concepts of prostho

Principles, concepts, and pract ices in prosthodontics - 1 9 9 4

A c a d e m y o f P r o s t h o d o n t i c s

P R E F A C E TO T H E E I G H T H E D I T I O N

This edit ion is the latest of a continuing effort by the Academy of Prosthodontics to update the principles, concepts, and practices in prosthodontics.

The seventh edit ion was a substantive update with the addi t ion of s ta tements and revision of some of the existing statements . Input for the seventh edit ion came from the Academy of Prosthodontics, American Academy of Fixed Prosthodontics, American Academy of Esthet ic Dentistry, American Academy of Implan t Dentis try, American Acad- emy of Maxillofacial Prosthetics, American Academy of Periodontology, American College of Prosthodontis ts , the Midwest Academy of Prosthodontics, Nor theas tern Gna- thological Society, Nor theas tern Prosthodont ic Society, and the Pacific Coast Society of Prosthodontics.

All organizations tha t par t ic ipated in the revision were asked for their editorial input in this revision. Some organizations, such as the Academy of Prosthodontics, sought input from each member; others worked by committee. Each contr ibut ing organization funded its own committee activities. Because the last revision was a major overhaul of the document in content and format, this revision has been l imited to pr imar i ly editorial changes. The Academy of Prosthodont ics is indebted to Mrs. Jud i th A. Farer, a professional editorial consultant, for her work in editing this document.

The Academy of Prosthodont ics wishes to thank all of the par t ic ipat ing organizations for their input. The section on Legal Considerations was developed and revised by Dr. Bur ton R. Pollack, who is an a t torney and dent is t and Dean of the School of Dental Medicine, Sta te Universi ty of New York, Stony Brook, New York.

The purposes of the Principles, Concepts, and Practices in Pros thodont ics- -1994 are:

1. To provide a reference for the practicing prosthodontist and general dentist of principles, concepts, and practices that are currently accepted by leading prosthodontists.

2. To assist predoctoral and postdoctoral students of prosthodontics, particularly the graduate student, in assessing the value of various ideas that are presented during their educational experience.

The first s tudy 1 was prepared in 1957 under the leader- ship of Drs. Luzerne G. Jordan, F rank M. Lott , and Rus- sell W. Tench. The six successive publicat ions 27 were prepared under the auspices of fellows of the Academy: Drs. George Hughes, 0. M. Dresen, Victor H. Sears, Leroy E.

J PROSTHET DENT 1995;73:73-94. Copyright | 1995 by The Editorial Council of THE JOURNAL OF

PROSTHETIC DENTISTRY. 0022-3913/95/$3.00 + 0. 10/8/59402

Kurth, S. Howard Payne, Chester K. Perry, Richard Kingery, Victor L. Steffel, Ar thur E. Aull, 0. C. Applegate, Davis Henderson, Henry E. Ebel, I. Kenneth Adisman, Charles Bolender, Jack Preston, Louis Boucher, Francis V. Panno, Ar thur O. Rahn, George E. Smutko, Ned B. Van Roekel, and Dale E. Smith.

Members of the Principles, Concepts and Practices Committee for the eighth edit ion were Drs. Ronald H, Jarvis, Chairman; Dorsey J. Moore, and Aaron H. Fenton. Drs. Noel D. Wilkie, Richard J. Grisius, Edwin J. Riley, and Gerald M. Barrack were consultants to the committee.

RESPECTFULLY SUBMITTED BY: DR. RONALD H. JARVIS, CHAIRMAN PRINCIPLES, CONCEPTS, AND PRACTICES COMMITTEE: DORSEY J. MOORE, AARON H. FENTON

P R I N C I P L E S , C O N C E P T S , A N D P R A C T I C E S I N P R O S T H O D O N T I C S - 1 9 9 4

Guide to PCP statements Definitions Diagnosis and treatment planning Prognosis Prerestorative treatment Treatment of oral structures Reevaluation and refinement of treatment plan Prosthodontic treatment

I. Basic to most areas of prosthodontics II. Fixed partial dentures

III. Removable partial dentures IV. Maxillofacial prosthetics V. Complete dentures

VI. Implant restorations Materials and devices

I. Articulators Interim restorations Auxiliary personnel and work authorization Legal considerations

D E F I N I T I O N S S

73 74 75 75 75 76 76 76 79 81 85 87 90 91 91 92 92 92

1. Prosthodontics is the branch of dentistry pertaining to the restoration and maintenance of oral function, comfort, appearance, and health of the patient by the restoration of natural teeth and/or the replacement of missing teeth and contiguous oral and maxillofacial tissues with artificial substitutes.

2. Fixed prosthodontics is the branch of prosthodontics concerned with the replacement and/or restoration of teeth by artificial substitutes that are not removable from the mouth.

3. Removable prosthodontics is the branch of prosthodontics concerned with the replacement of teeth and contiguous structures for edentulous or partially edentulous patients by artificial substitutes that are removable from the mouth.

4. Maxillofacial prosthetics is the branch of prosthodontics concerned with the restoration and/or replacement of stomatognathic and associated facial structures by artificial substitutes that may or may not be removable.

5. Implant prosthodontics is the phase of dentistry concerning the restorative phase following implant placement.

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D I A G N O S I S A N D T R E A T M E N T P L A N N I N G

A. Gathering information f o r a d iagnos i s 1. Diagnosis is a scientific evaluation of existing conditions. 2. At the first appointment, the pat ient should be encouraged

to describe previous medical and dental experiences. The dentist must be attentive and record the patient 's concerns and expectations.

3. A list of questions about prior dental experience may guide the pat ient to provide information not otherwise elicited in an open-ended discussion.

4. A diagnosis may require information from one or more of the following sources: medical and dental histories, a clinical examination, radiographic surveys, diagnostic casts, consultations with other health practitioners.

5. Tests, pret reatment procedures such as a diagnostic prosthesis, trial prosthesis, and surgery may yield additional information.

6. The pat ient should be considered a potential carrier of contagious disease. The dentist should follow current guidelines of the American Dental Association (ADA), the U.S. Centers for Disease Control and the Occupational Safety and Health Association (OSHA) during pat ient care.

7. Correctly mounted diagnostic casts are usually necessary for diagnosis and t rea tment planning.

B. Examinat ion 1. A standardized examination form may be used to record data

during the examination. 2. The oral cavity, visible pharynx, paraoral structures, and as-

sociated lymph nodes should be examined. Patients with special needs may require additional diagnostic procedures such as speech analysis, psychosocial assessment, occlusal analysis, diagnostic sounding procedures, sialography, photographs, and other testing mechanisms.

3. All patients with natural teeth should receive a thorough, systematic periodontal examination including a clinical and radiographic examination, pocket depth probing, and an evaluation of periodontal status.

4. The dentist should identify and record any active disease process and any defects created by disease. When indicated, the dentist should refer the pat ient to appropriate professionals for further diagnosis or treatment.

5. Assessment of the following conditions is essential to the periodontal examination:

(a) Gross periodontal pathosis including evaluation of topog- raphy of the gingiva and related structures

(b) The existence and degree of gingival inflammation (c) Periodontal pocket depth to determine the a t tachment

level and to provide information on the health of the subgingival area

(d) Presence and distribution of bacterial plaque and calculus

(e) Degree of tooth mobility (f) An adequate number of diagnostic quality radiographs (g) Documentation of loss of attached gingiva

6. Exploratory surgical procedures should be referred to the appropriate surgeon.

7. The oral mucosa is altered under a removable denture tha t has been worn.

8. Bruxism may produce destructive changes in the supporting tissues of removable dentures.

9. Because favorable response to loading from a prosthesis has been observed in both dense and porotic bone, bone density seen radiographically does not always predict a response to loading.

10. Bone resorption may be caused by many factors. 11. When possible, optimal periodontal health should be estab-

lished before completion of definitive restorative and prosthetic treatment. A thorough periodontal examination should contribute to a diagnosis tha t can help establish a logical t reatment plan. Re- ferral to a periodontist may be helpful.

C. Factors in diagnosis 1. For patients with orofacial defects, a psychosocial evaluation

may be a valuable aid for diagnosis and development of a and t reatment plan.

2. Factors tha t improve diagnostic capabilities include in-depth knowledge of anatomy, embryology, histology, physiology, micro- biology, patholody, psychology, biochemistry, pharmacology, and the physiology of oral function.

3. Maxillofacial defects may be congenital, acquired, or developmental.

4. Normal growth patterns should be understood so tha t devi- ations can be recognized and evaluated.

5. Healing processes of oral and perioral hard and soft tissues should be understood.

6. Inflammation may cause changes in the appearance and function of the oral mucosa.

7. Drug effects and interactions must be understood by both patient and dentist.

8. Aging causes change in body tissues, organs, and function that may affect patient response to a prosthesis.

9. Dimensional reduction of bone supporting dentures may lead to loss of the vertical dimension of occlusion.

10. Determining the vertical dimension of occlusion is usually a matter of judgment. Commonly used methods and guidelines include the following:

(a) A measurement of 3 mm less than physiologic rest position

(b) An evaluation of the closest speaking space (c) Proprioception or pat ient preference (d) Swallowing on soft wax cones (e) Relative parallelism of ridges (f) General appearance of the midfacial profile

11. The vertical dimension of rest is a postural position that is subject to change.

12. A record of the maxillomandibular relationship with the mandible in terminal hinge position is considered a necessary component of a comprehensive diagnosis.

13. Altering the vertical dimension of occlusion requires critical judgment. When a vertical dimension is to be altered, a trial period at the new position may be used to ascertain whether the new position is physiologically acceptable.

14. The occlusion of any pat ient tha t was established by prosthodontic procedures should be periodically reevaluated.

15. In maximum intercuspation, all posterior teeth should contact simultaneously.

16. Deflective occlusal contacts may cause altered mandibular positions to shift.

17. Systemic conditions should be identified for adequate t reatment planning. They can affect etiology, pathogenesis, and t reatment of periodontal disease. They have the potential to alter periodontal health.

D. Treatment plan considerations 1. Structures tha t provide valuable support, stability, and

retention for a maxillofacial prosthesis should be preserved. 2. Trea tment procedures for patients to be treated with dental

implants should include articulated diagnostic casts with a trial arrangement of artificial teeth on trial denture bases. A presurgical prosthodontic diagnosis is essential for implant site location and angle.

3. Selection of a fixed or removable partial denture is largely dependent on the number, location, condition, and supporting structures of the abutment teeth and the size and contour of the edentulous spaces.

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P R O G N O S I S 1. A prognosis is an opinion or judgment about the prospects for

success of therapy and restoration. Since prognosis is a forecast of probable results, it is given in advance of treatment.

2. Good oral hygiene and plaque control positively influence natural dentit ion and the longevity of restoration.

3. The oral cavity should be healthy before placement of definitive restorations.

4. Proper selection of materials and the skillful execution of t reatment enhance t rea tment success.

5. Tissue tolerance and pat ient adaptability affect the prognosis for the tissue-borne prosthesis.

6. Clinician and pat ient compatibility and clinician manner during t reatment influence t rea tment success.

7. General health and nutri t ion may influence the patient 's ability to use any prosthesis.

8. Psychological factors may pose insurmountable obstacles to successful denture wearing.

9. As physical defects become larger, successful prosthesis wearing is more likely to be compromised.

P R E R E S T O R A T I V E T R E A T M E N T S y s t e m i c and l o c a l

1. Altered oral mucosa may be the manifestation of such systemic disorders as diabetes, avitaminosis, or hormonal imbal- ances. This may indicate the need for supportive therapy before initiating prosthodontic treatment.

2. Dietary counseling may benefit prosthodontic patients with unfavorable tissue response, particularly senescent individuals.

3. Proper preparation of remaining oral structures enhances the success of a removable prosthesis.

4. Conditioning the oral mucosa and orofacial musculature for patients requiring removable prostheses is important.

5. The patient 's emotional status may influence the success of prosthodontic treatment.

6. Denture-st imulated gagging may have a psychologic component.

P a t i e n t e d u c a t i o n 1. Informed patients are usually more receptive and cooperative

than uninformed patients. 2. Treatment with dentures is individual and cannot be stan-

dardized. 3. Speaking about prosthodontic t reatment is more desirable

than focusing solely on making the denture. 4. Patients should be educated about the value and the short-

comings of complete dentures. 5. A prospective pat ient should be informed that neuromuscu-

lar adaptation contributes to success in wearing a removable prosthesis.

6. Both oral and printed information can help patients understand and accept t rea tment goals.

7. Education, instruction, and discussion about dental care should continue during the entire t reatment period and during recall visits.

8. Successful dental t rea tment is enhanced if the patient practices thorough oral hygiene. The dentist is responsible for teaching such procedures, and the pat ient is responsible for performing them.

9. Patients should be informed tha t residual ridge resorption occurs in varying, unpredictable degrees. It will affect the adaptation and function of their dentures.

10. Pat ients should be discouraged from using "do-it-yourself" denture relining kits because of their hazards.

11. Plaque control instructions and frequent periodic prophy- laxis should be part of care for patients who have had radiation

therapy to the head or neck. A through oral examination is essential. Fluorides should be self-administered daily.

12. Pat ient education and disease control should include the following:

(a) Teaching about diagnosis, etiology, and consequences of disease

(b) Training in personal plaque control and care of prosthetic restorations

13. Before t reatment completion, patients should be given the following information:

(a) The prognosis, both periodontally and prosthetically, is influenced by diet, systemic factors, and their ability to maintain a plaque-free environment.

(b) Even with proper professional and personal care, periodontal disease may recur.

(c) A doubtful prognosis for teeth retained after periodontal therapy could compromise the longevity of the restoration. When possible, such teeth should be extracted before or during periodontal therapy.

T R E A T M E N T OF O R A L S T R U C T U R E S 1. Each t reatment procedure should be directed toward pre-

serving oral tissues and normal functions to the extent possible. 2. Before missing structures are replaced with a prosthesis, pa-

thosis of hard and soft oral tissues should be corrected when possible. Treatment procedures (not in order of priority) may include the following:

(a) Periodontal therapy (b) Oral surgery procedures, including placement of implants (c) Occlusal corrections (d) Operative dentistry (e) Endodontics (f) Orthodontics (g) Crowns and/or fixed partial dentures to restore satisfac-

tory functional relationships 3. Traumatic occlusion should be treated appropriately. Treat-

ment may include interocclusal splints, occlusal restorations, selective occlusal adjustments, surgery, orthodontics, muscle exercise, or other corrective methods.

4. Before an impression is made for a removable prosthesis, a program of tissue conditioning should be considered when soft tissue is inflamed, irritated, or distorted.

5. If the examination shows the presence of periodontal disease, a periodontal consultation should be held.

6. Before the final preparation of abutment teeth, periodontal pathosis should be treated, and periodontal health should be stabilized.

7. When a patient is referred to a periodontist, the prosthodontic t reatment plan under consideration should accompany the written referral request. The periodontist should be advised of the criteria remaining teeth must meet if they are to be retained as part of a prosthodontic t reatment plan.

