of a conven-tional monoplane occlusion and has become popular and successful in the last fewdecades. It is also well received by patients.

Because both balanced and nonbalanced lingualized occlusions are easilyachieved, and boUi reduce some of the disadx'imtages while increasing some of theadvantages of conventional schemes, they are recommended for patients wheneverpossible.


Functional Inclines

Understanding the factors of occlusion is important in creating and maintaining abalanced occlusion. When completed, a balanced occlusion must exhibit bilateral ante-rior and posterior occlusal contacts in cenuic occlusion and excursive movements. Inaddition, the anterior and posterior teeüi act as a unit in excursive movements becauseall prematurities have been eliminated from opposing inclined surfaces.

The term functional inclines (FI) indicates Üie inclines of tbe cusps of the anteriorand posterior teetli tliat will contact when a patient moves into excursive movements.The inclines of the maxillary' anterior teeth that face the palate and the inclines of themandibular anterior teeth that face labially are the functional inclines. The posteriorfunctional inclines are detennined by the excursive movement. Cienerally, althougholher inclines may be involved, the following are the most frequent. Funclional inclinesfor the posterior teeth:

1. In protrusive movements, the fimcdonal inclines face anteriorly formandibular teeth and face posteriorly for maxillary teeth in protrusivemovements (Figures 9-7 and 9-8).

2. In working movements, Lhe functional inclines face buccally for themandibular teeth and Hnquallu for maxillaiy leeth in working move-ments.

3. In nonworking mo\ements, the functional inclines face lingually for themandibular leetli and buccally for ilie maxillary teeth in ntinworkingmovements.

Because of tooth anatomy and individual patient movement, other inclines on theteeth may be involved. Also all prematurities nn any of the inclines mast be eliminatedfor a balanced occlusion, while they are of minimal concern when using a monoplaneocclusion. Understanding these inclines is important in the following discussion.

Figure 9-7 Although highly stylized, these teeth arearranged to illustrate the relative position of the toothinclines when the teeth are arranged for centric occlusion.Horizontal overlap has been eliminated for better under-standing.


Figure 9-8 The mandible has assumed the protrudedposition, and the protrusive functional inclines of theopposing teeth are illustrated. The teeth have movedforward as controlled by the lateral pterygoid musclesand downward as controlled by the incisai guidanceand the condylar inclination.

•:Factors of Protrusive Occiuslon

There are five factors of protrusive occltision that must be considered when creating abalanced occlusion. Understanding the interrelationship between these factors will clar-ify how a balanced occlusion is achieved and how. once achieved, if one of the factors isaltered at leasl one other factor must also be altered to regain the balance.

Although slightly altered by the author, tiie protrusive factors of occlusion havebeen identified as follows: degree of incisai guidance (IG), degree of condylar inclination(CI), inclination of the plane of occlusion (PO), angulations of the cusps of the poste-rior teeth in relation to the overall occlusal surface (CA), and the steepness of thecompensating cune (CC). These factors are related in the following formulas, whichsimplify the understanding of the relationships ofthe factors. Cl X IG = PO X CA X CC

<\lthough these factors affect all excursive movements of the posterior teeth, forsimplicity, only the protnisive movement will be discussed and ilhistrated.

If the five protrusive factors of occlusion were completely tinder the control oftheclinician, making necessary alterations would usually be relatively simple. However, thecondylar inclination is beyond the control of the clinician, and the others can on!)' bealtered to a small degree. Therefore, when a problem develops, a combination ofchanges is necessary.

The author suggests the following fonnula to aid in the tmderstanding of the 5factoi"S of protnisive occlusion. IG X Cl = AFl

This fonnula indicates that, for a balanced occlnsion, to maintain posteriorcontacts and yet have no prematurities in the protrusive movement, the angulation ofthefunctional inclines {i\FI) of tlie maxillarv^ and mandibular posterior teeth must matchthe influences of the incisai guidance and condylai- inclination.


When a paîient protrudes, the mandibular teeth move forward and downward.The distance of tbe protrusive movement is determined by tlie action ofthe lateral ptery-goid muscles, while the angulation of tlie downward movement is determined bythe steepness of the incisai guidance in the anterior and the steepness of tbe condylarinclination in the posterior The inci.sal guidance and condylar inclination are sometimescalled the "end controlling factors." Because the denture teeth are almost all anatomi-cally closer to the incisai guidance than the condylar inclinatii)n. tlie incisai guidance(IG) has greater influence on tlie steepness of tbe required functional inclines of theteeth.

So how do clinicians make tbese fimctional inclines match the influences of theincisai guidance and condylar inclination, while still maintaining contact in excursivemovement and not having prematurities? For complete denture patients the incisai guid-ance is determined by the esthetic and phonetic demands ofthe patient and is a slightlyvariable factor. The condylar inclination, however, is a fixed factor ihat is detennined bythe steepness of the articular eminence. The condylar inclination is usually programmedinto the articulator by use of a protrusive record or lateral records made intraorally.

To iUustiate these concepts, two imaginary patients will be described. The firstpatient has a 20 degree angulation of both the incisai guidance and condylar inclination.Therefore, to maintain contact of the posterior teeth in the proti"usive movement, whilenot haveing prematurities, the functional inclines must be 20 degrees (Figure 9-9).

For the second patient, the incisai guidance is 15 degrees and the condylar incli-nation is 35 degrees. Remember that the incisai guidance has more of an infiiience onthe angulation of the tunctional inclines tban the condylar inclination. The requiredsteepness of the functional inclines should reflect that Even thought tbe teeth are closetogether in this illustration, note ihat a difference in ihe functional inclines still exists(Figure 9-10), These values have been chosen for illustration pui-poses but would be

Incisive Guidance/Condylaf Inclination

IG = 20degrees ^ ^ ^ ^ H ^ ^ ^ ^ H CI = 20degrees

Pron'usive Movement

Figure 9-9 With the incisai guidance and condylar incli-nations of this patient being 20°, it becomes necessary tohave the protrusive functional inclines of all the posteriorteeth be 20° A posterior tooth mold with 20° cusp angles,as supplied by a manufacturer, should be ideal for thispatient. Contact of the opposing teeth ¡n protrusive shouldbe maintained and yet minimal adjustments to eliminateprematurities should be expected.


Incisive Guidance/Condylar Incilnaiion

IG = 15 degrees l = 35 degrees

Protrusive Movement

Figure 9-10 With the incisai guidance changed to 15° andthe condylar inciination at 35°, the functional inclines varydepending upon the relative position of the tooth to thosecontrols. Because almost all teeth are closer to the incisaiguidance, it has more of an influence than the condylarinclination.The cusp angle of the posterior teeth in thisexample is 22°. Note that the second premoiars have beenslightly tipped to increase the effective cusp angle becausethe required functional incline has become iarger than 20°.

reasonably accurate. The closer these teeth are to the condylar inclination, thecloser the inclines come to 35 degrees. In fact, the inclines of the second molare may be25 degrees or more. Because the second molar is anatomically almost equidistancebetween the incisai and condylar iticlinations. the inclination of its functionalinclines is an average of the two (25 degrees). Table 1 demonstrates more examples(Table 9-1).

Table 9 FUNCTIONAL INCLINES - INCISAL GUIDANCEAND CONDYLAR INCUNATION

Example

ABCDE

Incisai Guidance

20°30°30°0°

20°

First Premolar

20*^30°28°8°

22*"

Second Molar*

20°30°25°17°27°

Condylar Inclination

20°30°20°35°35°

iNote that the incisai guidance has more influence over the functional inclines of the posterior teeth than

the condylar guidance. Hovwever, the closer the tooth is to the condylar inclination, the closer the func-tional inclines match that guidance. Once again, these "values are provided for understanding the inflLf-ences of the incisai and condylar guidances and are of no Importance to knov f otherwise.

* Because the second molar is anatomically positioned about equidistant between the incisai and condylarinciination, the angulation of the functional inclines of the second molar is almost an average of the twoguidances.


How does the clinician determine the cusp angle to be used when selecting theposterior teeth? If a nonbalanced lingualized occlusion is indicated, an anatomic maxil-lary tooth opposing a mandibular non-anatomic tooth would be the proper selection.Howe\'er, the situation become more complicated when a balanced occlusion becomesnecessary. In the example of the second patient pre\iously described, it would seem thata tooth with a 20 degree cusp angle may be a good choice for the premolar areas. Itwould not, however, be a good choice for the molar area because tbere would be aloss of opposing tooth contact when the required functional inclines became greaterthan 20 degrees. Even though a tooth with a 30 degree cusp angle would not be a badchoice for the molar area, it would caase significant prematurities when movinginto protiusive in tlie premolar area, and therefore would be a poor choice for thatarea. It may seem that a single set of posterior teeth with a single cusp angle as providedby the manufacturer (i.e. 20 degree), cannot match the changing fimctional inclinerequirements of the patient, and that teeth \\ith differing cusp angles must be used.However, selecting teeth with differing cusp angles would be difficult for the clinicianand cost prohibitive. This dilemma is resolved by altering ihe cusp angles of the dentureteeth and creating "effective cusp angles" that can match the required angulation of thefunctional inclines.

Effective Cusp Angles (EGA)

As manufactured, posterior denture teeth exhibit differing cusp angles and cusp heights(Figures 9-1 and 9-2). Some have minimal or no cuspal angles and are called non-anatomic teeth, while the ctispal angles of semi-anatomic and anatomic teeth vary fromapproximately 10" to 45". For simplicity of illusü^ation the cusp angles will be discussedfrom the buccal \"iew here.

The cusp angle, as indicated by the manufacturer, is only accurate when thedenture tootii is placed so that the long axis of the tooth is perpendicular to the plane ofocclusion (Figure 9-11). If the long axis of the tooth is altered, the cusp angle of the

Figure 9-11 The cusp angle of a tooth is the angulation ofthe functional incline as measured from the long axis ofthe tooth. The cusp angulation of this tooth is 30°.


Effective Cusp Angled (ECA)

-n 90 degrees

Tooth angeled 8 degrees

Figure 9-12 The effective cusp angle of a tooth Is theangle of the functional incline as measured from a lineparallel to the bench top. As a tooth is angled 8°, the effec-tive cusp angle, and hence functional incline, change in alike manner.The effective cusp angle can also be alteredby grinding the functional incline.

tooth relative to the occlusal plane is also changed. This altered cusp angle has beentermed the effective cusp angle of the tooth (ECA) (Figure 9-12). With the two imagi-nary patients discussed earlier, it should now become clear that tilting the teeth to differ-ing degrees becomes necessary to mecí the differing required functional inclines of apatient. Thus a single mold of posterior tooth (i.e. 20 degrees) can allow contact in theprotrusive movement of angles greater than 20 degrees. It should also become clear that,as the teeth are angled slightly more lhe fiu tliei- tliey are set posteriorly and as Lhe planeof occlusion is slightly raised, a compensating cune is developed. Additionally, if the cuspangle of the tooth is altered by grinding, the tooth now has a different ECA. When theocclusion on a patient has been equilibrated lo eliminate all excursive prematiirities, theEGAs will be funcüonal inclines.

r Example

In the case of another imaginary patient, the clinician has selected a balanced occlusioneven though there is no esthetic or phonetic need for a vertical overlap of the anteriorteeth. (Table 9-2, Example D)

Because there will be no vertical overlap of the anterior teeth, the clinician assumesthat there is no need for selecting a posterior tooth with a steep cusp angle (i.e.33 degrees) and tlierefore posterior teeth are selected with 20 degree cusp angles. Tliedental laboratory technician develops a balanced occlusion when arranging the dentureteeth. Tlie laboratory technician ivill have to equilibrate the cusps following processingto eliminate protrusive prematurities. This is because the cusp angles were steeper than


Table 9 - FUNCTIONAL INCLINES - INCISAL GUIDANCEAND CONDYLAR INCLINATION

Example Incisai Guidance First Premolar Second Molar* Condytar Inclination

D 35"

Because the second molar is anatomicaliy positioned about equidistant between the incisai and condylarinclination, the anguiation of the funcEional inclines of the second molar is almost an average of the Iwoguidances.

the required angulation of the functional inclines, but at least posterior contact in theprotrusive movement will be maintained.

At the trial insertion, Lhe clinician determines that, for esthetic or phoneticreasons, a vertical o\erlap of the anterior Leelh is necessar}'. The dental laboratoiy tech-nician rearranges the denture teeth to achieve vertical overlap of the anterior teeth.(Table 9-3, Example E)

At that point, the technician notes that the incisai guidance is now 20 degrees andhas resulted in a loss of posterior occlusal contacts when the articulaior is moved into aprotruded position. The technician no longer is concerned about protrusive prematuri-ties, but now lhe 20 degree cusp angles are insufficient to mainuin posterior protrusivecontacts. To regain tlie posterior contacts, steeper cusp angles are needed. The techni-cian knows that selecting and resetting new posterior teeth with steeper ctisp angles is achoice. Replacing a 20" denture teetli with 30" might satisfy this requirement of main-taining contact in the molar area. From a cost and time standpoint, however, it is not thebest choice. The technician knows that a better choice is to increase the EC\ of the teethby increasing the inclination of the plane of occlusion, the degree ofthe compensatingcurve, or a combination of both. For this padent the 20 degree teeth are rearrangedusing a steeper compensating cune, thereby making the EGA of the teeth more closelymatch the required angulation of the functional inclines, as pro\ided by the incisai guid-ance and condylar inclination.

Table 9-

Example

FUNCTIONAL INCLINES - INCISAL GUIDANCEAND CONDYLAR INCLINATION

Incisai Guidance First Premolar Second Molar* Condylar Inclination

20° 22"

Because the second molar is anatonnicallv positioned about equidistant between the incisai and condylarinclination, the angulation of the functional indines of the second nnolar is almost an average oí the twoguidances.


Even though this is a good choice, the posterior height of the plane of occlusionand the degree of tlie compensation cune can only be moderately moditied because ofestbetic concerns. Tliey can often be altered sufliciently, however, to satisfy functionaldemands ofthe tooth arrangement. However there are patients for whom, ifa balancedocclusif«! is to be maintained, compromises in estbetics may be necessary. Tbe desiredextreme vertical overlap of the anterior teeth may not be possible.

Conclusion

Tlie technician and the cUnician musi both have a complete understanding of occlusalconcepLsand the geometry of occlusion to satisiy tbe functional and esthetic needs of thepatient. This understanding is necessary to make all anterior and posterior denture teethinclines and surfaces fiuiction as a unit during excursive movements. Lingualized occlu-sions have more advantages and fewer disadvantages than conventional occlusal schemes.They can also be developed to create either a balanced or nonbaianced occlusion.Lingualized occlusions are usually more easily created by the technician and adjusted bythe chnician, and are therefore indicated for most patients. Because of the siniplicit)' andlack of problems or contraindications with a monoplane occlusion, a balanced occlusionis not required in most patients.

ReferencesBasconi, P. W.: Masticaron efficiency of complete dentures.J Prosthet Dent- 1962;12:453-59.Brewer, A. A.: Prosthodontic research in progres.s at the School oí Aerospace Medicine.

J Pro.sthet Dent. 1963; 13:49-69.Clough, H- E.. Knodle, J. M., Leeper, S. H., Pudwell, M. 1,., Taylor, D. T: A comparison of

lingnalized occlasion and monoplane uccltision in complete dentures. ( Prosthet Dent. U)83;5Û:176-79.

Graf, H., Bnisixm. In Ranitjord, S. P., Ash, M. M., eds.: Occlusion. Dent Clin North Am.Phihtdelphin: VV. B., S;iunders Company, 1<!69; 13:659^6.

Kydd, W. [-.: Complete denture base defornialioii with vrie occlusal tooth form. J Prosthet Dent.1956:6:714-18.

Lang, B. R.: C^omplete Denture Occlusion. In Engelmeier, R. L.. ed. Complete Dentures. Dtnt ClinNorth Am. Philadt-lphia: W.B. Saunders. 1996:40:85-101.

Michael. C G.. javid, N.S., Cohiizzi. F. A., Gibbs, C. H.: Biting sti'engtli and cbew forces in completedenture wearer.s.J Prosthet Dent. 1990:63:549-53.

Ortman. H. R.: Complete flenture occlusion. In: Winkler, S., ed. Essentials of complete dentureprosthodontiis. I""' Ed. Philadelphia: W. B. Saunders Company, 1979;30l-34l.

Payne. S. H.: Study of occlasion in duplicate dentures.J Prosthet Dent. 1951:1:322-6.Pound, E.: Lising speech to simplify a personalized denture senice. J Prostliet Dent. 1970:24:586-

600.Sheppard, I. iVI., Rakoff, S., Sheppard, S. M.: Bolus placement during mastication. J Prosthet Dent.

1968:20:506-10.Wyatt. D. M.. Macgregor, A.R-, eds.: Designing complete dentures. Philadelphia: W.B., Saunders

Company, 1976:385-387.


1. What is the difference between centric relation and centric occlusion?

2. What are the two major posterior occlusaJ schemes for complete denturepatients?

3. What are the primary- indications for a balanced occlusion?

4. What is a significant contraindication for selecting a balanced occlusion fora patient?

5. Both a sleep vertical overlap of the anterior teelli and no vertical overlapresult in some degiee of separation of the posterior teeth when the patientmakes a protrttsive movemciu. Knowing tJiat anterior disclusion of the poste-rior teeth is conuaindicated in most patients, why is il often acceptable in anonbalanced occlusion?

6. WTiy is an anterior disclusion of the posterior teeth a preferred occlusionof the natural teeth, but is contraindicated in complete dentures?

7. Why should lingualized occlusion be considered for patients?

8. What are the five factors of protrusive occlusion? Draw a formula that indi-cates their relationship.

9. What t\vo factors control tbe angulation of the functional inclines of tbeposterior teeth, and wliich has Uie most influence on most of the teeth?

10. What are effective cusp angles?

1. Centric relation is a positional relationship between the maxillaiT andmandibtUar arches. Centric occlusion is the occlusion of the denture teethwhen the patient is In the centric relation position.

2. Balanced and nonbalanced.

3. a. Significant vertical overlap of the anterior teeth.

b. If semi-anatomic or anatomic opposing posterior denture teeth arerequired because of esthetic concerns, the clinician believes they wouldimprove the masticator)' efficienc); the patient had existing dentures withanatomic or semi-anatomic denture teeth, or the necessity of a verticaloverlap of the anterior teetii.


4. The patient's lack of achieving a repeatable centric relation position.

5. A steep vertical overlap of the anterior teeth results in unacceptable func-tional forces being directed to the anterior soft and hard tissues, whileno vertical overlap ofthe teeth usually results in the contact of both theanterior and several of the posterior teeth. This distribution of contactswith no vertical overlap of the anterior teeth spreads the occlusal forces overan acceptably large area of the ridges and minimizes trauma to the underly-ing tissues.

6. The natural anterior teeth anchored in strong bone are able to bear strongexcursive forces and eliminate or at least greatly reduce these destructiveforces on the posterior teeth. Edentulous patients do not have natural teethanchored in bone but tiiey do have denture bases fitted to the residualridges. Therefore any forces limited to the anterior teeth are iuunediatelydirected almost exclusively to the anterior ridges. Because these forces arenot spread over a wnde area of the edentulous ridges, soft tissue abuse andbone loss are common.

7. Both balanced and nonbalanced lingualized occlusions are easily acbievedocclusal schemes. They reduce some of the disadvantages and increase someof the advantages of conventional schemes. Lingiializedocclusion is recommended for patients whenever possible.

8. The factors are degree of incisai guidance (IG), degree of condylar inclina-tion (CI), inclination ofthe plane of occlusion (PO), angulation ofthecusps of the posterior teeth in relation to the overall occlusal surface (CA),and the steepness ofthe compensating cur\'e (CC). These factors are relatedin the following formula, which simplifies their relationship.

CI X IG = PO X CA X CC.

9. Incisai guidance and condylar inclination. Incisai guidance.

10. Effective cusp angles are the resultant cusp angles of denture teeth, oncethe long axis of the teeth are no longer perpendicular to the bench top. oronce the cusp angle has been altered through occlusal adjustments.

C H A P T E R

, \MaxillomandibularRecords andArticulators

Dr. Kevin D. Plummer

161


The niaxillomandibular records appointment occurs between the fabrication of ihemaster casts and die arrangement oí the demure teetli, and the trial insertion appoint-ment. As might be imagined, this is an important appointment in which several goalsmust be accomplished. The maxillaiy record base and occlusion rim are used to transferthe correct orientation of the maxillarv- master cast reladve to the condylar elements andaxis-orbital plane of the articulator. This mimics the maxilla's relationship to the condylesand the patient's axis-orbital plane. The combination of both record bases and occlusionrims are used to transfer tlie correct horizontal and vertical posiüon ofthe mandibularmaster cast reladve to the maxillary master cast. This includes the proper centric relationposition at the appropriate occltisal vertical dimension (O\T)) for the patient (Figure10-1). The occlusion rims are also used to recoid contour foi" the proper positioningof the anterior and posterior denture teeth. Before proceeding with the maxillo-mandibular records appointment, an articulator must be selected to use for the treat-ment procedures.

Figure 10-1 Record bases and occlusion rims properlyoriented on tbe articulator.

Articulators for Complete Dentures

In the iabricatioti of dental prostheses, a mechanical de\ice called an articulator is usedto relate the opposing casts and simulate die movements that occur in the areas of theteeth. Although there are a myriad of articulators available with widely varying degreesof adjtistabilit), most have similar physical characteristics. All have an upper and iowermember to which maxillar>' and mandibular casts can be firmly attached and thenremoved as desired. Ah but the simplest articulators allow the maxillary cast to beattached to the articulator Mth an instrument called a facebow. A facebow relates themaxillary cast to the opening and closing axis of tbe articulator in the same relationshipas the maxilla relates to the anatomical hinge axis of the patient. All articulators allowvarying degrees of movement between the upper and lower members. Virtually allhave some part tbat represents the condylar head in the patient (commonly called the

Maxillomandibular Records and Articulators 163

condylar element or post on the articttlator) and anoöier part that represents theguiding sttrfaces or articular eminence (conimonîy called the condylar housing). Thecondylar elements and guidance surfaces should be thought of as cams that allow thearticulator to replicate the movement observed intraorally. Most have an adjustable panthat serves as a vertical stop in the front of the articulator (incisai pin) and heips main-tain the vertical dimension as set on the articulator. There is usually some type of lockingmechanism that m\\ keep the upper member in the centric position in relation to thelower member of the articulator. These are the basic parts seen on most adjustable artic-ulators (Figures 10-2Aand 10~2B).

Figure 10-2A Class III articulator. A: Upper MemberB: Lower Member C: Condylar Element or Post D:Condylar Housing E: Incisai Pin

Figure 10-2B Various articuiators are suited for completedenture fabrication.The most common type are Class IIIarticulators, which accept a facebow and can use protru-sive or lateral records to set the condyles


No matter the number of adjustable parts or programmabiliiy, it is tinlikely that anvarticulator will precisely duplicate the condylar movements in tlie temporomandibularjoints. However, for complete denture patients and many dentate patients, exact accuracyis not necessary. The complexity of an articulator, its ability to be progt ammed, and theability of the clinician to program the instrument will determine tbe accuracy of mimick-ing these anatomical movements. For an articulator to provide exacting accuracy, it mustbe precisely programmed. This programming is done by making recordings of patientmandibular movements and then forcing the articulator to duplicate these movements.These recording are accomplished with variotts technologies, but all require precise fitand adjiistabilit\' of the recording de\ices. To accurately record the patient movements,the device must be rigidly attached to the patient while the movements are beingrecorded. This is reasonably easy with the dentate patient because the device can usuallybe fiiTnly attached directly to tlie natural teetb. However, for edentulous patients, thedevice must be attacbed to the record bases/occlusion rims, wbich are somewhat mobilebecause they are resting on movable tissues. Therefore, extreme accuracy in program-ming tbese articuiators is difficult in complete denture patients. Fortunately this sameacctiracy is not required for edentulous patients, and complex articuiators are not indi-cated for their treatment.

Even though an articttlator may not reprodttce movements in an identical patternas that of the patient, it is still accut aif enough to establisb proper occlusal and estheticplacement of the artificial teeth. Because the completed dentures rest on movabletissues, the use of an articulator for the final occhtsal adJustmenLs is preferable to perfect-ing denture occlusions intraorally. This will be further discussed in the Chapter 14,Insertion.

.\rticulators are divisible into four classes. A class I artictilator is a simple holdinginstrument capable of accepting a single stiitic registration; vertical motion is possible.A class II artictilator permits horizontal as well as vertical motion but does not orient themotion to the lemporomandibularJoints (Figitre 10-3). A class III articulator simulatescondylar pathways by using averages, or mechanical équivalents, for all or part of themotion; these instruments allow for orientation of the casts relative to the jointsand may be arcon or nonarcon instruments (Figure 10-4 and 10-5). A class W articula-tor will accept three dimensional dynamic registrations; these instiuments allow for

Figure 10-3 Class II articuiators permit horizontal andvertical movement but do not orient the motion to thetemporomandibular joints


Figure 10-4 Class III articulators simulate condylar path-ways with mechanical equivalents and allow for castorientation relative to the temporomandibular joints.Arcon instruments have the condylar element on thelower member.

Figure 10-5 Class 111 articulators simulate condylar path-ways with mechanical equivalents and allow for cast orien-tation relative to the temporomandibular joints. Non-Arconinstruments have the condylar element on the uppermember.

orientation of the casts to tlie temporomandibular joints and simulation of mandibularmovements.

The complexity of tlie occlusal scheme to be produced or replicated will dictate thecomplexity of the articuiator to be used. Most dentures are fabricated on fairly simplearticulators without complex settings, .\rticulators for denture fabrication usually fall intothe Class III category and have the abitit)' to use a facebow and accept some type of intra-oral record for simple programming of the condylar elements.

Studies have shown that there is no need for a facebow orientation for mostcomplete denture cases, provided that the occlusal vertical dimension is not changed


Figure 10-6 A facebow is used to orient the maxillary castto the temporomandibular joints.

during the fabrication procedures. However, a facebow recording will place the denturesinto a closer relationship with the anatomical closure axis of tlie patient and help mini-mize errors. Because using the facebow is a relatively easy procedure, it usually makes thearticulating of the niaxillar)' cast simpler and results in benefits making the denture fabri-cation process more accurate (Figure l{)-6). The type of occlusal scheme (balancedversus nonbalanced) will also determine the need i'ov interocclusal records to programthe condylar inclination on the itistrunient.

The use of an arliculator is essential for proper occlusal equilibration during theplacement of the dentures. The tise of a remount cast and remount index fabricated bythe dental laboratoiy, will place the maxillar)- denture back on the articulator for theclinician prior to the placement appointment. A new centric relation record will orienttlie mandibular denture to (he maxillar\' denture, and the occhision can then be refinedon the instrument (Figure 10-7). See Chapter 9, Occlusal Concepts, and C;hapter 14,Insertion, for further information on denture occlusion.

Figure 10-7 The articulator is used during the remountprocedure to perform the final occiusal adjustments for thecompleted dentures

Maxillomandibular Records and Articuiators 167

W Maxjllomandibular Records

The retention ofthe record bases is often a concern to the clinician and the patient atthis lime. This lack of adeqtiate retention is usually caused by the requirements of thelaboratory procedure during fabrication ofthe record bases. The laboratorj technicianmust block out undesirable undercuts on the master cast prior to fabricating tbe recordbase in order to protect the cast during record base fabrication. This required blockoutresults in a space between the record base and tissues intraorally, and often causes a lossof retention of the record base. This lack of retention uill be present untiï the denturesare processed and may be a major concern to lhe patieni. The clinician must assure lhepatient that the record base is not tbe completed denture, and tJie retention uill be pres-ent when the dentines are processed. Some clinicians prefer to have processed recordbases fabricated on their master casts in order to minimize these problems. There is noblockout involved, and these are the actual denture bases that will be present in thecompleted dentures rather than an interim traditional record base. These record basesare processed just as if the denture was being completed. The occlusion rims are attachedand eventually have the denture teeth arranged for trial insertion on these bases. A disad-vantage of ha\*ing processed record bases is the extra expense involved in needing asecond processing step to attach the denture teeth to the base. Tbe obvious advantagesinclude the fact that the processed denttire base can be evaluated for retention early infabricating the dentures and additionally these bases will proride much better retentionand stability during the making of maxillomandibular records and the trial insertion ofthe dentures.

^ Contouring the Occlusion Rims

The objective of this procedure is to shape the record bases and occlusion rim so thatthey will replace, in size and position, the teeth and supporting structures that have beenlost Correctly fomied occlusion rims serve as excellent guides in the initial placement ofartificial teeth (Figure 10-8).

Before the initial placement ofthe record base into the patient's mouth, the recordbase nitist be carefully inspected for sharp or rougb surfaces or flanges. Once any irreg-ularities are corrected, the record base should be comfortable for the patient. If tliepatient experiences discomfort, it may be necessary to use pressure disclosing paste tolocate areas that may be causing the discomfort. Do not proceed if the patient is notcomfortable. A slightly loose-fitting record base should be expected because most under-cuts on the master cast were blocked out prior to record ba.se fabrication. However,patients should be asstired that these record bases are not the llnal denture, and that thecompleted denture will fit the ridges and soft tissues much better. The retention ofslightly loose record bases may be improved by iLsing a denture adhesive. However,extremely loose-fitting record bases should be evaluated for the catise. The fmal impres-sion may have been unsatisfactory; and if that is determined to be the cause of the poorretention, now is the time to remake that impression.


E

I

Figure 10-8 The record base will simulate the properposition of the teeth and establish the occlusal planewhen contoured correctly.

labial/Buccal Contour

Wax is usually removed ratber than added to the buccal and labial aspects ofthe maxillaryoccltision rim to achieve adequate lip support from an esthetic and phonetic perspective.Becatisc the labomtor)' technician probably had to block out labial luidercuLs prior tofabricating the maxillaiy record base, the upper lip may have the appearance of being oversupported. Tbinning or shortening the base may not fully correct the problem at tbis time.If it cannot be corrected, the patient mtist again be assured that this problem w\\ not existat den lure insertion. The buccal surface of tlie rim almost always indities labially froirt üieborder of the record base at abottt a 15 degree angle and is approximately 8-9mni labiallyfrom the center of the incisive papilla. A photograph of the patient wben he or she hadnatural teeth could lielp in this de te rtn i nation. A comparison of the lip suppcjrt with tliatfrom an existing denture, if one exists, is also helpili! in making tliis determination.

In the posterior, wax should be added or removed to achieve a bilateral "buccalcoiTidor" space for estbetic purposes. This space is created by sloping the maxillaiAoccltision rim inward in the posterior area. There shotild be pleasant amount of space onboth sides of the occlusion rim, which reproduces tlie space seen between the buccalsurfaces ofthe premolars and cbeeks/hps in dentate patients. Obliteratitig tliis space isa common mistake when setting the width ofthe maxillary denttire.

Incisai Length and Esthetics

The anterior height ofthe maxillary plane of occltision should be determined next. Thisis often called the incisai lengtli ofthe occlusion rim. The incisai length will be the levelat which the incisai edge of the maxillary central incisors will be positioned. ObvioiLslyesthetic and phonetic factors must be considered. Esthetically the length ofthe upper lip

Maxiiiomandibuiar Records and Articuiators 169

is an important guide because, generally speaking, the incisai edges of the central inci-sors should be slightly beiow the relaxed upper lip. It is common for the upper lip todrop slightly and become longer estheticalh as wax is removed from the contours ofmaxillary occlusion rim. Therefore, only after achieving the proper labial/buccalcontour of the maxillary occlusion rim, shotild the incisai length be considered.

Maxillary Up length must also be considered. The lip length can be evaluated byplacing the tip of an itidcx finger on the crest of the maxillar)- ridge in the anteriorregion and allowing the upper lip to rest down over the finger with the facial musclesrelaxed. OlMerve the amount of the finger covered hy the lip to get an approximation ofthe length of the lip. If the lip ends almost level with the crest of the ridge, the lip mightbe considered to be short. It the Up hangs down 4-5 mm below the crest of the ridge, itmay be considered to be normal in length. If the lip hangs down 6 mm or more, it isgenerally considered to be long.

If the lip is short, a significant amount of tiie anterior teeth, and some of thedenture base, may show in the completed denture even when the upper lip is relaxed.Tliis may be a significant concern esthetically to the patient and shotild be discussedbefore any furtlier treatment is cotnpleted. Surger>- to minimize this problem is generallynot indicated. If the upper lip appears normal in length, then the rim will often extendjust below ( 1-2 mm) tlie resting length of the lip. Maxillar>- anterior Leeth show on mostpatients when they smile. They do not, however, always show on patients when theirmuscles and lips are at rest. The amount of occlusion rim and eventually the dentureteeth that show when tlie patient is at rest may vary, from not being visible at all to show-ing 4 mm or more, depending on the patient.

The phonetic contact of anterior teeth with the lips and tongue are essential forproper fonn and function in a complete denture. The contour and length of the occlu-sion rim should match these parameters. The proper position and support from theocciusion rim will affect the quality of speech sounds such as the "f and "v" sounds,where the wet-diy line of the lower lip should gentiy contact the labial edges of the ante-rior occlusion titn. Sound stich as "th" will also produce a gentle contact of tlie tonguewith the lingual surfaces of the proposed position of the anterior teeth (Figure 10-9).

Figure 10-9 Proper contact of the wet'dry line of îhelower lip with the labial edge of the maxillary occlusionrim during a "f"/"v" phonetic check.


Figure 10-10sion rim.

Midline is marked on the maxillary occlu-

The midlineof the anterior teeth should also be marked on the maxillar\'rim at thistime. The philu um of the lip is the most common guide for marking the midline (Figure10-10). However, on some patients a difíerent position may be more esthetic if the nose,philtrum of the lip. and chin are not in a line. Marking the midline on the rim will makethis determination easier lor the clinician. It will also sei"ve to orient the maxillaiy rimcorrectiy on the facebow fork, which will be discussed in a subsequent section.

forming the Plane of Occlusion

With the Up length determined, the plane of occlusion can now be formed (Figure10-11). Tliree points will determine a plane, and at this point only the anterior length of

Figure 10-11 The anterior length is determined first andthen the occlusal plane can be established.


the occlusion rim senes as one point. The posterior portion of the plane will be estab-lished using the anterior point along uith other anatomical landmarks and esthetics. ATrubyte® Fox occlusal plane plate or tongue blade will help define the tentative plane ofocclusion. However, esthetics is used to determine the Onal plane.

The Trubyte® Fox occlusal plane plate will be used to establish the anterior planeparallel to an inteipupillary line, and the anterior^osterior plane parallel with Camper'splane (ala-tragus line). The occlusal plane of most natural posterior teeth is approxi-mately parallel with these landmarks. This plane ideally would be parallel to the inter-pupillary line, equally split the distance between the opposing ridges, be at the level of themiddle to upper third of the retromolar pad, be parallel to the remaining ridges, and bejust below tiie corners of the mouth when the patient smiles (FigureslO-12 and 10-13). It

Rgure 10-12 When the Fox plane guide rests on theocclusion rim, it should be parallel to the interpupillary line.

Figure 10-13 When the Fox plane guide rests on theocclusion rim, it should be parallel to the Ala-Tragus line(Camper's Plane).


will not often match all of tlie desired ideal critera on tills list. Esthetics and function arecertainly significant concerns for making the final determination. This initial estimate ofthe plane of occlusion is, therefore, tentative and may require adjustment during thesetting of the teeth or at the trial insertion appoinünent.

Mounting the Maxiiiary Cast on the Articulator

The master casts must now be acctirately positioned on an articulator so that properocclusion will be developed during die tootli arrangement The proper position of themaxillaiT cast relative to the condyles is an important concept for niany prosthodonticprocedures, and complete dentures are no exception. The orientation of the inaxillaiycast to the condylar elements of the articulator and axis-orbital plane must match theorientation of the maxillary arch to the hinge axis and axis-orbital plane ol" the actualpatient This is accomplished through use of the previously cotitoured niaxillaiy recordbase/occlusion rim and a facebow. The correct orientation of tlie casts to the openingand closing hinge axis will minimize errors in occhision that occur when there arediscrepancies in the arc of closure. A facebow orientation \vill ensure that the properrelationship will minimize this type of error.

Facebow.s are generally classified as either kinematic oi' arbitrary. Kinematic face-bows can precisely match the hinge axis position when used with tbe natural dentition.However, with the required used of movable record bases/occlusion rims with completedenture patients, that degree of accunlc^ is not normally achieved. They are not recom-mended for complete denture fabrication.

