New paradigms in prosthodontic treatment planning: A literature review

Benedict Rich, DDS,a and Gary R. Goldstein, DDSb

College of Dentistry, New York University, New York, N.Y.

New treatment modalities have expanded the choices available to prosthodontists and their patients. Atthe same time, an explosion of data has called into question the validity and efficacy of certain forms oftraditional prosthodontic treatment. Together, these factors have greatly complicated the treatment-planning process. The purpose of this article is to provide a framework for the prosthodontic treat-ment-planning process that incorporates the latest evidence-based information available. A review ofthe literature was undertaken through a Medline search. Articles published in English from 1975through 2001 were evaluated; selected articles were chosen for review on the basis of a subjective judg-ment of their relevancy and significance to the clinician. (J Prosthet Dent 2002;88:208-14.)

It has become predictably possible to replace virtuallyany and all missing teeth and supporting oral structures.Sinuses can be filled,1,2 bone can be induced to grow,3-6

and gingiva can be grafted or expanded to provide softtissues where needed.7,8 Implants9 and a great variety ofabutments10 are available to lend support to a medley ofprosthetic solutions. Adhesive dentistry has expandedtreatment options with stronger, longer-lasting materi-als that include both resins and porcelains.11-14 Thesedevelopments have not only broadened the ability totreat disease but also have given dentists the ability toenhance the esthetic appearance of teeth.15 These newtechniques and data have also vastly complicated thetreatment-planning process.16

Concurrently with the development of these newmodalities, researchers have produced information indi-cating that certain forms of traditional treatment maynot be necessary. In the beginning, the dental professiontreated disease or at least what was believed to be dis-ease. In general, there usually was one accepted treat-ment approach for any single condition. Now there aremany possibilities from which to choose, including non-treatment, which in many situations is a reasonable ap-proach.

This article provides a framework for the prosthodon-tic treatment-planning process that incorporates the lat-est evidence-based information available. A review of theliterature was conducted through Medline. Articlespublished in English from 1975 through 2001 wereevaluated; selected articles were chosen for review on thebasis of a subjective judgment of their relevancy andsignificance to the clinician.

LITERATURE REVIEW

The purpose of prosthodontic treatment is varied.According to DeVan,17 the first goal is to stop the pro-

gression of disease and maintain existing structures.DeVan stated that “The patient’s fundamental need isthe continued preservation of what remains of his chew-ing apparatus rather than the meticulous restoration ofwhat is missing, since what is lost is in a sense irretriev-ably lost.”17 The 2 diseases responsible for most lostteeth are dental caries and periodontal disease.18-21

Complete or partial edentulism that is not the result oftrauma or congenital malformation is not a disease, perse, but the sequel of disease left unchecked. Accordingto some authors, a second purpose of prosthodontictreatment is to restore a patient’s function and quality oflife.22-25 There are now good data to indicate that withregard to these 2 factors, patients do quite well withouta full complement of teeth.27-34

Some believe that as teeth are lost, the structural in-tegrity of the dental arch is disrupted with a “subsequentrealignment of the teeth until a new state of equilibriumis achieved.”26 The literature on shortened dental archesindicates that the loss of teeth does not necessarily leadto further problems. Shortened dental arches consist ofanterior and premolar teeth. In a subjective interviewstudy, patients with reduced dentitions reported an ac-ceptable degree of hindrance in their ability to chew, toperceive food acceptability, and to consume food.27 Inanother study that compared patients with shorteneddental arches with those with complete dentitions, it wasconcluded that tooth migration was within acceptablelimits.28 There is no convincing evidence that a short-ened dental arch provokes signs and symptoms of man-dibular dysfunction.29

In a study by Witter et al,30 oral comfort was com-pared among 3 groups of patients: those with completedentitions, those with shortened dental arches restoredwith removable partial dentures (RPDs), and those withshortened dental arches and no replacement. The resultsrevealed no significant differences among the groups.Functional impairment was reported by 8% of the short-ened dental arch group; 11% of that group had estheticcomplaints about missing maxillary posterior teeth. Ofthe RPD group, 20% stopped wearing their prostheses.

aAssistant Clinical Professor, Advanced Education Program in Prosth-odontics.

bProfessor and Director, Advanced Education Program in Prosth-odontics.