8. Plans for periodontal t reatment may include the following: (a) Instruction in daily oral hygiene (b) Removal of supragingival and subgingival calculus (c) Smoothing of root surface irregularities where appropri-

ate (d) Post t reatment evaluation of periodontal health (e) Reinforcement of daily oral hygiene and plaque control

care when needed (f) Recontouring supporting bone (g) Reorganization or augmentation of unat tached gingiva (h) Extraction before periodontal therapy of teeth lack

proper supporting structures, crown form, or position tha t would compromise the prognosis of a prosthesis

9. Treatment options when the periodontal condition is more severely involved may include the following:

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(a) Pocket reduction through the use of soft and hard tissue surgical procedures

(b) Grafting procedures.to enhance lost periodontal tissues and to provide an adequate zone of attached gingiva, particularly around teeth being prepared for prosthodono tic t rea tment

(c) Occlusal therapy to reduce occlusal t rauma (d) Minor tooth movement

10. Postoperative pat ient care is the joint responsibility of the periodontist and the prosthodontist, if the pat ient is treated by both specialists.

R E E V A L U A T I O N A N D R E F I N E M E N T OF T R E A T M E N T P L A N

1. After prerestorative t reatment is completed, the t rea tment plan should be reevaluated and modified as indicated by pat ient response to the following:

(a) Education (b) Efforts to eradicate or control disease (c) Exploratory and trial procedures

2. After completion of active periodontal therapy, supportive care, including regular reevaluations of the periodontal status, reinforcement of personal oral hygiene, and removal of any etiologic factors is critical to the long-range maintenance of pat ient health.

P R O S T H O D O N T I C T R E A T M E N T

I. B a s i c to m o s t a r e a s o f p r o s t h o d o n t i c s A. Design, fabrication, and classification 1. Selection and final arrangement of artificial teeth are the re-

sponsibility of the dentist in consultation with the patient. 2. Artificial teeth should be arranged for minimal inhibition of

the tongue, so tha t palatal vault is not substantially altered. 3. The external form of the prosthesis should be compatible

with the function of the oral musculature and overlying tissues. 4. Before extensive preprosthetic surgery is considered, pat ient

experience with an existing prosthesis should be evaluated carefully.

5. The relationship of tuberosities to retromolar pads is best vi- sualized with diagnostic cases. Such casts should be articulated in centric relation at an acceptable vertical dimension of occlusion.

6. There should be accommodation for the coronoid process during normal functioning range of mandibular movement in the retrozygomatic area of the maxillary denture base.

7. To control lateral stress to an abutment tooth as much as possible, the retainer should be designed to direct forces along the long axis of the tooth.

8. The prosthodontist should know and understand the physical and chemical properties of all materials used in the practice of prosthodontics.

9. Dimensional changes occur in resin materials during processing procedures.

10. Dimensional changes in dentures can occur from differences in coefficients of thermal expansion in gypsum products, resins, and metal flasks. Dentures should be processed with techniques tha t minimize these changes.

11. Four areas of concern in the fabrication of any new prosthesis are (1) comfort, (2) function, (3) esthetics, and (4) phonetics.

12. The design and fabrication of all restorations, provisional and definitive, should promote periodontal health.

13. Areas of concern in the design and fabrication of all restorations include margin placement, margin adaptation, contour of the restoration, and occlusal relationships.

14. The prosthodontic design should consider (a) Crown-root ratio (b) Length of the edentulous space (c) Root configuration and size

(d) Contour of the anterior edentulous ridge (e) Occlusal-gingival dimension (f) Size and configuration of the clinical crown (g) Occlusal scheme (h) Materials to be used

B. Tooth preparat ion and soft tissue management 1. The mucosa in edentulous regions may assume an altered

surface form and texture resulting from being covered by denture bases.

2. Surgery may be desirable to alter ridge contours, reduce pendulous tissues, and reposition tissue attachments.

3. Surgery may be indicated to improve maxillomandibular ridge relationships.

4. When a maxillary tuberosity approximates the retromolar pad or is pendulous, it may be reduced. This procedure is indicated to provide the desired interarch distance, a more stable denture base, or to permit proper orientation of the occlusal plane.

5. Before final impressions are made, irritated, inflamed, or distorted mucosa should be brought to maximum health.

6. Tissue conditioning is more effective when (a) The occlusion is corrected (b) The proper vertical dimension of occlusion is restored (c) Denture borders are properly extended (d) The conditioner is properly placed and changed as

required 7. Tissue-conditioning materials placed on the tissue surface of

a surgical prosthesis can help compensate for tissue alterations re- suiting from surgery.

8. Before denture placement, areas on the tissue surface tha t cause excessive pressure on the tissues should be identified and relieved.

9. Inflammatory papillary hyperplasia may require surgical removal before definitive t rea tment to prepare a maxillary arch to accept dentures.

10. Patients should be informed that the success of prosthodontic restorations depends on meticulous plaque control. Pa- t ients should be instructed in the proper maintenance of oral health.

11. Oral surgery procedures are indicated to reduce tuberosities, tori, or other hard or soft tissue interferences. In such situations, the diagnostic cast or its duplicate may be recontoured to the desired shape. A clear plastic template may be constructed also, or instead, to aid the surgeon achieve the desired residual ridge contour.

12. When a residual ridge presents unfavorable gingival contours for pontic placement, augmentation and/or revision should be considered.

C. Impressions 1. Custom impression trays, correctly designed and contoured,

will facilitate making impressions for fixed or removable partial dentures, complete dentures, and implant prostheses.

2. Impression trays for final impressions should remain dimen- sionally stable throughout the impression and cast-making procedure.

3. Preliminary impressions made with modeling plastic impression compound may be altered by tr imming and/or adding material so tha t they may be used as final impression trays.

4. Displacement or deformation of soft and pendulous tissues should not occur during final impression making.

5. Final impression borders should represent the extension and contours of the processed denture.

6. Maximum extension of denture bases, within physiologic limits, is helpful to distribute forces to the supporting structures, augment retention and stability, and minimize accumulation of food particles under the bases.

7. Soft tissue displacement during impression-making may be partially controlled through the placement of relief in the tray, by

7 6 V O L U M E 73 N U M B E R 1


escape holes in the tray, and/or control of impression materials' viscosity.

8. When plaster of paris, zinc oxide-eugenol paste, or similar materials are used for final impressions, sufficient space between the impression tray and the mucosa should be present. This applies in making both complete and removable partial dentures.

9. When gagging is a problem while impressions are being made, placing the pat ient in an upright or forward position, and/or judiciously applying a topical or infiltration anesthetic agent to the posterior palatal area and the posterior part of the tongue can aid in managing the problem.

10. The manufacturer 's instructions for each impression material should be carefully followed for optimum results.

11. Making impressions for diagnostic casts may provide useful knowledge about the patient, including unusual sensitivities of the mucosa structures, the tendency toward gagging, tolerance to oral procedures, and favorable and unfavorable tongue movements.

D. Casts 1. Diagnostic casts are helpful for diagnosis, t reatment plan-

ning, pat ient education, and as a permanent record of the status of the dentition.

2. All materials used in prosthodontics should be carefully selected. The materials should meet ADA specifications where possible and be used in accord with manufacturers ' instructions.

3. To produce accurate dies and casts, impression materials, gypsum products, and other die materials should be mutually compatible.

4. The cast should be completed immediately after the impression-making procedure or within the t ime recommended by the manufacturer of each material.

5. When cast materials are mixed, the manufacturers ' recommendations for the powder-to-water ratio should be followed.

6. Impressions should not be inverted on the same mix of stone when casts are formed; tha t is, either a two-pour or a boxing technique should be used.

7. The cast produced from an impression should accurately record all of the details captured in the impression, including the border contours.

8. Ordinary plaster of paris is not a suitable material for constructing master casts.

9. When hydration of a gypsum-materials cast is mandatory, avoid disintegration of the cast's surface. The cast should be soaked in slurry water instead of tap water.

10. Accurately mounted diagnostic casts with and without the patient 's removable prostheses may be necessary as an adjunct to proper diagnosis.

11. Unaltered diagnostic casts may be an important part of the patient 's t rea tment record.

12. Suitable means should be used to prevent the record base and other materials from adhering to or distorting casts.

13. Diagnostic waxing, tooth arrangement, or other preliminary procedures on articulated casts are helpful in diagnosis, t reatment planning, and making final restorations.

14. In mounting any cast in an articulator, procedures and materials tha t minimize dimensional changes between the mounted cast and the member of the articulator should be used.

15. Vacuum mixing and correct water-powder ratios are essential in mixing final cast materials.

16. Casts should be properly t r immed according to their intended use.

17. The accuracy of casts made from impressions may be checked with an occlusal index made in the mouth.

E. M a x i l l o m a n d i b u l a r records and r e g i s t r a t i o n s 1. Temporomandibular joints are capable of three-dimensional

movements. 2. A necessary component of comprehensive diagnosis is a

record of the maxillomandibular relationship when the mandible is in centric relation.

3. When posterior teeth are missing and mastication has occurred only on the anterior teeth, an eccentric functional relation of the mandible to the maxilla may have occurred. It should be recognized before jaw relation records are made.

4. Unilateral loss of posterior teeth may alter the relationship of the condyle to the glenoid fossa. Where possible, the proper conditioning or positioning of the condyles should be accomplished through prosthodontic services.

5. As used in dentistry, the term vertical dimension refers to the length of the patient 's facial profile established by raising and lowering the mandible in relation to the maxillae (opening or closing the jaws).

6. The term rest vertical dimension refers to the length of the patient 's facial profile when the mandible is in its rest position in relation to the maxillae.

7. Mandibular rest position is a postural position and is subject to the same physiologic and pathologic factors as posture else- where in the body. Thus, it is subject to change and may not be constant throughout life.

8. The interocclusal distance, when added to the vertical dimension of occlusion, equals the rest vertical dimension.

9. Although the interocclusal distance is relatively stable, it can vary with time; but variations are usually small.

10. Patients can best assume mandibular rest position when sitting erect in a chair without a headrest or back support or when standing erect.

11. In the absence of occlusal interference or pathosis, the mandible normally tends to return to its physiologic rest position after most functional movement.

12. Opposing teeth or occlusion rims should not be in contact when the mandible is in its physiologic rest position.

13. Reference points placed on the face may aid in registering vertical jaw relationships.

14. Before teeth are arranged in the denture base, properly assessing the correct dimension of occlusion can be difficult.

15. Altering the vertical dimension of occlusion requires critical judgment. Use of interim diagnostic restorations at the altered vertical dimension may be indicated.

16. Tissue changes tha t occur when dentures are worn may cause a loss of the vertical dimension of occlusion.

17. When parts of the natural denti t ion are missing, some vertical dimension of occlusion may be lost.

18. Recording maxillomandibular relations is best accomplished when the patient is relaxed. Therefore, patients should be trained to relax the muscles controlling the mandible before centric rela- t ion records are made.

19. Centric relation serves as a reference for analysis of an existing occlusion and for determining the type of occlusion to establish during treatment.

20. Centric relation is individual to each patient. 21. On an articulator, centric relation at a particular vertical

dimension of occlusion may not be the same at another vertical dimension of occlusion, unless the transverse horizontal axis determination has been made.

22. A new centric relation record should be made if it becomes necessary to alter the originally established vertical dimension of occlusion unless a transverse horizontal axis determination has been made.

23. Head position influences the recording of centric relation. 24. Centric relation records should be made with minimum

closing pressure. 25. Centric relation records should be repeatable. 26. Eccentric jaw relation records are made to adjust the guid-

ing elements of an articulator. 27. Recording the centric relation for a removable prosthesis

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requires rigid and accurately fitted bases that resist warpage during clinical use.

28. Properly adapted record bases should be stable on the casts. They should incorporate an accurate index on the occlusion nm into which they may be related for mounting casts on an articulator.

29. Record bases should not be adapted to severe undercuts on the casts. This might warp the bases or damage the casts when they are removed.

30. Shellac-type record bases are susceptible to deformation. 31. Thick record bases may interfere with recording jaw rela-

tions accurately. 32. Occlusion rims should be made of a material with the

following characteristics: (a) Easily softens and molds to the desired form (b) Easily attaches to the record base (c) Becomes sufficiently rigid when cooled to serve as a tem-

porary occlusal surface (d) Permits resoftening in selected areas

33. The labial, buccal, and lingual contours of occlusion rims may influence the results when jaw relation records are made. This consideration is especially important when phonetic determina- tions are used.

34. Recording jaw relations may be more accurate when the design of occlusion rims conforms to the positions and dimensions originally occupied by the natural teeth and their investing tissues.

35. If an average-value facebow is used, interocclusal centric relation records should be kept to a minimum thickness.

36. To set condylar guidance, factors such as the nature and extent of prosthodontic therapy and health of the stomatognathic system, instead of statistical averages determine the need for recording condylar movement.

37. A remount procedure on a suitable articulator with new maxillomandibular records is an effective method of identifying occlusal discrepancies before placement of a prosthesis.

F. Occlusion 1. Because occlusal relationships are not static, the neuromus-

cular reflexes may change in response to changes in the occlusal position.

2. All prosthodontically treated patients should receive sched- uled reevaluation of occlusion.

3. Opposing tooth contacts should be planned to allow free movement throughout the functional range of the mandible.

4. Artificial posterior teeth should be arranged to provide equalized contact in centric relation with no interference in eccentric excursion.

5. The factors of articulation directly under the control of the dentist during complete denture fabrication are (1) anterior guidance, (2) plane of occlusion, (3) cusp height, and (4) compensating curve.

6. Occlusion and articulation of artificial teeth should be physiologically compatible with the remaining natural teeth and other parts of the masticatory system.

7. In centric occlusion, all posterior teeth should contact simultaneously.

8. Orthodontic procedures may play an important role in correcting some occlusal disharmonies.

9. Occlusion should be analyzed, and necessary occlusal alterations should be completed before final impressions and a prosthesis are made.

10. Before an at tempt is made to create artificial occlusal surfaces in the partially edentulous patient, occlusal discrepancies in the natural teeth should be eliminated.

11. A thorough examination of the occlusion of the remaining natural teeth should include properly mounted diagnostic casts.

12. Tooth contact of the teeth during speech may indicate in- sufficient interocclusal distance.

13. Physiologic stimulation of teeth and ridge structures is advisable. Excessive forces or dysfunction can be harmful and destructive.

14. Eccentric occlusions can be developed to meet the patient's physical and neuromuscular requirements.

15. An acceptable vertical dimension of occlusion contributes to optimum function, acceptable interocclusal distance, comfort, satisfactory speech, and good appearance.

16. Extreme caution should be exercised when performing procedures that will change the vertical dimension of occlusion. If the existing vertical dimension of occlusion is to be altered, a trial period at the new position is recommended to ascertain that a physiologically acceptable position has been established.

17. Incisal guidance is important in establishing anterior tooth position and the occlusal patterns of posterior restorations.

18. The absence of harmony between the intercuspal position and centric relation may cause prosthodontic failure.

19. The occlusion of all new dentures should be refined after processing.

20. Abnormal swallowing closures do not necessarily terminate at centric relation.

21. Provision of food escapeways in artificial posterior teeth enhances chewing effectiveness.

22. Occlusal morphology and cuspal patterns should be developed to satisfy the patient's needs instead of to fulfill a stereotyped concept of cuspal form.

