Condyl Fossa

Analysis of the condyle/fossa relationship before and after prostheticrehabilitation with maxillary complete denture and mandibular removablepartial denture

Vania Cristina Pintaudi Amorim, DDS, MSD,a Dalva Cruz Lagana, DDS, MSD, PhD,b

Jose Virgilio de Paula Eduardo, DDS, MSD, PhD,c and Artemio Luiz Zanetti, DDS, MSD, PhDd

School of Dentistry, University of Sao Paulo and University of Sao Paulo City, Sao Paulo, Brazil;Paulista University, Campinas, Brazil

Statement of problem. The influence of the loss of posterior teeth on the condylar position and on tem-poromandibular disorders (TMDs) remains a controversial issue.Purpose. This study investigated whether prosthetic rehabilitation promoted modification of the condylarposition in subjects without symptoms of TMDs.Material and methods. The temporomandibular joints (TMJs) of 12 women (age 37 to 74), all with existingmaxillary complete dentures but no removable partial denture (RPD) restoring the Kennedy class I partiallyedentulous mandibular arch and no clinical signs of TMDs according to the criteria established by Helkimo, wereviewed in maximal intercuspal position with corrected lateral tomography before and after prosthetic rehabilita-tion with a new maxillary complete denture and a mandibular RPD. Before prosthetic rehabilitation, a mandib-ular stabilizing base was fabricated to prevent the existing maxillary complete denture from dislodging duringtomographic examination. Two methods were used to evaluate tomograms: (1) linear measurements of thesubjective narrowest anterior and posterior intra-articular joint spaces made from the tomograms by use of adigital caliper and (2) linear measurements of the anterior and posterior intra-articular joint spaces on the basis ofdrawings and tracings. Repeated-measures analysis of variance followed by orthogonal contrasts were used toevaluate differences between measurements carried out on the same subject under the different test conditions ofthe study (before prosthetic rehabilitation, before prosthetic rehabilitation with a mandibular stabilizing base inposition, and after prosthetic rehabilitation) (P�.05).Results. Before prosthetic rehabilitation, a predominance of posterior condylar positions was observed. Beforeprosthetic rehabilitation with a mandibular stabilizing base in position, a significant decrease was observed inposterior condylar positions (P�.03). This decrease was more marked after prosthetic rehabilitation (P�.02).The subjective evaluation and comparison on the basis of drawings and tracings used to analyze the tomogramsproduced similar results (P�.70).Conclusion. Within the limitations of this study, significant changes in the condylar position occurred afterprosthetic rehabilitation in subjects without symptoms of TMDs. (J Prosthet Dent 2003;89:508-14.)

CLINICAL IMPLICATIONS

In this study, posterior condyle displacement was more frequent than other positions in patientsmissing mandibular posterior teeth with existing maxillary complete dentures but no mandib-ular RPD. Prosthetic rehabilitation appeared to be responsible for a more favorable condyle/fossa relationship; however, there was no evidence that this improved the patient’s status relativeto the health of the TMJs or TMD signs and symptoms, because the patients were symptom freeinitially.

Different methods have been used to determine thecondylar position according to the relative dimensions

of anterior and posterior joint spaces between the fossaand the condylar surface.1-5 In spite of variations amongthe methods used, 3 types of condylar positions can beidentified:6 (1) condylar concentricity, in which the an-terior and posterior joint spaces are equal; (2) posteriorcondylar position, in which the posterior joint space issmaller than the anterior joint space; and (3) anteriorcondylar position, in which the posterior joint space isgreater than the anterior joint space. Some authors haveinvestigated the accuracy and reliability of the methodsused to evaluate the position of the condyle.1-3 In this

Supported by CNPq.aAssistant Professor, Department of Prosthodontics, University of Sao

Paulo City.bAssociate Professor, Department of Removable Prosthodontics,

University of Sao Paulo.cProfessor and Chairman, Department of Prosthodontics, Paulista

University of Campinas.dProfessor and Chairman, Department of Removable Prosthodontics,

University of Sao Paulo and University of Sao Paulo City.