Arbitrary facebows rely on facial and anatomical landmarks to record the positionofthe maxilla relative to tlie binge axis and axis-orbital plane (or base ofthe skull). Theyare accurate enough to place tiie articulator hinge axis \viuiin 6 mm of tiie true hingeaxis more than 80% ofthe time. This creates an acceptably accurate arc of closure, whichwill minimize occlusal discrepancies in the dentures. Arbitran' facebows are similarenough to fall into the same approximate use pattern, (-heck with the facebow manu-facturer for specific instructions for the partictilar facebow that will be used. Many arbi-trary facebows use the external auditoi'y meatiis and an anatomical landmark based onthe position of orbitale to make this three dimensional detennination.

A fork is commonly attached to the anterior portion ofthe facebow with a series ofadjustable fittings to allow tliree dimensional acljustments. Tlie facebow is attached to themaxillaiy record base and occlusal rim during die clinical procedtue, positionedon the patient, and the facebow recording is made. Four nonparallel notches are placedin the maxillar\- occlusion rim (two on each side), in the area tistially occupied by the firstpremolar and the second molar. The notches wiil serve to orient the maxillar)' occlusionrim, which is then usually attached to the facebow fork using a vinyl polysiloxane (VPS)registration material (Figtire 10-14). The adjustable fittings allow the fork attached tothe maxillary occlusal rim and record base to be adjusted to align tiie lacebow witb tbethird point of reference to establish the axis-orbital plane (Figure 10-15).

Once the recording is made, the record base/occlusion rim and facebow are disin-fected, the maxillaiy cast is placed in the record base, the facebow is positionedon the articulator, and tiie maxillary cast is attached to the articulator using mountingstone (Figiue 10-16). The articulator manufacturer's instructions should be followed toaccomplish this procedure. The master cast will need to be removed from this mount and


Figure 10-14 Four nonparallel notches 2 mm x 2 mmare placed on the maxillary occlusion rim in the area of thepremolars and molars. Notches orient the rim to the face-bow fork.

Figure 10-15 The maxillary occiusion rim is attached tothe fork, which is then secured to the properly adjustedfacebow using a series of adjustable toggles until theproper orientation is achieved.

returned dttring subsequent laborator>- procedures. To facilitate this removal orientationgrooves should be present in the master cast base and a Itibricating agent should beapplied to approximately fift>' percent of the base surface before the mounting stone isused. If tbe decision is made to make the interocchisal recording prior to mounting themaxillary cast, the facebow can be set aside and the cast can be articulated at a later time.If tlie cast is to be artictilated after using tiie maxillary rim to make the subsequentCR record, the occlusion rim and orientation grooves cannot be altered during the jawrelation procedure.


Figure 10-16 Maxillary cast and record base/occlusionrim supported by the facebow recording. The next stepwill be to attach the maxillary cast to the articulator usingmounting stone.

Establishing the Occiuding Vertical Dimension (OVD)

The centric relation (CR) position and occluding vertical dimension orientation of themandibular cast on the articulator must match the centric relation position and occlud-ing vertical dimension of ihat seen in the patient. The record bases/occlusion rims areused to transfer the correct horizontal and vertical position of the mandibular mastercast relative to the maxillaiT master cast.

Once the tnaxillar)' plane of occltision is established, the determination of theocclusal vertical dimension is made. When making tîiis determination, the proper inte-rocclusal distance must be maintained in order to minimize speech problems and poten-tial soft tissue irritation. Failure to provide adequate interocclusal distance producesexcessive interarch distance when the teeth are in occlusion. Most often the patient's facedoes not appear relaxed, and the lips cannot lightly touch when the patient is at rest. Thepatienl might appear to be stretching the lower lip to get contact. This position does notallow the muscles that elevate the mandible to complete their contraction. Tliereforethese mtiscles will continue to exert force to overcome this obstacle. This ofteti results indamage to the supporting tissues that includes soreness, possible ischemia, and eventualrésorption. This excessive occktsal vertical dimension may also result in some facialdisiortion because the patient has difficulty closing the lips togetlier properly. On theoUier hand, too much interocclusal distance can also cause problems. This overclosureor reduced occlusal vertical ditiiension at tooth contact can cause temporomandibularjoint damage, facial distortion, loss of mtiscle tone, and possibly angitlar cheilitis. Thepatient often has the appearance of the "nose being too close to the chin."

The initial detenninaUon of the occlusal vertical dimension is often achieved bymaking multiple measurements of different facial parameters becatLse there is no singlemethod of acctu^tely making this determination. One method begins by determining theproper resting vertical dimension (R\T)) for a particular patient and subu-acting approxi-


Figure 10-17 I.The resting vertical dimension (A) is estab-lished and marked on a tongue blade.The determination ismade between two marks, one on the nose and another onthe chin. 2.The rims are contoured to make even contact at2-3 mm less than the resting vertical dimension.This 2-3mm is the interocclusal distance and the resulting position(B) is the occlusal vertical dimension.

inately ^-^ mm (Figure 10-17). The testing position is theoretically a balance of muscleswhen the head is in a normal upright position. It can be detennined by ha\ing the patientrehix and letting the lips gently touch, or by ha\itig the patietit maintain a prolonged"mmm" humming sound. This measurement shotild be attempted several times, letting thepatient speak and relax between the measurements. Two to three millimeters is subtractedfrom the R\T) and the resulting meastirement is then the tentative occluding verticaldimension. Next the plane of occlusion of tlie record base and occlusion rim on themandibular arch is altered so that it is at the middle of the retromolar pads in tlie posterior,and slightly below the comers of the moutii anteriorly. Tlie maxillary and mandihularRBORs are inserted and the patient instructed to close into gentle contact. Tlie occlusionrims are adjusted to allow for even contact at the tentative OVD. Opposing teeth sbould nottouch during speech once the denture Is completed, so no matter which method is used todetermine the occlusal vertical dimension, there must be clearance between the opposingocclusion rims when the patient makes sibilant sounds. During sibilant sounds the teetiicome as close together as tliey ever do during speech. Therefore, if the necessar) interoc-clusal distance is present at this time it should be aNuilable once the dentures are inserted.This distance is often called tiie "closest speaking space," or interocclusal clearance. Theanterior teeth may come exüemely close together during this determination, but a rangeof 2-4 mm of interocclusal clearance in the premolar area is considered within the nonnalrange. Esthedcally, when the rims are in contact, the lips should gentiy touch and the chinshould not look too close to the nose (Figure 10-18).

As the correct occluding vertical dimension is approached, it may become neces-sary to change the preliminar\- height of tiie maxilhm' plane of occlusion. If it appears asthough the maxillary rim may be quite a bit longer than tlie mandibular rim, the initiallengtii of tlie maxillary^ rim should be modifted. In most instances, the maxillan' andmandibular rims will not be grossly diÖerent in height at the correct occluding vertical


I

Figure 10-18 Esthetically, when the rims are in contact,the lips should touch and the chin should not appear tobe too close to the nose

dimension, with the maxillary rim usually slightly larger than the mandibular. Alwayskeep esthetics, phonetics, and ftmction in mind when making these changes. If thefacebow recording and horizontal records are both being made before the maxillaiy castis mounted on the articulator, all adjustments of the maxillary rim must be made priorto the facebow recording. Changes to the rims after making tlie facebow recordings willchange tlie fit of tlie rims into the facebow fork.

Determining the Centric Reiation Position

The correct horizontal relationship for fabricating complete dentures is always thecentric relation position. Many techniques for establishing centric relation for dentatepatients are not applicable for edentulotis patients because of the uniqtie nature of tlierecord bases on tlie residual ridges of the edentulous patient. Edentulous padents do notneed to be deprogrammed prior to making tlie CR recording.

The clinician must be able to manipulate the patient's mandible to the centric rela-tion position, as it is: 1 ) the starting reference point for complete denture fabrication, 2)repeatable and it can be verified, and 3) is a functional position for denture occlusion.Complete dentures should always be fabricated so their initial and complete finalocclusal position is coincident with Lhe centric relation arc of closure. At the properoccluding vertical dimension, this position then becomes the centric occlusion positionfor the padenL

Because the centric relation position is somewhat dependant on head posture, thehead should be held fairly upright. The position of the dentist's hands is an importantfactor in making accurate centric reladon records and maintaining record bases in tiieircorrect position. The nondominant hand is inverted and placed in the mouth so that thesoft tissue of üie thumb and index fingers lies on the opposing buccai surfaces of themaxillary and mandibular occlusion rims, between the occlusal surfaces in the first molar


Figure 10-19 The inverted hand position stabilizes boththe maxillary and mandibular record bases during theCR record-making procedure. Note the thumb on thesymphysis ofthe mandible to guide the patient butnot displace the mandibular record base.

region. As the patient closes, the tissue of the fingers is allowed to move buccally so thatthe force of the closure maintains both bases in position with a minimum of displace-ment ofthe supporting tissue. The other hand is used to help guide the patient to centricrelation position. Care should be exercised to avoid displacing the mandibular recordbase in the posterior direction (Figure 10-19).

Because it is sometimes difficult to get the patient into the CR position, it is agood idea to practice this position with the patient prior to attempting to make therecording. Remember, you are attempting to capture tlie most superior/anterior relaxedposition from which the patient can make rotational and repeatable recordings. This istlie ceniric relation position and is the only verifiable position the patient can assume.Most patients cannot assume a relaxed centric relation position fironi a vertical dimen-sion that is grossly open from the desired final occlusal vertical dimension. Therefore,the patient should be close to the correct OVD prior to attempting to achieve theCR position. It is advisable to instruct the padent to "let your jaw relax, close slowlyand easily on yotir back teeth, and stop as soon as you feel the fii"st contact". Somepatients will automatically assume the CR position. Some, however, simply cannot relaxand close into this position. These patients may be very difficult and take all the skillsof the clinician to achieve and verily' the position. Practice witb the patient until boththe clinician and the patient are familiar with the desired position and procedure. Insome instances, other methods must be used to position the jaw in centric relation. Someof these include:

1. Having the patient completely relax the mandible while the cliniciangently shakes the mandible up and down. When the patient gets in acompletely relaxed state, the mandible should hinge up and down in arepeatable arc. This is the centric relation position. Cently continue toshake and lift the mandible until tJie correct OXTD is reached.

2. Placing the tip of the tongue in tiie top and back of the mouth.


S. Telling the paiieiit to ".Stick otu the tipper teeth." This niistiomer some-times will help the patient make tbe correct mandibular movement.

4. Tipping the chair and patient back to allow gravity to help position tbemandible.

5. Using a mirror so that the patient can see the CR mandible position.

When the patient is closing in centric relation, inform him or her that tbe closureis correct so that he or she becomes aware of the position by feel. Most patients will learnthe desired technique by means of these instructions.

The maxillary master ca.st has now been properly placed on ihe articulator using aface-bow recording. The mandibular occlusion rim has been adjusted so that tbere isunrestricted contact with the maxillary occiusion rim at the correct occluding verticaldimension, and it is in centric relation. This horizontal relationship will now be capturedwith some type of recording material. However, because we must make the recording atthe correct OVD, space must now be created to allow room for the record material. If thisspace is not created, the O\T) will be unacceptably increased during tbe record-makingprocedure. This space is created by vertically reducing approximately 2 mm of wax fromthe occlusal surface of tbe mandibtdaj- occlusion rim in the premolar and molar areasbilaterally (Figure 10-20). It is very important that, when the patient closes into contacton the anterior occlusion rims, minimal pressure is applied to the rims by the patient. Itis also tiecessary to ensure tbat the anterior contact does not displace the record base andocclusion rims during tbis procedure.

The opposing record bases/occlusion rims will be related to each other by makingan interocclusal recording. Modeling compound, wax or VPS is often used for thisrecording. Some t\pe of orientation grooves are necessary to be able to relate the oppos-ing occlusion rims once the interocclusal recording is made. The orietitation groovesused to make the facebow recording on the maxillary arch sbould still be present. VPSmaterial will not stick to tlie mandibular rim, so mechanical retention or adhesive isnecessary to keep the registration material in place on the mandibular rim. Undercut

Figure 10-20 The occlusion rims have been adjusted tothe occlusal vertical dimension and wax has been removedto allow for piacement of the record materiai for recordingthe vertical and horizontai mandibuiar position.


Figure 10-21 A modeling compound record has beenmade intraorally.

grooves or adhesives are both acceptable methods for retention. The retention is notnecessary if modeling compound or wax is used to make the recording because it willstick to tbe mandibular occlusion rim. Whichever material is used, tiie maxillaiy occlu-sion rim is covered with a thin film sepaniting medium, often Vaseline, the patient isclosed into the material at tlie correct OVD and in the CR position, and the material isallowed to polymei i/.e or cool until rigid. Due to the short set time of VTS recordingmaterials, the clinician should manipulate the patient into the proper CR position withboth ritns in the mouth and approach the correct OVT). Jtist before contact of the ante-tior of the ritns, an assistant should place the recording material between the rims. Thepatient should then be guided and closed to the final position. If modeling compoundor wax is used, it will be placed on the mandibtilar rim extraorally, properly healed,tempered, and then placed in tlie patient's mouth to make the record (Figure 10-21).

Retrieve and reassemble the rims and check to see if there is contact of the oppos-ing record bases in the posterior areas. If the record bases are totiching, they may îiavebeen displaced from their correct position on the ridge, and a new inteiocclusal recordmust be made after relieving these contact areas. The recording of the indices should besharp and well defined {Figure K)-22). The record bases and occlusion rims should bestable when reassembled.

Excess recording material is trimmed from the occlusion rim, and the occltisionrims are placed back in the patient's mouth. If the record appears to be correct, proceedwith articulating the mandibular cast. If there is any question about the mandible beingin the correct CR position, the record shotild be remade.

Articulating the Mandibuiar Cast

Tlie maxillary cast is either already positioned on the aiticulator using the facebowrecord or is positioned at this time following the articulator manufacturer's instructions.Once the maxillar\' cast is properly positioned, the occlusion rims are placed on their


Figure 10-22 Well-defined notches have been recorded,and there is even, smooth contact over the entire recordsurface.

respective casts, and the records are seated together. Observe tlie casts for possiblecontact in the posterior areas. If they make contact, the cast must be trimmed until thereis no cast-to-cast contact. Secure the mandibular cast to the maxillary cast to preventmovement during the articulation procedure. The articulator must be checked to verifythat the position of the incisai pin is correct and that the upper member of the articula-tor is locked in the CR position. The settings of the articulator should match the manu-facturer's instiiiction for the instrument being vised. Secure the mandibular cast to thelower nieinber of the articulator using mounting stone (Figure 10-23) (Figure 10-1).Orientation grooves and proper lubrication should be used for the mandibular cast asdescribed for the maxillarv cast earlier.

Figure 10-23 Mandibular cast and record base/occlusionrim secured into centric relation record and related to themaxillary cast.The mandibular cast is ready to attach tothe articulator with mounting stone.


Some clinicians make a verification of the CR record after the mandibular cast hasbeen articulated- This is simply a repeat of the initial recording made intraorally. Thesecond recording should match the original cast mounting. To verify the first recordingthe tipper and lower members of the articulator should be in the same relationship whenthe second record is introduced between the occlusion rims. The pin is raised ofF theincisai support and the centric holding latch is released. The occlusion rims are returnedto tlie casts and finnly seated into the new record. There must be no movement of thecondyiar heads away from their initial positions. If the second record does not verify thefirst recording, then a determination must be made about which recording is accurate.The clinician should note the discrepancy between the two recordings and make a thirdrecording. If this tliird recording matches lhe first recording, then the initial recordingis verified. If it does not match the first recording, but matches the discrepancy seen withthe second recording, then the mandibular cast shotild be removed from the articulatorand re-articulated. It may be necessary to verify tliis tliird recording. Verification recordsmay not be applicable to all types of aräculators and are not a guarantee that the recordis correcL

Compieting the Maxiiiomandibuiar Records Appointment

To complete tliis visit, it will be necessary* to select tlie correct denture teeth that will beused in the arrangement of the teeth. This will be covered in the Chapter 11, ToothSelection.

ReferencesFayz, F-, Eslami, A.: Deieimination of Occclusal Vertical Dimension: A Literature Review.J Prosthet

Dent 59:321-323, 1988.Hickey, J.: Centric Relation—A Must for Complete Dentures. Dent Clin N Am. 587-600, Nov 1964.Niswonger, M.: The Rest Position of the Mandible and Centric Relation. J .\m Dent Assoc: 1572-

1582, 1934.Pleasure, M.: Correct Vertical Dimension and Freeway Space. ) Am Dent A.ssoc 43:

160-163, 1951Rahn, A. O., and Heartwell, C. M-, editors: Textbook of Complete Dentures. 5"^ Ed. New York:

Lippincott, 1993.Swerdlow, H.: Vertical Dimension Literature Review.J Prosthft Dent 15:241-247, 1965.The Olossarv' of Prosthodonüc Term.s. j Prosthet Dent 94:10-92, 2005.Wagner, A. G.: Comparison of four methods to determine rest position of the mandible.

J Prosthet Dent 25:506. 1971Weinberg, L.: An erdluation of basic aniculators and their concepts, Part 1. Basic concepts.

I Prosthet Dent 13: 622, 1963.Weinberg, L.: .\n evaluation of basic articulators and their concepts. Part II. Arbitrary, positional,

semiadjustabie aniculators. J Prosthet Dent 13: 645, 1963.Weinberg, L.: .\n e\"aluation of baste articulators and their concepts. Pan III, Fully Adjustable

Articulators. J Prosthet Dent 13:873-888. 1963.Yurksias, A., and Kapur, K.: Factors Influencing Centric Relation Records in Edentulous Mouths.

J Piosihet Dent 14:1054-1065, 1964.


QUESTIONS

1. What is the objective of contouring the occlusion rims?

2. Which meastirements can serve as a guide for the initial anterior contours ofthe maxillary occlusion rim?

3. How can phonetics help determine the proper occhision rim contour?

4. The orientation of tbe maxillary cast to the condylar elements of the articu-lator and axis-orbital plane must match the orientation ofthe maxillary archto the hinge axis and axis-orbital plane of the acttial patient. How is thisaccomplished?

5. Which anatomical landmarks are typically used by arbitrary facebows toachieve proper orientation?

6. What is the normal range for interocclusal distance?

7. Wliy is the centric relation position so important for complete denture fabri-cation?

8. What does a facebow record accomplish when articulating a maxillary cast?

9. Why is recording extreme accuracy of mandibular movements not possiblewith fully edentulous patients?

10. What affects the accuracy of an articulator with regard to mimickinganatomical movements of the patient?

1. To shape the record bases and occlitsion rim so that they will replace, in sizeand position, the teeth and supporting structures that have been lost.Correctly formed occlusion rims seiA'e as excellent guides in the initial place-ment of artificial teeth.

2. The buccal surface of the rim almost always inclines labially from the borderof the record base at about a 15 degree angle and is approximately 8-9 mmlabially from the center ofthe incisive papilla.

3. The proper position and stipport from the occkision rim will affect the qiial-it\ of speech sounds such as the "P and "v" sounds, where the wet-dn line ofthe lower lip should gently contact the labial edges ofthe anterior occlusionrim. Sounds such as "tb" will also produce a gentle contact of the tonguewitli the lingual surfaces of the proposed position of the anterior teeth.


4. This is accomplished through tise of the pre\iously contotired maxillaryrecord base/occltision rim and a facebow recording.

5. Many arbitrary facebows use the external auditory meatus and an anatomicallandmark based on the position of orbitale to make this three dimensionaldetermination.

6. A range of 2-4 mm of interocclusal distance is considered to be within thenormal range.

7. This position is: 1) the starting reference point for complete denture fabri-cation, 2) repeatable and can be verified, and 3) a functional position fordenture occlusion. Complete denttires should always be fabricated so theirinitial and complete final occlusal position is coincident with the centricrelation arc of closure. At the proper occluding vertical dimension, this posi-tion then becomes the centric occlusion position for the patient.

8. A facebow relates tbe maxillary cast to the opening and closing axis of thearticulator in tbe same way that tbe maxilla relates to the anatomical hingeaxis of the patient.

9. The record bases that are attached to the recording devices are somewhatmobile because they are resting on movable tissues.

10. The complexity of an articulator, its ability- to be programmed, and tlie abil-ity' of the clinician to program the instrument will determine the accuracy ofmimicking anatomical movements.

C H A P T E R

Tooth Selection

Dr. Philip S. Baker

185


The growing demand for estiietic dentistry clearly demonstrates increased public aware-ness of the benefits ofa pleasing smile and, as shown in recent studies, tliis interest is notlimited to younger patients. In contrast to previous generations, today's middle-aged andolder adult is much more likely to be concerned with maintaining a healtiiy and youth-ful dental image. Because of this emphasis on the esthetic aspects of treatment, selectionof appropriate denture teeth plays an extremely important role in patient satisfaction.

The selection of denture teeth for complete deiitutes seems to be an area in whichmany dentists feel uncomfortable. The academic background of these clinicians may playa significant role in their hesitance to deal with esthetic details. Concern with facts,figiires, and logic often took precedence over artistic development in their education. Infrustration, they may delegate this task to auxiliar)' personnel, including laboratoiT tech-nicians. By doing so, these dentists lose an opportunity to develop the esthetic skills thatare vital to many other aspects of dental treatment and deprive themselves ofa tremen-dous source of satisfaction and accomplishment. In any case, the ultimate responsibility'for denture tooth selection remains with the clinician.

As with any skill, excellence in denture esthetics can be developed with patienceand persistence, in the selection of denture teeth to meet the esthetic desires of apatient, the clinician must: 1) correctly interpret the esthetic desires of the patient, 2)recognize the practicality' of those desires and discuss this information with the patient intreatment planning and again throughout treatment, and 3) coordinate the patient'srealistic desires witli the dentist's personal esthetic and functional philosophies inconstruction of the definitive prostheses.

Information necessary for the selection of appropriate denture teeth may actuallybegin with introduction of the dentist and patient. Valuable direct and indirect informa-tion is gathered tiirough careful obset vation as the patient describes their problems anddesires. The clinician should observe tlie patient's posture, personality, oral and facialcharacteristics, dress, speech, habits, and mannerisms. The clinician should evaluate thepatient both emotionally and physically. Compare the patient's assessment of their condi-tion and desires with these clinical observations. Unrealistic expectations should be dealtwith well before treatment begins, and the patient continually reminded of any limita-tions as care progresses. Negative factors, such the requirement for a severe Class II ante-rior occlusion (Figure 11-1), tiiat are pointed out to the patient after the dentures arecompleted, are often perceived as an excuse for error.

Figure 11-1 Mounted casts showing severe Class II ante-rior malocclusion.

Tooth Selection 187

Anterior Moid Seiection

Existing information

If the patient was relatively satisfied %\ith his or her previous appearance, diagnostic castsof the patient's natural dentition, which may be in the possession of the patient or avail-able from a previous care prouder, may be ideal sources of information. The size andform of tlie tiatural teeth can often be matched. However the clinician must be carefulnot to agree to perpetuate ajiy existing condition that may prove haraiful if incoiporatedinto new dentures.

Photographs can be an invaluable aid in tooth selection. Request that the patientbring in any pei sonal photographs clearly showing their natural permanent teeth.Approximate tooth size, existing diastmas, anterior tootli aligntnent, and shade may beob\ious in old photogniphs. However, many patients will bring in photographs that arcdecades old, and they musi be reminded that the physical changes that have occurredover those decades make it impossible to match the esthetics of the natural dentition ordentures as seen in very old picttues. It is xery important to safely store and return allpersonal photographs to tJie patient as soon as possible to preclude loss or damage.

A simple mathematical proportion may be developed using three known values inreference to the phoiogniph and the patient: the interpupillar\ distance and width of thecentral incisor from the photograph, and the interpupillar)' distance on the patient.Sohing for X gives the original width of the patient's central incisor.

photo interpupillar\ distance _ photo central incisor width

patient's actual interpupiliar)' distance X

Any old dentures can sen e as a guide for both the patient's likes and dislikes. If thepatient is satisfied with the size and shape of the teeth, these are usually the best choicefor new dentures. However, to repeat, the clinician must not agree to peipetuate anyexisting condition that may prove harmfttl to the patient. An irreversible hydrocolloidimpression of the existing denture can be made extraorally, and a stone cast potired forlater reference. These casts may become very important to the laboratoiy technicianduring tooth arrangement.

The patient's significant others are also an important source of infonnation fortooth selection. In addition, observing the teeth of close relatives can be helpful. Anyesthetic concerns brought up by this important group should be recognized and notedfor future consideration.

The frontal outiine form and size of the face, and lateral view of the patient's profilehave been considered gross gitides in tooth selection. There is, however, no scientificevidence to indicate that these are valid guides in the tooth selection process.

Although the size and shape of tlie residual ridges cannot actually determine aspecific mold selection, they are important guides to overall size. Large maxillary- ridgeswill usually require teeth with a "width of six anteriors on a curve" (canine to canine) ofat least .53 mm. Small ridges will usually be less than 50 mm. (Figure 11-2)

Record Bases and Occlusion Rims

Record bases and occlusion rims play a basic role in complete denture prosthodontics asthe means of transferring infomiation from the clinic to the laboratory. For patients


Figure 11-2 Example of an extremely small edentulousmaxilla, with a coin placed to illustrate scale.

unable to supply records of their natural teeth, record bases and occlusion rims can alsobe used in denture tooth selection. To be tiseful in the selection of denture teeth, theocclusion rims must be correctly contoured to provide adequate lip support and meetesthetic and phonetic demands. Additionally the plane of occlusion must be formed andthe vertical dimension of occlusion established.

The midline, high smile line and the "relaxed" comers of the mouth are scribedinto the wax intraorally. The high smile line indicates the normal minimum incisogingi-val height ofthe maxillary anterior teelh to avoid an unsightly display of gingis'al basematerial (the so-called "gummy" smile). The distance between the corners of the mouthmeasured along the incisai region ofthe facial curvattire ofthe occlusion rim representsan appropriate width for the six anterior teeth.

For patients with obvious contraction or distortion of the corners of the motith, theinteralar width technique may prove more reliable. It is based upon the observation tbatthe centerline of the natural canine teeth is roughly in vertical alignment with the outeredge of the ala of the nose. Clinicians need to add 7 mm to the interalar measurementto produce the widtli ofthe six maxillary' anterior teeth, from distal of canine to distal ofcanine. Generally, for Ai ri can-Am eric an patients, one size smaller category mold thanindicated by this value should be used, because of anatomical differences.

Commercial Guides

Many forms of commercial guides are available to the dentist to aid in selectionof denture teeth, including physical mold guides (Figiu^e 11-3). Although normallydesigned for a specific manufacturer's system, the information obtained can often beused with any other system.

One de\ice is the Trubyte® Tooth hidicator (Figtire 11—4), which can be tised forestimating the size as well as outiine and profile forms of maxillar>' anterior dentureteeth. Tooth width and length are based upon an average 16:1 ratio of the bizygomaticwidth and height of the face in relation to the width and length dimensions of the

Tooth Selection 189

Figure 11-3 An example of a physical moid guide. Notethat, although the denture teeth used in mold guidesappear to be the normal denture teeth as sold by theparticuiar company, the denture teeth in the moid guidemay be of poor quaiity and should not be used in actuaidentures. (Photo courtesy ivociar Vivadent, inc.)

natural maxillary central incisor The indicator's face plate has two registration bars, oneon tbe left side and one at the bottom, which are moved along slots and locked into posi-tion against the skin of the zygomatic region and underside of the chin, with themandible at rest. Maxillarv' central incisor width and length are read directly from thecorresponding scale, as indicated by the position of the bai' surface in contact witlithe patient's face.

Outline form is shown by comparing the facial form in relation to the vertical linesof the indicator, and is classified in tlie manufacturer's directions as square, square taper-ing, tapering, or ovoid (Figure 11-5). In the sqtiare form, the sides ofthe face roughlyparallel tlie vertical lines. For the square tapering form, the upper face outline will pat al-lei the lines and the lower will taper inward. The tapering iorm uill exhibit a diagonalfrom the forehead to the angle of tbe mandible. Tbe ovoid face shows an overall curvedoudine. This information is recommended for selecting denture teeth bv some denturetooth manufacturers. However, there is no scientific data to validate this recommenda-tion. This does not tnean that it is not useful information and should not be used.

The Ti-tibyte® Tooth Indicator may also be used to determine tbe patient's profilefonn for matcbing to the dentnre teeth. Witb the device held in place, tJie operatorobserves the relative straigbtness or curvature of the profile (Figure 11-6). Three refer-ence points are used: the forehead, the base of the nose, and tbe point of the chin, Ifthese points lie in a straight Une, the profile is considered stmight. If tlie forehead andpoint of the chin lie posterior to the base of the nose, the profile is curved. A ^ n , whileuseful, there appears to be no scientific findings that validate the use of this infonnation.

Another guide for maxillary anterior tooth selection is the Ivociar ViN'adentBlueLine^" Form Se lector '"' (Figure 11-7), which features a caliper, the Facial Meter, forcorrelation of the patient's interalar dimension with tooth inonid width. This system alsoincorporates cards with actual-sized photographs of the six maxillary anterior teeth.


Figure 11-4 TheTrubyte®Tooth Indicator. (Photo courtesyDENTSPLY® International, Inc.)

These cards are helpful in selecting tooth foiTn {soft or bold) and tooth length (shortto long).

Additional Guides

While no study to date has confirmed predilections for tooLh form, size, or shade, thefactors of sex, age, and personality may be considered to develop a pleasing and harmo-nious restoration. Delicate, small, and curved or tapering forms are considered morefeminine, while bold, large, and square forms tend touürd the masculine. With age, theteeth become less rounded at the incisai edges and interproximal contacts, exhibiting anoverall loss of cur\ature. Aging also produces a decreasing display of the maxillary ante-rior teeth and a greater display of the mandibuiar. The curve of the smile line also tendsto flatten over time.

Tooth Selection 191

SQUARE SQUARE TAPERING TAPERING QVOID

Figure 11-5 Use of theTrubyte®Tooth Indicator to deter-mine facial outline form. (Drawing courtesy DENTSPLYCB)International, Inc.)

Figure 11-6 Determining facial profile with theTrubyte®Tooth Indicator (Drawing courtesy DENTSPLY®International, Inc.)

Figure 11-7 The IvoclarVivadent BlueLine-" FormSelector™. (Photo courtesy IvoclarVivadent, Inc.)

Posterior Mold Selection

The selection of the mold of the posterior teeth that will be used for the dentures is theresponsibilit)- of the dentist. Almost all denture tooth manufactures have a guide torecommend the posterior teeth based on the size of the anterior teeth. Therefore, an


Figure 11-8 Effects of setting teeth over the steep slopeleading from the residual ridge to the retromolar pad.X indicates the beginning of the slope from the residualridge leading to the retromolar pad. Note the arrow indi-cating the potential movement of the mandibular dentureduring function if a second molar were placed on the slopeleading to the retromolar pad.

initial mold selection is indicated following the selection of the anterior teeth.Remember that manufacturer's recommendations are based on averages and opinions,and may not be acceptable for a particular patient. The final posterior mold selectionmay not be possible until the anterior leeth have been arranged and the remainingposterior space has been evaluated.

The overall mesiodistal length of the posterior teeth is governed by the length of theedentulous mandibular ridge. Posterior denture teeth are not set on the slope leadingfrom the residual ridge to the retromolar pad because of its tendency to act as an inclinedplane when the patient chews food. The mandibular denture sliding down this .slope maylead to severe irritation to the lingual aspect of die anterior ridge (Figure 11-8).

Prior to setting the posterior teetii recommended by the mold guide, a measure-ment is made from the distal surface of one of the mandibular canines to the beginningof the slope of the ridge leading up to the retioniolar pad. This measurement, inmillimeters, will he used to evaluate the recommended mold, and to select and alterna-tive if necessary. If no slope is apparent, measure to the beginning of the retromolar pad.The moid selection designated by the guide may be correct, but because of inadequatespace, a premolar or molar may be omitted from the tooth arrangetnent.

The selection of the occlusal scheme of tlie mandibular teeth is covered inChapter 9, Occlusal Concepts.

• Shade Seiection

Shade selection for denture teeth is usually made with a shade guide, which consists ofa number of tooth-shaped tabs with varied degrees of hue, value, and chroma, and

Tooth Selection 193

Figure 11-9 The BlueLine"' Shade Guide. A = Vita ClassicA - D shades. B = Bleach shades. Note the exceptionallywhite shades (010 and 030) intended to match natural teeththat may have been bleached. (Photo courtesy IvoclarVivadent, Inc.)

sometimes characterization (Figure 11-9). The tabs represent the range of shades avail-able for denture teeth. Although manufacturers have recently attempted to developshade cross-matching with other company's products, the shade guide specificallydesigned by the maker of a selected product line is recommended for the mostpredictable and consistent results. Both anterior and posterior shade selections are donesimultaneously and are the same shade in most manufacturers' systems.

The selection of shade is veiy difficult fbr some patients because it is not a scientificprocedure. The following aids are helpful:

1. The shade of teeth on any previous dentures is often the shade of choicefor patients.

2. Although teeth tend to darken over time, there is no specific shade ofartificial teeth that can be used for a given age group.

3. Tbe selection of tooth shade may be based upon die facial complexion.The least conspicuous shade is often the best choice.

4. Make use of any pre-extraction shade determination.5. Recentiy extracted teeth may be useful, but caution is advised. Extracted

teeth tend to lighten in shade with dr>ing or storage in disinfectant solu-tions.

6. Listen to the patient's desires.

Many patients have the misconception that their natural teeth were "pure white,"so the clinician must be careful wiien beginning tiie shade selection. Showing the patientthe entire shade guide is not recommended—at least tmtil an initial shade range isselected. This is because many patients will immediately focus on the lightest shade avail-able regardless of skin complexion and other considerations.

Compare possible shades by holding several likely tabs adjacent to the patient'sface. The operator may squint his eyes to reduce light intensity'. The tab that disappearsfrom vision first is in better harmony with the facial coloring than the other shades.


Figure 11-10 Shade tab with dark cervical region.

Do not allow the shade at the cenical of the tabs to distract the eye in this process. Thatarea of the dentiu-e teeth will lie beneath tJie ba.se material of the denture, and does notrepresent a final factor in tooth shade .selection (Figtn*e 11-10). Once a preliminaryshade has been determined, tlie actual shade guide tootli should be obsei-ved in threelocations; 1) outside the mouth and beside the cbeek, 2) under the upper lip with justthe incisai edge exposed and 3) under the upper lip with the mouth open and two-thirdsto three-fourths of tbe tootli exposed.

Selection of the shade for the denture teeth should be made, within reason, withthe consent of the patient and the patient's significant other. It is ver>' frustrating to havenewly completed dentures deemed unacceptable simply because the significant otberdoes not approve of the shade or mold of the teeth. It is always wise to select a range oftwo or three shades that seem natural for the patient and then let the patient and thesignificant other make the final decision.

Many patients desire very light shades, and it is tlie dentist's responsibility to pointout that such a choice may appear unnatural. However, some elderly patients do havevery lighdy shaded natural teeth, especially with the advent of bleaching. The gieatesterror in tooth selection is choosing teeth that are too light in sbade and too small in size.

It is very important that the clinician enter the mold and shade selection in thepatient's chart for future reference. Ifa repair or denture replacement becomes neces-sary, it may prove very difficult or impossible to exactly match the pre\ioush' selectedtooth mold and sbade. Even a very minor change in sbade or mold selection can lead tofailure in the eye of the patient.

References

Groba, R. E.: Dollars and sense of dentures in your practice. Dental Economics November2006:96:84^.

Mavroskotifis, F., Ritchie. G. M.; Na-sal widtii and incisive papilla as guides for the selection andarrangement of maxillarv' anierior teeth. J Prosthet Dent 1981;45:592-7.

Scrandrett, F. R., Kerber, P. E., Umrigar, Z R.: A clinical e\-aluation of techniques to determine thecombined width of the maxillarv- anterior teeth and the maxillary central incisor. T Prosthei Dent1982:48:15-22.

Young, H. A.: Selecting the anterior tooth mold. J Prosthet Dent 1954:748-60.

Tooth Selection 195

1. The collection of information for use in denture tooth selection begins:a) during contouring and marking of the occlusion rims.b) at the esthetic try-in appointment.c) with the introduction of tlie dentist and patient.d) after the casts have been mounted on the articulator.

2. Sources of information for anterior tooth mold selection include:a) patient photographs.b) diagnostic casts of tlie patient's natural dentition.c) existing dentures.d) record bases and occlusion rims.e) all of the above.

3. The high smile line scribed into the wax of the maxillary occlusion rimusually indicates the minimum incisogingi\'al height of the maxillary anteriorteeth to avoid a "gummy" smile.a) trueb) false

4. The factors of age, sex, and persotiality can be useful in developing an esthet-ically pleasing denture. This has been proven in several scientific studies.a) both statements are true.b) both statements are false.c) the first statement is true, and the second is false.d) the ftrst statement is false, and the .second is true.

5. The selection of molds for denture teeth is the responsibility of the:a) dental assistant.b) patient.c) detitist.d) laboratory technician.