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In a separate study of periodontal support in patientswith shortened dental arches with and without RPDsand patients with complete dental arches, there was atrend toward more bone loss in the patients with short-ened dental arches.31 This trend was significant for ter-minally located occluding premolars but not for anyother teeth in the study. However, it must be acknowl-edged that the shortened dental arch group had agreater incidence of existing periodontal disease.

A 6-year follow-up study of patients with shorteneddental arches showed that shortened dental arches wereocclusally stable.32 An RPD did not contribute to occlu-sal stability, and those teeth with periodontal involve-ment continued to break down. In the second part ofthat study, shortened dental arches were not found to berisk factors for craniomandibular dysfunction but didprovide long-term, sufficient oral comfort.33 The place-ment of an RPD in the mandible did not improve oralfunction in terms of oral comfort. In a 9-year follow-upstudy, differences between the groups remained con-stant over time, with occlusal changes being self-limit-ed.34

The research on shortened dental arches indicatesthat patients with missing teeth do not experience reper-cussions if the teeth are not replaced. This raises thequestion of whether the solitary tooth distal to an eden-tulous space is at greater risk without prosthetic inter-vention. Belief has had it that an isolated tooth is injeopardy.35 In a short-term retrospective study of poste-rior bounded edentulous spaces that were either un-treated or treated with a fixed partial denture (FPD) oran RPD, the majority of adjacent teeth were not lostwhen the missing tooth was not replaced. The survivalrate of the untreated group was not significantly differ-ent than that of the FPD and RPD groups. The survivalrate of the FPD group was significantly better than thatof the RPD group.36

Another study showed that not replacing missingposterior teeth did not lead to rapid or severe collapse ofthe arch.37 The effect on periodontal structures was sig-nificant in only a small number of patients; a few patientsexperienced clinically significant tilting of the teeth ad-jacent to the edentulous space. The authors suggestedthat further work was necessary to identify factors thatare predictive of adverse consequences. In a 10-yearstudy of the survival of teeth adjacent to bounded eden-tulous spaces, there was no significant difference be-tween the survival of teeth restored with an FPD andthose that were not treated.38 Edentulous spaces re-stored with an RPD had a significantly lower survivalrate.

Another belief is that teeth without opposing teethwill extrude.39 Data indicate that this is a serious prob-lem in children.40-42 However, in the older adult, it isnot clear that extrusion of unopposed teeth is a problem.A questionnaire study reported a 5% rate of moderate-

to-severe extrusion.43 Another study of unopposedmaxillary first molars found that all of these teethshowed signs of extrusion.44 In a more recent study inwhich patient age at the time of tooth loss was exam-ined, 18% of the teeth showed no signs of extrusion, 58%displayed less than 2 mm of extrusion, and 24% dis-played moderate-to-severe extrusion.45 Molars thatwere lost after the patient was older than 26 showed onlya 14% incidence of extrusion; when age at time of losswas unknown, a 29% incidence of extrusion was found.The authors concluded molar loss in adults was associ-ated with a lower risk of extrusion.

Not replacing missing teeth may not necessarily leadto future disease. Doubt remains with regard to thehealth ramifications of a diminished functional state.Chauncey et al46 suggested that people with impaireddentitions impose dietary restrictions on themselves thatcould compromise their nutritional status and ultimatelyplace them at health risk. The same authors found thatwhen patients with severe tooth loss received prostheticreplacements, masticatory function improved but thepatients’ perceptual estimate of food acceptability didnot.47 Carlsson48 pointed out that the chewing effi-ciency of complete dentures is lower than that of naturalteeth or implant-supported prostheses. He concludedthat the best method of ensuring masticatory efficiencyinto old age is the maintenance of the natural dentition.In a study of 480 residents of Finnish nursing homes,edentulous subjects and dentate subjects wearing bothmaxillary and mandibular prostheses reported more of-ten than subjects without prosthetic tooth replacementthat they could eat everything.49 Of those without anyteeth, 41% reported no restrictions on their dietary in-take.

In a separate study, 602 elderly institutionalized sub-jects were interviewed and examined dentally.50 A func-tional unit measure, which included not only the re-maining teeth but also the arrangement of those teeth,was found to be descriptive of the masticatory potential.Subjects with a reduced number of functional units re-ported greater difficulty in chewing and swallowing, aswell as food avoidance. Conventional removable pros-theses did not resolve these difficulties.50 In a study of638 men, it was found that calorie-adjusted intake de-creased with impaired dental status.51 Budtz-Jorgensenet al52 commented that “there is no evidence that theprovision of prosthetic therapies can markedly improvedietary intakes; however it might improve oral comfortand quality of life.” Walls et al53 questioned whetheraltered food choices increase a patient’s risk for develop-ment of life-threatening conditions such as arterioscle-rosis and cancer.