508 THE JOURNAL OF PROSTHETIC DENTISTRY VOLUME 89 NUMBER 5

study, 2 methods described as reliable in the literaturewere used, one method done by linear measurements ofthe subjective closest anterior and posterior intra-artic-ular space on the tomogram with a digital caliper,1 andanother method that took into account the linear mea-surements of the anterior and posterior intra-articularspace on the basis of tracings and drawings.2

Several authors have associated nonconcentric posi-tions with temporomandibular disorders (TMDs).7-12

However, in asymptomatic populations with no historyof occlusal or orthodontic treatment, a wide variety ofcondylar positions in the articular fossa have been ob-served. Not withstanding, a relatively greater number ofconcentric positions in symptom-free subjects has beenreported.13,14

In at least 2 studies, no association was found be-tween TMDs and nonconcentric positions of the con-dyle.15,16 Radiographic investigations, however, haveshown that patients with temporomandibular joint(TMJ) pain presented a higher ratio of posterior condy-lar positions than symptom-free subjects.17-21 This pos-terior displacement of the condyle has frequently beenassociated with the loss of posterior teeth17-19 and alsomay be associated with anterior disk displacement.20,21

A more superior and anterior position of the condylein the presence of good, integrated muscular activity,optimum occlusal stability, and an interposed articulardisk has been considered the ideal status of the con-dyle.22-25 Radiographically, however, this ideal dependson the thickness of the articular soft tissues, tissue de-generation and remodeling, and mandible posture, all ofwhich might alter the position of the condyle.26,27

Many patients can adapt to occlusion or condylarpositions that are not considered ideal. Because of fac-tors that reduce adaptive ability and cause unbalance ofthe masticatory system, other patients may have devel-opment of TMDs.24,25 The influence of condylar posi-tion and the loss of posterior teeth on TMDs remains acontroversial issue, as does the influence of lost molarreplacement by a removable partial denture (RPD).28-31

Nevertheless, some researchers have shown the impor-tance of prosthetic rehabilitation for reducing the symp-toms of TMDs.32,33

The purpose of this study was to analyze condylarposition by means of corrected lateral tomography in 12patients with existing maxillary complete dentures butno RPD for the partially edentulous mandibular arch(Kennedy class I). Analysis was performed before pros-thetic rehabilitation (with and without a stabilizing basein position) and after prosthetic rehabilitation (consist-ing of a new maxillary complete denture and a mandib-ular RPD). The goal was to determine whether the as-sociated prosthetic rehabilitation resulted in analteration of the condyle position.

MATERIAL AND METHODS

The sample of this study consisted of 12 women, ages37 to 74, in good general health, without symptoms ofTMD according to the criteria established by Hel-kimo,34 and presenting edentulous mandibular arches(Kennedy class I) but no mandibular RPDs. All subjectshad worn a maxillary complete denture for more than 5years and were seeking prosthetic rehabilitation at thedental clinics of the University of Sao Paulo or the Uni-versity of Sao Paulo City. The TMJs of the patients wereviewed with corrected lateral tomography (Quint Secto-graph, Los Angeles, California) twice before prostheticrehabilitation (with an existing maxillary complete den-ture in position only, and with an existing maxillarycomplete denture and a mandibular stabilizing base inposition) and once again after prosthetic rehabilitation(with a new maxillary complete denture and a mandib-ular RPD), always in maximal intercuspal position.

Before prosthetic rehabilitation with a new maxillarycomplete denture and a mandibular RPD, a mandibularstabilizing base35-37 was fabricated for the purpose ofstabilizing the existing maxillary complete denture, pre-venting it from becoming dislodged and losing contactwith the mucosa in maximal intercuspal position duringthe tomographic examination. The mandibular stabiliz-ing base was fabricated on a mandibular diagnostic castof each patient and consisted of an acrylic resin (Jet;Classico Ltd, Sao Paulo, Brazil) base relined with a zincoxide-eugenol paste (Lysanda; Lysanda Ltd, Sao Paulo,Brazil) on the cast lubricated with petroleum jelly (Va-selina; Beira Alta Ltd, Sao Paulo, SP, Brazil) to offset thedistortion caused by the acrylic resin polymerization con-traction. An occlusion rim made of wax (Wilson; PolidentalInd e Com Ltd, Sao Paulo, Brazil) was fabricated on thisacrylic resin base, which was placed in the mouth and con-toured to coincide with the existing vertical dimension ofocclusion and maximal intercuspal position presented bythe patient while wearing the existing maxillary completedenture. Afterward, 1 mm of the wax was removed toreceive a layer of zinc oxide-eugenol paste (Lysanda; Ly-sanda Ltd). The occlusion rim was once again placed in thepatient’s mouth to make a record of the maximal intercus-pal position at the vertical dimension of occlusion.