6. The overall mesiodistal width of the mandibular posterior teeth is governedby the amount of space available from the distal end of the canine tooth tothe beginning of the slope to the retromolar pad.a) trueb) false

7. Recently extracted teeth may be unreliable sources of shade information dueto the effects of drying or storage in disinfectant solutions.a) trueb) false

8. The most important source of shade information is the:a) tootli manufacturer.b) dendst.c) patient.d) photograph.


9. The shade that stands out most strongly when the operator squints the eyesis the best choice for harmony with tlie patient's complexion.a) trueb) false

10. The most common errors in denture tooth selection are too light in shadeand too small in size.a) trueb) false

C H A P T E R

_f Tooth Arrangetttent

Dr. Carol A. LefebvreDr. John /?. Ivanhoe

197


The anterior and posterior denture teeth must be arranged to meet the esthetic, func-tional, and phonetic needs oí the patient. Esthetic and functional guidelines were usedwhen contouring the occlusion rims at the maxillomandibular records appointment, andthe desired anterior and posterior facial and buccal contours as well as the plane ofocclusion were established. The midline was also marked. These previously contouredoccltision rims serve as the guide for the preliminary arrangement of the denture teeth.

Generally the teeth are arranged in the following order: (1) maxillary anteriorteeth—following the maxillary occlusion rim, (2) mandibular anterior teeth—using theocclusion rims and maxillary teeth as guides, (3) mandibular posterior teeth—using theanterior teeth, retromolar pads, and residual ridges as guides and (4) maxillar)' posteriorteetii—using the mandibular posterior teeth as guides.

r General Considerations for the Arrangement of the Anterior Teeth

1. The midline of tlie teeth should coincide with the facial midline(Figure 12-1).

2. For most patients, the position of the incisai edge of the maxillar)- ante-rior teeth provides esthetics and phonetics, while the position of thecervical portion, or necks, of the teeth and the fullness of the maxillaiydenture base determines lip support (fullness ofthe lips) (Figure 12-2).

3. The labial surfaces of the maxillary anterior teetii should generally beplaced slightly labial to the surface of die labial fiange. WTien viewed fromthe tissue side of the denture, a small but consistent amount of toothshould be present beyond the denture fiange (Figure 12-3).

4. A vertical overlap of the anterior teeth is not indicated unless specificallydetennined bv the clinician.

Figure 12-1 When arranging the central incisors, thedental laboratory technician will match the midline asmarked by the clinician. The midline will often match themiddle of the philtrum of the patient.

Tooth Arrangement 199

Figure 12-2 The position of the incisai edge of a maxillaryanterior tooth generally provides for phonetics and esthet-ics, whereas the cervical portion, or necks, of the teeth andthe fullness of the denture base determine lip support.Note that the position of the necks of the teeth and theIncreased fuMness ofthe denture base provides moreiip support in diagram A than it does in diagram B.

Figure 12-3 Note that, generaily, a smaii but consistentamount of tooth should extend beyond the denture fiangewhen viewed from the tissue side of the denture.

Maxillary Anterior Tooth Arrangement

Although asyinmetrv- can be esthetically pleasing, and an irregtilar alignment ofthe ante-rior teeth may be quite estlietic, {Figure 12-4) most patients desire the incisai edges ofall teeth to be on the same plane, no rotation of tbe indi\idual teetb, no diasmias, and a


Figure 12-4 This tooth arrangement illustrates theesthetic effects of completing an irregular arrangementof the anterior teeth. Note that, by rotating the caninesproperly, the distal halves of the teeth are not visible.This dramatically improves the esthetics of the tootharrangement.

very light tooth shade. Patients also generally desire no more than a moderate horizon-tal overlap of tlie opposing anterior teeth.

The exception is patients with existing dentures, who desire the arrangement of theteeth of the new denture to mimic those of tlie existing denture. Occasionally patientsreceiving immediate complete denttircs also desire that tlic artangement of the dentureteeth match the aiTangement of the natural teeth. For these patients, it is advisable toask if they desire that the new tooth arrangement mimic the existing one. If so, an irre-versible hydrocolloid impt ession of the existing denture should be made, a cast poured,and the cast forwarded to the dental laboratory technician to be tised as a guide inthe tooth arrangement. If tlie denture is to match existing natural teeth then a pre-extraction cast of the natural teetii should be included.

For the average complete denture patient, the maxillary central incisors should bepositioned so tliat the midline is in harmony with the midline of the face, and so that thelong axes are parallel with the long axis of the face. The labial position should tnatch thelabial surface of the occltision rim, as was contoured during the maxillomandibularrecords appointment. A correctly marked midline will generally match the middle of thephiltrum, (Figure 12-1 ) will usually coincide wiUi the middle of the incisive papilla, andmay or may not match the position of the labial frenula.

The alignment of the maxillary- lateral incisors can be slightly altered to create anatural-appearing denture. Changes include altering the: (1) inclination of the long axis,ustially distally (2) relationship to the incisai edges of the central incisors, (3) toothwidth, (4) levels of the gingi\'al margins, (5) tooth shade, and (6) shapes of incisai edges,angles, and proximal surfaces. However, as pre\iously mentioned, most patients do notdesire a characterized arrangement of the teeth, but prefer a symmetrical airangement.

The maxillary canines are generally positioned so that the incisai cusp tip is at thesame level as the central incisors. The long axis of the maxillarv' canine should be verti-cal or inclined distally, with the cervical portion appearing prominent because of its


labial position in relation to the lateral incisor. For esthetic purposes, the canine shouldbe rotated so Uiat the distal half of the facial surface of the tooth is barely usible whenviewed from the anterior (Figure 12-4).

Mandibular Anterior Tooth Arrangement

WTien arranging the mandibuiar anterior teeth, it is generally desirable to have somehorizontal and/or vertical separation of the opposing anterior teeth while in centricocclusion. This arrangement will minimize premature contact of the anterior teeth, elim-inating potentially excessive forces on the weaker anterior residual ridges. It should benoted that the maxillar)' anterior residual ridge is composed primarily of canceliousbone, which will rapidly resorb in some patients when subjected to excessive forces. Theincisai edges ofthe mandibular teeth should not be placed forward ofa plane perpen-diculai- to the center of the labial vestibule, and under no circumstances should they bepositioned over tiie anterior land area ofthe cast (Figure 12-5). Positioning the teeth insuch a manner will generally result in significant denture instability during fimcUon dueto the cantilever effect caused by positioning the mandibular teetii anterior to tlie resid-ual ridge. Mandibular canines should usually be positioned in the same relative manneras the maxillan- canines.

The mandibular central incisors are not initially arranged witb the maxillary ante-rior teeth vertically overlapping the mandibular, unless specifically determined by theclinician. Vertical overlap is generally indicated for esthetic, phonetic, or functional

Figure 12-5 Because of potential undesirable cantileverforces, the incisai edges of the mandibular anterior teethshould not be arranged beyond the center of the vestibule.These teeth are in excellent position. To minimize a signifi-cant horizontal overlap of the opposing anterior teeth, theincisai edges may occasionally be positioned over the landarea. However, position of the teeth in this manner is acompromise.


reasons. Vertical overlap of the anterior teeth is not allowed when arranging the teeth fora nonbalanced type of occlusion. Therefore, when vertical overlap of the teeth isrequired, the dental laboratory technician must anticipate the arrangement of the poste-rior teeth in a balanced occltision.

The degree of horizontal and vertical overlap of the anterior teeth determines theincisai guidance of the arrangement. The teeth should not be arranged with such a steepincisai guidance that the posterior teeth disclude in excursive movements. Christensen'sphenomena, lhe space that occtirs between opposing occlusal surfaces during excursivemovements, is not acceptable for complete denture patients. Generally, an incisai guid-ance more than 20 degrees greater than the anterior-posterior angulatii)n of the planeof occlusion is contraindicated. It is difficult, if not impossible, to create a balanced occlu-sion with an excessively steep incisai guidance. The dental laboratory technician shouldattempt to minimize the steepness of the resultant incisai guidance whenever possible.Tiiis can be accomplished by either decreasing the vertical overlap or increasing the hori-zontal overlap as much as is permissible (Figure 12-6). Decreasing the steepness of theincisai guidance minimizes the separation of the posterior teeth during excursive move-ments and hence the requirement for excessively steep cusp heights, compensatingcurves, and/or effective cusp angles when arranging the posterior teeth.

The opposing anterior teeth should contact ligbtiy in the protrusive and workingmovements. Anterior teeth tliat do not contact in the protiTisive movetnent cannot incisethin foods such as lettuce, which may be a significant problem for many patients.

Figure 12-6 The incisai guidance of the articular ¡s theresult of the horizontal and vertical overlap of the anteriordenture teeth and may be altered, within limits, by thedental laboratory technician while arranging the dentureteeth. The incisai guidance of the denture teeth and incisaitable is approximately 45 degrees in diagram A. In diagramB the vertical overlap of the teeth has been reduced, butthe incisai guidance has not changed because the horizon-tal overlap was also decreased. The incisai guidance indiagram C has been reduced because the vertical overlapof the teeth has been decreased while the horizontal over-lap has remained constant.The incisai guidance in diagramD has also been reduced by increasing the horizontal over-lap while maintaining the vertical overlap.


Figure 12-7 The long axis, incisai edges, and facial align-ment of these teeth have been arranged to provide excel-lent esthetics.These teeth have a horizontal overlap whenin centric occlusion. However, this illustration demon-strates the "kissing contacts" desired when the teeth aremoved into the protruded relationship.

The dental laboratory technician should ensure that the individual tooth orienta-tions combine to make the complete arrangement harmonize with die shape and rela-tive positions ofthe residual ridges (Figure 12-7).

Gênerai Considerations for Posterior Tooth Arrangeinent

1. As mentioned previotisly, vertical overlap of the anterior teeth is occa-sionally indicated due to the esthetic, phonetic, or functional demands ofthe patient. However, becatise the need for an overlap is often not obvi-ous during the maxillomandibular records appointment, initially anonbalanced type occlusion is generally created for patients. If, at thetrial insertion appointment the need for vertical overlap becomes obvi-ous, it is necessary' to make protrusive or lateral interocclusal records toset the condylar inclination ofthe articulaior Additionally, the clinicianmust determine the desired vertical overlap, select anatomic mandibulardenture teeth, and return the an-angement to tiie dental laboratory tech-nician. The denture teeth mtist be rearranged into a balanced occlusionand the tria! insertion appointment repeated.

2. To minimize mandibular denture dislodgement during function, dentureteeth should not be placed beyond the point at which the residual ridgebegins to slope up toward the retromolar pad. If insufficient antero-posterior space exists to place ail fotir posterior teeth, the first premolaror second molar is generally eliminated, depending upon the spaceavailable. A second molar vsill not be placed in this arrangement

204 Textbook of Compiete Dentures

(Figure 12-8). For improved masticatory function, it is generally better toeliminate the lirst premolar rather than the second moUr, wben possible(Figure 12-9).M^en completing a nonbaianced occlusion, the mandibtilar posteriorteeth are arranged on a flat occlusal plane with the long axes of the poste-rior teeth arranged perpendicular to the plane of occlusion (Figure12-10). For balanced occlusion, the posterior teeth are arranged to a

Figure 12-8 To minimize mandibular denture disiodge-ment during function, denture teeth should not be placedbeyond the point at which the residual ridge starts to slopeup toward the retromolar pad. A second molar will not beplaced in this arrangement. Although not seen, X indicatesthe beginning of the slope up to the retromolar pad.

Figure 12-9 To improve chewing potential, the firstpremolars have been eliminated from this arrangement,due to the lack of space for ail four posterior teeth.


Figure 12-10 Note that the mandibular posterior teeth arearranged on a flat occlusal plane with the long axes of theposterior teeth arranged perpendicular to the plane ofocclusion for a nonbalanced occlusion.

Figure 12-11 Note that, for a balanced tooth arrangement,a curved template is used.This creates an anterior-poste-rior and medial-lateral curvature of the occlusal surfaces.In complete dentures, this is called a compensating curveand is necessary to create the excursive contacts requiredfor a balanced occlusion.

compensating curve (Figure 12-11). See Chapter 9, Occlusal Concepts,for further explanation.The central grooves and centers of the marginal ridges of the teethshould lie in one continuous line, which may be straight or have a slightctirvature with the concavity being directed lingually or palatally(Figure 12-12).


i

Figure 12-12 The central grooves and centers of themarginal ridges of the teeth in this arrangement lie in onecontinuous line, which may be straight or have a slightcurvature with the concavity being directed lingually orpa lata My.

Manditiular Posterior Tootti Arrangement

The antero-posterior placement of the mandibular posterior teeth is relatively easy todetermine. The distal surfaces of the canines are the most anterior position for place-ment of the first premoiars. The disuU limit to placement of mandibular molars is thebeginning of the incline ofthe retromolar pad (Figure 12-8). By not arranging mandibu-lar teetii on the incline, the patient will not function in tliis area, and thus denturedislodgement during chewing is minimized. If no incline exists to ser\'e as a guide, thedenture teeth sbould not be placed over the retromolar pad. The maxillaiT teeth shouldnot be placed on the slope leading down to the hamular notches.

The medial-lateral placement ofthc mandibuiar posterior teeth is well established.The premoiars should be arranged so that the buccal surface of the fii'st premolar alignswith tlie buccal surface of the canine. In achie\ing this relationship, the central grooveof the first premolai" should align with eitlier the contact poitit between the canine andlateral incisor or the tip ofthe canine (Figure 12-13). Posteriorly the mandibular molars,particularly the second molar, should be positioned almost directly over the remainingresidual ridges (Figure 12-14). To help create this alignment, a line can be drawn alongthe crest of the mandibuiar residual ridges. Because tliis line cannot be seen once therecord base is seated, it is necessary to mark the land areas of the cast, indicating wherea continuation of this line would cross the land area (Figure 12-15). A guideline can nowbe visualized connecting the anterior (canine) to posterior (crest of ridge) guides. Thecorrect alignment ofthe premoiars and molars is indicated when the central grooves arecentered on this line and all central grooves align with each other (Figure 12-12).

The vertical placement of the mandibular posterior teeth is also well described.In the anterior, the teeth are set to the height of the canines. Posteriorly, the plane of


Figure 12-13 To maintain the proper alignment ofthe buccal surfaces of the mandibular canines and firstpremolars, the central groove of the first premolar shouldbe aligned along a line extending from the tip of thecanine and the mesial contact point of the canine andlateral incisor.

Figure 12-14 The central groove of the mandibularsecond molar is positioned almost directly over theremaining residual ridge.

occlusion is generally placed at the level of the middle to upper one-third of the retro-molar pad and ideally is located midway between the maxillan and mandibular residualridges and parallel to bo\h ridges (Figure 12-16). When alteration of the vertical heightof the occlusal plane become necessary; generally because of a lack of interocclusal clear-ance, tiie plane shotild be lowered whenever possible. Low ering the plane will decreasethe height of the denture teeth above the mandibular residual ridges, decrease cantileverforces, and increase the stabilitv of tlie mandibular denture.

Figure 12-15 The green lines indicate the center of the residual ridgeson this master cast. It is important that as many posterior teeth aspossible be positioned directiy over the residual ridges for properfunction and denture stability. The ideal position ofthe distal-mostdenture tooth (usually second molar) is indicated (X).This tooth shouldideally be place directly over the residual ridge and just anterior to theslope leading to the retromolar pad.The most posterior tooth is gener-ally the most important tooth to center over the residua! ridge. Thisis because anteriorly the premolars must align somewhat with thecanine and therefore are often placed slightly buccal to the ridge crest.Note that, on the right side, marks have been drawn on the land areasof the cast (Y) indicating the extension of the green line. When therecord bases and occlusion rims are placed on the cast, a straightedge can be placed between these marks, and a line can be drawn intothe occlusion rim indicating the center of the ridges.This line indicatesthe proper buccal-lingual alignment of the posterior teeth.

Figure 12-16 Ideally the posterior plane of occlusion is located atthe level of the middle to upper one-third of the retromolar pad (A),midway between the opposing residual ridges, and parallel to bothridges.

208


W Maxillary Posterior Teeth

When arranging the teeth for the trial insertion appointment, the posterior teeth areinitially arranged primarily to obtain good centric occlusion contacts. There is lessconcern for potential excursive prematurities at this time because tbe potential for excur-sive prematurities for a nonbaianced occiusion are minimal. If a balanced occlusion isbeing created, tbe condylar inclinations of the articulator have not yet been set andtherefore excursive contacts and prematurities cannot be properly e\aluated at this time.

For a iingualized occltision, eitlier balanced on nonbaianced, tlie maxillaryposterior teeth are arranged so that the buccal cusps of the opposing teetli are approxi-mately 0.5 mm above the antagonist teetb when tbe artictilator is moved into the work-ing position (Figure 12-17), Cross-tooth contact of opposing working side posteriorteeth is not indicated (Figure 12-18). This arrangement minimizes the difiñculty inarranging the denture teeth and in correcting excursive prematurities at insertion.

For a conventional balanced occlusion, tbe buccal and lingtial ctisps of the oppos-ing teeth are arranged into a "tight" intermeshing design (Figure 19). When correctlyarranged there is: (I) minimal spacing betAvccn the opposing occltisal surfaces in centricocclusion, (2) anterior and bilateral cross-arch contact in all excursive movements, andcross-tooth contact on tlie working side (Figure 12-18).

Additionally, an arrangement thai results in tbe buccal surfaces of both the niaxil-Iai7 and mandibular teetb being aligned vertically is contraindicated because of tbepotential for cbeek biting. Tberefore, the maxillary posterior teeth, especially secondmolars, must be aixanged to provide adequate buccal o\erlap to minimize cheek biting(Figure 12-20). To provide this alignment, ideally tlie lingttal cttsps of the maxillary teethare centered on the central grooves and marginal ridges of the mandibular teeth(Figure 12-21), which allows the buccal surfaces of the maxillary teeth to be more

Figure 12-17 For a iingualized tooth arrangement, thebuccai cusps of the maxiiiary teeth should be at least0.5 mm above the mandibular buccal cusps when the teethare in the woriiing movement. This is an exampie of anonbaianced linguaiized arrangement.


Figure 12-18 Cross-tooth contacts (D) are not seen withlingualized occlusion arrangements (A) however, thesecontacts are necessary for a conventional balanced occlu-sion (B). C indicates cross-arch contacts.

Figure 12-19 A "tight" alignment of the posterior teeth isnecessary to achieve a conventional balanced occiusion.The requirements for cross-tooth contacts in excursivemovements and a "tight" alignment of the teeth compli-cate the tooth arrangement and eventual occlusal correc-tion procedures for balanced occlusion.

buccally positioned than the buccal surfaces of the mandibtilar teeth (Figure 12-20).However, in attempting to maintain the opposing teeth over their respective residualridges this ideal alignment may not be possible. Therefore, it may be nece.ssar\' to slightlymove one or more teeth, particularly the second molars, in a non-ideal tooth posidon toprevent this vertical alignment. However, when arranging the mandibular teeth, thecentra] grooves of the teeth should continue to align and fall within a triangle as drawnfrom the ctisp tip of the canine and continuing to tlie buccal and lingual of the retro-molar pad. (Figure 12-22).


Figure 12-20 Buccal horizontal overlap of the posteriorteeth, especially for the second molars, is required to mini-mize potential cheek biting.The arrangement may consistof conventional overlap with the maxüiary teeth morebuccally positioned than the mandibular teeth, as in thisillustration, or it may be in the form of a reverse articula-tion (crossbite) alignment, as seen in Figure 23.

Figure 12-21 To achieve the conventional buccal overlapof the posterior teeth, the lingual cusps of the maxillaryteeth are positioned to contact the central groves andmiddle of the marginal ridges of the mandibular teeth.Theideal positioning of teeth is illustrated by the red dots inthis illustration.

Long-term studies indicate that, when Ú\e natural teeth have been extracted, themandibuiar ridge resorbs downward and outward white the maxillar)' ridge resorbsupward and inward. Because of these resorptive patterns, it may be necessaiy to create areverse aiticulation (crossbite) for the posterior teeth. The reverse articulation (cross-bite) may exist on all the posterior teeth (Figure 12-23) and is termed a full or complete


Figure 12-22 While there is some flexibility in the exactpositioning of the mandibular teeth in relation to the resid-ual ridge, the central grooves of the mandibular teethshould be arranged within a triangle, as drawn from thecusp tip of the canine and continuing to the buccal andlingual of the retromolar pad.

reverse articulation (crossbite). The maxillary buccai cusps become the functional cuspsin this type of occlusion. However, a reverse articulation (crossbile) alignment of theteeth may occur only in the second molar area, while a normal alignment exists in thefirst premolar area (Figure 12-24). This may be called a partial reverse articulatioti(crossbite), and it results in the second premolai-s and first molars being arranged astransition teeth. Then central grooves of the teeth should continue to be aligned. Thisarrangement is acceptable and in fact, esthetic in many patients. WTien arranging teethin a reverse artictilation (crossbite) situation, the teeth may require occiusal adjustmentto allow proper alignment.

When completed, both a balanced and nonbalanced occlusion will have bilateralcontacts of al! posterior teeth while in centric occlusion to minimize forces on the ante-rior residual ridges. Many clinicians do not desire anterior contacts while in centric


Figure 12-23 Complete reverse articulation (crossbite) ofthe posterior teeth. Note that all maxillary teeth are posi-tioned more palatally than the mandibular teeth, resultingin the buccal cusps serving as the functional cusps in thistype arrangement.This arrangement may be requiredbecause of the resorptive patterns of the opposing ridges.

Figure 12-24 A partial reverse articulation (crossbite) ofthe posterior teeth. Note that the first premolar is in anormal alignment, the buccal surfaces of the first molarsare in a vertical alignment (not ideal but necessary froman esthetic perspective), and the second molars are in areverse articulation (crossbite) alignment.

occlusion. In excursive movements, a nonbalanced occlusion should exhibit bilateralsimultaneous contact of the posterior teetii for one or more millimeters around thecentric occltision position. Christensen's phenomena may exist beyond this area.Generally a balanced occlusion will exhibit more excursive posterior contacts distributedover a wider range of movements than a nonbalanced occlusion. A balanced occltisionwill have both bilateral contacts of tbe posterior teetii and simultaneous anterior contactsin all excußive movements. Protnisive contacts shotild exist from centric occlusion until

214 Textbooit of Compiete Dentures

Figure 12-25 For a baianced occiusion to have good"timing," one or more posterior contacts, bilateraiiy, mustbe maintained through the entire excursive movement. Inthis exampie, the casts have been moved into a protrudedreiationship until the incisai edges of the opposing centralincisors are in contact. Note that muitipie contacts arepresent posterioriy. Contacts must also be present on theopposite side of the arch.

the central incisors are in the incisai edge-to-incisal edge position (Figure 12-25).Working and nonworking contacts sbould exist until tbe working side canines are cusptip-to-cusp tip (Figure 12-26). When contacts correctly exist throiigb this range, thetooth arrangement is said to have "good timing." Tbis arrangement will require someocclusal adjtistments to eliminate prematurities on some teeth, whicli cannot becompleted until tlie condylar guidances have been correcdy set on tbe articulator.

Figure 12-26 The dentures depicted in Figure 25 havebeen moved into a working position. Note that muitipiecontacts exist, and the canines are edge-to-edge.Nonworiiing contacts on the opposite side of the arch mustalso be present.


ReferencesFenton, A. H.: Selecting and arranging prosihetic teeth and occlusion for the edentulous patient.

In Zarb, GA., Bolander CX.. eds. Prosthodcnuc Treatment for Edentulotis Padents. 12th ed. St.Louis: Mosby Inc; 2004. pp. 308-328.

Parr, G. R.: .Arranging the artificial teetii for the trial denture, hi Rahn, A. O., Heartwell, G. M.,editors. Textbook of complete deniure.s. .'jth ed. Philadelphia: Lea Sc Febiger; 1993. pp. 351-356.

Rahn, A. O.: Developing complete denttue impressions. In Rahn, A. O., Heartwell. G. M., editors.Textbook of complete dentures. 5lh ed. Philadelphia: Lea & Febiger; 1993. pp. 323-.350.

Sowter, J. B.: Gu.stom impression travï. In Barton, R. E., ed. Remo\-able Prosthodontic Techniques-Revised edition. Ghapel Hill: University of North Carolina Press; 1986. pp. 58-79.

Tallgren, A.: The continuing reduction of the residual alveolar ridges in complete denture wearer:a mixed-Iongtidunal study covering 25 years. J Frosthet Dent 1972;27:I2()-32.

The Glossary of Prosthodontic Terms. J Prosthet Dent 2005;94(l):23, 69.

1. For most padents, when considering the arrangement of the maxillary ante-rior teeth, what determines esthetics? What determines the fullness of thelips (lip support)?

2. Most padents desire symmetrical arrangement of the anterior teeth withminimal variations that might provide a more natural look. Which twogroups of paùents might he an exception to this statement?

3. Alterations of the maxillary lateral incisors can he made to help create amore natural-appearing denture. What changes might he considered?

4. The alignment of the canines is important from an esthetic standpoint.How shottld canines he arranged in comparison to the central and latei alincisors?

5. WTiy is it itnportant to minimize the vertical overlap of the anterior teethwhen arranging these teeth for a halaiiced occlusion?

6. In what direction do the crests of the residual ridges resorb followingextractions, and what might tiiese resorptive patterns result in?

7. What anatomical feature limits the most posterior position of a mandibuiarmolar?

8. Ideally, how should the plane of occiusion relate to the retromolar pad,the interocclusal space between the ridges, and the ridge crests themselves?

9. If an adjustment is necessary to the vertical position of the plane of occlu-sion, which arch should he favored and why?

10. How should the buccal surfaces of the opposing, primarily second molars bealigned and why?


1. For most patients, the position of the incisai edge of the maxillary anteriorteeth determines esthetics, while the cer\ical portion, or necks, ofthe teethand the fullness of tlie maxillary denture base determine lip suppon (fuU-ness of the lips).

2. The exceptions are those patients with existing dentures, who would like thearrangement of the teeth of the new denture to mimic tiiose of the existingdenture. Occasionally patients receiving immediate complete dentures alsodesire that the arrangement of the denture teeth match the arrangement oftiie natural teeth.

3. Changes include; (1) inclination of the long axis, (2) leiationship to tlieincisai edges of the central incisor, (3) tooth width, (4) levels of the gingivalmargins, (5) tooth shade, and (6) shapes of incisai edges, angles, and proxi-mal surfaces.

4. The long axis of the maxillar)' canine should be vertical or distally inclinedwith the cervical portion (neck) prominentiy oriented because of its labialposition in relation to the lateral incisor. For esthetic purposes. Uie canineshould be rotated so that the distal half of the facial surface of the tooth isnot visible when \iewed for the anterior.

5. Decreasing the steepness of the incisai guidance minimizes the separation ofthe posterior teeth during excursive movements, and hence the require-ment for excessively steep cusp heights, compensating curves, and/or effec-tive cusp angles. This i eduction simplifies the an angement of the teeth andeliminates prematurities in both the laboratory and clinic remount phases oftreatment.

6. Long-term studies indicate that, when the natural teeth are lost, themandibular residual ridge resorbs downward and outward, while the maxil-lar)' residual ridge resorbs upwaid and inward. Becatise of these resoiptivepatterns, it is often necessary to create a reverse articulation (crossbite) forthe posterior teeth.

7. The most distal mandibuiar molar should be set no further posteriorly thanthe beginning of the incline leading to the retromolar pad.

8. The plane of occltision should ideally split the distance between the maxil-larv' and mandibular ridges, be parallel to both ridges, and be at the level ofthe middle to upper one-tiiird ofthe tetromolar pad.

9. If interarch space or esthetics are significant problems, the position of theplane of occlusion may be adjusted either superiorly or inferiorly to a smalldegree. When making adjustments to tile height of the occlusal plane, tliemandibular arch should be favored whenever possible because of thedecreased stability ofthe mandibular denture.

10. A buccal horizontal overlap ofthe posterior teeth, especially second molars,is required when airaiiging the opposing teeth. An airangement that resultsin the buccal surfaces of both the maxillar)' and mandibular teeth beingaligned vertically is contraindicated becau.se of the possibility of creating acheek-biting situation.

C H A P T E R

Trial InsertionAppointment


217


Tlie esthetic and functional tial insertion is the clinician's final opportunity toensure that the deiittires vvill meet the estlietic, phonetic, and ftinctional demandsof the patient and his or her significant other. Additionally it is the final opportunity toensure that the opposing casts are in the correct horizontal and vertical relationshipon the articulator before the dentures are processed. Using the criteria for denture tootharrangement found in Chapter 12 (Tooih Arrangement), all mechanical requirementsof anterior and posterior tooth position should be verified on the articulator. The clini-cian must critically and objectively evaluate the degree to which the dentures meet thedesired goals of each previous step. If there is any concern about some aspect ofthe denture, it must be addressed now.

If all of the previous procedures have been accomplished well, and the patientis reasonable in his or her expectations, this can be a short and rewarding appointment.If shortcuts were taken, and the patient is exacting or has unrealistic expectations, thiscan be a long and frustrating appointment. In either case, it is much easier to makefinal adjustments at this point while the dentures and teeth are still in wax. Once adenture is processed, changes can be expensive or even impossible to accomplishwithout starting over.

The trial insertion appointment will make assessments of the esthetic position ofthe denture teeth, facial support, phonetics, occluding vertical dimension (O\'T)),occlusal scheme, and the centric occlusal position. This procedure will also give thepatient an opportunity to see the esthetic results from the previous deliberations duringthe maxillomandibular records appointment and the tooth selection process. This is alsoan excellent opportunity for the patients significant other to see tlie proposed new pros-theses. It is often the significant other's response to the new dentures that will have tliemost infiuence on tlie patient's acceptance of their new appearance.

The trial insertion appointment should begin with adjustment of the record basesto ensure comfort and proper fit. If retention is a problem, it is advisable to use an adhe-sive to keep the record bases stable during the trial insertion procedure. The stabilit)' andretention is necessary for proper inspection and will also give the padent confidenceabout his or her new dentures. After fitting the record bases, a sy-stematic evaltiation ofthe procedures completed during the maxillomandibular records appointment isconducted, beginning with tlie evaluation of the OVD and centric occlusion position.Most clinicians make a quick assessment ofthe esthetics, but the tendency to concentrateon that area should be avoided tmtil the vertical and horizontal relationships of themounted casts have been evaluated.

I Evaluation of Occluding Vertical Dimension

The same parameters used to detennine the rest vertical dimension (R\T)) and theO\T) at the maxillomandibular records appointment should be used once again tocheck for the proper interocclusal clearance, phonetics, and vertical position of theocclusal plane. The O\D is evaluated first using sibilant sounds, as was done whenmaking the maxillomandibulai' records. The presence or lack of an acceptable degree ofinterocclusal clearance is used to evaluate the O\T). This interocclusal clearance isseen as a very slight separation of the anterior teetii during sibilant sounds and a littlemore space in the posterior areas (Figure 13-1). There should be no contact of the

Trial Insertion Appointment 219

Figure 13-1 Evaluating the interocciusai distance

opposing teeth during speech. If contacts exist, the tentative OVD may have been toogreat, resulting in the O\'D being too close to the RVD. This is often called excessiveOVD. Tlie correct amount of interocclusal distance must be regained by decreasing theOVD. If tlie desired decrease is more tlian 2 mm, a new interocclusal record must bemade in the CR position at the new OVD. To provide room for the recording materialwhen making the new records, the posterior teeth must be removed from either themaxillar\ or mandibular arch. If the anterior teetli prevent the proper O\T) positionfrom being obtained, they must also be removed from the same occlusion rim fromwhich tbe posterior teeth were removed. The OVT) is reestablished and a new maxillo-mandibular recording is made in CR. Tbe mandibular cast is removed from tlie articu-lator and re-articulated using the new recording. Many clinicians will verify tbis newmounting by making anotber maxillomandibular record and ensuring tbat it matchesthe cast relationsbips. The maxillar\- cast is not removed because it was mounted usingthe facebow and tbat relationship must not be lost.

Art excessive amount of space between the teeth may indicate that the tentativeOVD might have been "overdosed" or insufficient- If the desired change is more tlian2 mm, then a new interocclusal record made in tbe CR position is needed. Because ofthe excessive interocchisal distance, there is tisually ample space between the opposingteeth for a new record. Therefore, no posterior teeth need be removed prior to makinga new maxillomandibular recording. Again the mandibuiar cast should be re-articulatedon the articulator, and this mounting sbould be verified.

If the vertical relationship is deemed incorrect, but within 2 mm of being correct,the correction can be made on the articulator. This minimal change is possible on thearticulator because tbe facebow mounting established an arc of closure on the instru-ment similar to that of the patient. Studies have shown a negligible error would be pres-ent from making this minor change. If the necessary change is greater than 2 mm, or ifno facebow^ was tised when mounting tlie maxillary cast, tlien tbe clinician should makea new centric relation record at the proper OXD. Tbis demonstrates the importance ofusing a facebow wben mounting the maxillary' cast on the articulator. By capturing tbisrelationship, the clinician can make interocclusal records that will verify on the articula-tor at a slightly increased or decreased O\T), aiid also can make simple changes to the


OVT) on the articulator without making new interocclusal records. It also simplifies themoiuiting the maxillary cast.

The padent's skeletal relationships may also play a part in e\'a!uating the O\TD. Forexample, a Class 11 patient may have what seems to he excessive vertical and horizontalclearance due to the normal relationships of the residtial ridges in thai skeletal position.Class III patients may exhibit almost no interocclusal distance dtiring speech. This rela-tionship mtisl be taken into account when e\'aluating tlie ftuiction of the prostheses.

Evaluation of Centric Relation Record

An attempt was made during the maxillomandibular records appointment to articulatethe mandibuiar cast on the articulator in the centric relation position as it relates to themaxillaiy ca.st (Figure 13-2). Two tnethods are commotily employed by cliniciatis to eval-vtate and verif)' that the opposing casts are in the corred relationship oti the articulatorat the esthetíc trial inserdon. The first is to simply vistially inspect the closure of thedentures on the articulator and intraorally. They are e\'aluated for complete closure andevidence of inttltiplt- occhtsal contacLs with no slide present.

If the visual inspection is questionable or if the clinician prefers, a new centric rela-tion record is made to verify the horizontal position. The new centric reladon recotd ismade at a slightly increased OVT) to prevent contact of the denture teeth and possibleerrors frotn record base movement. PiS explained earlier, the facebow recording of themaxillar}' cast makes Lhis procedure possible. Place approximately 1.5 mm of passive waxon the occlusal surfaces of the mandibtilar teetii and soften by immersing in water at130"F (Figure 13-3). Place the denture intraorally and guide the patient to close into thewax when the jaws are in centric relation. Closure must be short of tooth-to-tootb contactdue to the chance that contact may displace the dentiue base (Figures 13^ and 13-5).The wax record is not acceptable il' the teeth penetrate the record to make contact.CareftiUy repeat the closure to verify that the patient can close into the record without

Figure 1 3 - 2 IH IL I ÍJ I Murizuntci i cinu ve r t i Ld i p o s i t i o n o f

the dentures at the wax trial insertion stage


Figure 13-3 Aluwax'" placed on the posterior teeth priorto making the verification record

Figure 13-4 Recording at a slightly increased occludingvertical dimension for verification of the centric relationposition - occlusal view

deviation from the centric arc of closure. The new recording verifies the initial record-ing if the opposing denture teeth close completely into the record with no slide. On thearticulator, the unlatched condylar element should remain in its correct position withinthe condylar bousing with no visible movement when the dentures on their casts areseated into the record (Figure 13-6). If the record verifies the original horizontal posi-tion, the clinician can continue with the remaining steps in the trial insertion visit. If therecord fails to match the current horizontal position, another record should be made—just in ca.se the first verification record was made in an incorrect position. If the secondrecord matches the first verification record, the clinician should consider re-articulatingtlie case and rearrange tlie teetii to function correctiy at the new horizontal position.If the cast is re-articulated, another verification record should be made to cbeck the newhorizontal position.


Figure 13-5 Recording at a slightly increased occludingvertical dimension for verification of the centric relationposition - lateral view

Figure 13-6 Condyle post remains in contact with theback wall of the condylar housing when the dentures arefully seated in the record.

• Eccentric Records

Complex occlusal schemes thai require precise mechanical equivalents of the truemandibtilar movement on the articulator will require eccentric records to set the condy-lar guidance. ProUusive position records, or lateral position records, are commonly usedfor this purpose. Refer to the artictilator manual for the preferred method for themachine being used. Lateral, or protrusive, records allow the slope of the articulareminence to be recorded, so adjusünenLs of tiiat parameter can be accomplished on thearticulator. The record captures the relative angle of the articular eminence as the


condyie travels down the slope. Tliis will make the final adjustment of eccentric positionsin a balanced denttire occhision much more accurate.