23. The protrusive movement has two elements that should be considered in articulation:

(a) Condylar inclination, which is established by the patient (b) Incisal guidance, which is determined by the dentist 's

judgment and the patient's esthetic demands and functional needs

G. Try-in and verification procedures 1. Mandibular artificial posterior teeth should not be positioned

farther distally than the anterior border of the retromolar pad, nor should they be positioned on the distal incline of the residual ridge.

2. When only the anterior teeth in a partially edentulous arch remain, the artificial posterior teeth should be arranged on a record base and tried in the patient 's mouth to verify the jaw relations, occlusion, and appearance.

H. Esthetic considerations 1. The color of naturalanterior teeth may become more uniform

as their incisal edges become worn. They may not present the same incisal edge translucency found in most artificial teeth.

2. Natural anterior teeth often have a lower color value and ac- quire a smoother surface as the patient ages.

3. Facial templates or facial measurements may be helpful in arranging artificial teeth.

4. Photographs, diagnostic casts, and radiographs made before complete extractions are valuable guides to satisfactory esthetics.

5. Irregular or asymmetric arrangement of artificial anterior teeth may enhance the natural appearance of prosthetic restorations.

6. Compromises between esthetics and function should be assessed and discussed with the patient before treatment is started.

7. Preextraction records may be helpful during future treatment. They become part of the patient's record before any remaining natural teeth are removed.

8. A preextraction profile record of the face is best made while the teeth are in maximum contact.

9. Dentists are responsible for esthetics. Their work authoriza- tions to technicians should give specific instructions regarding esthetic factors.

10. Appropriate terminology should be used in communicating to the dental technician about tooth color.

11. Dental treatment rooms and the dental laboratory need similar light conditions for optimum shade matching.

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ACADEMY OF PROSTHODONTICS THE JOURNAL OF PROSTHETIC DENTISTRY

12. Esthetic features of restorations should be observed in artificial and natural light.

13. Shade selection should be made under conditions tha t sim- ulate natural daylight.

14. Resin denture base materials should optimally reproduce the color and characteristics of oral tissues being replaced.

15. Incisal length of maxillary anterior teeth should be determined esthetically and phonetically by arranging the teeth on the record base.

16. The natural appearance of replacement teeth may be enhanced if various tooth colors and molds are used in arranging the anterior teeth artistically.

17. Reflective surface and texture are critical to attaining a shade match.

18. Modification of standard artificial teeth may improve the appearance of a removable prosthesis, especially for the mature patient.

19. The dentist needs a working knowledge of the science of color to match the colors of natural teeth.

20. A patient 's esthetic requirements should be met with due consideration for the periodontal health of the tissues and proper function. Rigid esthetic requirements tha t conflict with functional requirements may preclude treatment.

L Initial placement of restorations (insertion) 1. Adequate time should be allowed for appointments involving

initial placement of restorations so tha t patients fully comprehend the importance of their responsibilities in the success of the restorations.

2. Each denture base tissue surface should be evaluated and corrected, if necessary, before occlusal evaluation and placement.

3. At the preliminary placement of the prosthesis, all areas should be checked with pressure indicator material and all inter- fering regions should be assessed for selective relief.

4. Wri t ten instructions to the pat ient regarding home care and maintenance of the prostheses and oral tissues are positive rein- forcements of verbal instructions. Such instructions can become a future informational reference.

5. After the initial placement of a removable prosthesis, the pa- t ient should be recalled for necessary adjustments at an appropriate interval.

6. Explanation of common sensations and effects of wearing a prosthesis should precede initial placement of the prosthesis.

J. Care after placement 1. Prosthodontic t rea tment is a continuous service tha t does not

end with the placement of the oral or facial prosthesis. 2. The pat ient should be impressed with the need for routine

examinations to evaluate the occlusion and assess the oral environment 's response to the prosthetic restoration.

3. Proper diet should be emphasized to all prosthodontic patients.

4. The patient 's name, date, articulator number, condylar settings, and other pert inent data should be indelibly recorded on articulated diagnostic casts, t rea tment casts, and dies. The dentist should retain them. These records are a valuable aid for planning further t rea tment and for medicolegal reasons.

5. Care after placement should include maintenance and care of prosthetic restorations.

K. Inter im and immedia te restorations 1. After surgery and appropriate healing, the original prosthe-

sis may require revision or replacement. 2. Properly constructed interim restorations may alleviate some

temporomandibular joint symptoms. 3. An acceptable method of compensating for tissue changes

after surgery is to place tissue-conditioning materials on the tissue surface of a surgical prosthesis.

4. To help the pat ient adapt to wearing a prosthesis, a transi-

tional removable partial denture may be considered as a temporary t reatment modality before immediate complete dentures.

5. Immediate restorations are generally considered provisional, to be followed later by definitive treatment.

II. F ixed part ia l d e n t u r e s A. Diagnostic procedures 1. For most fixed partial dentures, the patient 's diagnostic casts

should be mounted in a semiadjustable or fully adjustable articulator capable of accepting eccentric excursive and centric relation records.

2. The maxillary cast should be mounted in the articulator with the aid of a face-bow.

3. Pantographic tracings may provide additional diagnostic information about the patient 's jaw movements.

4. Casts mounted in an articulator should be evaluated (a) To determine anteroposterior and lateral excursive in-

terferences (b) To select the appropriate path of placement (c) To decide whether to alter the vertical dimension of oc-

clusion to provide the desired plane of occlusion (d) To determine the types of dental restorations needed (e) To aid in pontic selection (f) To accomplish trial equilibration procedures

5. A diagnostic wax-up of proposed restorations is indicated in some situations:

(a) To provide useful information relative to the intended esthetic result

(b) To indicate the required amount of tooth reduction (c) To aid in making provisional restorations (d) To provide a visual aid during treatment-planning dis-

cussions with the pat ient (e) To plan occlusion

6. A second set of mounted casts may be used for trial tooth preparation.

7. A customized incisal guide table may be developed by use of the mounted diagnostic casts.

B. Tooth preparat ion 1. Preparation of a tooth should be planned and completed to

achieve adequate retention and to develop resistance form. 2. Adding boxes, grooves, or pinholes to a preparation may in-

crease a cast metal restoration's resistance to dislodgement. 3. Sufficient tooth structure must be removed to preserve the

integrity of the restoration, provide the desired esthetic result, and allow the restoration to be fabricated without being overcon- toured. The amount of tooth reduction needed will vary depending on the restorative material being used.

(a) Occlusal reduction for a cast metal restoration should be a minimum 1.0 to 1.5 mm for the lingual cusps of the maxillary teeth and the buccal cusps of the mandibular teeth.

(b) Preparation of occlusal surfaces should replicate as nearly as possible the anatomy of the cusps and grooves to avoid over or under reduction of the tooth.

(c) Peripheral reduction, especially near the margins, should be adequate to increase rigidity of the casting.

(d) Boxes, grooves, ledges, and occlusal shoulders may be used to increase the rigidity of a casting.

4. Supragingival placement of cast restoration margins may be desirable if requirements for retention, resistance form, and esthetics are satisfied.

(a) If subgingival margin placement is necessary, an adequate zone of attached gingiva should be present.

(b) Whenever possible, the margins of a restoration should be accessible to the dentist for finishing and to the pat ient for cleaning.

(c) The finish line should be placed on enamel if possible. In

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THE JOURNAL OF PROSTHETIC DENTISTRY ACADEMY OF PROSTHODONTICS

some situations, it may be necessary to locate the finish line on cementum, dentin, amalgam, or gold. Placing the finish line on composite resin should be avoided.

(d) There should be no occlusal margins in an area of occlusal function.

(e) During tooth preparation, the formation of a well-defined finish line such as the knife edge, chamfer, chamfer with a bevel, shoulder, and shoulder with a bevel is desirable

(f) The type of restorative material used and the location of the tooth being restored may dictate the choice of finish line.

5. Tooth preparation should be accomplished with minimal pulpal trauma. Teeth should be prepared in relation to healthy tissue.

6. During tooth reduction with rotary instruments, use of an air and water coolant is recommended.

7. Endodontically treated teeth may require the use of a core buildup or a dowel and core to obtain the desired retention and resistance form.

8. Periodontal health should be established before or in concert with the restorative treatment.

9. Preservation of supporting structures should be a primary consideration in designing and making fixed partial dentures.

10. The gingival terminus should not violate the epithelial at- tachment.

C. Impressions 1. An impression material should be selected because its phys-

ical, chemical, and working properties are best suited for the clinical problem being treated.

2. Impression materials should meet ADA Council on Dental Materials, Instruments, and Equipment specifications.

3. When elastomeric impression materials are used, a full-arch custom tray may facilitate making impressions.

4. Gingival displacement may be accomplished by using mechanical, chemical, or electrosurgical methods.

(a) Gingiva should be healthy and free of inflammation before final tooth preparation.

(b) Care must be exercised to avoid violating the integrity of the epithelial at tachment, no matter what method of gingival retraction is employed.

(c) Epinephrine-impregnated cords should not be used on patients with certain types of cardiovascular disease, hy- perthyroidism, or a history of epinephrine hypersensitiv- ity.

(d) Electrosurgical gingival preparation should not be used on patients with cardiac pacemakers.

5. Careful management of the interface between tooth and pe- riodontium is integral to preserving periodontal health. Ideally, an impression should not extend subgingivally, however, certain clinical situations may necessitate subgingival margin placement. Invasive techniques to displace gingival tissue should be minimally traumatic.

D. Interocclusal records 1. The time lapse between securing an interocclusal record and

its use in mounting casts in an articulator should be consistent with minimizing inaccuracies inherent in the recording material being used.

2. After the working casts have been recovered from the impressions, a separate appointment for making interocclusal records will enable records verification while the pat ient is present.

3. Numerous materials and techniques will enable accurate re- production of interocclusal relationships. Personal preference and clinical circumstances will dictate which methods are used.

4. Interocclusal records tha t are t r immed so that only cusp tip indentations remain, facilitate accurate cast positioning in the record before they are mounted in an articulator.

5. When limited numbers of teeth are being restored, the

interocclusal registration may be made with the remaining unpre- pared teeth in contact. The recording medium should avoid increasing the vertical dimension of occlusion and thus possibly incorporating an inaccuracy into the mounting.

6. Interocclusal registrations made with the teeth out of contact should be recorded bilaterally. The dentist should guide the patient to the desired centric relation or lateral excursive position.

7. An occlusal programmer or jig provides a vertical stop at the desired degree of vertical opening. It also assists positioning the condyles appropriately.

8. Lateral excursive recordings may be made by guiding the pa- t ient in a lateral movement until the opposing arches are in a cusp-tip to cusp-tip relationship. The recording medium then captures tha t relationship.

9. To verify the accuracy of the centric relation mounting of the mandibular cast in the articulator, at least two registrations should be used.

10. When a significant edentulous segment exists, an interocclusal record to relate the casts for a fixed partial denture should be made with a stabilized record base fabricated on the master cast.

11. Making interocclusal registrations, positioning the casts in the registration, and mounting them in the articulator are the dentist 's responsibility.

E. Provis ional restorations 1. Provisional restorations should incorporate the same quali-

ties as the final restoration, including marginal integrity, esthetics, form, and function, while maintaining the health of the abutment teeth and supporting structures.

2. Many acceptable materials are available for making provisional restorations. Tooth position in the arch, type of tooth preparation, expected length of service, and whether it is a single unit or a fixed partial denture will influence the choice of material.

F. Ocelusal considerations 1. A cusp-marginal ridge occlusal relationship is found in most

adult natural occlusions. This type of occlusal morphology may be used in making either single or multiple cast restorations.

2. A cusp-fossa occlusal scheme is rarely found in natural teeth. It is often advocated when multiple adjacent and opposing teeth are being restored with cast restorations to direct the forces of occlusion in a more axial direction.

3. A group function occlusion may distribute the occlusal load on the working side in lateral excursions.

4. The functionally generated path technique is an effective way to develop a group-function occlusion in cast restorations.

5. A mutually protected occlusion may be indicated under these conditions:

(a) There are periodontally healthy anterior teeth. (b) There is an Angle's class I jaw relationship. (c) The posterior teeth are not in a reverse occlusion. (The

maxillary and mandibular buccal cusps interfere with each other in a lateral excursive movement.)

6. In a mutually protected occlusion, only the anterior teeth are in contact in any excursive position of the mandible. Maximum intercuspation is coincident with centric relation. Occlusal forces are directed along the long axis of the posterior teeth. Anterior teeth protect the posterior teeth in eccentric movements. Posterior teeth protect anterior teeth in the intercuspal position.

7. Lateral excursive contacts on the balancing side are considered undesirable in either a group-function or mutually protected occlusion.

8. In making anterior restorations, care must be exercised so tha t the vertical and horizontal overlap and configuration of the lingual surfaces of the maxillary restorations are in harmony with the patient 's functional movements.

9. When the vertical dimension of occlusion is to be increased or decreased, it is advisable to have a trial period. During several

8 0 VOLUME 73 NUMBER 1


weeks to several months, the pat ient is allowed to function at the desired vertical dimension of occlusion before the definitive restorations are made.

G. Casting try- in and verification 1. After the provisional restorations are removed, the prepared

teeth should be examined carefully to assure they are free from temporary cement or any other debris before placement of the definitive restoration is attempted.

2. A binocular microscope may be used to verify tha t internal surfaces of cast restorations are free of small bubbles, investment, or deposits of veneering material. Then, placement on the prepared tooth can be attempted.

3. A disclosing medium may be used on the interal surface of a casting to locate discrepancies tha t prevent the restoration form seating completely on the prepared tooth.

4. Proximal contact areas of fixed restorations should be firm yet allow the passing of dental floss to maintain good oral hygiene.

5. Pontics should be designed to contact the residual ridge in a passive manner.

6. The apical form of the pontic should be designed and adjusted to enable the patient to maintain good oral hygiene.

7. In equilibrating the occlusal discrepancies of definitive restorations, relatively smooth rotary instruments and a thin mark- ing medium should be used.

8. During equilibration of the definitive restorations, articulat- ing strips of different colors can be used to help differentiate between centric and lateral excursive interferences.

9. When numerous teeth are being restored, a remount procedure may facilitate occlusal equilibration of the definitive restorations.

10. When access allows, margins of cast restorations should be refined on the tooth with the restoration in place.

11. To achieve the maximum esthetic result with ceramic restorations, the dentist should perform final surface characteriza- tion, contouring, and shade modification with the pat ient present.

12. Fixed partial dentures replacing anterior teeth should provide lip support and satisfy the patient 's esthetic, phonetic, and functional requirements.

13. The trial fitting procedure should include procedures tha t verify complete seating of castings, marginal integrity, proper em- brasure spaces, and contour for periodontal health.