Standardized procedures were performed for the fab-rication of the maxillary complete dentures and the man-dibular RPDs. After clinical examination, diagnostic im-pressions and casts of the maxillary and mandibulararches were made. New record bases and occlusion rimswere fabricated on the casts and transferred to a semi-adjustable articulator (Dent-flex 10600; Dent-flex IndCom Ltd, Ribeirao Preto, Brazil) with the aid of a face-bow transfer and a record made with the patient in thecentric relation position.22

Treatment planning was carried out for each patient.The mandibular diagnostic cast previously used to fab-

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MAY 2003 509

ricate the stabilizing base was mounted in a parallelom-eter (Bioart; Bioart Ltda, Sao Carlos, Brazil) to deter-mine the path of insertion and the need for abutmenttooth preparation to accommodate the desired RPD de-sign.37,38 After mouth preparation, a mandibular im-pression was made to evaluate the correctness of themouth preparations. A maxillary functional impres-sion39,40 was made and transferred to the articulatorwith the aid of a face-bow and transferring devices.41 Afinal mandibular impression was made and the cast wasformed in stone (Durone; Dentsply Ind e Com Ltd,Petropolis, Brazil). The RPD design was finalized, andthe metal framework was fabricated. Determination ofthe plane of occlusion was based on anatomic landmarks(retromolar pads and maxillary lip line).35,36 The verticaldimension of occlusion was established by combiningthe methods described by Willis,42 Pleasure,43 Silver-man,44 and Ricketts.45,46 Centric relation was initiallyrecorded by use of Dawson’s22 bilateral manipulationtechnique and then confirmed by the procedure for re-cording the centric relation as described by Smith.47 Thefinal mandibular cast and framework, along with themandibular and maxillary occlusion rims, were thentransferred to the articulator. Prosthetic teeth with 33-degree cusp inclines (Biotone; Dentsply Ltda, Sao

Paulo, Brazil) were selected and arranged in the maximalintercuspal position. The characteristics of the teethwere assumed to have been standardized by the manu-facturer and were chosen because of their reduced cost.After trial insertion and confirmation of tooth arrange-ment, the prostheses were finished and processed in theusual manner.48 The new maxillary complete dentureand the mandibular RPD were remounted in the artic-ulator, and occlusal adjustments were then made asneeded before insertion of the prostheses.49

Corrected lateral tomography (Quint Sectograph)was used to view the TMJs of all patients. All tomogramswere made at the Institute for Orthodontic Documen-tation and Radiodiagnosis (Instituto de DocumentacaoOrtodontica e Radiodiagnostico—INDOR S/C Ltda,Sao Paulo, Brazil), in the maximal intercuspal position:(1) before prosthetic rehabilitation (existing maxillarycomplete denture only) (Fig. 1, A and B); (2) beforeprosthetic rehabilitation with a mandibular stabilizingbase in position (existing maxillary complete dentureand mandibular stabilizing base in position) (Fig. 1, Cand D); and (3) after prosthetic rehabilitation (new max-illary complete denture and mandibular RPD) (Fig. 2).

Two methods were used to analyze the tomographicimages. Method A was a subjective analysis on the basis

Fig. 1. Subject 4. A, Existing maxillary complete denture without mandibular stabilizing base in maximal intercuspal position.B, Tomograms of right and left TMJs seen in A. C, Existing maxillary complete denture with mandibular stabilizing base inmaximal intercuspal position. D, Tomograms of right and left TMJs seen in C.