Much work has been done with regard to patientperceptions of dentures and the functional benefits ofreplacement prostheses. It is well known that patientperceptions of denture quality and qualitative measures

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of quality are widely divergent.54-58 No evidence hasshown that ill-fitting dentures cause increased resorp-tion of the residual ridges. At the 1972 InternationalProsthodontic Workshop held in Ann Arbor, Michigan,one speaker stated that patients generally are unreliableguides in terms of denture adequacy, especially if thedentures have been worn for any length of time.54 Neva-lainen et al55 found that the most justifiable replacementfor complete dentures was achieved when the dentistand patient assessed treatment need together. The au-thors concluded that successful treatment decisionsshould not be made solely on the basis of clinical exam-ination or a dentist’s subjective opinion, but should beformulated in close consultation with the patient.

Garrett et al56 found that structurally improved exist-ing dentures and new dentures had a negative effect onmasticatory performance. They concluded that adapta-tion to new or improved existing dentures could be along and drawn-out process. In another article on thesame group of subjects, more than 55% were fully satis-fied with their poorly fitting existing dentures.57 Most ofthe patients perceived improvements in chewing com-fort, chewing ability, eating enjoyment, food choices,security, and speech after the existing dentures weremodified. There was little correlation between objectivemeasures of masticatory ability and perceived satisfac-tion. In a study of 500 subjects, there was little or nocorrelation between patient appreciation and a clinicalassessment of complete denture quality when dentists orpatients rated the dentures highly.58

THE DIAGNOSIS AND TREATMENT-PLANNING PROCESSPatient interview and examination

The most important part of the diagnosis and treat-ment-planning process is and will always be the patientinterview.59-61 What does the patient want? Why does heor she want it? Are the patient’s needs functional, es-thetic, psychological, or external (a significant other per-ceives a need for treatment, for example)? If the dentistcannot understand the patient’s desires, there is littlechance that the appropriate treatment for that patientwill be selected. The patient arrives with experiences,attitudes, and biases, and the prosthodontist has a set ofhis or her own. The new patient examination providesnot only a forum for diagnosing disease but also amethod of establishing a connection with the patient. Agood patient-dentist relationship allows for a better un-derstanding of the patient’s overall needs.62 The patientinterview should include a review of the patient’s sys-temic health, because this may impact the patient’s oralhealth and/or ability to undergo certain proce-dures.63,64 Only after the completion of the patient in-terview is it appropriate to examine the patient.

The first step in the examination process is discerningwhether active disease is present. This is important given

that active disease must always be treated. Other condi-tions may require treatment depending on the specificneeds of the patient. Carious lesions require the removalof decay to stem the loss of additional tooth structureand to determine the extent of the destruction.65,66 Peri-odontal disease requires consultation to ascertain theviability of the remaining teeth and appropriate treat-ment for those that are maintainable.67-69 Endodonticabscesses should be treated, or the affected teeth shouldbe extracted.70-72 It also is critical to examine mucosaltissues for any abnormalities.73 The next step is to deter-mine whether the patient’s subjective complaints arerelated to what is seen intraorally. Unless there is a clearcorrelation between the subjective report and a clinicalentity, treatment is not advisable.

Evaluation of therapeutic modalities

Subjective information obtained at the interview andobjective information gathered from the clinical exami-nation, radiographs, and tests are combined to form adiagnosis. The next step in the treatment-planning pro-cess is to evaluate all possible treatments and the relativecost/benefit ratio attributed to each modality.74 Theprimary benefit of dental treatment is the elimination ofdental disease and the maintenance of the oral struc-tures. Secondary benefits accrue in terms of improvedfunction, enhanced esthetics, and improved psycholog-ical well-being. Prosthodontic treatment generally re-sults in secondary benefits.

Biological costs are those costs incurred as complica-tions of the treatment.75-77 Increasing the number ofprocedures performed on any one patient increases thelikelihood of that patient experiencing a complica-tion.75-77

Financial costs are fairly obvious. The cost of adjunc-tive procedures often is not calculated by prosthodon-tists because another specialist performs those treat-ments. When the financial costs of treatment areassessed, it is important to include an estimate of allnecessary treatments, not just those in the area ofprosthodontics. It also is important to provide an ap-proximate cost of the treatment that may be required toremedy possible complications.