14. It may be helpful to have individual units indexed from an intraoral try-in before soldering.

H. Cementation 1. In areas where adjustments have been made, metal should be

repolished and porcelain polished or reglazed before cementation. 2. To assess tissue and patient response, trial placement of the

restoration with a temporary cement may be indicated. 3. The cement selected should meet the specifications of the

American Dental Association Council on Dental Materials, In- struments, and Equipment.

4. Different types of cements are available for final placement of a restoration. The dentist should select the cement with the physical, chemical, and working properties best suited to each clinical situation.

5. The tooth should be cleansed, isolated, and dried. Where indicated, a cavity varnish should be applied before final cementation.

6. The manufacturer 's instructions for manipulating the cement should be strictly followed.

7. When multiple individual restorations are to be placed, each restoration should be cemented individually to assure complete seating.

8. After the cement has set, all of the extraneous material should be removed so tha t none remains to act as a gingival irritant.

9. The occlusion should be reexamined after cementation and should be equilibrated, if necessary.

10. Patients should be thoroughly instructed regarding oral hygiene procedures, aids, and devices tha t facilitate interproximal and pontic tissue surface cleansing.

11. The pat ient should be given a follow-up appointment for after-placement care.

I. Periodic recall exam in a t ion 1. Periodic recall after placement should be an essential part of

fixed prosthodontic therapy. 2. Early detection of potential problems through recall exami-

nation may prevent failure of the restorations.

III. Removable partial dentures A. Refining diagnostic procedures and preparatory

t reatment 1. Occlusion of the teeth should be compatible with normal

function of the stomatognathic system. I t may be necessary to treat the patient with occlusal splints, occlusal adjustment, or orthodontics to restore proper harmony between the musculature, the temporomandibular joints, and the occlusion of the teeth.

2. When treating a patient with a removable partial denture, the patient 's periodontal health is an important consideration.

3. Criteria for selecting removable partial denture abutment teeth include the following:

(a) Crown-root ratio of the teeth (b) Number of roots (c) Form and curvature of roots (d) Alveolar support (amount of bone) (e) Tooth inclination (position in the arch) (f) Mobility (periodontal health) (g) Stress evaluation (h) Previous response to stress (i) Restorability of the tooth (j) Occlusal relationships (k) Crown contour (1) Plaque control (m) Impending functional demands

4. Diagnostic casts mounted in an articulator assist in locating elements of the removable partial denture tha t relate to esthetics, design, and function. Spatial requirements for rest placement and preparation can be evaluated.

5. Diagnostic casts are necessary to evaluate the degree of mouth preparation and tooth modification required for removable partial denture framework design.

6. Planned mouth preparation and tooth modification may be carried out on the diagnostic cast before actual patient preparation, and can serve as a guide for subsequent intraoral procedures.

7. A dental surveyor must be used to locate undercuts and to guide surfaces in relation to the planned path of placement on the diagnostic cast.

8. Guiding surfaces are parallel surfaces tha t will contact a rigid part of the removable partial denture. Adequate guiding surfaces should be planned to establish the path of placement and dislodgement. Properly prepared guiding surfaces contribute to the retention and stability of the removable partial denture.

9. Because diagnostic casts are made by using stock trays and a viscous impression material, they may not be a reliable guide to soft tissue reflections, anatomy, and contour (for example, vesti- bular depth, frenum movement).

B. Design, fabrication, and classification 1. Treatment planning, mouth preparation, and designing re-

movable partial dentures are the dentist 's professional responsibilities. They must be completed before master casts are presented to the dental technician or dental laboratory where the prosthesis will be made.

2. Classification of a partially edentulous arch should permit immediate visualization of the type of arch being considered. This classification should also permit immediate differentiation be-

J A N U A R Y 1 9 9 5 8 1


tween the tooth-borne and tooth-tissue-supported removable partial denture.

3. Philosophies of removable partial denture support are based on principles of broad or selective distribution of occlusal forces.

4. The basic purposes of removable partial dentures' component parts are (1) to provide support by means of rests on abutment teeth and by denture bases on edentulous ridge areas; (2) to provide primary retention by direct retainers; and (3) to provide selective force transmission through placement of the rigid components of the removable partial denture.

5. A removable partial denture should restore arch integrity, thereby preventing further change of both maxillary and mandibular arches.

6. Maintaining and improving the health of the remaining teeth and supporting structures is an important consideration in removable partial denture design. Prosthesis impingement on gingival tissues should be avoided. Impingement of any part of the prosthesis on gingival tissues should be avoided.

7. When a removable partial denture is supported by both natural teeth and the residual ridge(s), the design should use both supporting units to their greatest potential.

8. In some instances, support and stabilization are as significant as retention in the design of a removable partial denture.

9. Retention of a removable partial denture is important for management of pat ient care, particularly for the first months after placement of the denture.

10. Removable partial dentures should be constructed to trans- mit occlusal forces to the abutment tooth nearly parallel to its long axis.

11. The design, contour, and finish of a removable partial denture should minimize food retention or impaction.

12. A survey of both the diagnostic and master casts is essential for making removable partial dentures.

13. One method of stress distribution to abutment teeth is the use of multiple abutments.

14. An isolated premolar adjacent to a distal extension base may not be an adequate primary abutment for a removable partial denture. The prognosis can be improved by splinting with a fixed partial denture. :

15. Forces tha t produce torque on abutment teeth and the:alveolar residual ridge should be controlled and minimized h ~he design of direct retainers for distal extension removable phrtial dentures.

16. A removable partial denture with distal extension bases may use stress directors to minimize stress distribution on abutment teeth.

17. Major connectors should be designed to have sufficient rigidity to distribute forces throughout the dental arch.

18. Most removable partial dentures move during function. The extent and direction of movement are influenced by the supporting structures, prosthesis design, and the accuracy of fit of framework and bases.

19. A removable partial denture base tha t derives par t of its support from the residual ridge should not displace the underly- ing mucosa except during masticatory function.

20. In tooth-tissue supported removable partial dentures, denture bases should provide optimum support during occlusal loading.

21. The form of the denture base for a mandibular distal extension removable partial denture should be similar to tha t required for a complete denture. Modification may be dictated by the path of placement.

22. In surveying a cast for a removable partial denture, the relationship of the vertical spindle of the surveyor to the cast indicates the most desirable path for placement and removal of the completed restoration.

23. Abutment teeth should be prepared by modifying unfavor-

able contours and preparing guiding surfaces and rest seats before the impression for the master cast is made.

24. Fixed restorations used as abutments for removable partial dentures should incorporate guiding surfaces, rest seats, stabilizing, and retentive areas.

25. Fixed restorations tha t are to be integrated with removable prostheses should be surveyed in the wax pat tern stage and verified after casting, after veneering, and before cementing.

26. Indirect retainers establish a positional reference point for the removable partial denture. They also provide better stress distribution by transferring forces to structures other than the abutment teeth.

27. A direct retainer (clasp) should be passive when the removable partial denture is in place and at rest.

28. Intracoronal or extracoronal retainers may be used in com- bination with stress-directing devices in extension base removable partial dentures.

29. Whenever possible, retainer elements should be kept at the same height relative to survey lines on opposing tooth surfaces so tha t unfavorable forces on abutments will be minimized.

30. Each direct retainer (clasp) requires reciprocation to reduce movement of the abutment tooth during placement and to avoid dislodgment of the removable partial denture.

31. For a direct retainer to be effective, components of the framework must contact the abutment tooth at three points or areas encircling more than 180 degrees of the tooth.

32. When appearance is a consideration, a direct retainer (clasp) design that will minimize the display of metal should be chosen.

33. The undercut gauge indicates the amount of infrabulge at the selected site. I t also indicates the distance which a retentive clasp arm must flex or deform to pass over the greatest contour of the tooth.

34. Direct retainers (clasps) should pot engage undercuts tha t require deflection beyond the yield strength of the metal being used.

35. Multiple occlusal rests and other supportive elements may provide a more advantageous transfer and distribution of forces to the existing natural teeth.

36. Occlusal and incisal rests are important supporting elements of removable partial dentures. They help resist horizontal and vertical forces applied to the prosthesis. Other components that contact teeth above the survey line may also provide stability.

37. The major connector should be located so that its contact is compatible with structures tha t move during function and gingival impingement is avoided.

38. Direct measurements of the distance between the active floor of the mouth and the lingual gingival tissues are essential to selection and placement of mandibular major connectors.

39. Major connectors join the denture base(s) to other parts of the removable partial denture and help distribute functional forces.

40. The angle formed by the occlusal rest and the vertical mi- nor connector should be slightly less than 90 degrees.

41. The use of permanent soft denture base material for definitive removable partial denture fabrication is not recommended.

42. When lingual inclinations of remaining teeth contraindicate the use of a conventional lingual major connector, mandibular labial bar major connectors may be used.

43. A hinged continuous labial bar may be indicated for patients with missing key abutments, unfavorable tooth contours, unfavorable soft tissue contours, and teeth with questionable prognosis.

44. The use of porcelain teeth should be limited to instances in which the opposing occlusal surfaces will not be subject to accel- erated functional wear.

45. When there is aberrant spacing in the edentulous area,

8 2 V O L U M E 73 N U M B E R 1


acrylic resin teeth should be considered for use in removable partial dentures.

46. Clasp elasticity varies in its length, thickness, width, curvature, taper, form in cross section, metallurgical composition, and handling.

47. The dentist is responsible for producing the work authorization or design. The dental technician is responsible for following it and creating a removable partial denture framework that accurately fits the undamaged master cast. If these criteria are met and the framework does not fit the mouth, the fault lies with errors occurring before the technical work.

48. The removable partial denture 's metal framework must not prevent the contact of natural teeth in occlusion, unless an increase in vertical dimension is planned.

49. Overdenture abutments can provide support for removable partial dentures.

50. An overdenture abutment supporting a removable partial overdenture may contact the metal framework or the acrylic resin of the denture base.

51. The use of acrylic resin contact with overdenture abutments in removable partial overdentures has several advantages:

(a) The abutment tooth may be recontoured or shortened and the denture base readapted with autopolymerizing or visible-light-cured resin.

(b) A coping can be placed at a later date and the denture base readapted.

(c) There are fewer problems in making an altered east impression or relining the denture base.

(d) The denture base can be adapted to the abutment tooth under some degree of occlusal loading of the artificial teeth.

C. Tooth preparat ion and soft tissue management 1. The occlusal rest should be spoon-shaped and deeper in its

central portion. The preparation's surface angles should be rounded and the preparation should be highly polished.

2. Spoon-shaped occlusal rest seats prepared in sound enamel are satisfactory to support a removable partial denture.

3. A rest seat on an anterior tooth should be placed on a recontoured lingual or incisal surface. The resultant force should be directed parallel to the long axis of the tooth. When recontouring is not feasible, a restoration tha t incorporates a rest seat may be required.

4. Rest seats must (1) be strong enough to endure functional stress; (2) preferably be prepared in enamel or a metallic restoration; (3) provide a vertical contact for the metal framework; (4) be rounded and conform to the existing coronal anatomy; and (5) have a preparation sufficiently deep to prevent rest fractures. The opposing dentit ion may require modification to provide space for adequate rest thickness.

5. If possible, rests should not be located on habitual occlusal contacts.

6. Cingulum rest seats may be prepared in teeth having a nat- urally accentuated cingulum.

7. Cingulum rest seats should have an outline tha t blends into tooth contours.

8. Incisal rest seats should be shaped as a rounded groove extending onto the labial surface of an anterior tooth and gingivally on the lingual surface. Incisal rest seats are used principally on mandibular anterior teeth.

9. An occlusal strap rest is a continuous occlusal rest extending through prepared central grooves of a group of natural teeth to provide stabilization of the dentition.

10. Teeth to be used as abutments for a removable partial denture should have favorable contours or be recontoured or restored as needed. Some tooth alteration is usually necessary for patients who initially receive removable partial dentures.

11. Heights of contour may be altered and guiding surfaces cre-

ated to aid retention and stability of the removable partial denture.

12. Guiding surfaces should be (1) aligned to the path of insertion; (2) curved buccolingually to follow tooth form; (3) straight occlusogingivally; and (4) dispersed in the arch as much as possible.

13. Guiding planes should be completed on the unrestored abutment teeth before crowns or other teeth are constructed. Thus, they serve as a guide for crown contours.

14. To permit bet ter framework placement, the following may be recontoured: (1) line angles of crowded anterior teeth tha t will receive a lingual plate or continuous clasp; (2) proximal line angles of tipped or rotated teeth; and (3) buccal and lingual surfaces of t ipped teeth.

15. The fixed splinting of teeth to be used as abutments for removable partial dentures may be indicated when the bone support of the abutment(s) is unfavorable or when rigid retainers are planned.

16. Fixed splinting of teeth may aid in counteracting forces tha t result in torque of abutment teeth.

17. Contiguous teeth and those separated by an edentulous space may be splinted together to provide more support for the removable partial denture.

18. Natural tooth surfaces tha t have been modified must be highly polished and should receive fluoride treatment.

19. Before impressions are made for a new removable partial denture, soft tissues tha t have been distorted and displaced by a previous removable partial denture should be returned to normal health and contour.

20. Plans for correcting discrepancies in the plane of occlusion should be noted during the diagnosis and incorporated into the t reatment plan.

21. Tooth contours on removable partial denture abutment teeth may be altered in certain situations through the use of composite resins or metal castings bonded to acid-etched enamel

D. Final impressions 1. When properly used, reversible and irreversible hydrocol-

loids and elastomeric impression materials may be acceptable for removable partial denture impressions.

2. One concept of making impressions uses a secondary impression (altered cast removable partial denture impression) to record the supporting tissues of the denture base. Mandibular distal extension removable partial dentures usually require a secondary impression technique or relining procedure to improve the stability and support of the prostheses.

3. One potential complication of the altered cast impression procedure is incorrect or incomplete seating of the framework in the mouth or on the cast.

4. Final impressions should be carefully inspected to verify tha t (1) all critical soft and hard tissue areas are accurately recorded; (2) voids are not present in rest seats; and (3) the impression material had not separated from the tray.

5. The impression tray must be carefully positioned and held without movement until the impression material completely sets.

6. Hydrocolloid impressions should be poured immediately after removal from the mouth.

7. Most final impressions should be cleaned of saliva and other debris, disinfected, and poured in improved stone immediately after removal from the mouth. A few impression materials require a delay in pouring.

8. When the posterior teeth are missing, the final impression of the partially edentulous mandibular arch should include the retromolar pad.

9. A posterior palatal seal on a removable partial denture with full palatal coverage may prevent the ingress of food and aid in retention during forceful expulsion of air through the mouth.

J A N U A R Y 1 9 9 5 8 3


E. Casts 1. The master cast must be an exact replica of the oral

structures. It should be (1) dense, (2) clear of debris, (3) without critical voids, and (4) possess an adequate base.

2. Master casts for removable partial dentures should be disinfected.

3. Master casts should be produced with an improved dental stone compatible with the material used for making the impression.

4. Duplicate casts are helpful to communicate removable partial denture design to the technician. Diagnostic casts are not recommended for this purpose if restorative procedures or recontouring have significantly altered the contours of teeth subsequent to making diagnostic impressions.