IntraoraJ protrusive records are made by recording the opposing dentures whilethe patient is in a protrusive position (usually with the anterior teeth end-to-end). It isimportant to stabilize the dentures during this record because the anterior contact maycause the record bases to become unstable. The protrusive record is used to adjust bothcondylar elements. Intraoral lateral records are made with the patient in a lateral posi-tion (usually the canines will be end-to-end). The left lateral record records tiie move-ment down the slope of the right articular eminence and is tised to adjtist the right sideof the articulator. Tlie right lateral record records the movement down the slope of theleft artictilar eminence and is used to adjust the left side ofthe articulator. The casts areseated into the record and the condylar housing, or guide, is adjtisted into contact withthe condylar element, which has moved forward and down. These records are mademore easily when teeth are present, and tlierefore are tistially made at the trial insertionappointment. This allows for adjustments to be made before processing and also willprovide for proper articulator settings for the insertion or placement appointment.

Facial Support. Esthetics, and Phonetics Evaluation

Facial support, esthetic placement of the denture teeth, and phonetics must be carefullyevaluated. Much of the support of the lips surrounding the mouth comes fi-om theproper position and angulations of the teeth and the supporting structures. In a denture,this translates to the artificial teeth and the wax supporting those teetli, and replacingmissing tissues. The proper position and support will affect the quality of speech soundssuch as the T and "v" sounds where the wet-dry Hue of the lower Hp should gentlycontact the incisai edges of the anterior maxillai-y teeth (Figure 13-7). Sound suchas "th" will also produce a gentle contact of the tongue with the lingual stu"faces of the

Figure 13-7 The "f" and "v" sound produces a gentlecontact of the wet-dry line off the lower lip with the incisaiedges of the maxillary teeth.


anterior teetb. The placement ofthe maxillary anterior teeth should follow basic estheticgtiidelines for tooth length and position (See (Chapter lu, Tooth Arrangement). Tbemandibular anterior teeth should be basically the same height as the resting lower lipand follow the same cur\'ature as tbat lip. Tbe evalttation sbould include rest and func-tional positions.

The midline, shade, and other esthetic factors, such as individual tooth positionpreferences, diastemas, and personalized esthetic concerns should be evalttated andcorrected if necessar)' before having the patient review^ tbe wax uial insertion. Tbepatient should evaluate the prostheses using a full-sized mirror at a conversationaldistance. Avoid letting the patient use a small hand-held mirror until after the totalestbetic results have been evaluated. After a genei"a! appraisal, tbe patient can be morecritical witb a smaller mirror if necessary. After tbe clinician and paäent are satisfied, tbepatient's significant otlier sbould be allowed to inspect the prostheses and make theirconcerns known. Listen carefully to patient's concerns at Ulis poiin of tbe evaltiatioii. Ifthe clinician fails to satisfy tbe patient's or the significant other's small estbetic demands,it may result in a general dissatisfaction of tbe prostheses that may be hard to isolate atsubsequent follow up appointments.

• Final Evaluations

Ifa custom gingival denture base shade is to be ttsed, it must be selected at this time(Figure 13-8). Additionally this is the final cbance to ensure tbat the posterior palatalseal has been prepared into the maxillary master cast. Some clinicians have the patientsign 'd consent form that indicates their satisfaction with tbe estbetic results at thistime. Many times this consent form will help when patients have questions concerningthe estbetic results of the final processed dentures. Only after the clinician, patient,and significant otlier are satisfied with all of the above-mentioned criteria sbould thedendires be submitted to the laboratory for denture processitig (Figures 13-9-12).

Figure 13-8 A gingival shade tab is used to pick a customresin shade.


Figure 13-9 Final wax-up ready for processing





References

Swoope, C. C: The try-in—a time for communication. Dent Clin North ,\ni 1970 jul; 14(3):479-Í91.

Travaglini, E. A.: Verification appointment in complete denmre therapy. J Prosthet Dent 1980 Nov;4 4 ) 7 8

1. What assessments should be made during the esthetic and functional try-inappointment?

2. If the interocclusai dist;mce is inadequate and the teeth touch at the restvertical dimension, how is space obtained to make a new centric maxillo-mandibular record at the proper occiuding vertical dimension?

3. If changes need to be made in the vertical position ofthe teeth, but thechange is less than 2 mm, those changes can be made by altering the occlud-ing vertical dimension on the ardculator. True or False?

4. UTiat type of eccentric records can be tised to program semi-adjustablearticulators to make the final occlusal adjustments in lateral posidons moreaccurate?


1. The triai insertion appointment will make assessments of the esthetic positionof the denture teetli, facial support, phonetics, occluding vertical dimension{O\'D), occlusal scheme, and tlie centric occlusal position. This procedure\dil also give the patient an opportunity to see the esthetic results from theprevious deliberations during the maxillomandibular records appointmentand die tooth selection process.

2. To provide room for the recording material when making the new records,the posterior teeth must be removed from either the maxillary or mandibulararch. If tlie anterior teeth prevent the proper O\T) position from beingobtained, they must also be removed from the same occlusion rim fromwhich the posterior teeth were removed.

3. True, if a facebow recording was used to position the maxillaiy cast on thearticulator.

4. Protrusive or lateral excursive records

C H A P T E R

InsertionDr. Kevin D. Plummer

229


The insertion of the completed dentures sbould follow a s>'stematic sequence of proce-dures, including evaluating tbe denture base, attaching tiie mandibular remotmt cast tothe articulator using an interoccltisal record, correcting occlusal prematurities, conduct-ing a final check of the prostheses, and issuing patient instructions. For some patients,this \isit may be time consuming, but it is absolutely necessary that adequate time bescheduled to thoroughly complete each procedure and answer any and all patient ques-tions and concerns.

Botb dentist and patient anticipate with pleasure the appointment for the insertionof the dentures. However, patients receiving their first complete dentures are familiarwith neither the physiologic requirements of denttires nor with the use and care of tbedentures. One ofthe most important steps in tbe insertion appointment is to educate tbepatient on what to expect from denttires. During insertion procedures is an opportunetime to discuss instructions and address concerns of the patient about the use and careof the new prostheses. Providing a w ritten letter of instruction at a previous appointmentwill make this discu.»öion clearer to the patient (Figure 14—1).

INSTRUCTIONS TO DENTURE PATIENTS

A. WHAT TO EXPECT FROM YOUR NEW DENTURES

1. You must learn to manipulate your new dentures. Most patients require at leastthree weeks to learn to tise new dentures, and some patients require more time.

2. Dentures are not as efficient as natural teeth so you sbould not expect to chew aswell with dentures as with your natural teetb. Dentures are better than no teethat all. Start with small bites of easy to manage foods. Do not try to bite witb yourfront teeth. Use the area of the canine teetb to bite foods, but it is even better tocut the food into small pieces before attempting to chew.

3. Speaking will feel awkward for a while. Diligent practice usually enables a patientwith new dentures to speak clearly within a few days.

B. .\DJUSTMENTS

1. You must return to your dentist for follow-up treatment after the dentures havebeen inserted. In nearly ever) instance, it is necessary to make some minor adjtist-ments to the denture.

2. Most patients must make some adjustments in their attitude and habits in orderto wear dentures successfully.

3. If you develop soreness, do not become alarmed. Call your dentist for an appoint-ment. Do not expect soreness to go away by itself.

4. If you are unable to reach your dentist dtiring weekends or holidays, remove yourdentures to prevent excess tissue damage.

C. CLEANING

1. Your dentures and supporting ridges must be cleaned carefully after each meal."Denture breath" is a result of dirty dentures.

2. Clean your gurns with a soft brush and toothpaste.3. Clean your dentures with liquid disb detergent, and gently brush with a soft

denture brush. Many toothpastes are too abrasive to use on the polished denttiresurface.

[Continued)

Insertion 231

4. Soak your dentures at night in a denture cleaner or a \vater/mouth\\"ash solution.5. .\lway5 keep your dentures wet when not wearing them to pt event warping.

D. YOUR ORAL HEALTH

1. Nature did not intend for people to wear dentures. You must, therefore, be ver\'careftil of the supporting tissue.

2. in addition to keeping the dentures meticulously clean, you must rest the tissuesat least eight houi^ a day. Most patieuts find it cotivenient to leave their denturesout at night.

3. The tissues that support your dentures are constantly changing. This will resultin denture looseness. However, looseness can result from many causes. With time,your detitutes will tieed either refitting or leplacement. hi any event, yoti shouldcall yottr dentist for an appointment when you notice exccessive looseness.

4. Annual examinations of the supporting tissue for ahnormalides and to assess thefunction and fit of the denture art- important for your overall dental health.

Figure 14-1 Example of a printed instruction sheet for a denture patient

I Eualuating the Denture Base

Before the insertion appointment, ihe clinician should inspect the denture bases todetennine thai tbe polished surfaces are smooth and devoid of scratches, that no imper-fections on the tisstte surface remain, and that the borders are round with no sharpangles—especially in the frenitm areas.

Next, each denture base should he individually evaluated for accuracy of adapta-tion to the tissues and for areas of excessive tissue/denture base pressure. Excessive pres-sure will result in irritation to the tissue and pain to tlie patient, and tnust be eliminated.It is most likely to occur in tJiose areas in which the rigid denture base must shde into anundercut or contact tissues that are almost noncompressible (Figtire 14-2). To ideniif}'pressure areas, the intaglio surface (tissue side of tlie denture) should be painted with athin film of pressure disclosing paste using uniform brush strokes (Figure 14-3). Thedenture is then inserted and removed. When removed, the pres.sure-disclosing paste andbrush strokes will be undistttrbed in areas of no tissue/denture base contact, exhibitminimal ttniform cotitact in those areas with the desired tissue/denture base contact, orbe wiped olTin tho.se areas of excessive pressure (Figure 14-4 and 14—5). Prior to reliev-ing the resin in the areas of excessive contact areas, this procedure should be repeatedto verif)- thai the markings are correct. It may be ad\'isable to have the patient insert andremove the denture, as the method and path of insertion may vary with two Índi\idtials.

Once positively established, excessive pt essure catised by the resin being placed andremoved from tuiderctu areas are addressed and carefully removed by relie\ing themwith an acrylic bur (Figure 14-6). Tîiis procedure is repeated until positive tissue/denture base contact exists and excessive pressure has been relieved. Excessive pressurein the area of an undercut can occur on the denture flange and, when relieving the area,it must be remembered that tissue/den tu re base contact is absolutely necessary to retainthe border seal of the denture and tbe resulting retention. Excessive removal of denture


Figure 14-2 Bilateral undercuts prevent seating themandibular denture.This area must be adjusted in orderto have the denture seat properly.

Figure 14-3 The initial application of pressure disclosingpaste should leave brush marks visible.

base resin will result in a loss of retention. Areas of exostosis or areas of bone coveredwith tissue that is not displaceable, such as the midpalatal sunire, often appear as pres-sure areas even when the denture is seated with little pressure. WTien these areas appearin Uie pressure-disclosing paste, they are relieved by grinding. Multiple insertions areusually necessary, as relieving one pressure area may reveal another. The most commonpressure ¡u eas are on the buccal slopes of tiie tuberosities on the maxilla. These occurdue to typical processing shrinkage ofthe acrvlic resin and may prevent the denture frommaking uniform contact with the palate and the palatal seal area. Use only finger pres-sure when evaluating these pressure areas. Do not let the patient bite on the dentures toplace pressure. Uncorrected premature occlusal contact may cause the pressure disclos-

Insertion 233

Figure 14-4 Arrows indicate areas of pressure or wipe-off from an undercut.

Figure 14-5 Arrows indicate areas of excessive pressure.

Figure 14-6 An acrylic bur is used to adjust the pressureareas identified by the pressure disclosing paste.


ing paste to be displaced, mimicking pressure areas. A final check of pressure areas maybe made with biting piessure alter the occlusion has been adjusted.

Evaluating Borders

The third step in the insertion appointment is to evaluate the borders and the contourofthe polished surfaces in the mouth. This\vill determine whether the border extensionsand contour are compatible witb the available spaces in the vestibules, the bordersare properly relieved to accommodate the frenum attachments and the refiection ofthe tissues in the hamular notch area and the dentures are stable during speech andswallowing.

Apply disclosing wax to the borders of the maxillary denture in the same manneras the impression compound or hea\y bodied \inyl polysiloxane siloxane material thatwas applied during the border refining procedures (Figure 14-7). Instruct the patient toopen the jaws as in yawning, push the lower jaw forward, and move the lower jaw fromright to left. Disclosing wax is ver\- displaceable, and slight ove rex te usions that mighthave been developed during border molding can be determined (Figure 14-8). Relieveany existing overextensions (lengtii or thickness) by grinding and then polish therelieved area. Appl) disclosing wax to the lemainiiig borders of the maxillary dentureand instmct the patient to smile, speak, laugh, and swallow. Relieve any overextendedareas by grinding, and tlien poiisb the relieved surface. Apply disclosing wax to themandibular denture borders in the same manner. Carefully evaluate the area of the inser-tion of the masseter muscle to make sure adeqviate space exists on the mandibulardenture for the muscle movement during chewing (Figtires 14-9 and 14—10). Thealtered exterior surface of the denture base is smoothed most often with a slurry ofpumice and water. It is polished widi polishing compound and a soft cloth wheel.Finishing and polishing points may be used for small areas. Wliichevei" method is used,all finishing and polishing is completed at a slow speed to prevent heating the acrylicresin, which may cause warping.

Figure 14-7 Disclosing wax applied to a border forevaluation.

Insertion 235

Figure 14-8 The exposed acrylic resin should be slightlyreduced in height where it shows through the wax.

Figure 14-9 The m¿indibu¡ai deníure bdse is overex-tended in the area of the masseter muscle.

Figure 14-10 The border is corrected for proper adaptation.


Correcting Occlusion

The fourth step in the inserdon procedures is the occlusal correction. Occlusal harmonyin complete denttires is necessary if the dentures are to be comfortable, function efFi-cietidy, and to present the supporting structures. It is diíEcult to see occlusal discrepan-cies intraorally witb cotnplete denlures. The resiliency of the supporting soft tissuesand the ahility of the tissues to displace in varying degrees tend to disguise prematureocctusal contacLs. The tissues permit the dentures lo shift; as a result, after the first inter-ceptive occlusal contact, the remaining leeth appear to make satisfactory contact.Patients are seldom aware of faulty occlusion in complete detituies; yet they alwaysseem to notice an improvement after the fault ha.s been corrected. The eye cannot berelied upon lo observe occlusal discrepancies, and tlie patient cannot be dependedupon to diagnose occlusal faults. It is the responsibility of tlie dentist to find and correctthese occlusal discrepancies and ensure that the dentures are free of occlusal dishar-mony.

It must be assumed that there are occlusal faulls in all complete dentures untilproved otherwise. Occlusal faults can be determined by obtaining an interocclusalrecord from liie patienl and remounting the dentures on an artictilaior. These faults canbe corrected with careful selective grinding procedures. Remounting the dentures ontbe articulator and selective grinding procedures should be carried out at the lime ofplacement of tlie dentures. Postponing this important step will lead to a deformation ofthe underlying soft tissues, discomfort, and destruction of Uie supporting bone. Later,tbe occlusal errors may be concealed, making them impossible to locate and correctbecause of distorted and swollen tissues.

Occlusal dishannony in the completed dentures may result from processingchanges tliat occur within the acrylic resin during the packing and decasting of thedenture, undetected errors in registering jaw relatiotis, errors in mounting casts on thearticulator, differences in tissue adaptation between the processed denture bases and therecord bases that were used in recording maxillomandibular relations, and changes inthe supporting structures since the impressions were first made. This is particularly trueif the patient is using other dentures.

There are many intraoral methods for correcting occlusal disharmony. However,the intraoral methods are not accurate enough to ensure proper occlusal contacts ofopposing dentures. The resiliency of the supporting tissues allows the dentures to shift;therefore, markings are frequently false and misleading. The denture hases can movefrom the b;isal seat, causing the teetii in the opposiie side of the arch or tlie opposite endof the arch to contact prematurely and produce an incorrect marking. Placing articulat-ing paper on one side of the arch may itiduce the patienl lo close toward or away fromthat side, .\ich-shaped articulating paper should be placed to minimize this problem, ifan intraoral adjustment is attempted.

Adhesive green ^flrax can be placed on the occhtsal surfaces of the mandibulardenture. Pointe of penetration that occur upon closing with tbe jaws in centric relationmay be marked with a pencil and relieved where indicated. This method may also locatepoints of interference during functional movements. Again, the disadvantage of thismethod is that shifting of the dentures over resilient supporting tissues may give falsemarkings.

Insertion 237

r Patient Remount and Selective Grinding

The patient remount method is to rearticulate the dentures on an articulator by meansof interocclusal records made in the patient's mouth. This is by far the most accurateocc lu t adjustment procedure. It has the following advantages:

1. It reduces patient participation.2. It pennits the dentist to see the procedures better.3. It provides a stable working foundation; bases are not shifting on resilient

tissues.4. The absence of saliva makes possible more accurate markings with the

articulating paper or tape.5. Corrections can be made away from the patient, thus preventing

occasional objections when patients see their new dentures beingaltered.

To carrv' out a patient remount procedure, orient the mandibuiar denture to themaxillarv- denture by means of an interocclusal record witb thejaw^ in centric relation.Place approximately 1.5 mm of passive-type wax on the occlusal surfaces ofthe mandibu-lar teeth and soften by immersing in water at 180°F. Place the denture intraorally andguide the patient to close into the wax when tiiejaws are in centric relation. Closure mustbe short of tooth-to-tooth contact due to the chance that contact may displace thedenture base. Tbe wax record is not acceptable if the teeth penetrate to make contact.Carefully repeat the closure to verif)' the patient can close into the record without devia-tion from the centric arc of closure (Figure 14^11 ). Other materials can be used for thisrecord but passive-tv-pe wax is the material of choice due to its excellent working time,short term high accuracy and ease of use.

Figure 14-11 A remount record in centric relation ismade with Aluwax " as close to the proper occlusalvertical dimension as possible.

238 Textbook of Connplete Dentures

Figure 14-12 The articulator, mounted maxillary remountcast, the mandibular remount cast, and the dentures aregenerally all returned from the dental laboratory. Remountcasts are made by blocking out undercuts on theprocessed dentures and making stone casts.The denturescan be removed and replaced on these casts.

The maxillar)' remount cast was fabricated and placed on the articulator by using aremount index made in the dental laboratory immediately after the dentures wereprocessed, in order to preserve the facebow record. The dental laboratoiy generallyreturns the ardculator with the properly positioned maxillar)^ remount cast and amandibular remount cast (Figure 14—12). After properly orienting the mandibulardenture to the maxillary denture by means of the interocclusal record, seat the mandibu-lar remount cast in the denture and attach it to the mandibular member of the artictila-tor ivith mounting stone (Figures 14-13 and 14—14).

Figure 14-13 The maxillary and mandibular denturesproperly related to each other and secured in their respec-tive remount casts.The casts are secured together for themounting procedure,

Insertion 239

Figure 14-14 Completed remount procedure. Denturesreoriented to the articulator in the centric relation position.

To veiify what has been recorded is the patient's centric occlusion position, makeanother wax interocclusal record in tlie same manner as the first. Replace the dentureson the articulator and, with the condylar elements unlatched, place the teetJi in theindentations in the wax record. The condylar elements shotild rest against the stops.Repeat the procedure until two consecutive records are accepted.

When cusp form posterior teeth are used, and balanced occlusion is desired, it isbest to have an even distribution oí tooth contacts bilaterally. This involves a cusp-to-fossamarginal ridge relation of maxi m ti m interctispation when the jaws are in üie terminalhinge position (See Chapter 9, Occlusal Concepts). When the teeth move to and fromcentric to eccentric positions, the niaxillar\- cusps track in three approximate directions(Figure 14-15). An articulator that travels in a straight path does not travel the same pathas the condyles in the fossae. It has been generally accepted that the error is so negligi-ble that the resiliency of the supporting tissues accommodates for tlie error. There is noscientific proof that this assumption is correct, and this may not be true in all situations.

Rgure 14-15 The direction that a maxillary lingual cuspwill track during mandibular movement. A: Nonworkingmovement B: Protrusive movement C; Working movement


Undoubtedly this error is tolerated by the majority of patients. WTien the jaws are movingto and from centric and eccentric positions, within tbe functional range ofthe teetli ingliding occlusion, the teeth can be altered to maintain harmonious contact on the artic-ulator. Tbis harmonious contact from fossae to cusp tips will not be exactiy repeated intiie tnouth, but is accepted as tlie most accurate adjustment possible.

When the teeth are altered by selective grinding to make simttltaneous cusptip-to cusp tip contact on both sides of tlie arch, and the jaws arc in a right or leftlateral position, balanced occlusion in a static eccentric position exists. Some of tbesestatic contacts may be repeated in the moutb. Wben the mandible is in a straightprotrttded relation with the maxillae and tbe posterior teeth are altered to make cuspcontacts at tbe same time the anterior teeth make incisai edge-to-incisal-edge contact,balanced occlusion in protrusion exists. One may expect this static occlusal and incisaiedge relation to exist in the mouth when the mandible is protruded to the same forwardposition.

Wben teeth are arranged and the anteroposterior horizontal relations of the jawsare even (considered normally related), the buccal cusps of tbe mandibular posteriorteeth and the lingual citsps ofthe maxillarj' posterior teeth maintain the occluding verti-cal dimension by contacting in the fossae and on the marginal ridges of their antagonists.Wheti tbe horizontal position of the mandible is in a more forw ard position tban themaxillae or in a situation where the mandible is larger in a lateral direction than themaxillae, tbe posterior teeth are frequently arranged in a reverse relation{crossbite, or reverse articulatioti). Tbe buccal ctisp tips of tbe tnaxillar)' posterior teetband the lingual cttsp tips of the mandibular posterior teetii maintain tiie occluding verti-cal dimension. After the occlusal surfaces of the teeth have been altered by grinding toachieve balanced occlusions with the jaws in centric relation, the cusps that maintain theoccluding vertical dimension are not altered in subsequent adjtistments.

I HSelective Grinding of Anatomic Teeth in a Balanced Occlusion

In tbe first step of selective grinding, cusp form teeth are altered by reshaping to obtainbalanced occlusion wben the jaws are in centric relation. Occlusal balance in a lateraldirection is obtained by having all of the posterior teetb and the canines in contact ontlie working side and posterior contact only on the non-working side. In protrtisivebalance, the anterior teeth should make incisai edge contact at the same time tbat tbetips of the buccal and lingual ctisps of the posterior teeth contact.

Adjust the horizontal and lateral condylar inclinations of the articulator to thesettings dictated by a protrusive interocclusal maxillomandibular relation record (SeeChapter 10, Maxillomatidibular Records and Articulators). Tbe incisai pin sbould beraised off the table and secured.

Witli the condylar elements against the centric relation stops, close the articulatoruntil the posterior teetb are in contact. Tbe anterior teeth should not be in contact.Examine the lingual cttsps of the maxillar\' posterior teeth and the buccal cusps of themandibular posterior teeth. Record the area or areas of premature contact with articu-lating paper. The contacts may be in varving amoitnts and may involve more tban onecusp or tooth. These varying situations make critical evaluation necessar)' prior to grind-ing procedures in the centric position.

Insertion 241

Before grinding or adjtisling the centric contacts, the excursive position contactsshould also be evaluated. With the right condylar element in the centric position, placethe lingual cusps of the maxillarv' posterior teeth in the nonworking relation with thebuccal cusps of die mandibular posterior teeth. This procedure aiso places the buccaland lingual cusps of the maxillar\' and mandibular posterior teeth and the canines intheir working positioti on the opposite side. The teeth are placed in these positions andnot shifted from the centric to the eccentric position with the teeth in contact. When tlieteeth on the nonworking side are not in the correct relation, the error appears on thenonworking or working side. If the nonworking contact is excessive, the working sideteeth will not be in contact. If the working side contact is excessive, the excess preventscontad on Üie nonworking side. If ihe teeüi on tlie working side are too long, there willbe no contact on the nonworking side. If a single tooth is high on the working side, therewill be contact neither on the nonwotking side nor on ihe working side. Record anypremature contacts with articulating paper and repeat the procedure with the left side asthe working side and record the premature contacts. If the cusp is high in the centric andin the eccentric position, reduce the ptemature cusp.

If the cusp is high in tiie centric and not in the eccentric position, deepen thefossae or the marginal ridges. After all intercepdve contacte have been removed in thecentric and full eccentric position, do not reduce the maxiliarj' lingual cusp or themandibular buccal cusp and do not deepen the fossa or marginal ridge of any tooth. Thiswill maintain the centric and eccentric holditig cusp relaiioiiships.

To refine the teeth to retain contact when the articulator is being moved to andfrom centric and eccentric position, additional adjustments are needed. On the workingside, reduce the inner inclines of the bttccal cusps of Lhe maxillary teetb and the lingualcusps of tlie mandibular teeth (BULL rule). On the nonworking side, redtice tlie innerinclines of the mandihular buccal cusps. If it is uecessar)' to eliminate a centric cusp tocorrect balancing prematurities, eliminate the mandibuiar buccal cusp. This maintainstbe centric occhisal contact on the maxillar)' lingual cusp, which will better direct theforces of mastication against the mandibular denture. Tbe mandibular denture is gener-ally less stable than the maxillar)' and will retain length to the lingual cusp, which is oftennecessary to establish protrusive balance. To achieve balance in protrusive excursion,reduce the dista l inclines of lhe maxillary cusps and ibe mesial inclines of the mandibtt-lar cusps. After completing the selective grinding procedtu-es to establish and maintainthe desired occlusion refine the occlusal anatomy.

Selective Grinding of Lingualized Balanced Occlusion

Correcting occltLsal disharmonies in a balanced lingualized occlusion is similar to a fullybalanced occlusion with the exception that oniy the lingual cusps of the maxillaryteeth or their antagonist surfaces are adjtisted. The same basic approach is used to eval-uate where the disharmony existe and then correct it by reducing the mandibular fos.saeor marginal ridges in centric reladon position. After the centric relation position isrefined, the eccentric movemente are adjusted on the slopes of the mandihular ctispsa-s indicated in the fully balanced occlusal adjustment section. Since only the lingualcusps of the maxillary teeth are in contact tliis balanced set up is much less complicatedto adjust.


I

Selective Grinding of Nonanatomic Teath

When noncusp form posterior teeth or a nonbalanced lingualized occlusal scheme areused, and selective grinding procedures are instituted, the occlusal surfaces of the maxil-lar)' posterior teeth are altered to make harmonious contact on the right side and on theleft side when the jaws are in centric relation.

Secure the condylar elements on the articulator against the condylar housings andplace articulating tape over the occlusal surfaces and incisai edges of all of the mandibu-lar teeth. Tap tiie teetii together to record the conuicting areas. Using an acrylic bur,grind the occlusal surfaces of the teeth until simultaneous even contacting areas onthe right and left are developed. The anterior teeth should be sligbtly out of contact inthe centric relation position., but can make a "kissing" contact during lateral excursivemovements. Smooth gliding movements from the centric position to eccentric positionsshould be developed by careful adjustment of opposing surfaces during excursive move-ments of the articulator. Exercise care to maititain the occlusal surfaces of the mandibu-lar arch on a plane.

Stripping Method for The Occiusai Equilibration of Nonanatomic Teeth

The simplest technique to refine the occlusion for cuspless, nonanatomic teetii or anonbalanced lingualized occlusal scheme is die carbomndum stripping technique,which was originally published by Dr. Gronas in 1970. It, like all procedures in dentistry,if followed correctiy, will yield excellent results. The primaiy purpose of nonanatomicposterior teeth, when set on a flat plane, is to eliminate cuspal inferences. Therefore, itis necessar)' during the selective grinding procedure in this technique to maintain thepreviously estiiblisbed flat occlusal scheme. A rotary instrument usually produces irregu-larities in the flat occlusal surfaces. Waterproof carborundum abrasive paper is the mostideal material to use with this metliod. A fine 320-giit paper is used for acrylic resin teeth.Strips of the abrasive paper should be cut in varving widths to allow for the reduction ofindividual teeth or to reduce entire quadranLs. It should be remembered thaL Lhe flatnessof the occlusal surfaces of the mandibular teeth must be maintained throughout theentire grinding procedure.

Locate the premature contacts with articiilating ribbon or paper (Figure 14-16). Ifthere is a grossly tipped tooth that is above the occlusal plane, reduce the tooth with astone or bur until a flat occlusal plane is ohtained. Place a carborundum strip of theappropriate width with the abrasive side against the teeth that are to be reduced (maxil-lary), and gentiy close the articulator in centric relation. Apply tight pressure to theupper member of the articuiator, and pull the strip briskly between the teeth (Figure14-17). Always puU the strip in the same plane as tiie flat occlusal surfaces of the teethin order to avoid rounding of the bucco-occiusal angle of the teeth. Evaluate the occlud-ing vertical dimension carefully throtighout the procedure, as the rapid reduction oftheocclusal surfaces could allow over closure past the original vertical dimension. Reductionof the contacts with the strips is continued by stripping an equal number of times untiluniform bilateral contacts on the posterior teeth are obtained (Figure 14—18). Finish tliereduction witb fmer griis of sandpaper süips in order to produce a smoother flat surface.

Insertion 243

Figure 14-16 Initial centric occlusion marks on a nonbal-anced, linguaiized occlusion.

Figure 14-17 Using a carborundum strip to refine thecentric occlusal stops on a nonbalanced, linguaiizedocclusion.


Figure 14-18 The final revised centric occlusal contactson a nonbalanced, lingualized occlusion.

Check each eccentric position (working, nonworking, protrusive) and removeany premattire contacts with a carborundtmi strip or an acrylic bur while maintaininga fiat occlusal plane. The anterior teeth should be slightly out of contact in tiie centiicrelation position, but can make a "kissing" contact during lateral excursive movements.Smooth gliding movements from the centric position to eccentric positions shotild bedeveloped by careftil adjustment of (jpposing surfaces during excursive movements ofthe articulator.

I Final Checks of The Prostheses

Once all adjustments have been made to the denture intaglio surfaces and the occlusionhas been finalized, the dentures should be evaluated for proper contour and tliickness.Improper contotir can aífect the final fit of the prostheses and make muscles work

Insertion 245

against stabilization instead of enhancing it. Contours of most external surfaces shouldbe slightly concave from tbe necks of tlie teetb to the denture borders. Occasionallysurfaces are left bulky for lip or cheek support, but that is an exception to the nonn. Thepalate should be 2-3 mm thick for proper strength and be thinned to blend with theposterior palate after tiie posterior palatal seal is fmalized. All surfaces should be smoothand highly polished (Figmes 14-19-25).

.\fter completing all fmal checks, it is time to let the patient tr>' out the newdentures. This is the clinician's opportunity to help the patient understand the limita-tions of the prosthetic devices they are wearing, give tips on making the new dentureswork properly, provide care instructions for both the moutb and the prostheses, and reas-sure the patient that he or she will be successful with diligence about the learning processfor using dentures (Eigures 14-26 and 14—27).

A written letter of instruction should be given the patient to help them recall theconversation and instructions they have received. A defmitive recall appointment should

Figure 14-19 Completed maxillary denture - frontal view

Figure 14-20 Completed maxiltary denture - Intagtio view


be arranged in case the patienl has problems that need additional attention. A good ruleof thtinib is to see the patient the next day. after one week, anci possibly abotu one montliafter insertion. It is important to stress the importance of annual recalls to make sure nodamaging wear patterns develop that could cause injtiry to ttnderUing supporting struc-tures. The need for periodic examinations of the soft tissue inüaorally as patients gelolder should also be emphasized.

Figure 14-21 Completed maxillary denture - lateral view

Figure 14-22 Completed maxillary denture - occlusal view

Insertion 247

Figure 14-23 Completed mandibular denture- lateral view

Figure 14-24 Completed mandibular denture - intaglio view

Figure 14-25 Completed mandibular denture - occlusal view


Figure 14-26 Frontal intraoral view of maxillary andmandibular complete dentures {nonbalanced, linguaiizedocclusion).

Figure 14-27 Lateral intraoral view of maxillary andmandibular complete dentures (Nonbalanced, linguaiizedocclusion).

References

Firtell. D. N., Amett, W. S., and Holmes, J. B.: Pressure indicators for removable prosthodontics.J. Prosth. Dent., 54:226, 1985.

Firteil, D. N., Finzen, F. C. and Holmes, J. B.: The effect of clinical remount procedures on thecomtort and success of" complete dentures, J. Prosth. Dent., 57:53, 1987.

Gronas, D. G.: A carborundum stripping technique for the occiusal adjustment of cnspless teeth.j , Prosth. Dent,, 23:218, 1970.

Jankelson, B.: Adjustment of dentures at time of Insertion to compensate for tissue change.J.A.D.A., 64:521, 1962.

Leary, J. M-, Diaz-Arnoid, A. M-, and Aquilino, S. A.: The complete denture remount procedure.Quint. Int., 19:623, 1988.

Insertion 249

Logan, G., and Nimmo, A.: The use of disclosing wax to e\'^uate denture extensions. J. Prosth.Deiu., .51:281, 1984,

Rahn. A. O., and Hcartwell, C. M., editors: Textbook of Complete Dentures. 5'*^ Ed. Philadelphia:Lippincott, 1993.

Sussman, B. A.: Insertion of a full upper and lower denture, J. Ontario Dent. Assoc, 34:16, 1957.Young, H. A.: Denture insertion. J.A.D.A.. 64:505, 1962.

1. What should be done to evaluate the fit of tlie intaglio surface of a denturefor proper ilt?

2. Should tlie patient bite on the dentures to help mark possible pressure areason the intaglio surface?

3. Is an intraoral occlusal adjustment of complete dentures the most accuratemetliod to evaluate and correct occlusal disharmony in complete dentures?

4- What procedure makes it possible to make a new interocclusal record at theinsertion appointment at a slighdy open OVl) without loss of accuracy?

S 2.

Each denture base should be individually evaltiated for accuracy of adapta-tion to the tissues and for areas of excessive tisstie/denture base pressure.Excessive pressure will result in irritation to tlie tissue and pain to the patieni,and nitisl be eliminated. It is most likely to occur in those areas in which therigid denture base must slide into an undercut or contact ti.ssues that arealmost noncompressible. To identify pressure areas, the intagHo surface(tissue side of tiie denture) should be painted with a thin film of pressure-disclosing paste using uniform brush strokes. The denture is then insertedand removed. When removed, tlie pressure-disclosing paste and brush strokeswill be undisturbed in areas of no tis.sue/den ture base contact, exhibit mini-mal uniform contact in those areas with the desired tissue/denture basecontact, or be wiped off in those areas of excessive pressure.

Use only finger presstire when evaluating these pressure areas. Do not let tliepatient bite on the dentures to place pressure. Uncorrected prematureocclusal contact may cause the pressure-disclosing paste to be displaced,mimicking pressure areas.

3. It is difficult to see occlusal discrepancies intraorally witii complete dentures.The resiliency of the supporting soft tissues and tlie tlie ability of die tissues


to be displaced in varying degrees tend to disgtiise premature occlusalcontacts. The tissues permit the dentures to shift; as a result, after the firstinterceptive occlusal contact, the remaining teetli appear to make satisfactorycontacts. Occlusal faults can be detennined by obtaining an interocclusalrecord from tbe patient and remounting the detitures on ati articulator.

4. The facebow positioning of the maxillary cast simulates the correct arc ofclosure posiuon.

C H A P T E R

Post Insertion


251


Corrcciing the many possible problems associated witli the use of dentures requirespersistence on tiie part of patients and skill and experience on the part of dentists.Dentists also need thorough knowledge of anatomy, physiologv; patiiolog>-, and psychol-ogy. They must be capable of differentiating between normal and abnormal ti.ssueresponses. They must distinguish between a physical disorder Uiat is aggravated by thepsychic and emotional processes of a patient and one that is solely physical. UTiendentisLs have knowledge ofthe basic sciences and the skill and experience to investigatethese denture-related problems, they will readily see tiiat, ui the majority of instances, theproblems are real and not psychosomatic.

Compatibility

r

Even though it is not living tissue, a denture is compatible when it is accepted bythe oral environment. The acrylic resin of the denture should be inert. The artificialteeth should be placed in positions that do not produce trauma when they are infunction and tbat are in balance with the various muscle groups of tiie face. Theforces of occlu.sion should be directed toward the most acceptable support. The artificialteeth should be arranged so that, when they make contact, they are in harmonywith mandibular positions and movements. Wiien the mandible is at the verticaldimension of rest, sufficient interocclusal distance must exist to allow for full contractionof the elevator muscles of the mandible before tlie occlusal surfaces of the posteriorteeth make maximum contact. The artificial teeth should be arranged to give supportto the lips and cheeks, and they should be compatible with their actions andthose actions of the tongue. The denture bases sbould cover the basal seat areas toachieve a "snowshoe" effect of maximum support. The soft tissues tliat are supportedby bone should be recorded in their undisplaced fomi to ensure even contact withthe tissue side of the denture bases and to minimize the pressure to the underlyingbone.