The time span of treatment and how many visits willbe necessary to complete the treatment should be estab-lished. Patients are concerned about the duration oftreatment for various reasons: lengthy dental treatmentmay encroach on time that would be used for otherinterests; some people simply dislike spending time inthe dental office, regardless of how gentle the doctor is,how attentive the staff members are, or how comfortablethe office is; other patients have mobility problems thatmake it difficult to travel to and from the dental office.

Another time-related issue is how long a prostheticrestoration will be serviceable. In implant prosthodon-

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tics, there is the additional question of whether parts willstill be available when the restoration requires service. Inspite of the fact that it is impossible to predict the life ofany individual restoration, information on the relativelongevity of different restorations is available. In a ret-rospective study, 89 FPDs were examined.78 Thirteen(15%) were considered failures or had already been re-placed. The greatest cause of failure was dental caries(38%). The mean length of service for the failed FPDsranged from 4.1 to 16.0 years. The authors reportedthat the number of years the denture was in service pro-vided no information about the future life expectancy.78

Scurria et al79 performed a meta-analysis on 8 English-language studies on the longitudinal survival of FPDs.The results showed that 15% of the FPDs were removedor in need of replacement at 10 years. By 15 years, nearlyone third of the FPDs were removed or in need of re-placement. In a retrospective study of 20-year-old FPDsfabricated by general practitioners in Sweden, a successrate of 65% after 20 years of service was reported.80

In an effort to understand the influence of differentrisk factors on FPD longevity, a multivariate analysis wasperformed on a group of FPDs that were 18 to 23 yearsold.81 The risk of losing an abutment tooth increased ifthe abutment tooth had received endodontic treatment,was a terminal abutment, was located in the mandibulararch, or had advanced bone loss. A combination of riskfactors seemed to be the most detrimental to the lon-gevity of the restorations studied.

Maintenance costs are those expenditures related tomaintaining the prosthetic restoration. It is importantthat the patient understand that any prosthetic solutionrequires some sort of maintenance. Palmer et al,82 whoreviewed many of the complications associated with im-plant-supported prostheses, recommended that the pa-tient be informed of potential complications and main-tenance costs before the prosthesis is fabricated. In astudy of the complications related to 25 mandibularimplant-supported fixed prostheses and 25 implant-sup-ported overdentures, overdentures presented with fewercomplications and maintenance requirements than fixedprostheses.83 However, both prosthesis designs requiredmaintenance over the study period. In another study,84

the complications and maintenance requirements of 66prostheses over a 6-year period were studied. Complica-tions were grouped into 1 of 2 broad categories: surgicalor prosthodontic. The authors included in the compli-cation rate not only the implant-supported prosthesesbut also the need to repair conventional prostheses op-posed by implant-supported prostheses. They con-cluded that it is necessary to put patients on a rigorousoral hygiene program and that the cost of the prosthesisshould include some of the anticipated maintenance.

One benefit of a prosthetic service is simply the abilityof the patient to enjoy better function at the completionof treatment. This aspect has been the most touted rea-

son for treatment. Studies have shown there is a signif-icant difference between patient perceptions of functionand quantified measurements of function.85-88

Esthetic benefits relate to improvements in appear-ance at the end of therapy. Dentist and patient percep-tions of esthetic perceptions have been know to differwidely.89 A thorough understanding of the patient’s de-sires is critical to providing the appropriate esthetic so-lution.90,91 Psychological benefits overlap esthetic ben-efits significantly. Psychological benefits are thosetreatment benefits that make a patient feel better regard-less of any quantifiable changes. A fixed restoration maymake some patients feel whole again when a removableprosthesis would not. Patients may derive psychologicalbenefits from dental treatment that are unique to thatpatient and not quantifiable.92-94

Nontreatment

After all treatment options have been evaluated, it isnecessary to evaluate them against the possibility of pro-viding no treatment. The costs of each treatment mustbe considered relative to the benefit of treatment and tothe risks of nontreatment. If the nontreatment risks arenot significant, the cost/benefit ratio of treatment mustbe attractive for treatment to be worthwhile.95,96

In the absence of symptoms, is it necessary to treatevery oral condition? It may be reasonable to invoke a“watchful waiting” type of approach. This is true only ifthe possible sequelae of the condition do not damageother teeth or the general health of the patient. It isunethical to leave active disease untreated.