5. The design of the removable partial denture framework should be drawn either on the master cast or on a duplicate of the master cast to t ransmit this information to the technician.

6. If needed for proper occlusal and framework relationships, an opposing cast mounted in an articulator should be provided to the technician as a guide in waxing the framework.

7. At its th innest area, a master cast should be at least 8 mm thick.

8. All casts submitted to the laboratory for framework fabrication should be tr immed so that the base is flat, the walls are vertical, and the land areas are definite. Mandibular casts should have flat smooth lingual land areas.

9. Accurate casts tha t have been neatly trimmed, carefully designed, surveyed, blocked out, and tripoded may instill a desire for the highest quality work from the technician.

F. Framework try-in 1. Initial seating of the framework should be gentle and slow to

allow minor repositioning of the abutments. 2. All parts of the framework must be completely seated. 3. Vertical elements of the framework for tooth- and tissue-

supported removable partial dentures must be physiologically adjusted to minimize undesirable stress on abutment teeth during prosthesis movement.

4. Occlusal surfaces of the framework must be in harmony with the occlusion of the natural teeth.

5. Most removable partial denture frameworks require some adjustment to achieve their optimal fit. Fitt ing can best be accomplished by using a disclosing medium.

6. Unless the framework is completely seated, retentive clasp arms of removable partial dentures may not be passive.

7. Extracoronal or intracoronal a t tachment removable partial dentures capable of vertical movement under stress should be adjusted to optimal occlusion before the vertical movement of the a t tachment occurs.

G. Maxillomandibular records 1. Before preparing an abutment and related teeth, it may be

helpful to refer to an accurate occlusal record used to mount diagnostic casts in an articulator at the proper vertical dimension.

2. The recording of maxillomandibular relation records for distal extension removable partial dentures requires accurately adapted denture bases at tached to the framework. This system should relate to the remaining teeth correctly.

3. For patients whose prognosis is good, and in whom the existing occlusion is physiologic, interocclusal registrations should be made with the natural teeth in contact at maximum intercuspation.

4. Before a definitive occlusal pat tern or arrangement is developed for patients who show evidence of traumatogenic occlusion, interocclusal registrations should be made in centric relation.

5. Maxillomandibular records for distal extension removable partial dentures should be made with minimal pressure.

6. A semiadjustable articulator is adequate to develop tooth arrangement for most removable partial dentures.

7. In tooth- and tissue-supported removable partial dentures, the recording of maxillomandibular relationships is best performed by using record bases at tached to frameworks fabricated after an altered cast impression procedure.

8. The vertical dimension of occlusion established for the removable partial denture must be coincident with the remaining natural dentition.

H. Occlusion 1. To articulate properly, the occlusion of a removable partial

denture should be developed with the remaining natural teeth at the correct vertical dimension of occlusion.

2. Contact only in maximum intercuspation is usually required in removable partial dentures opposing natural dentitions.

3. Before removable partial denture service is provided, the occlusal surfaces of opposing natural teeth may require adjustment.

4. Nonworking-side contacts usually are undesirable for removable partial dentures opposing natural teeth or another removable partial denture.

5. Generally, no part of the removable prosthesis should interfere with complete closing contact or eccentric movements of the remaining natural dentition.

6. Dentitions tha t include removable partial dentures provide less masticating efficiency than natural dentitions with similar contact areas.

7. Processed removable partial dentures may be returned to the articulator before removal from the master cast to adjust for processing changes. This procedure reestablishes and verifies the intended vertical dimension of occlusion.

8. Distal extension removable partial dentures may be re- mounted in the articulator to refine centric and eccentric occlusal contacts. This adjustment should follow base modification by using indicator paste.

9. Short-span tooth-supported removable partial dentures may have the static and dynamic occlusal relationships perfected in the patient 's mouth.

10. Occlusal relationships of tooth-supported removable partial dentures may be perfected in the patient 's mouth if opposed by natural teeth or another partial denture.

I. Try-in of the waxed removable partial denture 1. A try-in with the artificial teeth arranged in wax attached to

the framework is usually necessary. 2. Articulator mounting accuracy should be verified at the

try-in appointment. 3. The appearance of the removable partial denture should he

satisfactory to both pat ient and dentist. 4. Anterior artificial teeth should be tried in the mouth to ver-

ify their size, shade, position, and acceptability to the patient. 5. When esthetics is a primary concern, it may be helpful to have

a relative or friend of the patient present at the try-in appointment.

6. Before the denture base material is processed, waxing should be accomplished for proper esthetic form and for physiologic function.

7. Artificial teeth should be positioned for optimal centric relation and eccentric contacts.

8. After the accuracy of the vertical dimension of occlusion has been determined, centric relation should be verified.

J. Esthetic considerations 1. In designing direct retainers for removable partial dentures,

effect on appearance should be considered. 2. Artificial teeth adjacent to abutment teeth may be contoured

to accommodate retainers. 3. In the partially edentulous pat ient with a well-formed ante-

rior residual alveolar ridge, anterior teeth tha t are adapted to the ridge with no labial denture base may provide optimum appearance.

8 4 VOLUME 73 N U M B E R 1


K. Initial denture placement 1. Denture base border extension and thickness should be ver-

ified during placement. 2. The denture bases and major connector should be checked

with disclosing medium to identify areas of undesirable pressure. 3. The occlusion may require adjustment to provide planned

contacts in maximum intercuspation and lateral excursions. 4. Verbal or written home care instructions with demonstra-

tions are recommended. 5. When undercut areas prevent the seating of the denture bases

of removable partial dentures, judicious adjustment is required. The tissue surfaces of posterior bases are relieved so that border extent can be maintained. Anterior bases are shortened and contoured to blend with the remaining tissues to avoid an unnatural appearance.

6. Removable partial denture frameworks must be fully seated on the supporting structures before occlusal adjustment.

L. Care after placement of removable partial dentures 1. A major factor in the success of a removable partial denture

is proper maintenance of the prosthesis and the supporting structures.

2. Most patients who have removable partial dentures should be reexamined at least semiannually and more frequently, if indicated.

3. Wri t ten instructions aid in educating patients effectively. 4. To help patients cleanse removable partial dentures and

supporting teeth, properly designed brushes and appropriate cleansing instructions should be provided.

5. Instructions for cleansing and stimulation around abutment teeth and the remaining natural teeth are essential.

6. Application of fluoride to the natural teeth by means of the prosthesis or an individual applicator may be indicated.

7. Removable partial dentures should usually be removed from the mouth when the pat ient goes to bed.

8. Distal extension removable partial dentures should be examined periodically for evaluation of ridge resorption, stability, occlusion, and framework displacement. Variations from optimum should be corrected.

M. Interim restorations 1. Interim removable partial dentures may facilitate residual

ridge remodeling. They may also help maintain the vertical dimension of occlusion after removal of posterior teeth.

2. Interim removable partial dentures can be used for the following diagnostic purposes:

(a) In determining proper vertical dimension of occlusion (b) In determining esthetic and phonetic requirements (c) To assess pat ient ability to cooperate (d) To assess patient ability to cope with wearing a prosthesis

I V . M a x i l l o f a c i a l p r o s t h e t i c s

A. Scope of maxillofacial prosthetics 1. In a society tha t values appearance, those who lack eyes, ears,

noses, facial and mandibular tissues, or who exhibit severe scar tissue and malformed parts of the face, neck, and oral cavity may become socially alienated. Whereas developmental defects afford more time for adjustments to be made, a sudden traumatic and surgical defect may precipitate a crisis in the patient 's quality of life. Maxillofacial rehabilitation of the pat ient requires a broad knowledge of prosthodontics and the capacity for compassionate pat ient management.

B. Refining diagnostic procedures 1. The maxillofacial prosthodontist is an integral member of an

interdisciplinary team that treats individuals with oral, cranial, and facial defects.

2. Evaluation of the needs of a pat ient requiring maxillofacial care generally includes (1) dental history, (2) medical history, (3) surgical history, (4) psychosocial assessment, (5) speech evalua-

tion, and (6) clinical examination. Diagnostic aids include (1) articulated maxillary and mandibular casts, (2) oral radiographs, and (3) radiographs of related facial structures if required.

3. When possible, all prospective patients for head and neck surgery and potential candidates for any maxillofacial prosthesis should be seen by the maxillofacial prosthodontist for diagnosis and pretreatment evaluation before surgery, radiation therapy, or chemotherapy.

4. The prosthetic prognosis for patients after irradiation is less favorable because of changes in supporting structures. Consider- ation must be given to (1) trismus, (2) fibrosis, (3) xerostomia, (4) hypogeusia, (5) radiation, (6) caries, (7) soft tissue fragility, and (8) osteoradionecrosis.

5. Corrective surgery may be indicated to improve function, comfort, and natural appearance for patients requiring maxillofacial prostheses.

6. All dental structures tha t may provide valuable retention and support of a maxillofacial prosthesis should be preserved.

7. Facial prostheses are indicated when no further reconstruc- tive plastic surgery is to be performed or when an immediate or provisional prosthesis is needed after resective surgery.

8. The ideal material for facial prostheses should be (1) biolog- ically compatible, (2) flexible, (3) translucent, (4) able to retain extrinsic and intrinsic color, (5) easy to clean, (6) lightweight, (7) durable, (8) color stable, (9) inexpensive, (10) easy to fabricate, and (11) finishable to a fine edge.

9. The palatal lift prosthesis is indicated for palatal incompetency. It elevates the middle segment of the soft palate to approximate the posterior and lateral walls of the pharynx.

10. A palatal lift prosthesis may increase the activity and range of motion of the incompetent soft palate.

11. A speech-aid prosthesis is indicated to correct a palatopha- ryngeal deficiency or incompetency when surgical repair is de- ferred or contraindicated.

12. An obturator feeding aid may assist in the normal feeding of an infant with a cleft palate. I t can be discontinued when the infant can eat normally without it.

13. Preparing a patient for an obturator prosthesis may require supportive dental treatment, including restorations for the remaining denti t ion of both dental arches to achieve proper support and retention of the prosthesis.

14. After a hemimandibulectomy including the condyle, the patient should be instructed in exercises, or the pat ient may have a mandibular resection prosthesis with a guide made to minimize mandibular deviation toward the resected side on closure.

15. The prognosis for edentulous mandibulectomy patients becomes less favorable as the size of the resection increases.

16. A prosthesis placed at the time of surgery can aid the patient 's immediate postoperative convalescence.

17. A surgical obturator is generally delivered during the surgical procedure for resection of the maxillae.

18. Certain oroantral and oronasal palatal defects require simple coverage by the prosthesis base; others need obturation by extension of the prosthesis base to enhance retention, stability, and support of the completed restoration.

19. To enlarge the contracted socket before an acceptable artificial eye can be constructed, a custom conformer prosthesis, which sequentially increases in size, may be required.

20. Until definitive surgery is performed, maxillofacial prostheses may be transitional restorations.

C. Design features and considerations 1. A maxillofacial prosthesis should be designed and fabricated

so tha t the residual anatomic structures will perform the functions of speech, respiration, mastication, and deglutition with minimal impediment.

2. Maximum tissue coverage supported by residual bone is desirable for maxillofacial prostheses.

JANUARY 1995 85


3. A surgical obturator prosthesis should be (1) lightweight, (2) strong, (3) easy to repair and alter, (4) easy for the patient to place and remove.

4. Sometimes the patient 's existing complete maxillary denture may be converted into an acceptable surgical obturator prosthesis.

5. The use of hollow extensions is indicated when the weight of the prosthesis will compromise retention and place undue stress on the surrounding tissues.

6. For added retention of the prosthesis, resilient, flexible materials tha t extend into desirable undercut areas of nasal or palatal cavities may be used.

7. To maintain prostheses during growth, development, and postsurgical healing, use of resilient or adaptive lining materials may be indicated.

8. The pharyngeal part of a speech-aid prosthesis should extend to the level of maximal muscle activity in the nasopharnyx. Nor- mally, this will be slightly above the anterior tubercle of the first cervical vertebra or on the palatal plane in the adult patient.

9. The palatal extension section can be made of a cast metal bar tha t traverses the soft palate anteroposteriorly and ends in a retention loop midway in the nasopharyngeal cavity.

10. Speech-aid prostheses should be fabricated in maxillary, palatal, and pharyngeal sections. Each section may require refitting and use by pat ient before succeeding sections are made.

1t. A facial prosthesis should be formed so tha t peripheral borders are thin, translucent, and blend with facial anatomy to con- ceal the edges of the prosthesis.

12. Use of the following auxiliary aids for retention of maxillofacial prostheses should be considered on an individual basis.

(a) Resilient material into the undercuts (b) Spectacle, frames (c) Intermaxillary springs (d) Sectional swivel hinges (e) Magnets (f) Implants (g) Adhesives

13. To obtain retention from the remaining abutment tooth, a mandibular resection prosthesis should include multiple retainers. When minimal retentive undercut areas are available, swinglock or faciolingual continuous retainers may be employed.

14. When possible, contours of facial prostheses should harmonize with the natural contralateral side and remaining areas of the face from full-face, superior, and inferior views.

15. Intrinsic t inting of the facial prosthesis within the tolerance of the material will provide the most stable color.

16. Unfavorable anatomic relationships may limit the degree to which satisfactory appearance can be realized in maxillofacial restorations.

17. Direct retainers for maxillofacial prostheses should have strong stabilizing characteristics and enhance retention on abutment teeth.

18. Orthodontic bands with buccal tubes or appropriately contoured crown preparations on permanent or deciduous teeth can be used to retain a maxillofacial prosthesis.

19. The auditory meatus of an auricular prosthesis should align with the natural auditory meatus to assure normal hearing.

20. An orbital prosthesis can be made for placement after orbital resection.

21. A surgical obturator prosthesis improves speech, mastication, and deglutition; it maintains skin graft packings in position, and it may improve pat ient morale.

22. Using acrylic resin artificial teeth for maxillofacial prostheses is usually advisable.

23. This holds true even though the long spans and extended denture bases tha t incorporate maxillofacial prostheses pose special design problems.

24. The basic principles of support, stability, and retention remain the same for long spans and extended denture bases as for conventional removable partial dentures.

D. Tooth a l t e ra t ions in enamel 1. In maxillofacial prosthetics, the following aspects are basi-

cally the same as for conventional removable partial dentures: (a) Recontouring enamel judiciously to improve esthetics (b) Preparing guide planes (c) Removing interferences (d) Preparing rest seats (e) Correcting occlusal disharmonies (f) Using methods to augment retention

2. In developmental deformities, tooth positions may be more aberrant than normal. They may require an overdenture design after coronal reduction and complete coping coverage have been completed.

3. Although the remaining teeth and alveolar bone are of greater relative value in the maxillofacial patient, motivation for plaque control and good oral hygiene is often less than desirable.

4. In situations involving chronic tissue abuse with lack of proper oral hygiene and routine dental care, the dentist should exercise caution in the use of tissue conditioner relines, particularly where they may contact highly sensitive respiratory mucosa.

E. Final impress ions 1. Impression procedures for extraoral and intraoral defects are

influenced by the character of the remaining tissues. 2. Impressions for diagnostic casts of maxillofacial prosthetic

patients may require recording structures not normally included in impressions for conventional prosthodontic patients.