Problems with Mastication

The artificial nature of dentures means that they cannot function as efficiently as naturalteetii function. Patients will not be able to perform certain functions, such as chewingextremely hard or chewy and sticky foods. Incising with the front teeth is usually difficultv\ith dentures because they have little support directly under the incisor area. Thepatient will need to leani these limitations and be helped tiirough a training period tobecome more comfortable witb the limitations of their artificial teeth. Knowing that thecanine area \vill be more efficient for incising, that smaller portions will be easier tohandle, and that some foods may be "off limits" will help tiie patient have more realisticexpectations.

Post Insertion 253

W Soft Tissue Considerations

stress-Bearing Mncosa

Traumatic lesions of the stress-bearing mucosa of tlie palate and the crest and slope.s oftlie residual ridges are usually the result of imperfections in or on the surface of thetissue side of the denture base. Pressure areas on the tissue side of the denture candevelop from imperfections developed dtiritig the impression procedures or as a resultof damage to the master cast. Disharmony in occlusion in either the centric or the eccen-tricjaw positions can also produce traumatic lesions in these areas (Figure 15-1). Lesionsoccurring in the mucosa that covers the paîate and the crest of the residual ridges areusually small, well ci re um sci i bed, and indurated. The presence of excessive keratin oftencauses the area to appear white.

Lesions that are h\peremic and painful to pressure duritig ftmction are usually aresult of pressure directed toward an area of exostosis, a sharp spur of bone, or a foreignbody. These areas may not produce a noticeable soreness at the insertion appointmentbecause the abuse of the tissue occurs over time and is associated with the function of thedenttires.

Occasionally, severe irritation and a detaching of the overlying mucosa occur. Thismay be encountered over the mylobyoid ridge, the ciLspid etninences, the alveolar tuber-cles, and areas of exostosis. This is usuall)' produced by the denture flange dtiring theinsertion and removal of the denture or from excessive friction when the denture movesduring function.

Hyperemic, painftil, and detached areas of epithelitim that develop on the slope ofthe residual ridges are usually the result of disharmony of occiusion when the teeth are

Figure 15-1 Mucosal irritation in the canine and premolararea, where a large excursive prematurity existed in lateralfunctional movements


making unbalanced contact in eccentric jaw positions (Figure 1.5-2). A horizontal torqueor shearing force causes these lesions.

Figure 15-2 A large ulcération on the lingual slope of theanterior mandibular ridge caused by excessive movementof the denture base in an anterior direction during function

Basal-Seat Mucosa

Two problems associated with the basal-seat mucosa are hypertrophy and inflammation,hiflammatory reactions of the mticosa covering the ba.sal seat are tisttally the result of thepatient not removing the dentures to allow the tissues to rest. The constant pressure ofthe dentures retards the normal blood supply, which oxygenates the tissues and removesthe waste products. This is a generalized inflammation and is usually not restricted to onearea, btit covers all ofthe mucosa.

A generalized soreness of the crest and slopes of the residual ridges accompaniedby pain in tbe muscles attached to the mandible may be tbe result of insufficient inte-rocclusa! distance. The constant pressure from the denture bases, because the teeth arealvrays in contact produces hyperemia in the mucosa. The muscles of mastication mayalso become sore because they cannot reach a relaxed position, and are always slightlyoverstretched.

Hypertrophy, an abnormal increase in the size of the oral mucosa, is tinusual in thestress-bearing mucosa. However, in the midpalatal suture area, hvpertrophy of themucosa can occur. Small nodules, which are defined as 'papilloma-like hypertrophy,"develop throughout the area (Figure 15-3). A poor-fitting prothesis with poor retentionusually leads to this type of tissue reaction.

Transitional Submucosa

Hypertrophy can also occur in the areas of transitional submucosa, such as border exten-sions. The lesions occurring in the border extension areas are ustially laceration-type

Post Insertion 255

Figure 15-3 Papillary hyperplasia in the center of thepalate caused by a loose and poorly fitting maxillarydenture

Figure 15-4 Uiceration in the buccai frenum area causedby an overextension of the denture base (A).

fisstires. The fissures vary in length and deptb, are painful, and often become ulcerated.These lesions result primarily from overextension of the border, but can result fromsharp or unpolished borders (Figttre 15-^). The lesions can occur in any border area;however, tbey are most frequently encountered in tbe frenum attacbments, the retromy-lohyoid space, the retromolar pad, the masseter groove, the bamular notch, the floor ofthe mouth, and the soft palate (Figures 15-5-7).

Linino Mucosa

Abrasions appearing on the mucosa of the cheeks and lips are frequentiy tbe result ofcheek biting, rough margins on the teeth, or unpolished denture bases. Cheek biting


may he associated with a lack of horizontal overlap of the posterior teeth or the transi-tion from a normal to crossbite or reverse-articulation occiusal scheme (Figure Iñ-H).Occasionally tongtie biting can occur if the horizontal overlap is improper on the lingualcusp areas (Figure 15-9).

Figure 15-5 Ulcération and irritation caused by improperdesign of the notch and flange in the area of the maxillarylabial frenum

Figure 15-6 Irritation caused by a slightly overextendedborder or a sharp edge on a properly extended border

Post Insertion 257

Figure 1&-7 Ulcération of the hamular notch caused byoverextension of the posterior border or too much pres-sure from the palatal seal of the maxillary denture.Thiscan be extremely painful, and patients may believe thesoreness is located in the throat or mandibular retromylo-hyiod area.

Figure 15-8 Abrasion caused by cheek biting due to iackof horizontal overlap of the posterior teeth


Figure 15-9 Tongue injury due to improper horizontaloverlap of the lingual cusp area of the artificial teeth

Treatment Procedures

Examine each denture for stability and retention with the mouth at rest and also with themouth in function. To check functional stability and retention, instruct the patient tospeak, laugh, yawn, wipe the lips with the tip of the tongue, and swallow. The patient canalso gentiy chew on a cotton roll or small piece of gauze to simulate chewing on totighfood. If these procedures cause pain or dislodgement of the denture, the borders shouldbe checked with disclosing wax to determine if they are properly adjusted. Poor reten-tion may be due to borders that were shortened too much dtniiig initial placement orsubsequent adjustments. Adding disclosing vmx may temporarily alle\iate this problemand may indicate that a permanent repair to add flange length is needed. There may alsobe pressure areas on the tissue surface of the denture that prevent the denture base fromfully seating against tissue and reducing the interfacial surface tension, which results hia loose denture. Pressure disclosing paste should be used to identify and correct thoseareas. Indelible marking sticks may also be used to transfer information from muscleactivity or pressure to tbe denture base, to facihtate adjustments. Marking a suspectedproblem area and inserting the denture will transfer the mark to the denture base resinfor evaluation.

To check for undesirable undercuts, apply pressure disclosing paste to the tissueside of the denture. Instruct the patient to insen and remove the denuire. An tmdercutappears when the paste is removed from the denture, as if it were dragged from thesurface. When it has been definitely established that an undercut exists and that thedenture is abusing tlie mucosa, alter the tissue side of the denture base by grinding withan acr\1ic bur. It is better to grind too littie than too much becatise tissue contact withthe denture must be maintaitied. .\lwa>^ smooth and polish all ground areas. To checkfor pressure from occkisal prematurities, pressure disclosing paste is applied to tlie entiretissue side of the denture. Instruct the patient to insert both dentures and tap the teethtogether with the jaws in centric relation. Instruct the patient to exercise care wheninserting the maxillary denture and not to apply finger pressure to the denture. WTien

Post Insertion 259

the teeth have been tapped in place, an area of displaced paste on the tissue side of thedenture is a sign of pressure. It is best to repeat the procedure to veiify the marking. Thepressure area may result from premature tooth contact or an imperfection of thedenture base. The cause must be determined before institution of corrective measures.To determine if the pressure area is produced by faulty occlusion, institute patientremount procedures or mark the occlusal contacts intraoraily using articulating paper.When occlusion causes the pressure, adjust the occiusion. When the denture base causesthe pressure (Figure 15-10), relieve the denture base by grinding vith an acrylic bur;then smooth and polish. It is possible that both denture base and occlusion may needcorrection.

Figure 15-10 Injury caused by the maxillary andmandibular denture bases pinching soft tissue betweeneach other, if the bases do not have proper clearanceduring function

When a generalized inflammatory condition exists or hyperkeratosis is present inthe stress-bearing mucosa, evaluate a lack of interocclusal distance. Anotlier commonproblem associated with the lack of interocchisal distance is an audible "clicking" of theteeth during speech and chewing. If the interoccltisal distance is not adequate, alter theteeth to provide adequate space. If the teeth cannot be altered enough to provide theproper interocclusal distance, the teeth may need to be removed from lhe resin denturebase and rearranged. This procedure requires a new interocclusal record at thecorrected occlusal vertical dimensitm. The denture will have to be reprocessed afterarranging the teeth in the proper relationship. If the reduction of the occlusal verticaldimension creates interferences tliat cannot be adjusted between the anterior teeth, theymay need to be removed and rearranged also.

• Protilems with Maxillary Denture

Dislodgment during functions is a result of overfilled buccal vestibule; overextension inthe hamular notch area; inadequate notches for frenum attachments; excessively thick

260 Textbook of Compiete Dentures

I

denture base over the distobuccal alveolar tubercle area— leaving insufficient space forthe forward and medial movement of the anterior border of tbe coronoid process; plac-ing the maxillary anterior teeth too far in an anterior direction; placing the maxillaryposterior teeth too far in a bticcal direction; or placing the posterior palatal seal toodeep—causing excessive displacement of soft palate tissties. Lack of occlusal hatmonycan also cause dislodgement of the denture during function. Wheti the teeth do notmake harmoniotts contact, tbe lever action tilts the denttire base, and there is a lossof the seal between the tissues and the denture base. The result is loss of stability andretention.

Dislodgment when the jaws are at rest is a result of tmderfilled buccal vestibule,inadequate border seal, excessive saliva, or xerostomia. Wben the maxillary dentureslowly loses retention, the consistency of the saliva, excessive saliva, or the lack of saliva isusually involved. When the drop or loosening of the denture is sudden, the cause isusually mechanical.

il

Problems with Mandibular Denture

Dislodgment during function is the restilt of overextension in the masseter groove area;extending in a lateral direction beyond the external oblique line; overextension of thelingual flanges; placing the occltisal plane too high; catisitig dislodgment when tbetongue tries to handle tlie bolus of food; underextension of the lingual flanges, causingthe border to become tbe playground for the tongue; improper contour of the polishedsttrface; or overextension in tbe rctromolar pad area, causing contact between thedenture base that covers tbe alveolar tubercle and the denture base that covers tbe retro-molar pad when the mandible is protruded. This contact dislodges the mandibulardenture in tlie anterior section.

Other Common Problems

Commisstiral cheilitis, inflammation of the angles of the moutb, is frequentiy attributedto excessive interocchisal distance (reduced occluditig vertical dimension). However,placing the maxillary posterior teeth too far in a lateral direction eliminates the buccalcorridor. Wlien the crowns of the teetb are against tbe cheeks, tbe saliva collects at thenecks of tbe teeth and tnakes its escape in the area of tbe canines, ('.ommissural cheilitiscan also develop wben the occlusal plane ofthe lower teeth is too high. This prevents theregular action of the cbeek from eliminating the saliva from the lower buccai vestibule,so tlie saliva will exit through the coi ners of the mouth.

Gagging and Vomiting

Patients who develop a gagging or vomiting problem with denttires are frequentiy diffi-cult to treat, and the diffictilty is primarilv one of detennining the cause. Some patientshave a hypersensitive gagging reflex e\ident prior to and during the denture construc-tion. The insertion or removal of complete dentures may elicit gagging. However, occa-sionally a patient develops a gagging problem a/i«-denture insertion.

Post Insertion 261

A complete dennire patienl may develop a gaggiug or vomiting prohiem as a resultof loose dentures; poor occlusion; incorrect extension or contour of the dentures—particularly in the posterior area of the palate and the retromylohyoid space; underex-tended denture borders; placing the maxillary teeth too far in a palatal direction and themandihular teeth too far in a lingual direction so tliat the dorsum of tlie tongue is forcedinto the pharynx during the act of swallowing; an increased vertical dimension of occlu-sion; and ps)chogenic factors. Patients may refuse to sw'allow for fear that the dentureswill dislodge and strangle them. As a result of not swallowing, the saliva accumulates andtriggers the gagging reflex. A common prohlem often overlooked is tliat the po.steriorborder of the denture is too thick. It should be thinned to hlend into the palate and notcreate an uncomfoitahle hump in the posterior.

Burning Tongue and Palate

The huming sensation that some patients experience in the anterior third of the palatemay result frotn pressure on the nasopalatine area. Relief of ihe denture over the incisivepapilla is usually effective.

Summary

Problems associated with real, identifiahle causes can be eliminated by careful observa-tion and pliN-sical conection of Lhe cause. Occasionally a patient will return numeroustimes with vague problems, which are diíFicult to diagnose and correct. These patientsmay really he having a difficult time adjusting to the psychological realities of denturewearing and need time to overcome the fears they have associated with the prosthesesthey now wear. Patience and understanding along with further education will sometimeshelp these patients make this transition. The use of a powdered adhesive may make thedentures more stable and help the patient gain confidence in lhe use of the dentures.Also, be sure to investigate the esthetic result of the dentures with these patients; theymay actually have esthetic concerns (Uieir own or those of a significant other) thai theyfeel uncomfortable discussing, and may be using other problems as an excuse to makethe dentures appear unsuitable.

References

Bell, D. H., In: Problems in complete denture treatment. J. Prosth. Dent, 19:550, 1968.Berg, H., càri.sson, G. E.. and Helkimo. M.: Changes in shape of posterior parts of upperjaw-s after

extraction of leeth and prosthetic treatment. J. Prosth. Dent., 34:'¿62.1975.Collett, H. A.: Oral cotiditions associated with denttires. J. Prosth. Dent., 8:591,1956.Conny, U., and Tedesco, L.: The gagging problem in prosthodontic treatment. Pan 1—Description

and causes. J. Prosth. Denl., 49:601. 1983.Conny, U., and Tedesco, L.: The gagging problem in prosthodontic treatment. Part 11—Patient

management. J. Prosth. Dent., 49:757, 1983.Hanls, W. T, and Mack,J. F: Condltíoning dentures for problem patients.J. Prosth. Dent.. 34:141,

1975.Kapur, K., and Shklar, C: The effect of complete dentures on alveolar mucosa. J. Prosth. Dent.,

13:1030, 1963.


Koper, A.: Difficuli denture birds. I. Prosth. Dent., 17:532. 1967.Kouais. J. T.: Clinical evaluation of the gagging denture patieiu, J. Prosth. Dent.. 25: 613 1971.Lambson. G. O., and Anderson. R. R.: Palatal papillary hyperplasia. J. Prosth. Dent., 18:.528, 1967.

1. Why is typicaJ biting with the front teeth difïicult for denture patients?

2. What is the most likely cause of hyperemic, painful, and detached areasof epithelium that develop on the slopes of the residual ridges?

3. What could he possible causes for dislodgement ofthe maxillary dentureduring function?

« 4. What denture conditions can lead to commissural cheilitis?

1. There is no direct support under the incisai edges ofthe anterior teeth inmost instances due to ridge résorption. The long lever arm created by theseteeth tends to destabilize the denture when a bolus of food is placed betweenincisors for shearing.

2. They are asually tiie result of disharmony of occlusion when the teeth aremaking unbalanced contact in eccentric jaw positions.

3. Dislodgement during function could be the result of overfilled buccalvestibule; overextension in the hamular notch area; inadequate notchesfor frenum attachments; excessively thick denture base over the distobuccalalveolar tubercle area—leaWng insufficient space for tlie forward and medialmovement of the anterior border of the coronoid process; placing the maxil-lary- anterior teeth too far in an anterior direction; placing the maxillaryposterior teeth too far in a buccal direction; or placing the posterior palatalseal too deep causing excessive displacement of soft palate tissues. Lackof occlusal harmony can also cause dislodgement of the denture duringfunction.

4. Commissural cheilitis, inflammadon of the angles of the mouth, is frequentlyattributed to excessive interocclu.sal distance (reduced vertical dimension ofoccltision). However, placing tiie maxillary posterior teeth too far in a lateraldirection eliminates the buccal corridor and, when the crowns of the teeth

Post Insertion 263

are against the cheeks, the saliva collects at the necks of the teeth and makesits escape in the area of the canines. Commissural cheilitis can also developwhen the occlusal plane of the lower teeth is too high. This prevents theregular action of the cheek from eliminating the sali\a from the lower buccalvestibule, so the sali\'a will exit tlirough the comers of the mouth.

C H A P T E R

ij Overview of SingleDentures,Overdentures, andImmediate Dentnres

Dr. Dennis KiernanDr. Kevin Plummer

265


No textbook on complete dentures would be thorough without at least a brief mentionoí certain spetia! circumstances tiiat demonstrate the versatility of the complete dentureprostiiesis. Tbe goal of this chapter is to provide a brief overview of the major indications,advantage.s, and disadvantages of single dentures, overdentures, and immediatedentuies. All of these treatment modalities are far more challenging for the dentist andtile patient than tbe fabrication of a conventional set of complete dentures would be.However, if botli parties are fully aware of tbe limitations and have reasonable treatmentexpectations, die outcome can be veiy gratifying.

Single Dentures

WHien only one arch is being restored with a denture, it is called a single denture (Figure16-1). Single dentures may be fabricated to oppose:

Figure 16-1 Wax set-up of a maxillary single denture;opposing natural teeth on the mandibular arch

1. An arch containing a sufficient number of natural teeth and fixed restora-tions so as to not require any other piostiieses.

2. A partially edentulous arch in wbich the missing teeth have been or willbe replaced by a removable partial denture, ftxed partial dentures, orimplant-supported prostheses.

3. An existing acceptable complete denture, whether it be mucosal-borne,tooth-supported, or implant-supported.

The conditions leading to the recommendation of treatment by means of a singlecomplete denture can be quite varied. Patient availability, financial ability, desires, andthe old prosthodontic principle to "preserve tbat which remains," may all influence theeventual treatment plan and should be carefully considered duting the diagnostic evalti-ation appoinunent. A frank di.scussion of treatment advantages, disadvantages, limita-tions, and patient expectations of the treatment should ensue. Any alternative treatment

Overview of Single Dentures, Overdentures, and Immediate Dentures 267

Figure 16-2 Wax set-up of a maxillary single denture;opposing natural teeth on the mandible. Note the occlusalplane discrepancy on the patient's left side.This mightresult in difficulty balancing the excursive contacts duringfunction of the denture.

regimens should be discttssed so that the patient can make the most informed decisionpossible.

Wlien the dentist and the patient have chosen the single denture as the treatment,both should fully realize that the ability to achieve stabilitv, retention, and support of thenewly fabricated single denture is of paramount importance to its success. Because theopposing arch may not be treated, the dentist's ability to obtain an optimum occlusalscheme may he compromised. Therefore, the fabrication of the single denture may hedifficult, and the end result from a functional or even esthetic standpoint, may be lessthan idea! (Figure 16-2).

Maxillar)' single dentures are often more successful than mandibulai- dentures fora number of reasons. First, the mandihular arch is the moveable member of the stom-atognathic system (mouth, jaws, and related structures), which inherently decreases itsstahilit)'. Additionally, the proximit>' of Lhe mandibtilar denture borders to the tongueand other moveabie mucosa may lead to easier displacement. Thirdly, the mandibularedentulous ridge, with its limited amount of attached suhmucosal tissue, provides lesssupport for the denture base. Therefore, if stabiUt\ of the single denture is of primaryimportance for its success, it is clear why patient satisfacdon is greater with maxillarysingle dentures.

Stability and retention of the single denture can he increased by means of adjunc-tive treatment using dental implanLs and attachmenLs (Figure 16-3). Dental implantshave tlie added benefit of preserving alveolar bone. This is even more important for theyounger patients who, after many decades of support loss, may find themselves unable totolerate denmres.

.Anotlier way of potentially increasing the stabilit)' and retention of the singledenture is to use anatomic-fonn posterior denture teeth and a balanced occlusal scheme.By pro\iding bilateral balancing conuicts when the patient moves through the eccentricmovements, the denture is not subjected to tipping forces that can lead to its dislodge-ment. If the opposing dentition has been worn flat and is not being restored, a mono-plane denture setup may accomplish die same result.


Figure 16-3 Two implant attachments located in theapproximate area ofthe canines provide both retentionand stability for the single maxillary denture.

A frequent obst;\cle to obtaining a balanced occlusion is an irregular occlusal planeof the teeth in the opposing arch, as a restilt of supraeruption—or tilting of the teeth. Aconsequence of this irregular plane is an imfavorable distribution of forces. The irregu-lar occlusal plane may also compromise the final esthetic otitcome of the single denture.This problem may be resolved by orthodontic repositioning of the opposing teeth or byaltering tbe clinical crowns of the teeth by means of selective grinding or with restora-ti<}ns. Of course, the clinician may be forced to accept good centric occlusion contactsand premature contacts in the eccentric positions. The excessi\e premature contactsoften cannot be eliminated.

Fracturing the denture ba.se of the single denture is a common complicationbecause the denture is often opposed by a full or nearly full complement of natural teetbor fixed restorations. The restating high occlusal forces on the denture combined with atypical denttire base thickness sometimes results in fracture. Careful control over theocclusion or use of a cast metal base are considerations to prevent this problem.

The single denture offers various challenges to the clinician. Careful evaluation andtreatment planning are essential to the success of tlie prosthesis. M long as tiie dentistand the patient are aware of tJie treatment limitations and have reasonable expectations,the final outcome can be a very gratifying experience for both.

Overdentures

An overdenture i.s a remo\-able dental prosthesis that covers and resLs on one or moreremaining natural teeth, the roots of natural teeth, and/or dental implants. Theimplants or modified natural teeth provide for additional support, stability; and retentionof the overdenture than the edentulous ridges alone can provide (Figures 16-3 and16-4). This is particulaily adv-antageoas in Uie mandibuiar arch, where edentulous ridgesmay resorb at a rate four times greater than that of the maxillar) arch.


Figure 16-4 Two impiant fixtures with simple "snap"attachments help maintain bone, and provide retentionand stability for complete dentures.

There are several ad\untages to the overdenture. Implants or the roots of naturalteeth are present to pro\ide stimulation to the alveolar bone, which is conducive to bonerepair and maintenance, thus preserving the alveolar ridge. A definite vertical stop isprtnided, which can be advantageous in situations where hypertrophie soft tissue is pres-ent. Horizontal and torquing forces can be minimized, and stability and support areincreased, thereby reducing forces of occlusion on the supporting tissues. Finally, a realp.sychological advantage can be realized in patients who are unwilling to lose the last oftheir remaining natural teeth.

Overdentures should be considered for any patient facing the loss of the remainingdentition. The younger the patient, the gieater the indication for this treatment may bebecause of the anticipated significant bone loss over many years. If retention is expectedto be difficult to obtain or is of primary importance, attacbments may be particularlyuseful. Examples oí where attachments would be beneficial include severe cases of xeros-tomia, minimal alveolar ridge height in edentulous areas, loss of a part of the maxilla ormandible, or congenital deformities such as cleft palates.

Teeth to be prepared for denture abutments are iLstially reduced to a coronalheight of 2-3 mm and then contoured to a convex or dome-shaped surface (Figure16-5). In order to accomplish this, most teeth usually require endodontic treatment, theteeth are shortened and contoured, and the pulp chamber is simply sealed with an amal-gam or composite restoration. Those teeth requiring the replacement of lost tooth struc-ture or contour, often a result of caries, are prepared to receive a cast metal post andcoping. Intraradicular attachments may be used as the fmal restoration when an increasein retention is desirable. These treatments add significant overall cost and time to thetreatment plan, and tbe patient should be adequately informed.

Contraindications of this treatment should be carefully considered. Obviously,increased cost could preclude the patient from accepting this treatment modality.Patients who, for one reason or another, cannot maintain adeqttate oral hygiene are poorcandidates for overdentures; recurrent caries or periodontal disease of the natural toothabutments would obviously lead to treatment failure. Additionally, problems related toendodontic or periodontic therapy could result in less-than-ideal abutments and should


Figure 16-5 Natural teeth that have been prepared toserve as overdenture abutments

be carefully evaluated for suitability. The absence or inability to obtain a sufficient zoneof attached mticosa around the proposed abutment teeth to gtiard against inllammationshould be considered a contraindication. Excessive mobility of die abuunent teeth mayalso be a catise of concern, but mobilit)' may improve as the clinical crown is reduced,thereby resulting in a more favorable crown to root ratio. Tbe number and position ofthe abutment teeth in the arch should be caiefully considered when treatment planningfor an overdenture. The ideal situation exists when four or more abuunent teeth arespread out over as wide a rectangular area as possible. This configuration pro\ides formaximum denture stability. Three widespread remaining teeth will generally pioWde fora tripod effect and would be the next-most-favorable arrangement. One or two teeth,thotigb less than ideal, can be used satisfactorilv. Preferably, there should be severalmillimeters of space between adjacent retained teetli to minimize compromises in softtissue health.

A complication may arise in the positioning ofthe denture teeth over the abutmentteeth if the available interarch space is limited. Potential weakness of the acrylic resindenture base over these areas may require fabrication of a cast metal superstructure,which increases cost and treatment time. Also, any undercuts present on the abuunentteetli Avill need to be relieved in the denture base (if they were not blocked out duringthe impression appoinünent) in order to achieve complete seating of the overdenture.Attachments, if used, are secured to the denture base either during processing or chair-side at tlie time of overdenture insertion.

Fabrication of the overdenture follows standard prosthodontic procedures forcomplete dentures. These include preliininar\' impressions, abutment tootli reductionand recontouring, final impressions, interocclusal records, trial insertion, insertion, andpostinsertion appointments. There can be major exception to the presented sequence oftreatment. Ideally the abutment teeth are prepared prior to the final impression appoint-ment so that the master cast reflects an exact replica of the prepared teeth. Occasionallytlie abutment teeth cannot be prepared imtil the day of insertion. Tliis is usually tlieresult of a patient needing to retain the abutment teeili becaitse tiiey are also the abut-ment teeth for an existing removable pamal denture that will be replaced by the over-dennjre. For these patients, the master cast uill refiect tiie natural contour and length ofthe abutment teeth prior to preparation. A complete trial insertion is not possible


becattse the natural teeth are occupying the space ofthe future denture teeth. However,a trial insertion appointment should be completed to verify tiiat the casts are correctiypositioned on the articulator. Following the trial insertion appointment and prior toinvesting and processing, the abtitment teetli are prepared on llie tnaster cast to theanticipated and desired height and contour. The remaining denture teeth are thenarranged, and the denture is invested, processed, and fmished. The insertion appoint-ment will be more time consuming for these patients than for conventional overdenturepatients because of the need to prepare the abutment teeth on the day of insertion.Additionally, because the teeth as prepared on the master cast and those prepared intra-orally are invariably different, time must be spent making tbe denture ftt the abtitmentteeth. Occasionally, the denture must have an autopolymerizing aciylic resin placed toobtain the desired support from the newly contoured abtttments. Once the fit of theintaglio surface is verified, the remainder of the insertion appointment is the same asconvetitional complete dentures.

K Immediate Dentures

An immediate denture is defined as any removable dental prostiiesis fabricated for place-ment immediately following the removal of a nattiral tooth or multiple teeth (Figures16-6A ajid 16-6B). Immediate denttires niay be a single denture in either arch or onedenture in each arch. They are often more challenging to fabricate than routinedentures. Because an esthetic trial prior to extracting the teetli is not possible, tbepatietit's expectatiotis of tbe appearance and fit may not be fully realized at tbe time ofinsertion.

ikM

Figure 16-6A The patient In this treatment scenario hadposterior teeth missing for a number of years and worea removable partial denture until the anterior teeth wereno longer able to support the prosthesis. Impressions for amaxillary immediate denture were made, and the insertionoccurred the same day as the extraction of the remainingteeth.

(Continued)


Figure 1&-6B Initial insertion of the immediate denturesfollowing surgery.

Generally, there are two types of immediate dentures. The first is the conventional(classic) immediate denture in which the denture is intended to serve as a long-termprosthesis. Following tlie completion of tlie healing phase (usually a minimum or threeto six months), the conventional immediate denture may he relined to maintain its basaladaptation to the supporLing sLructLues. The second type of immediate denture is theinterim (transitional, "throw-away") immediate denture, which is designed to sen'e for alimited amount of time, usually through the healing phase, after which it is replaced bya more definitive type of prosthesis.

There are many advantages for immediate denture fabrication. Because ihere is nocompletely edentulous period, the patient's appearance is maintained, and potentialsocial embarrassment is avoided. The denture base serves as a bandage following tooLhextraction to help control bleeding, protect against trauma, and protect the blood clot.Thus, more rapid healing is promoted, and le^ postoperative discomfort is likely to heencountered. Furthermore, the position of the tongue, lip, and cheeks are maintained,allowing the patient to hetter adapt to denture service. Without an extended edentulousperiod, patients often adapt more easily to speech and mastication, and are thus able tomaintain good nutritional intake. Additionally, it is easier to replicate the shape andarrangement of the natural teeth (if desired) and to maintain the occiusal verticaldimension.

Despite all the potential advantages, there are a few specific disadvantages of imme-diate dentures. Becau.se of the difficulty and demanding procedures required, additionaland longer appointments are required, which increase cost to the patient Bone résorp-tion and shrinkage of the healing soft tissues occur at a greater rate compared to alreadywell-healed tissues. These changes often require reline procedures to maintain a well-adapted fit. Moreover, the esthetic arrangement of the anterior teeth cannot bepreviewed prior to tooth extractiotis and the denture insertion. Also, the remaining ante-rior teeth may create an anterior ridge undercut that is diificult to capture with theimpression procedure and may necessitate a sectional impression technique.

An additional consideration to tliis treatment modality includes the necessity ofa surgical template whenever alveoloplasties or tuherosity reductions are necessary(Figure 16-7). This template serves as a guide during tlie surgery and is made from a


Figure 16-7 A surgical template (duplicates the intagliosurface of the denture) will help to identify severe pres-sure areas where additional surgical intervention isneeded. The arrow indicates blanching of the tissue, whichmay mean excessive pressure from the denture base.

thin, u-ansparent material that has the form of the intaglio surface of the immediatedenture. Use of this template helps ensure that the interim denture will seat as intendedand lessens the chances of occlusal discrepancies or postsurgical discomfort.

The impression procedure for immediate dentures depends on the number ofremaining teeth. Undercuts and anatomy make border molding veiy diflicult when morethan just the anterior teeth remain. For patients witli anterior and posterior teeth algi-nate impressions in stock trays may the procedure of choice. This usually results inoverextended final impres.sions and requires precise information transferred to theimpres.sion in order to minimize the potential problems at the insertion appointment.

When only anterior teeth remain, a split tray or sectional impression technique mayproduce a more suitable master cast. A custom tray is fabticated for tiie posterior areasand rests on tlie remaining anterior teeth. The tray is border molded and a wash impres-sion made. The tray is re-seated in the patient's mouth and a heavy body impression puttyis used to form the anterior segment capturing both the teeth and to border moldthe anterior vestibule. This impression can be separated into two pieces the facilitateremoval from the patient's mouUi and then reassembled to pour the master cast.

The vertical and borizontal relationships of the maxilla to the mandible arerecorded in a similar manner as conventional complete dentures. However, the recordbase and occlusion rim will only cover tlie edentulous areas of the residual ridges.Stabilization of these partial record bases can be a challenge during these procedures.

Tooth selection proceeds as described for conventional complete dentures and atrial insertion of the dentures can be accomplished for those areas where the teetii havealready been removed. This is rarely an esthetic trial insertion but rather a functionaltrial insertion to verifS' the maxillomandibular records.

Following extractions, the denttire is inserted. The intaglio surface is adjusted withpressure disclosing paste until a comfortable pressure free fit is obtained. In order not toprolong the insertion appointment, the occlusion is adjusted intra-orally to obtain solidcontact in the posterior on the patient's arc of closure. The remount and final adjtist-


ment usually occurs one or two weeks after tlie initial insertion. It is important to havegood retention and stability of the imtnediate denttire otherwise the denture may actu-ally prolong postnaperative bleeding and discomfort. The patient is instructed to avoidremoving the immediate denture for the first 24 hours. Premature removal of thedenture can lead to swelling that may prevent the denture's reinsertion for several days.If swelling occure, but the denture is still able to be reinserted, the number of sore spotswill often increase because tbe fit of the dentitre has been altered. After 24 hours, thepatient should return to the dentist's ofFice for removal of the denture, at which time aninspection of the tissues is performed to identify and adjust irritated areas induced by thedenture. The patient is instructed to continue wearing the denture at night for aboutseven more days, or until the swelling has subsided. During this time, the patient shouldbe instructed to only remove the denture after meals to clean it and rinse out the mouth.The denture shotild be also removed prior to bedtime to again clean and rinse themouth. After a week has passed, the patient is instructed to leave the denttire out duringthe night. Further follow-up care may be done on a weekly basis or on request of thepatient to address any additional sore spots.

The immediate denture serves quite an important role for the newly edentulouspatient. Though technically demanding, when accomplished successfully, the immediatedenture can satisfy the requirements of function, esthetics, and emotional supportduring the healing phase following multiple tooUi extractions.

• Summary

Single dentures, overdentures, and immediate dentures all pose different challenges tothe patient and the dentist providing care. However, despite the extra effort required,when used appropriately, all of these prostheses can lead to a very satisfying result.Careful treatment planning and patient selection are paramount to success. As thecurrent trend of an aging population of longer-living individuals continues, there will beno shortage of edentulous patients who may be in need of these services.

ReferencesJerbi, F: Trimming the cast in the costruction of immediate dentures. J Prosthet Dent 16:

1047-1053, 1966.Pound. E.: Controlled immediate dentures. J South Calif Dent Assoc 38: 810-817, Sep 1970.Rahn, A. O., and Heartwell, C. M., editors: Textbook of Complete Dentures. 5''' Ed. Philadelphia:

Lippincott, 1993. Chaptei-s 22, 23, and 24.Rudd, K., Morrow, R.: Occlusion and the single denture, j Prosthei Dent 1973; 4-10.Stansbur), C: Single denture constmction against a non-modified natural dentition. J Prosthet

Dent 1951; 692-699.


1. The primar)' reason for failures when attempting single maxillary denttiresopposing natural dentition is:a. Optimum occlusal scheme may be compromisedb. Retention is impossible to obtainc. Poor impression techniqued. Dentist's errors

2. What is one way to increase stabilit)' and retention of single maxillarydentures?

3. Overdentures usually cover and rest on:a. Natural leethb. Implantsc. Roots of natural teethd. Ali of the above

4. Immediate dentures cannot be accessed for esthetic restilts prior to the inser-tion appointment.a. TRUEb. FALSE

1. a.

2. Using adjimcdve treatment, such as implants and attachments.

3. d.

4. a.

C H A P T E R

Relíning CompleteDenturesDr John R. IvanhoeDr Kevin D. Plummer

277


Patients often present wilh existing complete dentures that, while still structurally sound,are not retentive or stable because they no longer properly lit the soft tissues and resid-ual ridges. These patients often present with obvious occltisal and/or facial changes.They may exhibit poor esthetics hecause excessive hone loss under the prostheses hasresulted in a loss of face height or repositioning of the anterior teeth. Their occludingvertical dimension (OVD) and their occlusion may also be compromised because thedramatic tissue changes have caused the dentures to lose tiieir proper ridge orientation.The tissue underlyitig Lhe dentures is frequendy abused and irritated. Most of thesechanges are the result of poorly fitting dentures. If these changes are not too great, andthe denlures are still in reasonably good condition, these problems may he corrected hyrelining the dentures. Relining is a procedure to resurface the tissue (intaglio) surfaceof an existing denture with new denttire hase material. Other indications for reliningmay have to do with flange length problems or nondisplaced fractures of existingdentures.

If conditions have led to abused support tissues, some corrective actions must hetaken prior to the relining procedtires. A dsstie conditioning material is often ttsed inconjunction with other procedures (such as surgery) to return abused oral tissues to ahealthy state. Becatise tissue conditioning material has a short, usable, functional life,both lhe tissues and material must be examined freqttentiy, with the material beingreplaced as necessary.

The decision to reline an existing denture is based on a numher of factors. Theoccluding vertical dimension must be correct or it must be able to be corrected duringthe impression procedtire for the reline. The patient's centric relation occlusal positionmust he stable or correctable through occlusal adjustment. The general appearance ofthe teeth must he satisfactoiT to the patient, and tliere should not be severe occltisal wear(Figure 17-1). Speech patterns should also be satisfactory. As stated previously, the softtissue must be healthy or correctable.