Evidence-based outcome data

Data that quantify the costs and outcomes of treat-ment are now available.97-100 Studies have shown that,for some patients, a simple restoration may be just asbeneficial as more complex treatment.101,102 Other stud-ies have shown that whereas more patients are morecomfortable with implant-retained prostheses, a significantnumber of patients are still satisfied with conventionalcomplete dentures.103 It is important to understand thatdentist and patient perspectives on success can divergewidely. A number of articles discuss patient-centered ap-proaches to understanding success rates.104-106

Determining the proper course of action

The prosthodontist must present the possible treat-ment options along with the pros and cons of each treat-ment to the patient. The dentist is not a disinterestedparty. One dentist may be more comfortable fabricatinga fixed prosthesis than a removable prosthesis, or viceversa. There may be a greater financial incentive to selectone type of treatment over another.107 Moreover, if onetype of treatment is “in style,” some dentists may feel animpetus to use it even when the conventional treatment

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would work just as well for the patient under consider-ation. Dentists must be aware of these issues and disclosethem to the patient.

When a treatment approach is chosen, one interestingfactor is whether the treatment is reversible. A patientmay choose to have a relatively simple treatment per-formed as long as that treatment does not preclude morecomplex future modalities. In the event that the simpletreatment does not result in patient satisfaction, themore complex treatment can be instituted.

If treatment is deemed necessary, the patient mustdetermine whether the benefits of treatment justify thecosts. The duty of the prosthodontist is to supply thepatient with enough information to arrive at an in-formed decision about the most appropriate treat-ment.108 If the patient chooses a treatment that theprosthodontist believes is not suitable for that patient,the prosthodontist can decline to treat the patient.

SUMMARY

Treatment planning is no longer simply a result ofdiagnosis. It is a complex process that involves a combi-nation of diagnostic information, patient desires, evi-dence-based outcome data, and a thorough review ofthe treatment alternatives. The culmination of this pro-cess should be the dentist choosing the most appropriatetreatment for an individual patient.

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Noteworthy Abstractsof theCurrent Literature

Effect of selected literature on dentists’ decisions to removeasymptomatic, impacted lower third molars.van der Sanden WJ, Mettes DG, Plasschaert AJ, Grol RP,van’t Hoff MA, Knutsson K, Verdonschot EH. Eur J Oral Sci2002;110:2-7.

Purpose. Several authors have stated that tradition-based dentistry treatment decisions are mainlybased on practice observations, experience and intuition. The contention is that aspects of evi-dence-based dentistry, such as the integration of best available evidence and explicit patient values,play a less dominant role. The removal of asymptomatic, impacted mandibular third molars iscommon practice in clinical dentistry. Studies have shown that considerable intra- and inter-dentistvariation exists in treatment decisions regarding the removal of asymptomatic, impacted mandib-ular third molars. The aim of this study was to assess the effect of studying selected literature bydentists on their decision to remove mandibular third molars.Material and methods. Two groups consisting of 16 general practitioners in each group were usedin a pretest/posttest design. Thirty-six “cases” were developed which represented a wide range ofimpaction types. The “cases” were characterized by the position of the third molars, the degree ofimpaction, and the age of the patient. Each “case” was presented as a print of a radiograph togetherwith information regarding the sex and age of the patients and the type of impaction. For each“case” the participants were asked to answer the question, “Should this impacted mandibular thirdmolar be removed?” After studying selected literature on this subject by the intervention group,both groups were asked to assess the same “cases” again. The selected literature was based upon“randomized controlled trial,” “indication for mandibular third molar removal,” “complicationsafter mandibular third molar removal,” and “mandibular third molar related pathology.”Results. The results are presented in a table composed by cross-tabulating the indication to removea mandibular third molar with each of the 3 studied parameters: age of impaction, position ofimpaction, and age of the patient. The t test was used to test the significance of the differencebetween pretest and posttest decisions. The overall number of indications to remove asymptomatic,impacted mandibular third molars decreased by 37% in the intervention group. In the controlgroup, the difference between pretest and posttest was not significant.Conclusions. The authors state that the participants in this study were not randomly selected andtherefore did not fully represent the general dental population. They did conclude that the provi-sion of selected literature significantly influences treatment decision making by dentists in a thirdmolar decision task. 31 References.—ME Razzoog

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