3. Because of their drying and irritating effects on oral mucosa, metallic oxide and plaster impression materials are contraindicated for many irradiated patients.

4, A complete or sectional facial impression may be indicated for making an orbital prosthesis.

5. A sectional facial impression is acceptable in the fabrication of an auricular or nasal prosthesis.

6. The maxillofacial pat ient should be seated in a nearly upright position while the facial impression is being made.

7. Complete and sectional facial impressions may be made with irreversible hydrocolloid material supported with a plaster of paris backing.

8. The form and position of the pharyngeal section of any speech aid is determined by visual inspection, speech evaluation, and the patient 's response.

9. In making any speech-aid prosthesis, the nasopharynx impression should be made during speech, postural movements, and swallowing.

10. Usually, an impression material tha t can be physiologically molded is the best for making impressions of the nasopharyngeal regions.

11. Because the lateral wall and the scar band of the maxillary- resected patient are dynamic, functional impression materials, such as dental impression wax, may be needed for an improved border seal.

F. M a s t e r cas ts 1. Master casts for maxillofacial patients require the same con-

siderations and qualities as for removable partial denture casts. G. Framework try-in 1. Framework try-in and maxillomandibular recording proce-

dures are similar to those for removable partial dentures. 2. Making jaw relation records on large mobile record bases re-

quires additional care to avoid displacement of the record base during registration.

3. When jaw relation registrations are attempted, discontinuity defects of the mandible require special skills, methods, materials, and patience.

4. With the loss of mandibular continuity, some movements of

8 6 V O L U M E 73 N U M B E R 1


the remaining mandible can be recorded. Currently, no articulat- ing instrument is capable of accepting all these functional records and their aberrations.

5. Mandibular resections may hinder repeating centric relation position. Thus, an acceptable functional jaw record should have a consistent pat tern of duplicable relationships made without tension or force.

H. Wax try-in 1. Wax try-in procedures are similar to those for complete and

removable partial dentures. 2. Processed acrylic resin bases have value for early testing of

fit, comfort, retention, and stability of prostheses associated with maxillofacial defects.

3. Before final processing, a clay or wax sculpture with a properly aligned artificial eye should be used for trial fittings of an orbital prosthesis.

I. Occlusion 1. Changes in the tissues supporting a maxillofacial prosthesis

may be more rapid than in those supporting a more conventional prosthesis. Therefore, the occlusion and base adaptation must be reevaluated frequently. Corrections can be made by selective grinding of the occlusion or refitting the base of the prosthesis.

2. All occlusal pat terns in maxillofacial reconstructions must be physiologically compatible with the patient 's residual anatomic structures and functional capabilities.

3. Occlusal stress should be minimized for the irradiated patient requiring complete dentures. Acrylic resin teeth with a reduced occlusal contact area may be indicated.

4. Altering the cusp angle of posterior teeth may influence the stability of the prosthesis placed on an edentulous resected maxilla or mandible.

5. It may be necessary to accept an occlusion that is not bilaterally balanced in eccentric occluding positions for an edentulous resected maxilla or mandible.

6. When needed, occlusal ramps or platforms may be placed on the opposing maxillary prosthesis to direct the resected mandible into a more desirable maxillomandibular relationship.

J. Initial placement 1. Initial placement procedures are similar to those for remov-

able partial dentures. There should be special emphasis on pat ient education.

2. Placement of a surgical obturator prosthesis for maxillary resections may eliminate the need for or facilitate early removal of a nasogastric tube.

3. Placement of a surgical obturator prosthesis may help to shorten the patient 's hospital recovery period.

4. Extensions of the prosthesis should be evaluated and adjusted to acceptable positions.

K. Initial care after placement 1. After placement, the focus is on the care and cleaning of the

prosthesis and on maintaining the health of the remaining oral structures.

2. Speech therapy is often necessary after placement of any speech-aid prosthesis for a cleft palate patient.

3. Speech-aid prostheses for patients with soft palate defects may require adjustment in the size and contour of the pharyngeal section, because wearing the prosthesis may stimulate palatopha- ryngeal changes.

4. It may be necessary to place tissue-conditioning material in a newly placed prosthesis, before refitting with more permanent materials.

5. Rehabili tation of the maxillofacial pat ient after surgery may require speech assessment, psychosocial evaluations, physical therapy, and vocational guidance.

6. Patients with oral neoplasms often have a history of mouth ne- glect and poor oral hygiene. Preventive dentistry and education in good oral hygiene are necessary components of effective aftercare.

7. Facial prostheses require periodic replacement because of tissue changes and the unstable properties of available materials.

8. Adhesives used to retain facial prostheses should be (a) Nonirritating and nontoxic to the skin and mucous mem-

brane (b) Sufficiently flexible to move with surrounding tissues (c) Compatible with the material of the facial prosthesis and

the patient 's skin (d) Strong enough to retain the prosthesis (e) Easily cleaned from tissue and prosthesis (f) Stable (g) Incapable of supporting bacterial growth

9. Frequent reevaluation is necessary for maxillofacial patients because of possible rapid tissue and occlusal changes often associated with the use of unstable restorative materials.

10. Surgical orbturator prostheses provided for a maxillary resection must be relined periodically during the healing period to assure pat ient comfort and function.

V . C o m p l e t e d e n t u r e s A. Refining diagnostic procedures 1. Many signs of systemic disorders, such as diabetes or avita-

minosis, manifest themselves in mucosal structures; these may indicate the need for other therapy before prosthodontic treatment.

2. Nutritional guidance should be a part of t reatment for many complete denture patients.

3. Psychologic maladjustment may result from associating denture wearing with advancing age.

4. Patients with psychotic tendencies may use their maladjust- ments to dentures to avoid traumatic interpersonal situations with friends, relatives, and others.

5. Prosthodontic t reatment for patients who have had radiation therapy in or about the oral cavity should carefully take into ac- count time of radiation therapy, radiation methods, and radiation dosage.

6. Most irradiated patients can wear removable prostheses if the effects of radiation therapy are not severe and the patient fol- lows instructions for the use of the prosthesis.

7. The risk of osteoradionecrosis is greater in the mandible than in the maxillae.

8. Important physical criteria for establishing a prognosis are (1) evaluation of the patient 's arch form, (2) cross-sectional shape of the alveolar ridges, (3) retromylohyoid extensions, and (4) tongue position

9. Relief or alteration of the denture base to accommodate undercuts associated with root eminences of overdenture abutments may cause reduced retention, stability, and border seal.

10. Patients for whom overdentures are planned should be informed that overdentures may be less stable and retentive than fixed or removable partial dentures.

11. Endodontic t reatment of an overdenture abutment is usually required so tha t the tooth can be reduced sufficiently to allow placement of the artificial tooth esthetically.

12. Overdentures should only be considered if the patient can achieve and maintain satisfactory oral hygiene.

B. Design features and considerations 1. The space available for complete dentures is controlled in

part by the oral and circumoral structures surrounding the space and their movements in function.

2. Maximum coverage and intimate contact of the denture foundation area are essential for the support of a complete denture prosthesis.

3. The dentist should establish a posterior palatal seal for the maxillary complete denture either in the impression procedure or by proper alteration of the master cast.

4. The posterior palatal seal should extend bilaterally through the pterygomaxillary notch areas.

JANUARY 1995 87

THE J O U R N A L OF PROSTHETIC DENTISTRY ACADEMY OF PROSTHODONTICS

5. Palatal relief should not be routinely placed in the maxillary complete dentures.

6. Artificial anterior porcelain teeth should not be used with posterior artificial acrylic resin teeth, but anterior artificial acrylic resin teeth may be used with posterior artificial porcelain teeth.

7. Int imate tissue contact and border seal permit atmospheric pressure to serve as an important physical factor in complete denture retention.

8. Neuromuscular control contributes to complete denture re- tent ion and stability. I t becomes increasingly effective in the ex- perienced denture patient.

9. Optimum denture retention at denture placement can help the pat ient learn the neuromuscular control needed to use complete dentures effectively.

10. Anatomic regions tha t resist resorptive changes most effectively should be covered to promote long-term support and minimize changes in the relation of the denture to the maxillae or mandible. Horizontal portions of the hard palate, the retromolar pad, and the buccal shelf are examples of such areas.

11. In preparing overdenture abutments, it is important to reduce the crown-root ratio to prevent undue lateral stresses and to provide ample room for artificial teeth.

12. For overdentures, sufficient attached gingivae should be present around the abutments. The moving denture base should not impinge on or cause strangulation of the tissue of the free gingival margin.

13. The angle of emergence of the coping or a t tachment of an overdenture abutment tooth should be compatible with gingival health and hygiene maintenance.

14. Although retentive devices can enhance overdeuture retention, they may not be essential for successful pat ient care.

15. When available, canines are the most desirable teeth to support overdentures.

16. The clinical crown length of an overdenture abutment should be 2 to 3 mm above the proximal gingival margin to avoid migration of the gingival tissue.

17. For overdenture abutments, the tooth reduction on the labial or buccal surfaces should be sufficient to allow esthetic positioning of the artificial teeth.

18. Overdenture abutments aid in providing support and stability to a prosthesis.

19. Overdenture abutments provide a degree of tactile sense, which aids proprioception.

20. Overdenture abutments assist in preserving alveolar bone. C. Soft tissue management 1. Pat ients who are already using dentures should remove them

for a t ime before final impressions are made and before new dentures are placed.

2. Factors to consider in determining the length of time for complete tissue rest include (1) the patient 's age, (2) the condition of the supporting tissue, (3) the length of time the prosthesis has been worn continuously, and (4) the thickness of the mucoperios- teum.

3. Before impressions are made of tissues tha t have been supporting a removable prosthesis, the tissues should be returned to a physiologic status through tissue conditioning, massage, and/or complete rest.

4. Residual ridge resorption under complete dentures may alter occlusal relationships, which can further hasten ridge resorption.

5. For overdenture abutments, periodontal health should be established and maintained. Educating the pat ient in proper teeth and denture maintenance is important. Daily, the pat ient should clean the teeth under the denture and apply fluoride.

D. Impressions 1. There is a relationship between the requirements for an ad-

equate impression and the contemplated external form of the prosthesis. Before the impression procedure is started, a concept

of the completed denture border form should be developed. This is determined from the diagnostic cast and by visual and digital examination of the denture-bearing area, including the influence of the tongue on the level of the floor of the mouth.

2. A maxillary preliminary impression should completely fill the labial and buccal vestibules and extend posteriorly beyond the hard palate and into the pterygomaxillary notches. A preliminary mandibular impression should include the entire residual ridge and the retromolar pad, and extend lingually into the floor of the mouth including the retromylohoid fossa. The distobuccal extensions should include the external oblique ridges, and should approach the anterior borders of the rami.

3. Final impressions should record the entire denture foundation area to be covered by the denture base.

4. The fovae palatinae are anatomic landmarks. They can be used as one aid to determine the posterior limit of the maxillary denture.

5. The location of the junction of the movable and immovable soft palate is used to determine the posterior extension of a complete maxillary denture.

6. The curved borders of the labial, buccal, and lingual areas of final impressions represent the extension and contours to be reproduced in the processed prosthesis.

7. Areas of the impression tray tha t may exert excessive pressure on the denture foundation area should be determined and relieved before an impression is made.

8. Impressions of edentulous arches should record the form of healthy tissue at rest. They should extend to the physiologic limit of border tissues in order to maintain a border seal and to assure tha t functional stresses are distributed over the greatest area of support.

9. The complete denture final impression provides for intimate tissue contact and border seal of the denture base, excluding ingress of air between the denture base and soft tissue. These physical factors permit atmospheric pressure to serve as the primary physical factor in complete denture retention.

10. Selective pressure complete denture impressions permit the recording of certain anatomic regions with minimal pressure and other areas with mild pressure. This promotes less positive contact of the denture base with anatomic regions that are not ideal stress-bearing areas because of the friable nature of the mucosa or the susceptibility to pressure-induced resorption.

E. Casts 1. Complete denture impressions should be boxed before pour-

ing master casts. 2. Type II dental stone has adequate physical properties for

complete denture casts. 3. Complete denture casts should have a clearly defined land

a rea .

F. Record bases, occlusion rims, and m a x i l l o m a n d i b u l a r records

1. The incisal length of maxillary occlusion rims should be established after the desired contour of the facial surfaces has been set.

2. To prevent displacement of complete denture bases, it is particularly important tha t the centric relation record be made with a minimum of closing pressure.

3. Mechanical recording devices are more accurate when (a) Neuromuscular control is good (b) The residual ridges are ample (c) The soft tissues are not highly displaceable

4. Methods for recording maxillomandibular relationships include

(a) Interocclusal records (b) Mechanical devices (c) Chew-in techniques (d) Cephalometric radiographs



5. Recording centric relation at the correct vertical dimension of occlusion is one of the most important factors in complete denture construction.

6. Centric relation is a desirable position to record and transfer to an articulator during the fabrication of complete dentures.

7. Centric relation should be recorded at the correct vertical dimension of occlusion unless casts ar e mounted on the transverse horizontal hinge axis on an appropriate articulator.

8. Before the centric relation record is made, the vertical dimension of occlusion usually should be established.

9. Centric relation records should be verified regardless of the posterior tooth form tha t is used.

10. A face-bow is important when any change in the vertical dimension of occlusion is anticipated during therapy. Such changes in vertical dimension include

(a) Compensation for interocclusal record thickness (b) Excursive movements when cusped teeth are used (c) Alterations in the vertical dimension of occlusion, includ-

ing occlusal adjustment 11. In determining posterior reference points for a face-bow

record, an anatomic average transverse horizontal axis is generally acceptable for tissue- or tooth-tissue-supported prostheses.

G. Complete denture occlusion 1. To prevent deflective occlusal contacts, the cuspal inclines of

artificial teeth may require selective alteration. 2. A universally accepted concept of articulation and occlusal

form for complete dentures has yet to be scientifically established. Several concepts for eccentric occlusal relationships may be used with success.

3. A reduction in the vertical dimension of occlusion as a result of either a loss of supporting tissues or wear of teeth shifts the mandibular jaw position and occlusion anteriorly.

4. The vertical and horizontal jaw relations of natural teeth should be evaluated before immediate denture service is initiated.

5. When a vertical overlap of anterior teeth is necessary, sufficient horizontal overlap is desirable to prevent tooth interference during speaking and masticating.

6. The occlusal plane should be located according to mechanical requirements for (1) denture stability, (2) efficient mastication, (3) preservation of supporting structures, (4) anatomic landmarks, (5) esthetics, and (6) phonetics.

7. The stability of the denture bases supporting artificial teeth is important in maintaining a previously created balanced articulation.

8. Bilateral eccentric contact can be developed with anatomic or nonanatomic posterior teeth.

9. To evaluate changes in occlusion caused by processing, complete dentures may be returned to the articulator before removal from the cast.

10. Incorrect vertical dimension of occlusion increases the po~ tential for bone resorption beneath immediate or conventional complete dentures.