Making the impression for a reline is much like the conventional final impressiontechnique. However, there are some differences and several additional objectives thatmust be achieved simultaneously when making the impression for relining a denture, as

Figure 17-1 Dentures have severe wear and poor generalappearance, which may preclude a successful relineprocedure.

Relining Complete Dentures 279

opposed to a conventional complete denttire impression. The most obvious difference isthat an existing denture is used in place of the custom impression tray. A second andsignificant difference is that, when relining a denture, the final impression must becompleted while maintaining ihe correct occlusal vertical dimension and making surethat the patient remains in the centric relation position through the border moldingprocedures and the fmal .set of tiie impression material. Maintaining the occluding verti-cal dimension and the centric relation position is not a consideration when making aconventional final impression. This may be a diificult procedure on some patients, anda poor occlusal scheme may complicate this endeavor (Figure 17-2). An occlusal equili-bration of tiie existing dentures may be necessar)' before the reline procedure to insureadequate positionitig of tlie dentures during the impression procedures.

Figure 17-2 A poor occiusai plane (A) that cannot becorrected Is a contraindication to a reline procedure.

Dentures demonsu'ating simple looseness v\ithout appaient occlusal disharmony,and without noticeable changes in the vertical dimension of occlusion or appearance,are ideal candidates for being relined. However, becatise these dentures fit closely to theunderhing tissues, an extra step is necessary prior to making the final impression. Theviscosity of the impression material can prevent a denture from being properly seatedwhen attempting the impression, if instifficient space or sufficient relief exisLs for theipression material. Additionally, even if tissue conditioning was done, some areas of thedenture mav be placing unacceptable forces on the underlying tissues. Thereforeapproximately 1.5 mm of resin must be removed from tlie tissue side of tiie denttire priorto making the impression. This may be difficult or impossible in those dentures whosebase may be little more than 1 mm in thickness.

Both the maxillaiy and mandibular denture for some patients may require relining.When both dentures must be relined, one denture at a time is relined rather thanattempting to complete opposing relines simultaneotisly. When deciding which dentureto reline first, usually the less stable of the two is relined first. If there is no significantdifference between the stabilitv- or retention of the opposing dentures, then the maxil-laiy denture is often selected. Once relined, it will provide a stable opposing arch whenrelining the mandibular denture.


Dentures may be relined using either a "closed-" or "open-" niotiih technique.Because one of the piimarv' objectives of a denture relitie is maintaining the properocclusion, many clinicians select the closed-mouth technique. The primary difference isthat with the closed-tnotith technique, the patient is required to close and tnaintain thedentures in proper occlusion at the correct OVD while the impression material sets.With the open-mouth technique, the patient is not allowed to maintain occlusal contact.The open mouth techniqtte usually reqtiires extensive occltisal equilibration at insertionand can even alknv the denture to be misaligned in its proper relationship to the resid-ual ridges.

• Impression Technique

The denttue fianges are reduced so that 2-3 mm of space exists between the fiange.s andtlie depth of the vestibules to provide space for the border molding material (Figure17-3). To allow the laboratory technicians to remove the denture from the master castduring processing, enough resin is removed from the tissue side of the denture to elim-inate all resin undercuts on the denture base.

Next, to create space for the impression material, reduce at least one millimeter ofthe remaining unreduced denture base material over the entire tissue surface (Figure17-3). At this point, space for the impression tnaterial has been created btit, the plane ofocclusion has been changed and the vertical dimension of occlusion has been overlyreduced by approximately 1—1 .ñ mm. This loss can be regained by adding 4 "stops." Smalltisstte slops are created with spots of heavv-bodied vinyl polysiloxane material abotit 3tnm in diameter. The stops are placed in the canine and second molar areas, the dentureis gentiy seated, and the patient is closed into the CR position at the proper O\T) (Figitre17-4). A small dot oí adhesive will be needed to keep Uie VPS material in position. If the

Figure 17-3 Borders have been shortened, and 1-1.5 mmof acrylic resin has been removed from the intaglio surfaceof the denture.

Relinîng Complete Dentures 281

Figure 17-4 Vinyl polysiloxane material has been placedto create tissue stops, to maintain the denture at theproper occluding vertical dimension during the impressionprocedures.

denture cannot be positioned properly by creating these stops, it may be necessary toreevahiate the reline prt)cedure as a treatment option.

Border molding is now completed, as with a conventional impression, with theexception that tlie vertical dimension of occlusion and centric occlusion positions mustnot be compromised (Figure 17-5). The occlusion is continuously evaluated to makesure no changes in denture position have occurred.

Four to six holes are placed into the maxillary denture, spaced approximately 12mm (half inch) apart through the palate of the denttire with a round bur (#6). Tbeseholes provide escape vents to minimize hydraulic pressure buildup during the washimpression. Three holes are generally placed following the midline raphe, beginningwith one hole at the incisive foi ainen. Two holes are cut on each side lateral to the

Figure 17-5 Border molding is complete.


midline, in approximately the canine areas. Care should be exercised to avoid makingthese holes through the existing denture teeth. Generally, unless tbe denture is verylarge, no holes are required on the mandibular arch—unless the ridges are massive andthere is concern about hydraulic pressures within the impression material tbat mayprevent tiie complete seating of the denture. When reqtiired, holes may be placedapproximately 12 mm (half inch) apart.

The impression material is mixed and loaded uniformly inside the denture. For themaxillar) - denture, the denture is seated onto the ridges by exerting gentle pressureupward and backward. Tbe patient is instructed to close into the centric occlusion posi-tion, and the clinician mttst manipulate the denture until tbe desired occlusion isachieved at the-correct vertical dimension of occhision (Figure 17-6). While maintainingthe correct occlusal position the musculature of the mouth is border molded in samemanner as a conventional complete denture impression. Centric occlusion, occltidingvertical dimension and denture position are all examined for correcmess at tiiis time.The impression material is allowed to set according to the manufacttirer's instructions.

After the impression material has set, the denture is removed from the moutb, andthe excess impression material is trimmed from tbe denture and surfaces of the teetb(Figure 17-7). The vertical dimension of occlusion and centric occlusion are recon-firmed. If they are acceptable and retention and stability is adequate, the denture is thenready for the laboratory procedures.

If tbe clinician or staff pours the final impression in dental stone, it is essential thatthe denture not be removed from the cast prior to submission to the laboratory. Ifremoved, it may be impossible for tbe laboratory technician to properly reseat tliedenture on the cast and the proper cast/occlusion orientation will be lost. The laboratorytechnicians will invest the denture in a processing flask prior to removing it from tbe cast.If any resin undercuts were not removed prior to making the impression, it may beimpossible for the technician to remove the denture from the cast without breaking thecast. That is why it was important to remove all resin tmdercuts prior to making theimpression. Ifa posterior palatal seal is required it is usually cut into the cast just beforeprocessing the denture.

Figure 17-6 The final impression is made with the patientin the proper occlusal position at the proper occludingvertical dimension.

Relining Complete Dentures 283

Figure 17-7 Completed reline impression

Figure 17-8 Completed reline with new acrylic resin onthe intaglio surface

The denture is returned from tiie labora tory just as if it were any oiher new denture(Figure 17-8), Insertion, adjustment, and post-insertion procedures are followed, just asfor a conventional denture. Because tiiere was no facehow made, the relined dentureswill have remount casts but no index to place the maxillary remount cast/denture on thearticulator in the proper relationship to the condyles. A facebow recording and a centricrelation record may he necessary for extensive occlusal equilibration.

References

Boucher. C. O.: The relining of complete dentures, j Proslhet Dent. 1973;3():521-6.Bniden, M.: Ti.sstie condlüonere. 1. Composition and structure, j Dent Res. 1970;49:145-8.Nassif, J.. jumbelic, R.: Current concepts for relining complete dentures: a survey. J Prosthet Dent

1984;51:n-5.Zarb, G. A., Jacob. R. F.: Prolonging the useful life ui complete dentures: The relining technique.

In: Zarb. G. A., Bolander, C. L., eds: Prosthodontic Treatment (or Edentulous PatienLs. 12 th ed.SL Louis: Mosby Inc: 2004. pp. 471-480.


1. WhaL are some of the clinical features that wotïld indicate that a patient'sdentures need to be relined?

2. Wliat pre-ieliiie procedures may be nece.ssary for a patient with abused oraltissues underlying the existing dentures?

3. Not all existing dentures can or shotild be relined. List several indicationsfor completing a denttire reline.

4. What are the two reline techniques, and how are they different?

5. List several differences between a conventional and reline impression.

6. When both dentures must be relined, one denttire at a time is relinedrather than attempting to complete opposing relines simultaneously. Whichdenture should be relined first?

7. Al! resin undercuts on a denture base must be eliminated prior to using thedenture to make the final impression. Why is this important?

8. To allow space for the impression material and to minimize direct contactbetween the denture base and undeii>ing tissues, 1-1.5 mm of resin isremoved from the intaglio ofthe denture prior to making the impression.Wiiat features of tiie denture may become unsatisfactoiy and must becorrected prior to making the impression?

9. WTiat t vo methods may be used to create a posterior palatal seal in thedenture?

H). Why are foiu- to six holes cut into tiie maxillary denture following theborder molding and prior to making the impression?

I. Patient presents with some ofthe following:a. Existing complete dentures that, while still structurally sound, are not

retentive or stable.b. Occlusal and/or facial changes.c. Poor esthetics because excessive bone loss under the prostheses has

restilted in a loss of face height or repositioning of the anterior teeth.d. Compromised occlusal vertical dimension (OVD) and occiusion.e. Tissue underlying the dentures is abused and irritated.

Retining Complete Dentures 285

2. If the patient exhibits abused support tissues, a tissue conditioning materialis often ti.'ied in conjunction with other procedtores (such as surgery) toreturn abused oral tissues to a healthy state.

3. Dentures demonstrating simple looseness without apparent occlusal dishar-mony, and without noticeable changes in the vertical dimension of occlusionor appearance that do not abuse ilie underlving tissues, are ideal candidatesfor being relined. A denture can usually be satisfactorily relined if thefollowing features are observed:a. The occluding vertical dimension is correct or can be corrected during

the impression making procedure.b. Centric relation occhtsal position is stable or correctable through

occlusal adjustment.c. The general appearance of the teeth is satisfactory to the patient aud

there is not severe occlusal wear.d. Patient's speech patterns are acceptable.e. Tlie soft tissue is healthy or can be made healthy.

4. Open- and closed-mouth techniques. With the open-mouth technique, thepatient is instructed to come into an initial occtusal contact, so the cliniciancan achieve the desired vertical and horizontal relations oí the dentures,and then open and remain open while tlie impression material is allowed toset. In the closed-mouth technique, the patient is allowed to maintain lightocclusal contacts between the opposing dentures while the impression mate-rial is allowed to set.

5. Differences between a reline and conventional impression include:a. .\n existing denture is used in place of the custom impression tray.b. Tbe final impression must be completed wbile maintaining the correct

occlusal vertical dimension and making sure that the patient remains inthe centric relation position through the border molding procedures andthe final set of the impression material.

c. An occlusal equilibration of the existing dentures may be necessarybefore the reline procedure to ensure adequate positioning of thedentures dtning the impression procedures.

6. When deciding which denture to reline firet, usually the less stable of thetwo is relined first. If there is no significant difference between the stabilityor retention of the opposing denttires, then the maxillary denttire is oftenselected. Once relined, it will provide a stable opposing arch when reliningthe mandibular denture.

7. When pouring the master cast for a reline procedure, if dental stone ispoured into a resin undercut of the denture, it becomes extremely difficultfor the laboratorv- technician to separate the denture from the cast withcausing breakage to the cast and/or the denture. To allow the laboratorytecbnicians to remove the denture from tbe ma.ster cast during processing,enough resiti is removed from the tissue side of the dentiu-e to eliminate allresin undercuts on the denture base.


8. The plane of occlusion may have been unacceptably altered, which may bean esthetic problem, and the vertical dimension of occiusion has been overlvreduced by approximately 1-1.5 mm. This loss can be reversed by adding 4"stops." Small stops are created witb spots of heavy-bodied poMinyl siloxanematerial, about 3 mm in diameter. The stops are placed in the canine andsecond molar areas.

9. One method is achieved clinically, and the second is achieved as a labora-tory procedure. The laboratory procedure involves cutting the posteriorpalatal seal into the master cast, as is usually done with a conventionaldenture. Modeling plastic is warmed and formed across the posterior borderofthe denture in the clinical method.

10. Four to six holes are placed into the maxillary denture—spaced approxi-mately 12 mm (hall inch) apart—to allow the escape of excess impressionmaterial, thereby minimizing hydraulic pressure buildup, which may preventthe denttue from being properly seated, or to displace soft underlyingtissues.

PreliminaryImpressions

303


Mandibular Impression

Figure A1-1 The edentulousmandibular arch must be thor-oughly evaluated prior to makingthe preliminary impression. Theproperly made preliminary impres-sion will be used to fabricate a diag-nostic cast. The cast must be asaccurate a representation of theridges and undistorted surroundingtissues as possible because this castwill be used to fabricate a customimpression tray, which will be usedto make the final impression.

Figure A1-2 It is extremely impor-tant to capture the retromolar pad inthe preliminary impression.This is acritical area of support for thecompleted denture.

Rgure A1-3 The masseter musclearea will often exhibit a fatty pad orroll of tissue partially covering theretromolar pad. The diagnostic castwill not be an inaccurate representa-tion of this area if this tissue roll iscaptured in the impression.

Preliminary Impressions 305

Rgure A1-4 The cheek must begently stretched away from the areaduring the impression making proce-dure. When properly stretched, thefatty roll is eliminated from theimpression area.

Figure A1-5 The retromylohyoidarea is located lingual to the retro-molar pad area. A custom impres-sion tray will be fabricated as thenext procedure and must be properlyextended into this area to obtainan acceptable final impression.Fabrication of a properly extendedcustom tray won't be possible if theentire extension of this area is notcaptured in the preliminary impres-sion.

Figure A1-6 An excessivelyenlarged tongue can make all stepsin the fabrication of completeddentures very difficult. Practiceinserting the trays and have thepatient close slightly during impres-sion procedures to keep the tongueas relaxed as possible


Figure A1-7 The buccal shelf areais extremely important in the fabri-cation of mandibular completedentures because it is the primarystress-bearing area of the mandibu-lar arch. A very accurate impressionof this area, not artificially overex-tended, is also important.

Figure A1-8 Many brands of stockimpression trays are available, butsome are poorly shaped and makeobtaining excellent preliminaryimpressions almost impossible.These are examples of well-shapededentulous impression trays.(Border-Lock ImpressionTray, Accu-Liner Products, Woodinville,WA).Note particularly that the massetermuscle areas of the trays have nosharp corners. The flange of thesetrays cover the buccal shelf area andthen approach and cross the retro-molar pad into the mylohyoid areasas a smooth continuous border,

Figure A1-9 A stock tray of thegenerally correct size is selectedand then must be evaluated in allvestibular areas and posteriorly.


Figure A1-10 Properly desiredextension ofthe tray in the anterior.A well-fitting tray should provideapproximately 6 mm of spacebetween the flange and undistortedvestibule.

Figure A1-11 A properly fittingimpression tray must not be overex-tended and should not distort thesoft tissues. This tray follows thevestibule in the buccal shelf areavery nicely.

Figure A1-12 This impression trayis too long and improperly shapedfor this distobucca! area.


Figure A1-13 Once the "best fit"trays are selected, they mustusually be modified with peripherywax. A properly fitting tray musthave approximately a 6 mm spacebetween the tray and the tissues, ifa larger space exists or if the exten-sion of the tray must be increased,periphery wax is indicated.

FigureA1-14 Typical required traymodification. Do not add wax unlessneeded! Wax is occasionally neces-sary to protect the soft tissues, if thetrays have sharp flanges.

Figure A1-15 The appropriateadhesive for the impression mate-riai selected should be placed onany added periphery wax. Whenmaking preliminary impressions forcomplete dentures, placing adhe-sive on the impression tray itselfmay not be necessary if the trayhas retention holes or rim locks.


Figure A1-16 Irreversible hydrocolloid impression mate-rial is an ideal material for making preliminary impres-sions. It is inexpensive, provides acceptable workingtimes, and makes excellent impressions. Using the water-to-powder ratio suggested by the manufacturer is recom-mended, varying the ratio slightly is acceptable to modifythe viscosity of the impression material in order to meetthe desires of the clinician. Most manufacturers recom-mend adding the powder to the water in the mixing bowlto minimize the capturing of bubbles within the mixture.However, proper mixing technique will minimize theproblem.

Figure Al-17 When properly mixed, the irreversibleimpression material should be completely smooth.Thereshould be no dry powder remaining when the mixing iscompleted!


Figure A1-18 The impression trayshould be loaded only approxi-mately three-quarters full.

Figure A1-19 Using fingers or alarge syringe, a small amount ofimpression material should beplaced in areas that may be difficultto capture in the impression. Theseareas often include the retromylohy-oid areas.

Figure A1-20 When inserting thetray, an effort is made to minimizewiping off the impression materialfrom the tray by pulling the lips andcheeks away from the impressiontray and material. Forthose patientswith small mouths, a mouth mirrormay be necessary to retract thecorners of the mouth; the fingersmay be too large for this task.


Figure A1-21 As the tray is seated,the cheeks and lips are stretchedaway from the ridge crest. This willallow the impression material tototally fill the vestibular areas andcaptured air bubbles to be expelled.This is especially important in themasseter muscle area, where thefatty tissue roll will often becaptured in the impression if care isnot taken.

Figure A1-22 Once the tray iscompletely seated, the patient isinstructed to lift and extend thetongue to form the lingual surfaceof the impression. The patientshould not make any exaggeratedmovements.The tongue should onlybe protruded to just beyond thelips. It can also be moved laterallyuntil the tip gently touches theinside of the cheeks.

Figure A1-23 The cheeks are liftedgently at about a 45-degree angleupward and outward and manipu-lated anteriorly and posteriorly toreduce overextension of the bordersof the impression.This manipulationcan be continued until the workingtime of the material has beenreached. Manufacturer's instructionswill indicate the working time of thematerial being used.


Figure A1-24 Once all manipula-tion has been completed, theimpression is prevented frommoving by gently maintaining itsposition. Basically tbe clinician issimply preventing the impressiontray from being lifted away from theridge until the impression materialhas reached its setting time. Liftingthe cheek to break the seal aroundthe impression will make removaleasier.

Figure A1-25 Note that thisimpression captured the fatty tissueroll in the masseter muscle area. (A)Note also that tbis impression trayhad a corner in this area. {B)This isnot an ideal tray for the mandibulararch. This impression should beremade.

Figure AI-26 This massetermuscle area is accurately captured.


Figure A1-27 A well-mademandibular preliminary impression.Note that all vestibules and poste-rior extensions have been capturedwithout grossly overextending theimpression. Mininnal bubbles andvoids have been captured in theimpression. A well-made preliminaryimpression should closely resemblea well-made final impression.

Figure A1-28 A well-mademandibular preliminary impression.This impression should immediatelybe taken to the laboratory andpoured with a dental stone.

Maxillary Impression

Figure A1~29 The edentulousmaxillary arch must be thoroughlyevaluated prior to making thepreliminary impression.


Figure A1-30 Multiple areas of thearch must be evaluated before andduring impression making.The labialfrenulum area is often prominent andeasily displaced. Care must be takenwhen making an impression of thisstructure.

Figure A1-31 The hamular notcharea.This is a critical area that mustbe accurately and completelycaptured ¡n both the preliminaryand final impression.

Figure Al-32 The vibrating linearea must be visualized.This Is alsoan area that must be accuratelycaptured in both the preliminaryand final impression, therefore theimpression tray must cover this area.


Figure A1-33 As in the mandibulararch, a stock impression tray isselected to "best fit" the arch.Thisis a reasonably well-fitting impres-sion tray.

Figure A1-34 As in the mandibulararch, small amounts of impressionmaterial are placed by finger inareas that may be difficult to capturein the impression.

Figure A1-35 Care must be takenwhen initially inserting the impres-sion to capture all desired areas ofthe arch and yet minimize discom-fort to the patient.


Figure A1-36 Seat the posteriorof the tray first, rolling the anteriorportion into position while displac-ing the cheeks to allow air to escapein front of the impression material.The cheeks are then manipulatedto reduce overextension of theimpression.

Figure A1-37 The impressiontray must not be allowed to moveduring the setting of the impressionmaterial.

Figure A1-38 Even though theimpression material on the flangesis slightly thicker than desired, thisis a well-made maxillary preliminaryimpression. Note that the incisaifrenulum, hamular notches, andvibrating line area are all capturedwith minimal bubbles and blebs.This impression should immediatelytaken to the laboratory and pouredwith a dental stone.

Creating DiagnosticCasts

317


Figure A2-1 Dental stone is mixedaccording to the manufacturer'sinstruction using a technique thatminimizes the capturing of airbubbles within the stone mixture.The stone for a diagnostic cast doesnot need to be vacuum mixed,however it may be.

Figure A2-2 The preliminaryimpression is carefully and slowlyfilled generally beginning in oneposterior area and continuing toflow the material around theimpression using gentle vibration.

Figure A2-3 This slow fill isfollowed until the stone completelyfills the impression.This first pourof stone must cover all anatomicalsurfaces of the impression withoutextending onto the impression tray.

Creating Diagnostic Casts 319

Figure A2-4 Separating the impression and tray from thediagnostic cast can be very difficult if stone is allowed tobe in contact with the tray. Care should be taken to restrictthe stone to covering only the impression material. Notethat nodules were placed on the stone surface.Thesenodules will aid in bonding and strength between thisfirst and the second base pour of stone.

Figure A2-5 Excessive stone has been allowed to flowover the sides of this impression. The impression tray willbe captured in the stone, and separation of the cast fromthe impression will be very difficult.


Figure A2-6 Once an impression has been made, caremust be taken to prevent distortion of the impressionmaterial.This may happen through loss of water or physi-cal displacement from the tray.Typically unsupportedimpression material will extend beyond the posterior ofthe impression tray and, if allowed to contact the benchtop, physical displacement may cause distortion. Thispotential is increased once the weight of the stone isadded to the Impression.Therefore, once the initial pourof stone is completed, the impression tray and materialshould not be allowed to contact the bench top until atleast the initial setting of the stone has occurred.

Figure A2-7 Slightly flatten the retention nodules parallelwith the crest ofthe ridges.This will stabilize the first pourwhen it is inverted into the stone for the base of the cast.


Figure A2-8 Following the initialsetting of the stone, a second pour ofstone is prepared and piled to aheight of about 5 cm.The impres-sion/cast is inverted and placed ontothis base, making an attempt to visu-alize and make the crest of the ridgesparallel to the bench top.

Figure A2-9 An attempt is madeto remove excessive stone to mini-mize trimming at the next step.Thestone is allowed to set according tothe manufacturer's instructions.

Figure A2-10 Once the stone hasset, the Impression is carefullyremoved from the stone cast.

322 Textbook of Connplete Dentures

Figure A2-11 Example of a nicelypoured maxillary diagnostic castbefore trimming.

Figure A2-12 Even though anattempt was made to have the crestof the ridges parallel to the benchtop during the making of the baseof the cast, this goal is seldomachieved.The necessary trimmingmust be visualized. In this example,it is obvious that the cast is thickeron one side that the other.Therefore,the ridge crests are not parallel tothe bench top. When trimming thecast, the first objective will be tocorrect this thickness discrepancyand make the ridges parallel to thebench top. Remember this may bean anterior-posterior problem also.

Figure A2-13 Prior to trimmingthe cast, it should be thoroughlydampened by soaking in water forapproximately five minutes. Soakinglonger than this can damage thesurface ofthe cast. The purposeof wetting the cast is to prevent"slurry" material from sticking toa dry cast. See Figure A2-15 on nextpage.


Figure A2-14 Using a model trim-mer, the initial trimming of the castwill be to the bottom of the cast andwill be to correct inconsistent and/orexcess cast thickness. Remember toalways have water running whenusing a model trimmer and to rinseoff all stone slurry once the trim-ming is completed.

Figure A2-15 As the cast istrimmed, the stone mixes withwater and forms a slurry mixture.This mixture will stick to a dry castand can make a cast unusable.Thiscast was thoroughly dampenedprior to beginning to trim the castin an attempt to prevent the slurryfrom sticking to the cast.

Figure A2-16 The cast must repeat-edly be rinsed to remove all slurrymixture.


Figure A2-17 The bottom of thebase of this cast has now beentrimmed so that It is not too thick orthin and is reasonably parallel to thecrest of the ridges. See Figure A2-18X. Remember, a cast must be suffi-ciently thick to prevent breakage,but excessive thickness is undesir-able. Excessive thickness becomessignificant when creating mastercasts because those casts must fit ina flask when processing the denture.

Figure A2-18 Diagramatic view ofdesired dimensions of a trimmeddiagnostic or master cast. X: thick-ness of cast (12-18 mm in thinnestarea).Y: width of land area (2-3mm). Z: depth of vestibules (2-3mm).

Figure A2-19 Once the bottom ofthe base of the cast is corrected, thesides of the base can be trimmedusing the model trimmer. SeeFigure A2-18Y. Prior to trimming thesides of the base, always verify thatthe platform of the model trimmer(A) is perpendicular to the trimmingwheel (B).

^ A

/I


Figure A2-20 Once the land areason the dry cast are the correctwidth, an acrylic bur can be used toreduce the height as necessary tocreate the approximate desireddepth ofthe vestibules.This isnecessary, particularly on mastercasts, so that the laboratory techni-cian has access to all areas of thecast and also reduces the possibilityof cast breakage during laboratoryprocedures. See Figure A2-18 Z.

Figure A2- 21 An arbor band canalso be used to reduce the landareas to create the approximatedesired depth of the vestibules.See Figure A2-18 Z. Once again, thecast must be dry prior to using anarbor band.

10 20 30

-• AT MARK INDICATING

EFT CUSPID Figure A2-22 These land areashave been trimmed to the correctwidth, and any excess vestibulardepth has been eliminated.


Figure A2-23 On the mandibularcast, the tongue area should alsobe contoured so that the vestibulesare the correct depth and the stoneis either flat or gently curves fromone side to the other.

Figure A2-24 Once the cast isproperly trimmed, wet and drysandpaper can be used to smooththe trimmed portions of the cast.

Figure A2-25 Examples of excel-lent diagnostic casts

Cnstom ImpressionTrays

327


Mandibular Cusiom Tray

Figure A3-1 A mandibular diag-nostic cast properly trimmed andready for custom impression trayfabrication.

Figure A3-2 The desired tray exten-sion has been drawn on the cast.Generally the extension is approxi-mately 2-3 mm above the depth ofthe vestibule, if the vestibule was notartificially overextended during themaking ofthe impression.

Figure A3-3 Desired tray extensionproperly indicated on the lingual

Custom ImpressionTrays 329

Figure A3-4 The nonstress-bearingareas have been delineated on themandibular cast. Note that relief waxwill not be extended to the buccaland lingual of the anterior ridge (A)because they are considered second-ary stress-bearing areas. Note alsothat the buccal shelves will not haverelief wax because they are theprimary stress-bearing areas (B).Theretromylohyoid areas receive mini-mal wax relief (C) in order to havegood adaptation of this area.Thisarea must receive enough block-outwax so that the impression tray canbe removed from the cast.

Figure A3-5 A half sheet of warmedbaseplate wax being adapted to cast,to form the layer of relief wax (1.5mm thick). . .

Figure A3-6 The relief wax istrimmed back to the desired outline.It should be lightly tacked to the castby melting very small areas of thewax to the cast, about every 12 mm.


Figure A3-7 The mandibular castwith relief and block-out waxplaced.

Figure A3-8 A separating mediummust cover all exposed areas ofstone even extending somewhatdown the sides of the cast. Vaselineis commonly used in a very thinfilm.

Rgure A3-9 Separating mediumproperly extended on mandibularcast. Note that the material is onlya very thin film. It is not used as ablock-out material.


Figure A3-10 Autopolymerizingresins are commonly used asimpression tray materials.

Figure A3-11 The resin is mixed ina paper cup with a tongue blade,using the manufacturer's directions.The powder-to-liquid ratio is often3 to 1.

Figure A3-12 Once completelymixed, the resin is allowed begin topolymerize until it can be handledwithout sticking to gloves.The traymaterial must be thoroughlyblended using the fingers.


Figure A3-13 The tray materialmust be thinned to approximately3 mm in thickness.This wilt providesufficient strength to the tray whilenot being excessively thick. Twoglass slabs can be used to createa sheet of resin of the correct thick-ness. Vaseline should be used as aseparating medium on both glassslabs.The material can be shapedto reseaible the mandibular archusing a sharp knife.Three smallpieces of the trimmed resin areretained to make one anterior andtwo posterior handles.

Figure A3-14 The resin is initially carefully placed on thecast and then properly extended almost to the depth ofthe vestibules and posteriorly completely through theretromylohyoid area. An effort is made not to thin thematerial. Excess material should be trimmed back to thelines indicating the desired extensions with a sharp knife,while the material is still in a softened state.This willmake further shaping much easier. While still workable,the tray handles are added. See Figure A3-18 for theshape of the handles. The anterior handle should beperpendicular to the arch and approximately 16 mm inheight, 12 mm in width, and 6 mm in thickness.The poste-rior handles should be approximately 10 mm in height,14 mm in length, and 6 mm in thickness.


Figure A3-15 Once the materialis completely polymerized, it isremoved from the cast. Oftenremoval is difficult, and the trayshould be removed by first attempt-ing to lift one side with a laboratoryknife before switching to the oppo-site side.This is continued untilthe tray is removed. Because theretromylohyoid areas are oftensignificantly undercut in relation toeach other, if insufficient block-outwas completed, it will very difficultto remove the tray, and the castmay be broken.

Figure A3-16 Often the pencil linesplaced on the diagnostic cast delin-eating the desired extension ofthetray will be visible on the tray. Ifpresent, these lines are used toproperly shape the impression tray.

Figure A3-17 Using an arbor bandor large resin trimming bur, alloverextension is eliminated.


Figure A3-18 When completed,the tray should extend to within2-3 mm from the depth of thevestibules and to the most posteriorextent to the retromylohyoid area.All excessively thick areas of thetray are thinned to approximately3 mm in thickness. Sharp areas aresmoothed.

Figure A3-19 Mandibular traylength properly reduced

Figure A3-20 Completed mandibu-lar impression tray as seen from thetissue side


Maxiilary Custom Tray

Figure A3~21 A maxillary diagnos-tic cast properly trimmed and readyfor custom impression tray fabrica-tion.

Figure A3-22 A maxillary diagnos-tic cast with desired tray extensionmarked. Even though the desiredextensions are generally approxi-mately 2-3 mm short of the depth ofthe vestibules, in this situation theanterior lines are placed approxi-mately 6 mm short of the depth ofthe vestibule (A).This placement iscaused by muscle attachments closeto the ridge crest.

Figure A3-23 The nonstress-bearing area is indicated for a layerof relief wax on the maxillary arch.Note its mushroom-shaped appear-ance (A).This area is neither aprimary nor secondary stress-bear-ing area.This area extends fromapproximately 5 mm short of theanticipated distal-most extensionof the impression tray and extendsanteriorly staying 3 mm on eitherside of the midline suture. It thenturns diagonally toward the ridgecrest just posterior of the rugaearea.


Figure A3-24 The mushroom-shaped area extends just over thecrest of the ridge.

Figure A3-25 Relief wax adaptedto the maxillary cast. Note that it istacked down in several areas bysimply melting a small area of waxonto the cast (A). Also note thatirregular areas of the cast have beenadditionally blocked out with thinlayers of wax (B). Note also that thelabial frenum has been blocked outto prevent breakage.

Figure A3-26 Two holes areprepared in the relief wax. Resin willbe placed in these holes to createtissue stops.They should be placed12 mm from the incisive papillaarea.They should be approximately3 mm X 3 mm.These tissue stopsare necessary in case the reliefwax must be removed during theborder molding step of the finalimpression.


Figure A3-27 A very thin film ofseparating medium is placed on themaxillary cast.

Figure A3-28 The maxillary impres-sion tray is made in the same manneras the mandibular tray. In this exam-ple a light polymerizing resin isdemonstrated. When this material isselected, a separating medium isplaced on the cast as recommendedby the manufacturer. In this example,a sheet of colorless resin (TriadTrutray, Dentsply International Inc.,York, PA) has been initially positionedon the maxillary cast, and excessmaterial is being removed.Theexcess material is retained to make ahandle forthe tray.

Figure A3-29 When properlyadapting the tray, care should betaken to not overly thin the material.


Figure A3-30 The tray materiai isproperly extended on the maxillarycast.

Figure A3-31 The handle is madefrom the excess material trimmedinitially.

Figure A3-32 When completed,the handle should be approxi-matelyl2 mm in length and width,and 6 mm in thickness. It shouldangle toward the anterior to approx-imate the centrai incisors.


Figure A3-33 All areas of thelight polymerized resin are coatedwith an air-inhibiting material thatprevents oxygen from contactingthe resin and allows more thoroughpolymerization.

Figure A3-34 The light polymerizedresin can now be polymerized.

Figure A3-35 The cast and trayare placed in a light polymerizationunit (Triad 2000 Light Curing Unit,Dentsply International Inc., York, PA)and polymerized according to themanufacturer's recommendations.The tray is removed from the cast,the internal surface is covered withan air barrier coating, and againpolymerized with the internalsurface facing upward.


Figure A3-36 The impression resintray has been removed from thecast. In this example the relief waxhas not been lost from the heat ofpolymerization of the light polymer-ized resin. However, because of thatpotential, two tissue stops werecreated. Prior to further procedures,it is absolutely necessary to thor-oughly remove the air barriercoating from the impression trayfollowing polymerization, hisrequires thorough cleaning underrunning water.

Figure A3-37 The relief wax waslost from this tray, and the tissuestops are visible (A) in the canineareas.The impression tray istrimmed similar to the mandibulartray, with the exception ofthe traybeing trimmed to the vibrating linein the posterior.

Figure A3-38 A maxillary autopoiy-merized acrylic resin impressiontray neatly trimmed


Figure A3-33 This tray has beentrimmed 2 mm short of the depthof the vestibules.

Figure A3-40 A well-fabricatedmaxillary custom impression tray,as viewed from the tissue side

Figure A3-41 The completed maxil-lary and mandibular custom trays

Finai impressions

343


Maxillary Impression

Figure A4-1 Examples of maxiiiaryand mandibular custom impressiontrays.

Figure A4-2 Maxillary acrylic resincustom impression tray.

Figure A4-3 The trays must be eval-uated for fit and extensions. Ideallya tray should cover all tissues to beimpressed and have an even spacingof approximately 2 to 3 mm betweenthe tray flanges and the depth of thevestibules. The borders of this trayare impinging on the soft tissues ofthe vestibule.

Final Impressions 345

Figure A4-4 The flange length hasbeen corrected. The evaluation andcorrection is continued around theperiphery of the tray to include theposterior length trimmed just slightlylonger than the vibrating line.

Figure A4-5 The opposite side isalso overextended and must becorrected.

Figure A4-6 Special care must betaken to create space in the labialfrenulum area because this tissuehas no muscle fibers and is veryeasily displaced. More relief isneeded on this tray.


Figure A4-7 The posterior palatalseal area must be visualized whentrimming the tray.

Figure A4-8 Additionally, althoughevaluated during the initial diagno-sis of the patient, the depth of thedisplaceable tissues must bereviewed because this informationwill be used when forming themaxillary master cast. The orange/red areas indicate places in whichthe tissues can be depressedapproximately 1 to 2 nnm.The greenarea indicates that the tissue can bedepressed approximately 0.5 to 1mm.The blue area indicates that thetissues can be depressed up to 0.5mm.

Figure A4-9 The vibrating line Islocated. The vibrating line is thejunction between the reasonablyunmovable tissue of the hard palateand the movable tissue of the softpalate.The mark in the figure indi-cates the beginning slope of the softpalate just distal to the vibratingline. The tray will be slightly longerthan the vibrating line in order torecord the anatomical detail neededfor this landmark.


Figure A4-10 This line has been properly placed on thevibrating line.This line could be extended bilaterallythrough the hamuiar notches but generally is unnecessarybecause, for most patients, the vibrating line is a gentlycurved line that extends from this midline mark throughthe hamular notches.This is a very typical vibrating line.Note that it is a curved line that is concave toward theanterior as compared with the line drawn straight fromone hamular notch to the other. A vibrating line drawnstraight across the palate is almost never correctly drawn!

Figure A4-n This tray has been correctly trimmed backclose to the vibrating line. Once again, note that the poste-rior of the tray is concave in shape toward the anterior.This tray is now ready to be border molded.


Figure A4-12 For illustration purposes, modeiingcompound will be used when border molding the maxil-lary arch. Vinyl polysiloxane will be used for the mandibu-lar arch. Either material could have been used forthemaxillary or mandibular arch.The recommended sequenceof border molding is indicated in this picture when usingmodeling compound. Had vinyl polysiloxane been used,longer sections, up to half the tray, can be completed atone time.

Figure A4-13 When border molding with modelingcompound, several pieces of equipment and suppliesmust be used. A primary requirement is a Bunsen burner.


AJcohoiTorch

Figure A4-14 A second piece ofequipment required is an alcoholtorch. An alcohol torch is used toreheat the modeling compoundwhen necessary. It is not usedto initially heat the modelingcompound because the flame is nothot enough. A significant amount oftime will be lost in trying to use thealcohol torch to initially heat themodeling compound.

Figure A4-15 The modelingcompound is slowly rotated duringheating to thoroughly heat thematerial. It should be removed fromthe flame when it begins to slump.

Figure A4-16 The modelingcompound is thoroughly heateduntil to flows freely and Is addedin small increments to the impres-sion tray following the sequencesuggested in Figure A4-12 above.About 2-3 mm of material is neededbecause that is how much theflange of the tray was shortenedfrom the depth of the vestibules.


Figure A4-17 Prior to inserting atray into the mouth with heatedmodeling compound, the materialmust he tempered in a hot waterbath set to 60° C (140* F). Temperingcools the material to a level that iscomfortable to the patient whilemaintaining the temperature at alevel that keeps its viscosity lowenough to freely flow. Working timenow becomes an important issue.

Figure A4-18 The impression trayand modeling compound is insertedbeing careful not to wipe the mate-rial off on the cheeks, tongue, etc.Modeling compound becomesunacceptably rigid in severalseconds, the clinician must be quickto insert the tray properly andperform the border molding musclemovement.

Figure A4-19 Once inserted, theclinician has only about a 10 secondworking time before the modelingcompound becomes too rigid to beusable. While the material is stillflowing, the border molding proce-dures are quickly but thoroughlycompleted.


Figure A4-20 Once removed, thetray/compound is immediatelyinserted into a bowl containingwater to increase rigidityand minimize possible distortion.Five seconds in the iced water issufficient.

Figure A4-21 The border moldedarea can now be evaluated. Anyexcess modeling compound, eitherinside the tray or in thickness, isremoved with a sharp knife. Ifnecessary, additional compoundcan be added, and the area bordermolded again if the initial attemptwas unacceptable. This procedureis repeated as necessary until thisparticular area is totally acceptable.Do not begin a second area until theinitial area is totally acceptable. Thisapplies through the entire bordermolding procedure.

Figure A4-22 When acceptable, thecompound should have a smoothbut matte (dull) appearance to itssurface, it should not be shiny.


Figure A4-23 A particularly difficultarea to border mold can be thelabial frenulum. Because thisfrenulum is very flaccid, it must bethoroughly manipulated, and thecompound sufficiently warmed tobe workable during the bordermolding procedure.

Figure A4-24 Example of a nicelyborder-molded labial frenulum area.

Figure A4-25 The border moldingis complete. Notice that thecompound does not extend muchbeyond the tray in the posteriorpalatal seal area. The tray was cutto the proper extension so the mate-rial should be close to the samelength as the tray in this area.


Figure A4-26 The relief wax isnow removed to create the reliefchamber.

Figure A4-27 Five to six holes canbe placed in the relief chamberusing a #8 round bur. These holeswill allow the impression material toescape as hydraulic forces buildduring the impression procedure.

Figure A4-28 The wax has beenremoved and the holes have beenprepared.


Figure A4-29 Any sharp areas atthe wax/resin interface are removedwith an acrylic bur. Note the holesthat have been prepared.

Figure A4-30 Some cliniciansremove approximately 0.5 mm ofthe nnodeiing compound to allowspace for the final impression mate-rial. With the low viscosity materialsavailable, this is probably not neces-sary if the border molding wasaccurate.

Figure A4-31 The appropriateadhesive for the impression mate-rial being used is applied in a verythin film to the entire tissue surfaceof the tray and extends out on thebuccal, labial, lingual, and posteriorabout 6 mm. Basically all tissuesurfaces of the tray and compoundshould have adhesive added.


Figure A4-32 There are a myriad offinal or "wash" impression materi-als available. With many choices ofworking and setting times available,vinyl polysiloxane impression mate-rials are commonly used. Most ofthese materials use a "gun"-typemixing device to express theimpression material. Care is takenwhen loading the impression mate-rial into the tray to preclude thecapturing of air bubbles within thematerial.

Figure A4-33 The entire tissueside of the tray and compoundshould be covered with impressionmaterial. However only enoughmaterial should be placed to coverthe tray with a 3mm thickness ofmaterial. Slightly more materialmay be placed in the relief chamberareas. The entire border-moldingmaterial should be covered for atleast 6 mm on the buccal, labial,and lingual.

Figure A4-34 Most impressionmaterials are hydrophobic. Prior toinserting the impression materialinto the mouth, the patient shouldswallow to remove excess saliva.Any remaining saliva should bedried with gauze.


Figure A4-35 Care should be takenwhen inserting the tray/material tominimize any contact with lips,cheeks, and tongue, as this maywipe material off the tray resultingin a poor impression. The patientshould be instructed to totally relaxthe lips, cheeks, and tongue.

Figure A4-36 Once inserted, allnecessary border molding iscompleted and the tray/material isthen secured until the material sets.Manufacturer's information shouldbe consulted concerning workingand setting times. Generally a mate-rial with a two and a half- to three-minute working and setting time isexcellent. It provides sufficient work-ing time and yet minimizes loss ofclinical time while waiting for thematerial to set.

Figure A4-37 Example of a well-made and trimmed maxillary finalimpression


Figure A4-38 Note that the poste-rior palatal seal area has beendrawn on this impression. This isimportant in order to transfer theoutline to the master cast An indeli-ble marker can be used to outlinethe area in the mouth, and theimpression can be placed back inthe mouth. With this technique,when washing and disinfecting theimpression, much of the outlinemay be washed off the impressionand must be redrawn.

iVIandibular impression:

Figure A4-39 Mandibular customimpression tray

Rgure A4-40 Note that thenonstress-bearing areas of this traywere blocked out with relief wax,which will be removed followingborder molding.


Figure A4-41 As was done with themaxillary tray, the mandibular traymust be evaluated and extensionscorrected.

Figure A4-42 Because it may be adifficult area to visualize, the desiredextension in the buccal shelf areaand masseter muscle areas havebeen marked with an indeliblemarker. If using this technique, thetissues should be reasonably dryprior to marking to minimize thespreading of the material through-out the entire area.

Figure A4-43 The tray is replaced.


Figure A4-44 The marks havetransferred to the tray.

Figure A4-45 The marks wereplaced in the depth of thevestibules, so the tray must be cutback 2 mm short of the marks toprovide space for the border mold-ing material.

Figure A4-46 The tray is sufficientlyreduced in the buccal shelf area.However, it still must be reducedin the masseter muscle area.


Figure A4-47 For most patients,a correctly trimmed mandibularimpression tray will exhibit severalcharacteristics. First, unless thepatient has had some type surgicalextension of the vestibule, thebuccal and lingual flange lengthsin the anterior should be approxi-mately the same length.

Figure A4-48 Second, the massetermuscle extension of the tray shouldapproach the crest of the ridge at agradual 45° to 60° angle and flowsmoothly into the retromyiohyoidarea.There are no sharp corners inthese areas. A denture made froman impression with sharp cornerswill cause severe discomfort to thepatient because it will abrade thetissues rather rapidly.

Figure A4-49 Third, the lingualflange should begin approximatelyeven with the buccal flange in theincisai area and then gradually getlonger than the buccal flange as itgoes posteriorly. The lingual flangeshould form an almost straight linewith minimal curvature. (A)


Figure A4-50 Finally, the mostdistal extent of the impression trayis going to be in the retromylohyoidspace area (A), just lingual to theretromolar pad. The retromylohyoidextension should exhibit a smoothcurvature from the retromolar padarea to the lingual flange area. (B)

Figure A4-51 The suggested sequence for border mold-ing, if modeling compound is to be used. If vinyl polysilox-ane is to be used, generally the entire buccal and thenlingual flanges can be completed and then each retromylo-hyoid area is border molded. Generally, because ofthesize and strength of the tongue, even though the entirevestibular extension can be obtained in the retromylohyoidareas using vinyl polysiloxane, the thickness of the mate-rial will not be acceptable on the first attempt. It will oftenbe knife edged. On subsequent insertions with additionaiborder molding material added, the area can be moreeasily thickened if the patient closes slightly as the tray ispositioned and asked to moisten their lips with the tonguegently to accomplish the border molding.


Figure A4-52 Prior to border mold-ing, the correct adhesive for theimpression material is applied tothe flanges and about 6 mm insideand outside the tray. It ¡s allowed todry according to the manufacturer'sinstructions. Do not place the adhe-sive on the entire internal surface ofthe impression tray at this time.

Figure A4-53 A layer of heavy-bodied impression material isapplied to the flanges making anattempt to minimize excess material.

Figure A4-54 Care is taken wheninserting the tray for border mold-ing to minimize toss of materialonto the cheeks, lips, tongue, etc..The cheeks should be gentlystretched outward while insertingand seating the tray/material toavoid wiping the material from thetray, to remove the fatty roll oftissue in the masseter muscle areas,and to allow any capturedair bubbles to escape. It may benecessary to use a mouth mirrorto stretch the corner of the mouthif the fingers are too large.


Figure A4-^5 Once completelyseated, the border molding canbegin.The patient should protrudethe tongue to form the retromylohy-oid areas, move the tip of thetongue from cheek to cheek to formthe posterior lingual areas, and thengently protrude the tongue to formthe anterior lingual area. Somepatients will attempt to exaggeratethe tongue protrusion, but thetongue should only be protrudedto a normal functional range.

Figure A4-56 The buccal shelf andnnasseter muscles should be care-fully evaluated,

Figure A4-57 This entire tray wasborder molded in a single attemptwith reasonably good results. Otherthan some minor areas of pressure(show through) the major problemis in the lingual anterior area. Areasthat show through the border mold-ing will need correction.


Figure A4-58 Prior to correctingproblem areas, all excess materialis removed with a sharp knife. Itshould be easy to remove if theadhesive was properly placed.

Figure A4-^9 Excessive pressureareas to be corrected are noted.

Figure A4-60 All areas of pressureare removed with an acrylic bur.


Figure A4-61 Adhesive is addedto any newly exposed resin andallowed to dry, heavy-bodied mate-rial is again added, the tray/materialis reinserted, and border molded.

Figure A4-62 This impression trayis acceptably border molded.

Figure A4-63 Relief holes areplaced approximately every12 mm using a #6 or #8 round bur.Adhesive is applied to all internalresin surfaces; the tray is properlyfilled with light-bodied impressionmaterial; tray/material is inserted,and border molding is completed.


Figure A4-64 Acceptable mandibu-lar final impression. Note theapproximately 45° angle in themasseter muscle area, and smoothcontinuous flow of material fromthe masseter muscle area across theretromolar pad into the retromylo-hyoid area. Note also the excellentcoverage of the buccal shelf areas.

Figure A4-65 Acceptable mandibu-lar final impression

Creating MasterCasts

367


Rgure A5-1 Prior to attemptingto pour the final impressions, aform should be created around theimpressions to simplify the proce-dure and to give the proper sizeand shape to the master casts byconfining the dental stone while theimpressions are poured.This proce-dure is called beading and boxingthe impression. Multiple materialscan be used to bead and box animpression, including combinationof dental stone and pumice, irre-versible hydrocolloid, etc. In thisexample, Play-doh is being used tobead the impression.

Figure A5-2 The Play-doh shouldbe built up approximately 75 cm inheight and extended at least 3 mmbeyond ail border of the impression.This will support the impression andprovide for a proper land area onthe master cast. In this example, aresin support is being used but isnot necessary. AM borders of theimpression are exposed by approxi-mately 2 mm so as to provide forsufficient depth to the vestibule inthe master cast.

Figure A5-3 On the mandibulararch, the tongue area is flat fromone side to the other. Note that theentire roll has been exposed In themasseter muscle, retromolar pad,and retromylohyoid areas. On themaxillary arch, it is also necessaryto expose the entire roll at theposterior border of the impression.

Creating Master Casts 369

Figure A5-4 The material will beboxed with two pieces of red boxingwax.They should be joined togetherwith the tape. Approximately 7.5 cmof tape is left extended beyond thewax on one end.

Figure A5-5 The boxing wax isclosely adapted to and encloses thebeading material, forming a chim-ney-like form that will retain thedental stone during pouring. Caremust be taken not to compress thebeading material or collapse thewax chimney. If either occurs, it maybe impossible to form a properlyshaped and sized base of the mastercast. One end of the wax overlapsthe other end of the wax, and thetape is used to seal the two endstogether.

Figure A5-6 To allow for sufficientthickness of stone, the boxing waxchimney should extend 16 to 18 mmabove the highest surface of theimpression (usually a flange).Twoadditional pieces of tape (A), oneabove and one below the first piece,are used to totally seal the form.


Figure A5-7 When properlycompleted, the boxing wax shouldcompletely seal the impression andbeading wax. Additionally, the bead-ing wax must not be compressednor should the walls of the chimneycollapse. Example of a well-beadedand boxed mandibular finalimpression.

Figure A5-8 A well-beaded andboxed maxillary final impression.The posterior palatal seal area hasbeen marked with an indeliblemarker. This will usually transferto the master cast, making It easierto create the posterior palatal seal inthe master cast.

Figure A5-9 The dental stone ofchoice is prepared according to themanufacturer's instructions andvacuum mixed to minimized airbubbles from becoming entrappedin the mix and being transferred tothe master cast. A small initial fill isstarted, and the stone Is flowed intothe impression using a vibratorset to a low to moderate level.Thevibrator should be set to a levelsufficient to slowly flow the stonearound the impression.


Figure A5-10 Stone is slowlyadded in small increments.Thiswill allow the stone to slowly fillall impressed areas and minimizetrapping bubbles within the mastercast.

Figure A5-11 The importance ofslowly adding small incrementsof stone to the boxed impressioncannot be excessively emphasized.The technician must observe thatthe stone flows over and covers allimpressed surfaces.

Figure A5-12 The slow fill isfollowed throughout the pouringof the impression.


Figure A5-13 Sufficient stone mustbe added so that the base of thecast will be at least 16 to 18 mm inthickness. This will provide sufficientthickness for necessary strengthduring laboratory procedures andyet not be excessively thick. Oncecompletely filled, the stone isallowed to set until cooled.

Figure A5-14 The impression iscarefully removed from the stonecast and, just as for the diagnosticcast, the base of the cast is evalu-ated to determine the model trim-ming necessary to make the ridgecrests parallel to the bench top. Inthis example, the purple line indi-cates the trimming necessary.

Figure A5-15 To prevent slurryfrom sticking to the cast duringmodel trimming, the cast should besoaked in water for three minutes.


Figure A5-16 The bottom of thebase is the first part of the casttrimmed. It should be trimmed asnecessary to make the bottom ofthe cast reasonably parallel to thecrest of the ridges.

Figure A5-17 Remember to contin-ually check the cast for any slurrymixture.

Figure A5-18 Immediately rinse offall slurry mixture from the cast.


Figure A5-19 The bottom of thisbase has been trimmed so that it isparallel to the crest of the ridges.

Figure A5-20 Next the width of theland areas is trimmed as necessary.

Figure A5-21 Ideally the bottom ofthe base ofthe cast should be 12 to18 mm thick in the thinnest area (X).The land areas should be trimmedso that the width of the land areas is2-3 mm (Y).


Figure A5-22 When properlytrimmed, the casts should fit withinthe flasks used during processing.They should be evaluated in theflasks, and any necessary additionaltrimming should be completed.

Figure A5-23 The cast should beallowed to thoroughly dry and then,using either an acrylic bur or anarbor band, the land areas shouldbe trimmed so that the depth of thevestibules is 2-3 mm.

Figure A5-24 The posterior palatalseat (PPS) area must now beprepared into the cast. Intraorallythe orange area (A) indicates areasthat were able to be compressedapproximately 1 mm in the mouth;the green area (B) indicates tissuesthat were able to be compressedapproximately 0.5 to 1 mm; the blueareas (C) indicate areas that werecompressible for 0 to 0.5 mm.Thevibrating line (D) is the posteriorlimit of the PPS.


Figure A5-25 In this example, thePPS area was transferred to themaster cast using an indeliblemarker and can be easily visualized.If necessary it can be drawn in witha pencil.

Figure A5-26 The posterior limit ofthe PPS, the vibrating line, can bedelineated with a #6 round bur. Itwill be approximately 0.5 to 1 mmin depth.

Figure A&-27 All other depths arecreated into the master cast as indi-cated by the compressibility of thetissues. See Figure A5-24. All roughareas are then smoothed using alarge cleoid/discoid instrument. Theanterior border of the PPS shouldbe feathered (A).


Figure A5-28 The completed PPS

Figure A5-29 Example of an excel-lent maxillary master cast

Figure A5-30 Example of an excel-lent mandibular master cast

Record Bases andOccinsion itims

379


Figure A6-1 Record bases and occlusion rims will beneeded for basically all of the remaining steps in the fabri-cation ofthe complete dentures. These are examples ofwell-formed maxillary and mandibular record bases andocclusion rims.

Figure A&-2 Because autopolymerizing acrylic resin willbe used to create the record base, all irregularities andundercuts on the master cast are blocked out with base-plate wax.The resin will flow into these areas and poly-merize into a rigid unit. If these areas are not blocked out,the master cast can be broken in attempting to remove therecord base. All small irregularities are simply filled withwax even with the surrounding surfaces (A).The block-outwax in undercut areas of the cast may be reasonably thickat times. Enough wax must be placed to eliminate theundercut in relation to the path of withdrawal of therecord base from the cast (B).

Record Bases and Occiusion Rims 381

Figure A6-3 The cast should beinverted in a bowl of water to helpeliminate air bubbles that could risefrom the cast into the autopolymer-izing resin and result in porosity.The bottom of the cast should beabove the water line; this will allowair to more easily escape asopposed to having the entire castunder water. The cast should besoaked for three to five minutes.

Figure A6-4 The cast is removedfrom the water and, once thesurface of the cast has no standingwater, the anatomical portion of thecast and surrounding land areas arecoated with a separating medium.

Figure A6-5 This cast has beencoated with a separating medium.The separating medium was alsoextended onto the sides of the cast.


Figure A6-6 An autopolymerizingacrylic resin is used to form therecord base using the "sprinkle-on"technique.The powder has beenplaced in a squeeze bottle, and theliquid has been placed in the bottlewith an eye dropper. _J

Figure A6-7 With the spHnkle-ontechnique, first a small area of thecast is wetted using the monomer;then the polymer is sprinkled ontothis wetted area. All polymer mustbe wetted with the monomer tominimize porosity.

Figure A6-8 The buccal vestibule isalmost filled with resin.The resinshould be allowed to set for approx-imately one minute to become moreviscous before tipping the cast to doanother area. Once again monomeris added to a small area of the castand then polymer is sprinkled intothe monomer


Figure A6-9 When adding the resin, the cast should betipped so that the surface you are working on is parallel tothe bench top.This will help maintain the resin on thedesired surface until it has become viscous.

Figure A6-10 The process is continued.


Figure AB-II The sprinkle on technique is continued untilthe tissue surface of the cast is covered and the resin isapproximately 3 mm in thickness. Excessively thin areascan be thickened following polymerization ofthe recordbase. All necessary resin shouid be added prior to separat-ing the record base from the cast. Once the record basehas been removed, if more thickness is desired, it must bereseated on the cast and new resin added.

Figure A6-12 A laboratory knife can be wedged betweenthe resin and cast on the land areas, and used to gently liftthe record base from the master cast. Care is taken not todamage either the record base or the master cast.Theknife shouid be positioned on one side, then the other,and then in the anterior slowly working the record base offthe cast. Additionally an effort is made to lift the recordbase vertically from the cast in the direction of the anteriorridge as opposed to rotating it off. Attempting to rotate therecord base off the cast will often break the master cast.


Figure A6-13 When properlyfabricated, the record base can beremoved from the master cast withno breakage and there should beminimum porosity. The record baseshould be completely extended tocover all anatomic portions of thecast and should have a minoramount of "flash" (A) extendingonto the land areas.

Figure A6-14 The flash can beremoved with either an acrylic buror arbor band. Care should be exer-cised to avoid the sharp edges ofthe flash material.

Figure A6-15 When properlytrimmed, the record base should fitcompletely on the master cast withminimal effort, and the flangesshould fit flush with the land areas.If the record base is not completelystable on the master cast at thistime, it must be remade.


Figure A6-16 The record baseshould be checked for proper thick-ness.Two to three mm is ideal.

Figure A6-17 A boley gauge can beused to check the palatal thickness.

Figure A6-1B Denture teeth will beset on this record base. Therefore,the areas that will eventually receivedenture teeth should be very thin,less than 1 mm.


Figure A6-19 The area to eventu-ally receive denture teeth during thetooth arrangement procedure isoutlined on this record base.

Figure A6-20 This area must bethinned using an acrylic bur untilit is less than 1 mm thick. Whenthinning this area, a finger can beplaced opposite the area beingtrimmed and the finger will feel theresin start to flex just before a holeis created. A small hole is no prob-lem because it can be covered withbaseplate wax at the next stage.However, a large hole may requirerepair with new resin.

Figure A6-21 This record base hasbeen properly thinned in the areathat will receive denture teeth.


Figure A6-22 The next step willbe the fabrication of the occlusionrim.The occlusion rim should becentered over the posterior ridges.A pencil should be used to mark thecrest of the posterior residualridges.

Figure A6-23 The crest of the ridgeof this cast has been marked and astraight edge was used to extendthe mark to the anterior and poste-rior land areas (A and B).

Figure A6-24 A prefornned waxpattern can be used to form theocclusion rim.


Figure A6-25 The occlusion rimis softened in hot water or over aflame and positioned on the recordbase. It is shaped by hand until it iscentered on the posterior ridges andextends labially in the anterior.

Figure A5-26 Before it is bonded tothe record base, the preliminaryposition of the occlusion rim ischecked to verify that it is centeredon the residual ridges in the poste-rior and overextends slightly inthe anterior. If the position is notcorrect, the occlusion rim isremoved and repositioned.

Figure A6-27 When viewed fromthe tissue side ofthe record base,the occlusion rim should besymmetrically positioned, and asmall amount of occlusion rim visi-ble extending beyond the flange ofthe record base. It should extendoutward by approximately 2 to 3mm.This same positioning shouldbe present when fabricating themandibular record base and occlu-sion rim.


Figure A6~28 Once properly posi-tioned, the occlusion rim is firmlyattached to the record base with hotbaseplate wax. AH voids and irregu-lar areas should be filled.

Figure A6-29 The occlusion rîmcan be smoothed by using a hotspatula to melt the wax and thor-oughly bond the occlusion rim tothe record base. There should beno voids or layering within the wax.Once the wax has cooled but beforeit gets cold, a laboratory knife isused for finishing.The occlusion rimshould taper from the record baseto the occlusal plane.

Figure A5-30 When properlyformed, the occlusion rim shouldextend slightly beyond the recordbase in the anterior (A), tapertoward the occlusal plane, and haveno voids in the wax.


40

REAO MC

Figure A6-31 The height of the occlusal plane shouldnow be corrected and made basically parallel to residualridges. Ideally the wax will approximate the desiredocclusal plane height intraorally with minimal correctionby the clinician. Generally the length of the anterior occlu-sion rim should be approximately 20 to 21 mm from thenotch indicating the labial frenulum on the maxillary archand 18 to 20 mm on the mandibular arch. A rubber bandcan be placed at the desired length to help when correct-ing the height of the plane.

Figure A6-32 The height of the plane in the posterioris generally 9 to 10 mm on the maxillary arch and at thelevel of the top of the retromolar pad on the mandibulararch.


Figure A6-33 A large, flat, hot spat-ula can be used to form the occlusalplane. A well-formed occlusion rimhas a single, smooth occlusa! plane.

Figure A6-34 The occlusion rimshould now be trimmed to becentered on the posterior ridge andbe approximate the width of theteeth that will be positioned at alater step.This will feel reasonablynormal to the patient. The completedwidth of the occlusion rim should be8 to 10 mm in the posterior and 6 to8 mm in the anterior.

Figure A6-35 Using the marks thatwere originally placed on the landareas of the master cast, indicatingthe center of the residual ridges, aline can be drawn on the occlusionrim in the posterior.


Figure A&-36 Using that line andthe line that was placed on themaster cast in the anterior, a poste-rior center line can be drawn intothe occlusion rim indicating thecrest of the ridge.

Figure A6-37 The posterior widthof the occlusion rim is now formedby using a spatula to remove excesswax from the medial and lateralsurfaces. Four to five mm of waxshould remain on both sides of thecenter line.

Figure A6-38 An occlusal view ofa well-formed maxillary occlusionrim. Note that it is 6 to 8 mm in theanterior |A) and 8 to 10 mm wide inthe posterior {B).The desired labialsupport was created when initiallypositioning the occlusion rim on therecord base so the anterior width iscorrected by removing wax from thelingual surface only! (C)


Figure A6-39 A properlycompleted maxillary record baseand occlusion rim.The height ofthe rim in the anterior should beapproximately 22 mm (A). Theposterior height should be approxi-mately 10 mm (B).The anterior ofthe rim should protrude at approxi-mately a 15° angle (C), and theposterior of the rim should betapered at approximately a 45°angle (D).

Figure A6-40 Anterior view of aproperly finished maxillary recordbase and occlusion rim

Figure A6-41 Small differencesexist between the maxillary andmandibular record base. Here asmall area has been removed fromthe mandibular record base.Thisportion ofthe record base is notnecessary for the stability of tberecord base. Removing this areawilt make inserting the record baseinto the retromylohyoid area easierduring the interocclusal recordsappointment.The cutout shouid bein the diagonal corner of the recordbase and should be approximately12 to 14 mm wide at its base (A).


Figure A6-42 Just as for the maxil-lary arch, the mandibular recordbase must properly fit the mandibu-lar master cast and be stable.

Figure A6-43 A well-formedmandibular record base and occlu-sion rim. Note that the width of theocclusion rim in the anterior isapproximately 6 to 8 mm (A) and8 to 10 mm in the posterior (B).

Figure A6-44 A well-formedmandibular occlusion rim as seenfrom the anterior.


Figure A6-45 A properlycompleted mandibular occlusionrim.The height of the rim in theanterior is approximately 18 mm (A)and, although not visible, and at thelevel of the top of the retromolarpad in the posterior. The anterior ofthe occlusion rim should protrude atapproximately a 15° angle (B).

Figure A6-46 The last procedureprior to the maxillomandibularrecords appointment is to preparefour small remount indices intothe bottom of the base of the cast.A medium-sized acrylic resin burcan be use.

MaxîilomandibularRecords

397


Figure A7-1 Contoured recordbases and occlusion rims (RBOR)are used to aid the technician intooth placement, provide a guidefor facial support estimates, deter-mine the occlusal plane, and makeboth vertical and horizontal records

Figure A7-2 The maxillary RBOR ismost commonly contoured first.Proper facial contours and thecorrect occlusal plane are deter-mined using various methods.Heated spatulas and plates arecommonly used to melt wax andchange contours and planes on theocclusion rims.

Figure A7-3 The proper facialcontour and length of the maxillaryRBOR is established using bothphonetic and esthetic indicators.This figure represents the initial try-in of the maxillary RBOR, whichrequires adjustment.

Maxillomandibular Records 399

Figure A7-4 The anterior contourand length is determined by thenormal esthetic placement of teeth,phonetic sounds, such as "f" and"v," and other functional andesthetic determinants.

Figure A7-5 Tbe lateral incisaiplane can be determined using aFox Plane Guide and the patient'sinterpupillary line. A tongue bladecan also be used during this deter-mination.

Figure A7-6 The initial evaluationofthe anterior-posterior occlusalplane of the maxillary RBOR revealsa discrepancy from the normalanatomic determinants of theproper maxillary occlusal plane.Theocclusal plane is often parallel tothe ala-tragus line (Camper's Plane).


Figure A7-7 Correction of the ante-rior-posterior occlusal plane on themaxillary RBOR using the Ala-Tragus line (Camper's Plane) as theinitial guide.

Figure A7-8 Proper tip support foresthetics is evaluated with thecontoured maxillary RBOR in place.

Figure A7-9 Phonetic checks areused to verify the incisa! length andanterior edge of the maxillaryRBOR. In this figure, the "f" and "v"sound produce contact of thevermillion border of the lower lipwith the incisai edge of the maxil-lary RBOR.

Maxillonnandibular Records 401

Rgure A7-10 Midtine marked onthe maxillary RBOR.The philtrumof the lip, mid-face line, and otheresthetic determinants contributeto the decision of where to place themidline ¡unction between thecentral incisors.

Rgure A7-11 Index grooves areplaced in the surface of thecontoured RBOR for attaching afacebow fork and eventually to beused during the centric relationrecord making procedure.

Figure A7-12 Maxillary RBOR isattached to a facebow fork usingvinyl polysiloxane (VPS) recordmaterial. Consult the facebowmanufacturer's instructions for thisprocedure.


Figure A7-13 A facebow record is made to facilitate plac-ing the maxillary master cast/RBOR on the clinician'schoice of articulator.

Figure A7-14 The facebow record is used to attach themaxillary master cast to the articulator of choice.Thisrecords the relationship of the maxilla to the condylarcomplex and refines the arc of closure as it relates to theposterior teeth.


Figure A7-15 The initial placement of the mandibularRBOR.This figure shows the initial placement with prema-ture contact in the posterior, and the patient at an openvertical position.The two RBORs will now be used todetermine the proper Occluding Vertical Dimension (OVD)for the patient as well as to record the proper horizontalposition of the mandible for denture fabrication. Mostadjustments at this point will be made on the mandibularRBOR because the maxillary RBOR is establishing thelateral and anterior-posterior occlusal plane from previousadjustments.

Figure A7-16 The mandibular RBOR is adjusted to allowsimultaneous contact of the rim surfaces at the correctoccluding vertical dimension.The resting vertical dimen-sion is determined for the patient by using various meth-ods. The interocclusal space requirements are determined,and the final occluding vertical dimension is established.(lA) Resting Vertical Dimension, (2B) Occluding VerticalDimension, (2 A-*B) = Interocclusal Distance. See Chapter10 (Maxillomandibular Records and Articulators) for moredetailed information) on this procedure.


Figure A7-17 Care is taken duringthis procedure to ensure no contactofthe acrylic resin record basesoccurs in the posterior. Contact ofthe record bases can lead toimproper vertical and horizontalpositions.

Figure A7-18 After contact of theRBORs at the correct OVD is estab-lished, approximately 2 mm of waxis removed from the mandibularRBOR in the posterior to providespace for recording material tocapture the patient's mandible inthe centric relation position at thecorrect OVD,

Figure A7-19 A record is madebetween the maxillary RBOR andthe mandibular RBOR at the correctOVD and in the centric relationposition. See Chapter 10(Maxillomandibular Records andArticulators) for more detailed infor-mation) on this procedure.


Figure A7-20 The centric relationrecord should be stable and shouldrecord the detail of the notchesmade in the maxillary RBOR.Therecording material could also havebeen a vinyl polysiloxane materialor any material that meets therequirements for stable records.

Figure A7-21 After trimming therecord, it can be returned to thepatient to verify that the mandibularrecord arcs correctly into thenotches (A) on the maxillary RBORin the centric relation position.Themandibular cast is now positionedon the articulator. See Chapter 10(Maxillomandibular Records andArticulators) for more detailed infor-mation) on this procedure.

Tooth Selection

407


Clinical and Tecünical Procedures

Figure A8-1 To select dentureteeth, the following information isnecessary: height, width, and shapeof the crown of the central incisor;and the measurement from thedistal of one canine to the distal ofthe second (as measured on thelabial ofthe anterior teeth). Thisinformation is obtained from thepatient and used along with a moldguide to select the teeth. Moldguides are in either a paper form ora physical form. The paper moldguide has pictures and informationabout the teeth.This is an exampleof a mold guide.

Rgure A8-2 This portion of a pagefrom a mold guide provides exam-ples of anterior tooth molds avail-able. The information is generallythe mold itself, the width and heightof the central incisors, and themeasurement of the maxillary sixanterior teeth as measured from thedistal of one canine to the distal ofthe opposite canine. In this exam-ple, the shape of the tooth is alsoindicated.This information is usedto select the desired denture teeth.

Figure A8-3 There is usually simi-lar information on the mandibularanterior teeth.

Tooth Selection 409

Figure A8-4 Information on theposterior tooth forms available isalso presented.

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Figure A8-5 Suggestions are oftenmade for recommended combina-tions of anterior and posterior teeth.Remember, these are only recom-mendations and may be altered asnecessary for a specific patient'sneeds.

— Figure A8-6 The physical moldform has actual denture teethdisplayed. However, the teeth are ofone shade only and are usually notof the same material quality as theteeth to be used in a denture.Theyshould not be used in a denture,Theteeth may be removed from thisguide and placed next to thepatient's face or when attemptingto match a tooth in an existingdenture.


Figure A8-7 Denture teeth are generally selected to eithermatch the mold and/or shade ofthe teeth on an accept-able existing denture or, when no acceptable existingdenture exists, they are selected using multiple guides andmeasurements nnade from the patient. In this example, thepatient has presented with an existing denture and wishesthat the mold and shade of the anterior teeth be matched.The importance and/or shape of an anterior denture toothare strictly empirical and subject to debate, in this exam-ple, the tooth might be considered to be tapering,although some may find it ovoid, and others square-tapering. A tentative selection for the shape should bemade.The patient should be informed that differentdenture tooth manufacturers use different molds andshades; therefore an exact match may not be possible.

Figure A8-8 The width of the crown of the anterior toothcan be closely estimated by measuring.The exact directmeasurement of tbe crown is not possible because of theproximal teeth.

Tooth Selection 411

Figure A8-9 The height of thecrown can be reasonably accuratelymeasured.

Figure A8-10 The measurementfrom the distal of one canine to thedistal of the opposite canine ismeasured on the labial surface ofthe anterior teeth.

Figure A8-11 The flexible rulershould be positioned so that theruler rests against the teeth, and themeasuring marks are along theincisai edges.


Figure A8-12 Once again, this isnot an exact direct measurementbut is acceptably accurate. In thisexample the measurement is 51mm.

60 70 80

Figure A8-13 With the tooth meas-urements and information providedin the paper mold guide, a tentativemold selection can be made.

Figure A8-14 Because severalmolds may very closely match themeasurements obtained, sometimesthe shape of the canine is the decid-ing factor.

Tooth Selection 413

Figure A8-15 The physical moldguide can now be used to view thepotential moid or molds selected.

Figure A8-16 The individual teethin the mold guide can be comparedto the existing denture.

Figure A8-17 Once a mold isselected, then a shade guide can beused to match the existing teeth.The patient should be informed thatdifferent tooth manufacturers mayuse different shade guides; there-fore an exact match may not bepossible. It can be seen from theprevious figures that matching theteeth in an existing denture can besimple and quickly completed.


Figure A8-18 The second and mostoften-used method of selectingdenture teeth is that of using multi-ple guides to establish an originalmold and shade. Using a photo-graph to provide general size andshape of the natural teeth can some-times be helpful. A common prob-lem with this guide is that patientswill often bring pictures that are toosmall, may not show teeth, etc.. Theteeth of siblings may also provideuseful information. Existing castswith the natural teeth present maybe extremely beneficial.

Figure A8-13 Once the occlusionrims have been properly shaped,the midline mark is the startingpoint for tooth selection.

Figure A8-20 Next, the width of thesix anterior teeth can be estimated.This measurement can be obtainedin several different ways. A conven-tional method is to use the relaxedcorners of the mouth to indicate themiddle to distal edges of thecanines. Marks are made on themaxillary occlusion rim indicatingthis relaxed position. Getting somepatients to relax may be difficult,but this is an important landmark,so effort should be made to obtainaccurate marks.

Tooth Selection 415

Figure A8-21 A measurement is made around the labialof the occlusion rim between the two marks, just as wasdone when making the measurement on the existingdenture. A measurement should be made from one markto the midline mark, and a measurement repeated for theopposite side. If the two measurements differ by morethan 2 mm, the relaxed corners ofthe mouth should beremarked and the measurements made again. Once thecorners are correctly marked and measured, some clini-cians would suggest adding 3 to 5 mm to this measure-ment. It is more common that this method will producea slightly smaller measurement than normal and addingthe 3-5mm may help make a more natural looking toothselection.