11. Malocclusion increases the potential for ridge resorption in the prosthodontically restored edentulous patient.

12. Occlusal discrepancies may result from the dimensional changes of materials used to process resin dentures.

13. Malocclusion often occurs after residual ridge resorption: Complete dentures should not be relined until such malocclusion has been corrected.

14. Proper use of a semiadjustable articulator is advantageous in complete denture construction.

15. An adequate occlusal scheme can be developed for complete dentures on a sere:adjustable articulator.

16. Before single complete dentures are made, the opposing natural teeth should be restored or recontoured to favorable occlusal form.

It. Try-in and verification procedures 1. Any t reatment sequence for complete dentures should in-

clude a try-in of artificial teeth with stable denture bases to evaluate the vertical and horizontal maxillomandibular relationships, esthetics, and phonetics. The pat ient and, when possible, a family member or friend should participate in the evaluation.

2. Assessing the correct vertical dimension of occlusion before all of the teeth are arranged on the denture base is difficult.

3. Enunciation is diagnostically more accurate with trial dentures than with wax rims.

4. Aging, physical limitations, previous dental history, and lack of neuromuscular coordination may combine to render impossible the absolute verification of maxillomandibular relationships.

5. Verifying accuracy of the vertical dimension of occlusion should follow verification of centric relation and securing eccentric records.

6. After the try-in appointment, teeth should be repositioned for optimal contacts in the centric relation and eccentric positions. The dentist should take care not to alter the appearance of the dentures.

I. Complete denture mater ials 1. To minimize distortion, previously processed acrylic resin

denture bases should not be heated above 165 ~ F. 2. Processed resilient denture base materials may be of value for

patients demonstrating persistent soreness and inability to wear well-constructed dentures with hard resin bases.

3. Using porcelain teeth in complete dentures tha t oppose natural teeth or gold restorations may cause undesirable wear of the opposing teeth.

4. The dentist should understand the role of various denture base materials and their influence on supporting tissues.

J. Esthetic considerations 1. In the arch, the relationship of artificial teeth to each other

affects the apparent size and color of individual teeth. Placing a tooth more anterior in the arch creates an illusion of a lighter shade and larger tooth. Placing the tooth more posterior in the arch creates an illusion of a darker shade and a smaller tooth.

2. The level of the occlusal plane in the mandibular premolar area is usually at or slightly below the commissure of the lips.

3. Posterior teeth of a natural-appearing length should be used whenever the interridge distance permits.

4. A common defect in facial appearance results from positioning the maxillary anterior artificial teeth too far palatally.

K. Init ial placement 1. To correct occlusal discrepancies after initial adjustment of

the dentures ' tissue surface, complete dentures should be re~ mounted to a semiadjustable or a fully adjustable articulator.

2. Mounting the completed restoration in an articulator with a proven interocclusal record is an accurate method of developing final mandibular position and occlusion. It is more accurate than intraoral occlusal correction.

3. During the initial placement of complete dentures, the dentist should evaluate (1) border extensions, (2) border seal, (3) retention, and (4) esthetic values.

Areas where the denture exerts excessive pressure on the denture foundation area should be located and relieved.

4. When porcelain teeth have been ground during occlusal adjustment, their surfaces should be polished.

5. At the initial placement appointment, previous educational efforts should be reinforced. The patient should receive verbal and/or written instructions regarding the wearing and care of dentures and cleansing procedures for the supporting tissues.

6. To maintain good tissue health, complete dentures should be removed from the mouth for several hours during each 24-hour period. The patient may prefer to leave dentures out during sleep.

7. For future reference, a record of the vertical dimension of occlusion should be made at initial denture placement.

JANUARY 1995 8 9


8. Patients should not be given removable restorations before occlusal discrepancies are eliminated.

9. Instructions to overdenture patients must emphasize meticulous daily cleansing of retained overdenture abutment teeth and the importance of using nonacidulated fluoride daffy in the denture over abutment teeth.

L. Care after placement 1. During the early wearing period of processed resin dentures,

some adjustments of the tissue surfaces should be expected. 2. Complete denture t reatment should include provision for

adjustment appointments after initial placement of the dentures. 3. Complete denture patients should be examined at least an-

nually to determine the health of oral tissues and condition of dentures. The importance of these factors should be stressed to each patient.

4. Pat ients should be advised and reminded tha t complete dentures require periodic adjustment and eventually will require modification, which may include relining or remaking to main ta in proper tissue adaptation and occlusion.

5. When dentures are initially placed, and at subsequent appointments, the dentist should emphasize adequate hygiene maintenance of both the mucosa and the dentures.

6. Dietary recommendations for the patient during the adjustment period are advisable.

7. The form of the denture-bearing area for complete dentures continues to change throughout life.

8. Residual ridge resorption under complete dentures causes malocclusion.

9. Pat ients should receive a careful explanation of the possible deleterious effects of a complete maxillary denture opposed by mandibular anterior natural teeth and a distal-extension removable partial denture. The need for frequent examination, continuing t rea tment when necessary, and removal of both dentures while sleeping should be emphasized.

10. The proper relining of complete dentures requires skill and meticulous care.

11. Altering the vertical dimension of occlusion should not occur during relining unless it is required to restore proper vertical dimension.

12. Relining complete dentures must include restoring proper occlusion. This may require a clinical remount procedure after the reline and before the denture is seated.

13. The overdenture pat ient must be seen for regular, frequent recalls to reevaluate and reinforce oral hygiene practices, correct any new or recurrent periodontal problems, restore carious lesions, and adjust the denture adaptation to the teeth and tissues.

M. Immedia te and interim restorations 1. For introducing patients to complete dentures, immediate or

transitional dentures are the desired method of treatment. They should be constructed only after the patient has been informed of the requirements of immediate denture service. Where indicated, an interim or transitional partial denture may facilitate the patient 's adjustment to complete dentures.

2. Properly constructed and adjusted immediate dentures aid the healing response of the denture-bearing tissues.

3. When teeth are extracted for placement of immediate dentures, unnecessary bone removal should be avoided.

4. Immediate denture t rea tment is time-consuming and exact- ing.

5. After the immediate denture has been placed, the pat ient should re turn to the dental office at stated intervals so tha t border extensions, occlusion, and tissue irritation can be evaluated and needed corrections can be made.

6. The immediate denture or one that has been constructed soon after extraction of the remaining teeth mus t be maintained with additions and subtractions for the entire healing period. Eventually, relining, rebasing, or denture refabrication will be necessary.

7. Before definitive relining or secondary denture treatment, the use of successive temporary relines for immediate complete dentures is recommended. During the healing period, they maintain (1) support, (2) stability, (3) comfort, and (4) function.

8. When duplication of the arrangement of natural teeth is desirable, the teeth should be removed from the cast one at a time so that the remaining adjacent and contralateral teeth serve as guides for positioning each artificial tooth.

9. The vertical and horizontal jaw relations established by the natural teeth should be evaluated before implemention of immediate denture service.

10. Because swelling and edema follow placement of immediate dentures, malocclusion should be corrected after swelling and edema have subsided.

11. In the interim immediate denture procedure, all remaining teeth are usually extracted at denture placement.

12. An interim complete denture used during the healing period has several advantages over the conventional immediate denture:

(a) Final impressions and jaw relation records for definitive dentures are performed after healing.

(b) A wax try-in is possible for the definitive denture. (c) The pat ient can retain the interim denture to serve in an

emergency. 13. An interim prosthesis may need to be relined or remade

shortly after placement to compensate for changes in the denture foundation area.

14. In immediate denture t reatment , the use of interim dentures for initial placement and during the healing period is recommended. Better quality secondary dentures can be constructed on completely healed supporting tissues.

15. Prior to beginning fabrication of a conventional immediate denture, all posterior teeth are extracted except those necessary to provide occlusal contacts adequate to maintain interarch distance.

16. A t ransparent surgical template may be used as a guide to the amount of surgery required during placement of immediate dentures.

VL Implant res torat ions A. Diagnostic information 1. The clinical evaluation of a pat ient requiring implant prosth-

odontic t rea tment should include dental, medical, and surgical histories. Speech and psychologic testing may also be needed.

2. Unrealistic expectations may affect the prognosis in implant patients.

3. Radiographic examination may require intraoral, panoramic, cephalometric, and tomographic imaging techniques.

4. Age does not appear to be a factor in the success of dental implants.

B. Diagnosis 1. Need for an implant-supported prosthesis should be estab-

lished as an alternative to conventional denture therapy. 2. Patients to be treated for endosseous dental implants should

have diagnostic casts articulated with a trial arrangement of artificial teeth on trial denture bases. A presurgical prosthodontic evaluation analysis is essential for site, number, and position of the implants.

3. The type of implant for use in a patient must be selected relative to the quality and quanti ty of osseous tissue available to support the implant.

4. An analysis should be made of attached and nonat tached gingiva surrounding implant sites and consideration should be given to the adequacy of attached gingiva at the permucosal site of implant posts.

5. Prosthodontic t reatment must be planned before implant surgery.

C. Prognosis 1. The pat ient should be informed of benefits, risks, time, cost

of treatment, and alternative treatments.



2. Meticulous sterile surgical techniques are essential to the initial and long-term success of any dental implant system.

3. Alveolar bone surrounding osseointegrated implants has the potential to maintain slower resorptive patterns than alveolar bone supporting conventional tissue-borne prostheses.

4. Replacement teeth should not be arranged for appearance in a position tha t could cause an unfavorable force distribution and compromise oral hygiene.

5. Future health changes could change the prognosis for sur- vival of an implant restoration.

19. P r e r e s t o r a t i v e t r e a t m e n t 1. The oral structures, dentulous or edentulous, should be in a

state of optimal health. 2. Any systemic disorder must be recognized and evaluated rel-

ative to dental implant success. 3. Before proceeding with treatment, pat ient response to edu-

cational efforts should be assessed. 4. If an interdisciplinary team provides treatment, one mem-

b e r - u s u a l l y the restorative dent i s t - -mus t supervise and direct treatment.

E. P r o s t h o d o n t i c t r e a t m e n t 1. Dental implants may be classified as subperiosteal, endo-

dontic, endossteal, transosteal, intramucosal inserts, supraperi- osteal or subperiosteal augmentation.

2. Fixed, removable, fixed-removable, and overdenture prostheses can be used with dental implants. The prosthesis must match the implant capabilities.

3. Casts for diagnosis and/or custom implant design and fabrication may be obtained by the following means

(a) Conventional intraoral impressions (b) Surgical degloving followed by a bone impression (c) Computerized axial tomography to produce a computer-

generated model 4. Direct impressions of the alveolar bone must be made with

nonirritating materials. All particles of impression material must be removed from the bone surface and tissue after removal of the impression.

5. A totally implant-supported prosthesis does not depend on soft tissue for support. The impression needs only extend to regions necessary for landmark identification.

6. An implant- and tissue-supported prosthesis uses soft tissue areas for support. Therefore, an impression should be made according to accepted principles for optimal support, extension, and stability for tissue-borne prostheses.

7. I t is the dentist 's responsibility to design the implant- supported restoration.

8. An immobile occlusal record base facilitates obtaining accurate and verifiable maxillomandibular relation records.

9. Fixed, fixed-removable, removable partial, removable complete dentures, and overdentures in implant dentistry have varied occlusal requirements. Occlusion should be developed to reflect the prosthodontic capabilities of the dentist, the available support, and the needs of the patient.

10. Occlusal pat terns tha t direct forces to the regions selected for stress distribution should be developed.

11. All implant-supported restorations should seat passively over implant abutments.

12. Overdentures supported completely by implants may not require border extensions or palatal coverage to the same extent as conventional complete dentures.

13. The pat ient must be informed of the need for continued regular maintenance.

14. Diligent home care is necessary with periodic professional maintenance.

F. M a t e r i a l s a n d dev ices 1. When planning the prosthesis, the dentist should be aware of

the implant type, number, design, and stress distribution to the surrounding tissues.

2. Materials and techniques must be biocompatible. G. I n t e r i m r e s t o r a t i o n s 1. Immediate restorations on endosseous implants may or may

not be placed depending on the style of implant and philosophy of use.

2. Interim restorations may consist of removable complete dentures, removable partial dentures, or fixed prostheses depending on the implant supported and the system used.

3. Interim dentures for patients with osseointegrated dental implants should be periodically relined with soft lining material during the healing period to prevent t rauma to the implant sites.

M A T E R I A L S A N D D E V I C E S L A r t i c u l a t o r s 1, An articulator is a mechanical device that represents tem-

poromandibular joints and jaw members. Maxillary and mandibular casts may be attached to articulators. Some or all mandibular movements may be simulated.

2, The ideal articulator should be capable of reproducing all the patient 's jaw movements during function and parafunction. It should maintain the mounted relationship of the opposing casts.

3. The use of an articulator is essential in most types of prosthodontic care.

4. An articulator is no more accurate in reproducing mandibular movements than the records used to adjust the instrument.

5. Articulator types can be classified as simple hinge, average value, sere:adjustable, fully adjustable, and fossae molded:

6. Simple hinge articulators can be accurate in centric occlusion when casts are mounted at the correct vertical dimension of occlusion. Eccentric positions cannot be reproduced. Changes in the vertical dimension of occlusion accomplished on the articulator invalidate the centric occlusion.

7. Average value articulators have the same limitations as simple hinge articulators. However, they will permit minor changes in vertical dimension of occlusion if a transverse horizontal-axis face-bow is accepted by the articulator and utilized. Eccentric positions only approximate the patient 's eccentric positions.

8. Semiadjustable articulators used with a kinematic face-bow and eccentric records allow (1) centric relation records to be mounted at an increased vertical dimension; (2) minor changes in vertical dimension; and (3) closer approximation of the pat ient 's mandibular movement at the end points of eccentric movement than when an average value articulator is used.

9. When provided with the proper kinematic records and pro- gramming, a fully adjustable articulator or fossae molded articulator will encompass all of the features of the semiadjustable articulator. It will also closely approximate the patient 's mandibular movement on all points along its eccentric movements.

10. Casts mounted in an articulator provide important data to analyze, diagnose, and plan treatment.

11. Verification of the relationship of the casts mounted in the articulator is a prerequisite to developing accurate occlusal contacts of completed restorations.

12. The adjustable guidances of an articulator should permit alteration to harmonize with the recorded and/or anticipated mandibular movements.

13. The anterior guide of an articulator should be adjustable and/or have a provision for custom guide fabrication.

14. A face-bow record should be used for mounting the maxillary cast on an articulator that will accept an axis transfer.

15. Before a prosthesis is finalized or luted in place, an occlusal scheme developed on any articulator should be clinically evaluated in the mouth.

16. When extensive fixed occlusal restorations are planned, a fully adjustable articulator or technique giving equivalent accuracy is desirable.