Figure A8-22 A second guide that can be used to estimatethe canine-to-canine measurement Is to measure betweenthe centers of the left and right hamular notches (A) andadd 10 mm.This is a very easy, quick, and an acceptablyaccurate estimate for most patients. However, it is alwaysadvisable to use multiple methods to arrive at this size esti-mate


Figure A8-23 Method that mayprove useful in estimating thedesired height of the central incisoris to have the patient smile andmark the bottom of the upper lip onthe maxillary occlusion rim.Thismark is called the "high smile line"

Figure A8-24 A direct measure-ment between the "high smile line"and the occlusal plane can be madeto indicate the desired height of thecrown ofthe central incisor. Theaddition of 1 to 3 mm may benecessary to provide a meaningfulmeasurement.

Figure A8-25 Another guide thathas proved very useful fcr manyyears is that of using anthropomét-rie averages to indicate the heightand width of the central incisorStudies indicate that a relationshipexists between the height andwidth of the face and central incisor.A ratio of 16 to 1 is the acceptedstandard.

Tooth Selection 417

Figure A8-26 A "TrubyteToothindicator" may be used to estimatethe height and width of the centralincisors. The device is centered onthe face, and adjustable arms aremoved into contact with the face.The lower arms (A) wilt indicate aheight, and the upper arm (B) willindicate a desired width of thecentral incisors. Additionally, paral-lel lines drawn on the indicator maybe used to determine the face shape(square, tapering, ovoid, etc).Thisshape may be used to select a toothshape. This patient has a square tosquare-tapering face.

Figure A8-27 The position of thelower arm on this patient indicatesthat the desired height of the centralincisors should be approximately11.25 to 11.5 mm.

Figure A8-28 The position of theupper arm indicates that the desiredwidth of the central incisors shouldbe approximately 9 to 9.5 mm.


5OUARE SCHJARi TAKRIN6 TAPERING OVOID

Figure A8-29 Example of usingface shape to select a central incisorshape

Figure A8-30 Additional guides areavailable. Some studies indicatethat a relationship exists betweenthe width of the nose and the sizeof the anterior teeth. This is anexample of a Facial Meter fromIvoclar Viadent. The device is placedagainst one side of the nose, and amovable arm is placed against theopposite side.

Figure A8-31 An arrow indicates arange of possible molds.

Tooth Selection 419

Figure A8-32 Finally, a shade mustbe selected. Again, take note of thefact that different denture toothmanufacturers use different shadeguides.This is an example of ashade guide from lvociarVident.The teeth are grouped into differingshades. When matching existingdenture teeth, this shade arrange-ment is useful. It may, however, beless useful when selecting a newshade.

Figure A8-33 A suggestion is madeto arrange the teeth from the light-est to the darkest when selecting anew shade.


Figure A8-34 When selecting a shade, the object is toselect a shade which, while being satisfactory to thepatient, blends in with the patient's skin tones and doesnot stand out as being too light or dark. Showing theentire shade guide to a patient is not recommended. Manypatients will automatically select the lightest shade with-out regard for any other factors. The clinician should selecttwo or three shades and then allow the patient to makethe final decision. In starting to eliminate obviously unac-ceptable shades, with the shade guide arranged fromlightest to darkest (Figure A8-33), the two extremes areplaced next to the patient's face. In this example, theshades are obviously too light and too dark.

Figure A&-35patient.

The same holds true for this dark-skinned

Tooth Selection 421

Figure A8-36 Less light and lessdark shades have been selected.While the light shade is very close,the dark shade is still too dark.

Figure A8-37 Finally, two accept-able shades have been selected.This is the clinician's recommenda-tion, however the patient and any"significant other" must beconsulted and the shade approved.Approval ofthe mold selection maybe important, but not as much asthe shade.

Figure A8-38 At times, attemptingto matdi the sciera of the eye maybe of some value.


Figure A8-39 The patient shouldview the recommended shadesstanding before a mirror ideally at aconversational distance. Input fromthe spouse or relative or someoneclose to the patient should besought. No matter the clinician'srecommendation, the desires of thepatient should be followed. Anacceptable tooth mold and shadehas now been chosen.

Figure A8-40 This is also an excel-lent time to make one final shadeselection, Some patients have mildto heavy pigmentation of theirgingiva. If available, a gingivalshade guide should be used toattempt to match the gingivalshade of the patient. Dental labora-tories may be able to provide thistype of shade guide to their clients.

Figure A8--41 Matching the gingivalshade can be difficult because theentire gingiva is not one singleshade and in fact often variesdramatically from one part of themouth to another. The shade thatbest blends with the overall gingivaltone should be selected.This shadewill be used during the preparationof the denture base material for thepacking and processing of thedenture.

Esthetic andFunctional Triaiinsertion

423


Figure A9-1 The esthetic and func-tional try-in allows the clinician andthe patient to carefully examinethe proposed prostheses fromboth a functional and an estheticperspective. Maxillary trial set-up.

Figure A9-2 The esthetic andfunctional try-in allows the clinicianand the patient to carefully examinethe proposed prostheses from botha functional and an estheticperspective. Mandibular trial set-up.

Figure A9-3 The trial dentures areassessed for proper facial support,esthetics, phonetic function, properoccluding vertical dimension andcentric relation occlusion using thesame criteria that was used duringthe maxillomandibular recordsappointment.The basic require-ments for speech and estheticsmust be balanced with patientdesires and expectations. This is anideal time for both the patient and a"significant other" to approve of theappearance of the dentures beforethey are processed.

Esthetic and Functional Trial Insertion 425

Figure A9-4 A new centric relationrecord is made during the trialinsertion appointment to verify thehorizontal position ofthe mandibu-lar cast is correct. See Chapter 13(Trial Insertion Appointment) formore detailed information.

Figure A9-5 The pin on the articulator is raised to avoidinterference with seating the dentures into the recordcorrectly. The centric holding device is unlocked to ensurethe teeth may occlude into the record without influencefrom the condylar elements.The dentures are firmlyseated into the records, and the fit into the records ischecked. At this point, the condylar elements are evaluatedto make sure they have remained in the centric relationposition with regard to the condylar housing. If they arecorrectly positioned, the new record verifies the centricrelation position already recorded on the articulator.


Figure A9-6 If the new record doesnot verify the position of the origi-nal record, a third record is madejust in case the second recordmay be in error. If the third recordmatches the first record it verifiesthe original record. If the thirdrecord fits similar to the secondrecord, the mandibular cast isremoved and remounted in thenew position. The teeth may need tobe re-set if the records were incor-rect from the original maxillo-mandibular recording.

Figure A9-7 If the occiusal schemerequires setting the horizontalcondylar guidance (a balanced typeocclusion), a protrusive record ismade to adjust the articulator.

Figure A9-8 If gingival shadeguides are available for customizedshade selection, this is the lastchance to make these selections andcommunicate this information to thelaboratory technician.

Esthetic and Functional Trial Insertion 427

Figure A9-9 After evaluation,adjustments, and patient consent,the final prostheses are sent to thelaboratory for processing.

insertion

429


Figure A10-1 Clinicians shouldopen and inspect the processeddentures prior to patient arrival.Obvious corrections can be made tosharp edges, blebs, and other suchproblems. The prostheses can thenbe disinfected and will be ready forthe initial insertion procedures.

F1gureA10-2 The dentures shouldbe gently seated, and severe under-cuts that limit placement should beadjusted.The dentures should seateasily with no discomfort reportedby the patient. Any severe pressureor areas of extreme discomfortshould be eliminated prior toproceeding.

Figure AlO-3 Pressure IndicatingPaste (PIP) or Pressure DisclosingPaste is placed uniformly on theintaglio surface of the denture.

Insertion 431

Figure A10-4 The denture is seatedwith firm pressure, Do not placeboth dentures and have the patient"bite."This may introduce errors inthe PIP from occlusai discrepancies.

Figure A10-5 Pressure areasshould be identified and eliminatedby judicious grinding. The mostcommon initial pressure areas willbe bony prominences and themedial surfaces ofthe posteriorbuccal flanges. Excess pressureprevents the denture from fully seat-ing and may cause soreness andpoor retention until the excess pres-sure is eliminated,

Figure AlO-fi Acrylic burs in a slowspeed hand piece are the idealmethod for eliminating these prob-lem areas.


Figure A10-7 Repeated testing andelimination of pressure areas willproduce a uniform appearance tothe PIP after seating pressure isapplied.

Figure A10-8 The mandibulardenture is evaluated with the PIP ina similar manner.

Figure A10-9 Border extension canbe evaluated both visually and withDisclosing Wax •'•* to located possibleproblem areas.

Insertion 433

Figure A10-10 Overextendedborders will show through thedisclosing wax after the waxreaches mouth temperature.Theycan be adjusted with an acrylic bur.

Figure AlO-11 Visual inspection ofthe denture borders may also revealareas that need adjusting. Bordersshould be similar to this figure andfit snuggly into the vestibule with-out extending the tissues.

Figure A10-12 Active musclegroups should be evaluated forexcessive pressure against thedenture borders. In this figure, themasseter muscle can pull across thedistobuccal border of the mandibu-lar denture (arrows) and unseat theprosthesis during function. Properadjustment of the border will elimi-nate that problem.


Figure A10-13 The dentures wereevaluated for esthetics and properfunction at the previous try-inappointment.The dentures areinserted and evaluated in a similarmanner before refining the occiu-sion.

Figure A10-14 Final occlusatadjustments should be accom-plished by mounting the processeddentures on a properly set articula-tor. The maxillary remount cast isreturned to the articulator topreserve the facebow orientation. Anew centric relation record is usedto mount the mandibular denture inthe correct horizontal position forccclusal equilibration.

Figure A10-15 The new centricrelation record can be made withAluWax'"-', PVS, or modelingcompound. It is made at a slightlyopen vertical dimension {<lmm) toprevent contact of occlusal surfaces,which may introduce errors due topossible shifting ofthe denturebases fronn premature contact.

Insertion 435

Figure A10-16 The centric relationrecord returns the dentures to astable platform to make the finalocclusal equilibration more accurateand easier to accomplish.

Figure A10-17 Centric relationcontacts are established using mark-ing paper, and refined using a tech-nique established for the type ofocclusai scheme present on the newdentures. See Chapter 14 (Insertion)for more detailed information.

Figure A10-18 Initial centric rela-tion contacts in a nonbalancedlinguaiized occlusal scheme areseen in this figure.


Figure A10-19 The opposingocclusal surfaces in a nonbaiancedlingualized occlusal scheme areseen in this figure.

Figure A10-20 In a nonbalancedlingualized occlusal scheme, alladjustments are performed on themaxillary arch because themandibular teeth are set on a flatplane and present a uniform flatsurface to adjust against.Carborundum strips are a commoninstrunnent to use for this adjust-ment. The heaviest occlusal contactsare systematically reduced until allpossible contacts are found andequilibrated.

Figure A10-21 All maxillary cusptips are now in equal contact withthe opposing arch.

Insertion 437

Figure A10-22 Maxillary cusp tipsare now in equal contact with themandibular arch.

Figure A10-23 In a lingualized balanced occlusal scheme,the centric relation contacts would be refined and then theright working and nonworking, the left working andnonworking, and then protrusive eccentric movementswould be refined. In balanced occlusal schemes, theadjustments are made on the mandibular arch.A) Nonworking scribe line showing path of a maxillary

lingual cusp during a left mandibular lateral movement.B) Protrusive scribe line showing the path of a maxillary

lingual cusp during a mandibular protrusive movement.C) Working scribe line showing the path of a maxillary

lingual cusp during a right mandibular lateral move-ment.

See Chapter 14 (Insertion) for more detailed information.


Figure A10-24 The dentures arepolished, and appropriate instruc-tions are given to the patient.(Maxillary)

Figure A10-25 The dentures arepolished and appropriate instruc-tions are given to the patient.(Mandibular)

Figure A10-26 A final intraoralevaluation is performed, and thepatient is scheduled for an appropri-ate post-insertion check.

indexNOTE: Letter "f" denotes figures.

Acids, mild, 20Adhesives

paste-based, 21powder-based, 20problems, 20recommending, 22-23

AFI {síí Functional inclines).Ma-tragus line, I7l, 400f.•Mginate hydrocolloid

impressions, 58, 89fmixing, 309fproperties, 21-22, 93uses, 14-15

Allergies, 47Aluwax™, 17, 221f, 237fAlveolar mucosa, 27, 28fAlveolar process, 27Alveolar (residual) ridges

alveoloplastv'

intraseptal, 69-70ridge, 68-69

anatomy, 29-30, 3Üfand base materials, 8definition, 8

Alveoloplastyintraseptal, 69-70, 70fridge, 68-69

edentulous, 70see also Surger)'

Anatomyarches

mandibular, 34-41masseter notch, 34, 36f,

41-42mylohyoid ridges, 40nonstress-bearing area,

lOOf

retromolar pad, 34, 35f,42

retromylohyoid area(fossa), 36f, 41,43

maxillary, 30-34nonstress-bearing area,

98f, lOOfbones

alveolar process, 27buccal shelf, 36, 37f, 42canine eminence, 27, 29cementum, 27hamular process (hamulus),

32,42torus mandibularis, 39f, 40torus palatinus, 30-31, 31f

extraoral features, 26-27grooves

labiomental, 26-27, 26fnasolabial, 26, 26f

philtrum, 26, 26ftubercle, labial, 26, 26fvermillion border, 26, 26f

musclesanguli oris

depressor (triangularis),29

levator, 29buccinator, 27. 34-35, 110genioglossus, 77geniohyoid, 77incisivus, 27masseter, 35, 110mylohyojd, 76-77tongue, 37veli palatini tensor, 32

ridgesalveolar (residual), 8, 29-30

edentulous, 26-43mandibular, 54maxillar)', 53, 55

vestibule, facial, 27-29flaps (mucoperiosteal),

67-68fornix, 27, 28f, 42fovea palatini, 31-32, 32f, 42frenulum, lingual, 38ffrenum

buccal, 27-29, 28flabial, 27-29, 28f-29f, 42

gingivaattached, 27free (marginal), 27-28,

28funattached (alveolar

mucosa), 27, 28fhamular notch, 30f, 31-32palatal seal area, posterior,

31, 33, 34fpapillae

incisive, 30-31, 31f, 42interdental, 27, 28flingual, 37paroud, 39, 40f

raphaémidpalatine, 30-31, 32fpterygomandibular, 27,

34, 35frugae, palaune, 30-31, 31fsublingual caruncle, 39, 39fsublingual folds, 39, 39fSUÍCUS

gingiva, 27limitans, 58

milla, 30-31vibrating line, 31-32, 33f

439

440 Index

Apnea, sleep, 32Arches

mandibular. -14-41. lOOí"buccal shell", 36. 37fmasseier notch. 34, 36fmyiohyoid ridges, 40retromolar pad, 34, 35f, 42retromylohyoid area (fossa),

36f, 41maxillarv; 30-34, 30í"

nonstress-bearing area, 98f,lOOf

Arrangement, tooth. 198-216Articulation, reverse {see

Cross bite).Ajüculators

and centric relation (CR). 174classes, 164-165

Class 11, 164. 164fClass III, ]63f, 164, 165f

for complete dentures,162-166

definition, 4, 163facebow, 165-166, 166f. 172.

402fand registration materials,

17mandibular, 179-181maxillary, 172-174and registration materials, 17

BBalanced occlusion (see

Occlusion)Bar substructure (sííeProstheses)Bases

evaluation, 231-234as impressions, 13materials, 8-10

alginate hydrocolloid, 14-15fluid-pour, 9polyether (PE), 15-16poly-merized

auto, 9, 101heat, 8-9light, 9, 101microu^ve. 9shrinkage, 9. 21-22

poK-vinyl siloxane (PVS),15-17

purpose. 8re basing, 5see also Occlusion linis; Record

bases

e * Shade Guide. 193fBone files. 68, 70. 72. 77Bone rongeur, 69fBones

alveolar process, 27buccal. 73f-74f

shelf. 36, 37f. 42canine eminence. 27. 29cementum, 27hamular process (hamulus),

32,42recontouring, 83-84torus mandibularis. 39f, 40torus palatinus. 30-31. 31f

Borders, 108f. 234-235Buccal bone, 73f-74fBuccal shelf, 36, 37f, 42, 306fBuccinator, 27, 34-35, 36f, 110BULL rule. 241

CCalcium sulfate hemihydrate, 16

see also Stone, dentalCamper's plane, 171. 400fCanine eminence, 27, 29Casts

and iirticulatorsmandibular, 179-181maxillar>. 172-174

creating, 122-127, 368-377diagnostic. 58, 58f, 86-104,

86f, 107fcreating, 318-326pouring, 94—95shaping, 95-97

evaluationhorizontal relâtîorishîp.

220-222vertical relationship,

218-220limitations, 86mandibular. 127f, 377fmaster, 127f, 377fmaxillary, 127f, 377ftrimming, 95. 96f, 126-127see also Impressions

Centric relation (CR) positionand articulators, 174and centric occlusion. 159definition. 4determining, 177-179importance, 182-183and trial insertion, 219

Cheek muscle {see Buccinator)

Chelitisangular, 48, 50fcommissural. 260. 262-263

Christensen's phenomenadefinition, 4and monoplane occlusion,

147-148and tooth arrangement, 202

Q (JííCondylar inclination)Cleansers

abi'asive. 19 isolution

acids, mild, 20hypochlorites, 19oxygenating agents, 19

ultrasonic, 19Clearance, interocclusal. 5Closest speaking space, 4Combination syndrome, 4Compatibility, 252

see also InsertionCompensating curve (CC). 4,

152, 160Complete dentures {see

Dentures)Computerized tomography (CT),

66, 84Conditioners, dssue. 13, 21-22Condylar inclination (CI).

152-154, 160CR position (ie* Centric relation

position)Crossbite

and balanced occlusions,146

definition, 4and mandibular résorption, 29and tooth aiTaiigement,

211-212, 213fCryotherapy, 81-82Cusp angles

definition, 155, 155feffective (ECA), 155-156, 156f,

159-160Custom trays (jcf Impressions)

DDental stones (sei? Stone, dental)Dentures

completeimplant supported, 288-299interim, 5materials, 8-23relining, 278-286

Index 441

immediate. 5, 271and ueatment planning, 61

overdentures, 5, 268-271problems

mandibular, 260-261maxillarv', 259-260

relining, complete, 278-286single. 266-276statistics, 2wear, 278f

Depres.sor anguli oris, 29Diagnosis

additional information,58-60

ca.st5, 86-104creating, 318-326

examinationextraoral, 48-50intraoral. 51-56

forms, 49-50history

dental, 48medical, 46-47

medical condition, 47menial attitude, 46, 57overview, 46Six also Examination;

TreatmentDiastema, 28Dimensions

interarcb distance, 78interocclusal distance, 5occluding vertical (OVD)

and articulaiors. 174-176deliiiition, 5and dental history, 48examination,55—56and tooth material. 11and trial insertion, 218-220

relationshipsantero-posterior, 56medio-lateral, 56

resting vertical (R\T))and articulators, 174-175,

175fdéfinition, 5and trial insertion, 218-219

Disease. 37Dry mouth (sa? Xerostomia)

EECA (icfCusp angles)Edentulism, 59-60Edentulous maxilla, 188f

Edentulous ridgesalveoloplast), 70anatomy, 26-43definition, 8

Epulis fissuratum, 52, 53f,80-81

Estheticsexamination, initial. 48gingiral shade tab, 224f, 422f.

426fincisai length, 168-170inseruon. 22.V224tooth selection, 192-196

Ex-aluation, surgery', 66Examination

extraoral, 48-50mandibular movement, 48

forms, 49-50intraoral, 51-56

mucosa, 51—52relationships

antero-posterior, 56medio-lateral, 56

ridges, space between,54-55

saliva, 52-53memal attitude, 3, 57radiographs, 53, 66, 78see also Diagnosis

Excisionepulis fissuratum, 80-81hyperplasia, 80-81tissue, redim-

dant/h)'permobile, 80see also Surger)'

Exostosis, 71-72, 71f-72f, 232see also Surgery

Expectations (padenc), 66

Facebow (ÍÍ* Articulators)Fattv pad, 91f, 304fEl (îo'Functional inclines)Flange length

impressions. 109f, lllf-113fcustom, 108-109, 112

molding, border, 113Flaps (mucoperiosteal), 67-68,

71f, 83Flasking, 9Fomix, 27, 28f, 42Fovea palatini. 32. 32f, 42Frenectomy, 78-80, 79f-80f

see also Stirgery

Frenutumbuccal (5eí Frenum)lingual, 38, 38f

Frenumbuccal, 27-29, 28f, 117-118labial, 27-29, 28f-29f, 42,

117-118Functional inclines (Fl)

angulation of (AFi), 152definition,151-152, 152fand incisai guidance, 153-154,

160

GGagging/gag reflex. 53, 260-261Gingiva

attached, 27free (marginal). 27-28, 28funattached {alveolarniucosa),

27, 28fsee also Papillae

Glands, parotid, 39Grinding

occlusion, 240-241lingualized, 241

.selective. 237-240teeth, nonanatomic, 242see also Impressions

Guidance {ss Incisai guidance)Gypsum (sév? Stone, dental)

HHamular notch

anatomy. 30f, 32, 33f, 314fulcération. 257f

Hamular process (hamulus), 32,42

Hamulus, pter\'goid, 27Hinge axis, 4Hyperkeratosis, 51fHyperplasia

fibrous, infiammatory, 81fexcision, 80-81

maxillary, 72papillary. 52, 52f, 81-84, 82f,

255fand poor fit/function, 77-78see aba Mticosa

Hypertrophy, 254Hypochlorites, 19

IIG (ïcf Incisai guidance)Immediate dentures {see

Dentures)

442 Index

Implants, supporting, 288-299Impressions

acceptable, 92, 93fanal, 120-121

mandibulai, 357-366, 366fmaxülary, 106Í, 344-357,

356f 'removal of old prostheses,

106limitations, 86iiujiding, border. 113-116

mandibular arch, 118-119maxillai7 arch. 117-118wiih modeling compound,

116-117and old bases. 13palatal seal area, 122, 346f,

37,5iphilosophies, 98-99, 1Ü7preliminary, 58f, 94f-95f

beading and boxing,124-125

making, 87-93, 310-312mandibular, 93f. 304-313maxUlaiy, 93f, 123f, 313-316

relining, 280-283remaking, 92, 121trays, custom, 108f. 12()f

extensions, 97-98, 107-113fabrication, 98-99, 101-103,

lou; io9fmandibular, 87f, lOlf. 110.

328-334maxillary; 102f, .335-341preparation, 119-120selective pressure. 99stress-bearing areas. 99

tray's, stock. 86. 87f-89f,306f-307rmaterials, 14

waxes, 99-101sae also Casts

Incisai guidance (IG)and balanced occlusions,

148-149. 160definition. 5and functional inclines,

152-l.M, 160Incisive fonunen, 31Incisi\ais muscle. 27Inclines {w? Functional inclines)Infections, fungal. 46. 52. 81Insertion

facial support, 22S-224

final, 244-248e\'aluation. 224-226

grindingocclu.sion, 240-241selective, 237-240teetb, nonanatomic, 242

post, 252-263compatibility; 252mastication, 252soft-tissue, 253-258treatment. 258-259

remount, 237-240stripping method, 242-244Lrial. 218-227

esthetic and functional,424-427

Inierocclusal cleaiance. 5Interocciusal distance, 5Interpenetrating polymer

network (IPN), 11Ivoclar Vivadent

BlueUne^^i Form189. I91f, 419f

Facial Meter. 418i'

Labiomental groove. 26-27, 26fLesiom, hype rke rato tic, 5IfLevator anguli oris, 29Liners

and stability; 12tissue conditioners, 13see {¡ho Relining

Linguae profundtis. 38Lips

examination, 48length, maxillary, 169-170

MMandibular arch

anatomy. 34—41buccal shelf. 36, 37fmasseter notch, 34, 36f,

nonstress-bearing area,lOOf

retromolar pad, 34, 35f, 42retromylohyoid area (fossa),

36f, 41, 43atrophied, 40f, 41edentulous, 304fmolding, border, i 18-119mytohyoid ridges, 40

Ma.ssetcr notch, 11 If. 304f, 312fanatomy. 34-35, 36f. 41-42

Masticationproblems. 252and tooth arrangement, 204

Materialsadhesives, 20-21base

alginate hydrocolloid,14r-15, 21-22

fluid-pour. 9metal. 10poiyethcr (PF). 1.5-16polymerized

auto, 9, 101heal. 8-9light, 9, 101microwave. 9shrinkage. 9, 21-22

polyvinyl siloxane (PVS),15-17

resin, 8-9cleansers

abrasive, 19solution. 19-20

conditioners, tissue, 13, 21-22dentures, complete, 8-23impres,sions

characteristics, 128-129resins. 331f-332f

liners, 11-13molding, border

modeling compound,113-116. 116f-117f.348f-349f

Play-Doh™. 124-125, 368fvinyl polysiloxane (\TS).

115-116. 280-281. 281fregistration, 17-18

interoccltisal, 17-18relining

chairside, 12laboratoi-y, 13

repair, 14siîicone, 13stone, dental, 16-17surfactants. 16teeth

polymer (plastic), IIad\-antages. 11. 21-22

porcelain. 10-11retention, 10

tinfoil substitute. 134waxes, 8-9, 18

Index 443

baseplate, 18boxing. 124, 369fdisclosing, 234periphery. 88-89. 103-104relief, 100-103. lOOf-lOlf.

329fMaxillary arch

anatomy, 30-34nonstress-bearing area. 98f,

lOOfedentulous. 313fmolding, border, 117-118

Medical/dental history, 46-48SW also Diagnosis

Medications. 47Mental health (s«-Examination)Methyl iiiethacrylaie, 8Modeling compound, 113-119,

128-129Molding

anterioradditional guides, 190-191commercial guides, 188-190occlusion rims, 187-188record bases. 187-188selection. 187-191

border. 113-116definition, 128-129

mandibular arch, 118-119maxillar)' arch. 117-118with modeling compound,

116-117posterior, 191-192see ntm Impressions

Monoplane occlusion {seeOcciusion)

Mucoperiosteal flaps (5eíí Flaps)Mucosa

basai-seat, 254exaniinaiion, 51

lesions, hyperkeratodc. 51flining. 255-258stress-bearing, 253-254submucosa. 254-255see also Hyperpiasia;

HypertrophyMuscles

angtili orisdepressor (triangularis). 29levator, 29

attachments, 55buccinator. 27, 34-35. 110examination, 48genioglossus, 77

geniohyoid, 77incisivtis, 27masseter, 35. 110m)-lohyoid, 76-77veli palaiini tensor, 32

Mylohyoid ridges, 40, 76-77

NNasolabial groove, 26, 26fNonworking side, 5

OOccluding vertical dimension

(OVD)and articuiators. 174-176definition, 5and dental history. 48examination, 55-56and looth material, 11and trial insertion, 218-220

Occlusionbalanced. 144^147, 159

definition, 4excepdons, 147-149grinding, selective, 240-241

centric. 4and centric reladon (CR),

159disharmony, 236-237examples, 156-158lingtialized, 149-150,150f,

159-160grinding, selective, 241

monoplane. 5. 142,147lingualized, 150

plane of (PO), 152, 160forming, 170-172posterior, 208f

posterior, 142-144principles, 142protrusive factors, 152-155stripping method, 242-244vertical dimension, 5

occluding (OVD). 174-176,218-220

resting (RVD). 174-175.218-219

see also Occlusion rimsOcclusion rims

contouring. 167-168labial/buccal. 168

fabricaüon. 136-138. 136f.380-396maxillary, 137f

molding, 132f-133f, 138fanterior, 187-188

see also Bases: OcclusionOVT) (iii-Occluding vertical

dimension)O\erdentures (ißi Dentures)Overextension

definition. 5of denture base. 106of diagnostic casts. 108, 108fimpressions, 97-98and mandibtilar e\'aluaticn,

35see also Impressions

Oxygenating agents, 19

PPalate

burning, 261hard. 32, 54hyperpiasia, 81-82seal area, posterior

anatomy. 31.33. 34fimpressions, 122, 123rlocation. 128-129

soft, 32, 62classes. 54

Papulaecircumvallate, 38incisive, 42

anatomy, 30, 30f, 31, 31f,42

examination, 55interdental. 27-28, 28flingual, 37parotid. 39. 40fsee aha Gingi\-a; H^-perplasia

Parotid orifice. 39-40, 40fPadent instructions. 230-231PDI (.íí'í'Prosthodondc

Diagnostic Index)PE (jíí Poiyether)Philtrum. 26. 26fPhonetics

evahtauon, 223-224intraoral, 56

incisai length. 169-170and occlusion, 182problems, 137

Physiologic resting position, 5Plane of occlusion (i«

Occlusion)Play-DohTM, 124-125, 368fPO (s« Occlusion)

444 Index

Polyether (PE)and border moiding, 113and impressions, 15—16

Polymerized materials {seeMateriais)

Polymethyl methacrylaie, 8Polyvinyl siloxane (PVS). 15-17Positioning. 176-179

centric relation (CR), 4, 174,177-179.219

closest speaking space, 4hinge axis, 4inierocclusal clearance, 5physiologic resting, 5

Posterior palatal seal area {seePalate)

Proceduresclinical, 304-326

implant supported, 294technical, 304-326

Prognosis. 61see nkn Treamient

Proprioception, 3Prostheses

bar substructurenew, 297retention, 291, 292f, 295fletrofiiting, 294-295

ERA components, 291, 291f,295f

irritation, 51-52satisfaction, patient, 48single component

new, 297-298retrofitting, 296

surgical considérations, 66-84see also Retention; Stability

Prosthodontic Diagnostic Index(PDI)..58-60

Protrusion, 5PVS (5«e Polyvinyl siloxane)

RRadiographs, 53. 66. 78

.see also ExaminationRanine vein, 38, 38fRaphé

midpalatine, 30-31, 32fpterygomandibular, 27, 34, 35f

Rebasing, 5see also Prostheses

Record basescharacieristics, 139-140

fabrication, 132-1.36, 136f,380-396

mandibuiar, I33f, I.38fmaxillary, 132f, 138Ímolding, 187-188"sprinkle-on" technique, 134,

139-140see also Bases

Recordseccentric. 222-223maxillomandibular, 162-183,

398-406Reductions

genial tubercle. 77maxillary tuberosity, 72

soft-tissue, 78mylohyoid ridge, 76-77.see aho Surger\'

Registration (interocclusal),17-18

Relation, 4Relining

of complete dentures, 278-286impression teclinique,

280-283definition, 5, 12delivery gun, 12materials

chairside, 12laboratory, 13

see also LinersRepair, 14Residual ridges (sei Alveolar

ridges)Resin-based materials (see

Materials)Re.sorpiion, 55Resting position

physiologic, 5vertical dimension, 5see aho Positioning

Resting vertical dimension(RVD)and articulators, 174-175. 175fdefinition, 5and trial insertion, 218-219

Retentiondefinition. 6factors, 106mechanical deWces, 288f-289f,

293f, 296ftooth. 10see also Prostheses

Retrofitting (existing prostheses)bar substructure. 294-295single component, 296

Retromoiar pad, 3()4fanatomy, 30f, 34. 35f, 42and border molding, 119

Retromylohyoid area (fossa)anatomy, 36f, 4Î.43and Ixjrder molding. 119examination, 55and preliminary impressions,

3()5fReverse articuladon {see

Crossbite)Ridges

alveolar (residual), 8, 29-30alveoloplasty

intraseptal, 69-70ridge. 68-70

mandibuiarmuscle attachments, 55résorption, 55shapes. 54

maxillaryrésorption. 55shapes, 53-54

opposing, bb-oQreductions, 76-77

Rims (.ïi-pOcclusion rims)Rugae, palatine, 30-31, 31fRVD (j«-Occlusion)

Saliva, 52-53Selection, tooth (^iwTeeth)Snoring, 52Soft-tissue problems

mucosabasal-seat, 254lining, 255-258stress-bearing, 253-254

submucosa, 254-255see also Mucosa

Speech (.ÍÍW Phonetics)Stability

and adhesives, 20definition, 6and liners. 12of .single dentures, 267and soft tissue, 77and torus palatinas. 31

Stomatitis, 52fStone, dental

Index 445

and alginate hydrocoiloid, 15Ltnpressions, 3]9f. 321f

mixing, 94materials, 16-17mixing, 318ftypes. 17

Sublingual caruncle, 39, 39fSublingual folds, 39, 39fSulcus

gingival, 27limitans. 38

Support, 6Surgery

alveoloplastyintraseptai, 69-70ridge. 68-70

contraindications, 46-47evaluation, 66excision

fibrous hyperplasia, 80-81redundant tissue. 80

exostosis. buccal, 71-72expectations (patient), 66flaps. 67-68guides (templates), 82-83and lip length, 169pre prosthetic

consideradons, 66-84procedures, 68-77tori, 72-75, 75-76

reductionsgenial tubercle, 77maxillary tuberosity. 72.

78mytohyoid ridge, 76-77

soft-tissue proceduresfrenectomy, 78-80hyperplasia, 81-82

TTeeth

anatomic. 149anterior, 198-199arrangement

lingualized, 209fmandibular, 201-203,

206-208maxillary. 199-201, 209-214"tight" alignment. 210f"timing," 214

incisai length, 168-170materials

IPN, 11

polymer (plastic), 11advantages, 11,21-22

porcelain, 10-11retention, 10

mechanical bonding, 10morphologies, 142, 142f-143fnonanatomic

grinding, selective, 242stripping method, 242-244

posterior, 203-206selection, 186-196

procedures, 408-422shade, 192-194

Templates (ÍPÍ Surgery)Temporomandibular disorders

(TMD), 48. 59-61Temporomandibular joint

(TMJ),48Tinfoil substitute, 134Tongue

anatomy, 37. 37fburning, 261examination, 56

large, 57f, 305finjury, 258fretracted, 56. 62

Toothpastes, 19Tori

mandibular, 55f, 74fsurgery, 72-75touts mandibularis, 39f, 40

maxillary, 75fhard palate. 54pedunculated, 54fsurgery; 75-76torus palatinus. 30-31, 31 f

Transverse horizontal axis {seeHinge axis)

Trays, custom (sf? Impressions)Treatment

implant supported, 289-293planning, 46-63. 60-61

forms. 49-50goals. 67problem list, 67

post-insertion. 258-259see also Diagnosis

Triangularis ( see Depressoranguli oris)

Tnihyte® Fox plate. 171, 17U,399f

Trubyte* Tooth Indicator,188-191, 190f, 417Í

Tuberclegenial, 40f, 77labial, 26, 26f

Tuberositiesanatomy. 29-30, 30fmaxillary, 72. 73fat OVD, 56reductions, 78

UUiceradon, 254f-257fUndercuts, bilateral, 232fLnderextension

definition, 6impressions, 97-98

Uvula. 30-32Uvulopalatojjharyngoplasty

(UPPP),32

Valsalva maneuver, 110Vermillion border, 26, 26fVertical dimension of occlusion

{see Occluding vertical dimen-sion)

Vertical dimension of rest (seeResting vertical dimension)

Vessels, bloodlinguae profundus, 38ranine vein, 38

V estibule, facialbuccal, 28f. 108fflaps (mucoperiosteal), 67-68fornix, 27, 28f, 42fovea palatini, 31-32, 32f, 42frenulum, lingual, 38ffren um

buccal. 27-29, 28flabial, 27-29, 28f-29f, 42

gingivaattached, 27free (marginal), 27-28, 28funattached (alveolar

mucosa), 27, 28fhamular notch, 30f, 31-32palatal seal area, posterior, 31,

33, 34fpapillae

incisive. 30-31. 31f. 42interdental, 27, 28flingual, 37parotid, 39, 40f

raphaé

446 Index

Vestibule, facial (Continued)midpalaiine, 30-31, 32fpterygomandibular, 27, 34.

35frugae, palatine, 30-31,

3]fstructures, 27-29sublingual canmcle, 39, .39fsublingual folds, 39, 39fsulcus

gingiva, 27limitans, 38

uvula. 30-31vibrating line, 31-32. 33f'iâee also Gingiva; Papillae

Vibrating lineanatomy, 31-33, 33fimpressions, 109-110, ]09f.

preliminary, 314fVinyl polysiloxane (VPS), 113,

115-116, 118,280-281,281f

Vomiting, 260-261VPS (see Vinyl polysiloxane)

WWaxes

base materials. 8-9baseplate, 18

sticky wax, 18disclosing, 234, 234fimpressions

block-out, 99-101, lOOfboxing, 124, 124f, 369frelief, 99-101, 100f-102f

materials, 18periphery, 88, 89f, 103-104relief. 329f

Working side, 6

XXerostomia

and medications, 2, 47, 62and prostheses, 52-53

textbook of complete dentures plummer 2009

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