17. The dentist should know the limitations of the articulator being used and how to compensate for them.

JANUARY 1995 91


18. A third point of reference is important in a face-bow transfer because it

(a) Permits subsequent remounts of the maxillary cast in the same position

(b) Permits use of previously recorded condylar path settings (c) Allows the maxillary cast to be oriented in the articulator

in the same relation to the horizontal axis as the maxillary arch is to a Similar plane selected on the pat ient

(d) Permits the application of anatomic average values as condylar path settings when such settings are adequate

INTE R I M R E S T O R A T I O N S 1. An interim restoration is a dental prosthesis used for a short

interval for esthetics, mastication, occlusal support, convenience, or to condition the pat ient to accept definitive prosthodontic therapy.

2. Some temporomandibnlar joint symptoms may be alleviated by properly constructed interim restorations.

3. Tissue-conditioning materials placed on the tissue surface of surgical prostheses can compensate for tissue changes after surgery.

4. Transitional removable partial dentures may be used to facilitate osseous healing and to help maintain the vertical dimension of occlusion after posterior teeth have been removed.

5. Interim restorations may be desirable before placement of endosseous implants

(a) To maintain function and appearance during the postsurgical healing phase

(b) To aid in presurgical planning of the location and angu- lation of implants

6. Interim restorations should be used in fixed prosthodontics when the vertical dimension must be restored and dental esthetic requirements determined.

7. An interim prosthesis may be constructed to aid in stabilizing the dentit ion during periodontal treatment.

8. Interim restorations should meet all restoration guidelines for periodontal health, esthetics, and function. They should stabi- lize the occlusion and position of the remaining teeth. Where lost vertical dimension of occlusion is to be restored, the interim restoration can verify this occlusal dimension so it can be restored in harmony with oral facial function.

A U X I L I A R Y P E R S O N N E L , WORK AUTHORIZATION, AND LABORATORY UTILIZATION

A. Auxi l iary personnel 1. Clear, concise communication among all members of the

dental health team enhances the quality of the dental service tha t a pat ient receives.

2. Auxiliary personnel may help the dentist obtain diagnostic information for t reatment planning purposes.

3. Delegating specific procedures to qualified auxiliaries is acceptable where legally permissible. However, the dentist is responsible for t reatment within the framework of liability established by the governing jurisdiction.

4. The dentist is responsible for the quality of the completed prosthesis even when parts of the fabrication are delegated to a dental laboratory.

5. The dental technician is a valuable member of the prosthodontic team. Communication between the technician and the dentist enhances patient 's treatment.

6. To improve the quality of the finished restorations, the dental technician's skills and training should be recognized and properly used as an adjunct.

7. The dentist is required to use auxiliary personnel in compli- ance with state dental practices.

8. The dentist should be in the office when auxiliary personnel perform intraoral procedures as permit ted by state laws.

9. The dentist should recognize special needs of patients and, when necessary, refer them to qualified specialists for treatment.

10. Cooperation and communication between the dentist and the oral and maxillofacial surgeon is essential for preprosthetic surgery procedures.

11. Prosthodontists, dental assistants, and dental technicians should prevent contagious disease contact and transmission. They should be immunized. Instruments, impressions, and casts should be sterilized; environmental surfaces should be disinfected. Gloves, protective ey e wear, and facemasks should be used.

12. When indicated, a dentist, physician, or nutritionist should provide the patient with nutritional advice.

B. Specific to maxillofacial prosthet ics 1. A prosthetist, under the supervision of a prosthodontist, may

make facial prostheses in contact with the patient. C. With authorization and laboratory utilization 1. A properly executed work authorization can be an effective

way for the dentist to communicate with the dental laboratory technician.

2. All work delegated to a commercial dental laboratory should be accompanied by a detailed written work authorization that complies with the applicable state dental laws.

3. The dentist 's specific work authorization is essential to quality control during the laboratory phase of making prostheses.

4. The dentist should provide a completed work authorization form tha t states the specifications of materials tha t will best meet the needs of the patient. When artificial teeth are involved, the specification should include manufacturer, material, shade, mold, and design.

5. Accurate interocclusal records are essential to mount casts properly in an articulator. Accurate interocclusal records are the dentist 's responsibility.

6. The dentist must provide the laboratory with adequate diagnostic casts, mounted casts or (as a minimum) complete-arch casts with a stable interocclusal record. Master casts should have dies t r immed and finish lines marked by the dentist.

7. Removable prostheses should be returned to the dentist for wax trial evaluation before they are completed.

8. The dentist is responsible for selection and final position of artificial teeth.

9. The flasking of a removable prosthesis in artificial stone or other suitable material should be done in sections to facilitate separation of the prosthesis from the investment material.

10. When a fixed restoration is to be placed in conjunction with a removable partial denture, the design of both should be coordi- nated by designing the restorations with the use of a diagnostic cast.

11. The dentist should request tha t the metal ceramic framework be waxed to full contour as directed by diagnostic waxing and be cut back to allow proper veneering control.

12. Whenever the cast metal portion of any prosthesis is com- plicated, a framework try-in should be requested. Framework try- ins of extensive ceramic restorations should be routine.

13. Direct dentist-technician communication is necessary in working with ceramic restorations. An appropriate method of communication should be used to facilitate final shading and staining.

LEGAL C O N S I D E R A T I O N S A. Basic to all prosthodontics 1. The laws of each jurisdiction are different and, although this

is written with generic law in mind, laws tha t apply to specific jurisdictions may be obtained from a local attorney.

B. The dentist-patient relationship 1. Contract law governs the relationship of the dentist and the

patient. 2. A contract is an agreement between competent parties to

perform, or not to perform, some legal act.



3. Except in special situations, usually not related to the dentist-patient relationship, the terms of a contract need not be in

writing to be enforceable. 4. The written contract serves as evidence that an agreement

between the parties was reached. 5. The terms of a contract may be expressed or implied. 6. Usually expressed terms include

(a) The fee

(b) Nature of the treatment to be performed (c) Time in which the treatment is to be completed (d) Payment arrangements (e) Other specific items)

7. There are many additional implied terms (duties) that attach to the doctor-patient relationship.

8. In jurisdictions in which cases have attempted to attach implied warranties of fit and satisfaction, the courts have ruled against such warranty.

9. The courts have consistently held that the fee paid for the fabrication of a prosthesis is for the service required to complete it and not for the physical prosthesis. However, guarantees m a d e

by the dentist would constitute an express term in the contract. 10. Unwarranted claims about the outcome of care that could be

interpreted as guarantees are unethical and in some jurisdictions illegal.

11. Guarantees may result in loss of a suit based upon breach of contract rather than on malpractice.

12. In a breach of contract suit, negligence need not be shown. 13. In many jurisdictions, unless the care provider makes an

express guarantee, breach of contract suits brought against health providers are held to the same rules of law as suits of malpractice.

14. Many suits alleging malpractice are initiated because the dentist brought an action against the patient to collect the fee.

15. There are times when a patient, dissatisfied with the service, demands the return of the fee, in part or in whole, paid to the dentist. Failure to comply with the patient's request may result in the patient initiating a suit against the dentist. To avoid such an event, the dentist may elect to comply with the demand. However, before any of the fee is returned, the dentist should require the patient to sign a waiver of claims for prior acts. The waiver effectively protects the dentist from a suit brought based on services provided before the waiver was executed.

C. The s t a n d a r d of care 1. In malpractice cases, the standard of care to which courts

hold dentists requires that they use the same degree of knowledge, education, and training that a reasonably prudent dentist would provide in the same or similar community.

2. Dentists who hold themselves out as specialists are generally held to the standard of care of other specialists in the same field. Thus, generalists who provide the same service are held to a lesser standard of care. This double standard to which practitioners in the community are held is the trend in many jurisdictions. In effect, there is a move by the courts to apply a national standard of care to board certified specialists.

3. In general, because of rules of evidence, it is difficult to use texts, guidelines of professional organizations, or what is taught in a dental school as a means of establishing the standard to which a defendant dentist will be held.

4. Consistent with the definition of the standard of care, specialists usually are held to the standards of other specialists, and general practitioners are usually held to the standards of other general practitioners.

5. If one holds oneself as a specialist, although a generalist, the courts are likely to apply the standards of a specialist.

6. Another risk for the generalist (depending on the quality of treatment provided) is that if it can be shown that other generalists in the same community would have referred the patient to a specialist, not having made the referral could constitute negligence.

7. Generally, it is desirable to limit treatment to aspects of dentistry in which the dentist is qualified and competent. Dentists should make appropriate referrals on a timely basis, and maintain their skills and knowledge consistent with advances in their field of practice.

D. Consent 1. It is firmly established that a doctor who treats a patient

without informed consent may be liable for damages, even if the treatment benefitted the patient.

2. In the landmark case of Canterbury vs. Spence, decided in 1972, the court indicated that consent must be informed to be valid. Guidelines were established by which to judge whether the consent was truly informed.

3. During the past decade, most courts have adopted the Can- terbury view, either in whole or in part.

4. The question that remains is: How much must the patient be told for the consent to meet the test of being informed? The states are divided on this issue. The traditional standard of informed consent determines by expert testimony what other practitioners in the same community disclose to their patients when faced with a similar treatment. The defendant practitioner is held to that measure of disclosure.

5. Another standard of informed consent is the "the professional community." There are two divergent views expressed by the courts using this standard: the objective test and the subjective test. In the former, the measure is: How much would any reasonable person have to be told to make an intelligent decision? In the latter: How much should the specific patient be told?

6. Much of the problem of informed consent centers around disclosure of risks.

7. In jurisdictions that adhere to the reasonable person standard, the general rule is that risks that are "material" should be disclosed.

8. A material risk is defined as one that may influence the patient's decision.

9. A legislature may adopt any option to define informed consent. As an example, New York, by statute, chose the professional community standard.

10. Many courts have distinguished between total lack of consent and inadequate disclosure in obtaining consent. The former may be considered assault and battery. In the latter, the dentist is negligent for failing to obtain informed consent.

11. In an emergency, where immediate care must be provided to protect the health or life of an injured person, and where consent could not be obtained, consent is implied by law.

12. Documentation of consent, if it was obtained, plays a major role in the outcome of a legal procedure.

13. The documentation that consent was obtained depends on the mode of practice by the dentist.

14. In general, the more invasive the procedure and the greater risk to the patient, the more documentation becomes important.

15. Consent may range from a note made on the patient's record to a note made on the record initialed by the patient. Consent may also be obtained by having the patient sign a separate form. A s igned copy is placed in the patient 's record folder.

16. The dentist must weigh the legal risks against the resources of the practice in time, personnel, and effort in documenting that consent was granted.

17. When faced with decisions to which risks may be attached, the practitioner should, before any action is taken, make an "informed decision." Elements that enter into the decision-making process should include legal issues, ethical issues, and the benefits and risks to the patient.

E. P a t i e n t records 1. In some jurisdictions, the law requires that accurate records

of the diagnosis and patient treatment be maintained as part of care.

JANUARY 1995 93


2. In the eyes of the law, good records are as important in patient care as the diagnosis and treatment.

3. Failure to keep accurate records may result in penalties im- posed by the state

(a) If the requirement to maintain records is mandated by law

(b) If there is a negligence finding by a court in a civil suit brought by a patient

(c) If a malpractice suit is lost because the defendant-dentist was unable to document the care provided

4. Entries on the patient 's treatment record may become pub- lic information. The dentist should keep in mind that the record may eventually be seen and subject to review by the patient's attorney, a judge, and a jury.

5. If the records are required for the defense of an allegation of malpractice, they should be kept indefinitely for complete protec- tion.

6. A reasonable rule of thumb is to retain records of adults for 10 years after the last treatment visit.

7. In the case of minors, the records should be kept for 10 years after they reach majority.

8. Except when acting under the order of court, the dentist should never part with the original record, radiographs, consultation reports, or any other document relating to care of a patient.

9. Entries in the record should be made in black ink or ballpoint pen.

10. Entries should be initialed or signed in offices where more than one person is permitted to write on patients' records.

11. Errors should not be blocked out so they cannot be read. 12. A single line should be drawn through the error and the word

error written above. The correction should be made on the next available line.

13. What does not belong on the patient's record is sometimes as important as what should be on it. Subjective notes about the patient's mental state should be avoided.

14. In many jurisdictions, the patient may have access to dental records. Dentists who are sued should not note on the treatment record conversations with any attorney or insurance company representatives. Such notes should be placed in a separate file.

15. If an attorney request the records of a patient, the dentist, before complying, should make certain that the attorney includes in the demand a properly executed release signed by the patient.

16. It is best not to include financial information on the treatment record. Such data should be kept separately.

17. The den t i s t should never t a m p e r wi th the records. Fraud m a y be suspec ted i f t r e a t m e n t records appear to have been tam- pered with.

18. The patient's record is a legal document. F. Associates and employees 1. In partnership practice, each innocent partner may be held

accountable for the negligent act of any other partner. When one or more dentists appear to be partners, although they are not, they may be treated by the courts as if they were partners and may be held jointly or severally liable for the negligent act of one.

2. Corporate practice usually relieves an innocent shareholder from liability for the negligent acts of other shareholders. Only the negligent individual and the corporation may be held liable. Treatment that has begun must be completed.

3. An employer is liable to an injured party for the negligent acts of an employee.

4. A dentist 's employee becomes the dentist 's agent in dealing with patients.

5. When a hygienist, assistant, or secretary-receptionist makes assurances to a patient regarding the treatment to be provided by the employer-dentist, the dentist is bound by such assurances.

6. Employees should be informed of the responsibilities that flow from their relationship with their employer and cautioned about statements made to patients.

G. Managing difficult situations and issues of abandonment

1. There are situations in which discontinuing treatment is the only reasonable alternative to predictable failure in care, for example, when the patient fails to

(a) Cooperate in the care (b) Keep appointments (c) Live up to financial agreements

If the dentist cannot function effectively under such circumstances, the patient should be so informed.

2. To avoid being found guilty of abandonment, the courts have provided health practitioners with the following guidelines:

(a) Treatment should not be discontinued when the health of the patient is placed at risk.

(b) The patient should be given adequate time to secure the services of a substitute dentist.

(c) The patient must be assured that you will cooperate with the substitute dentist in the care of the patient.

(d) Copies of all records and radiographs relating to the patient's treatment should be made available to the substitute dentist upon request.

3. In notifying the patient of an intention to discontinue treatment, it should be remembered that it is in the patient's best in- terest and that the patient should be advised to seek the services of another dentist.

4. After telling the patient of a decision to discontinue treatment, the dentists should send a certified letter with return receipt requested. The letter should state what the patient was told and assure cooperation with the substitute dentist.

5. It is best to let the patient select the new dentist.

R E F E R E N C E S

1. The Academy of Denture Prosthetics. Principles, concepts, and practices in prosthodontics. J PROSTHET DENT 1959;9:528-38.



4. The Academy of Denture Prosthetics. Principles, concepts, and practices in prosthodontics--1967. J PROSTHET DENT 1968;19:180-98.




8. The Academy of Denture Prosthetics. Glossary of prosthodontic terms. J PROSTHET DENT 1994;71:41-112.

R E P R I N T S Reprints of the eighth edition of the Principles, Concepts, and

Practices in Prosthodontics are available from the Education and Research Foundation of Prosthodontics. Send to Dr. Clifford Van Blarcom, 5350 West 94th Terrace, Suite 205, Prairie Village, KS 66207-2572.


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