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510 VOLUME 89 NUMBER 5

of a method established by Pullinger and Hollender,1which consisted of linear measurement of the narrowestjoint spaces, both anterior (A) and posterior (P), with adigital caliper (Starrett; Starrett Ltd, Itu, Brazil). Thevalues were transferred to the following formula fromPullinger et al:11

P � AP � A � 100

This equation determined the percentage of anterior orposterior displacement of the condyle, with concentric-ity as a reference. Results smaller than –12 indicated thatthe condyles were in a posterior position; results rangingfrom –12 to �12 indicated that the condyles were in aconcentric position; and results greater than �12 indi-cated that condyles were in an anterior position. Themeasurement was repeated 3 times to avoid errors, andthe arithmetic mean of the 3 values was recorded as thefinal result.

In method B (Fig. 3), drawings and tracings for eachTMJ were made on tracing paper with a 0.3-mm leadpencil in accordance with Kamelchuk et al.2 Posteriorand anterior joint spaces of all tomograms were mea-sured with the digital caliper. The formula proposed byPullinger et al11 to evaluate condylar position was usedwith this method as well.5

Because several different distances were obtainedfrom the tomograms of each patient, it was felt thatthese measurements could be used for correlation pur-poses. Repeated-measures analysis of variance followedby orthogonal contrasts was considered appropriate forstatistical analysis of the data, because of its ability toaddress the issue of covariation between measurementsin the same subject.50 Among the available techniques,profile analysis was chosen.51 Differences were consid-ered significant at P�.05.

Because measurements obtained by methods A and Bwere based on the anterior and posterior joint spaces,these 2 methods were compared. A single model was

adjusted for the statistical analysis, which included themethod of evaluation, joint side, and type of prosthesisas factors and determined any interactions among thesefactors.

RESULTS

The distribution of condylar positions on the rightand left sides are shown in Figures 4 (method A) and 5(method B). Profile analysis (Fig. 6) showed that pros-thesis type had a significant effect (F2,11�10.21,P�.003) but that the measurement method did not(F1,11�0.15, P�.70). The mean distances obtained bythe 2 methods were considered equivalent.

An effect on the basis of the particular side seemed toexist (in spite of a finding of F1,11�2.94, P�.11) be-cause, on average, the figures representing the left sidecondylar position were higher than those representingthe right side. This suggested that there was a distinctbehavior difference between the 2 sides, even thoughthe data from the study did not detect this difference.Because no significant effect of method was found, an-other analysis was performed that included only side andtype of prosthesis as factors (Fig. 7). This second analysis

Fig. 2. Subject 4. A, New maxillary complete denture with mandibular RPD in maximal intercuspal position. B, Tomogramsof right and left TMJs seen in A.

Fig. 3. TMJ tomography with tracings used in Method B. A,Anterior joint space; P, posterior joint space.


MAY 2003 511

indicated that the interaction of prosthesis and side wasnot significant (F2,24�0.13, P�.88). Nevertheless,prosthesis alone (F2,24�20.11, P�.0001) and sidealone (F1,24�5.55, P�.03) significantly affected thecondylar position.

The increase in the mean value of the condylar posi-tions was significant when a stabilizing base was addedto the existing maxillary complete denture (F1,24 �5.08, P�.03), regardless of whether it was on the rightor left side. Likewise, the mean value of condylar posi-

tions increased significantly after prosthetic rehabilita-tion compared to the existing maxillary complete den-ture without a stabilizing base (F1,24�5.65, P�.02),and with a stabilizing base (F1,24�4.59, P�.04).

DISCUSSION

In this study, patients who had lost posterior supportshowed a predominance of posterior condylar positions.This reduction of the posterior intra-articular space may

Fig. 4. Method A results. A, Condylar positions on right side TMJ. B, Condylar positions on left side TMJ.

Fig. 5. Method B results. A, Condylar positions on right side TMJ. B, Condylar positions on left side TMJ.

Fig. 6. Mean profiles of condylar position � standard devi-ation (in relation to method and side). Fig. 7. Mean profiles of condylar position � standard devi-

ation (in relation to side but independent of method).



represent a compression on the bilaminar zone, which isresponsible for the blood supply and the nutrition of theTMJ26 and may also be related to the anterior displace-ment of the joint disk.20,21

It was observed that prosthetic rehabilitation causedchanges in the condyle/fossa relationship, reducing theincidence of posterior condylar positions and increasingthe incidence of concentric condylar positions. Afterprosthetic rehabilitation, the degree of retrusion wasobserved to be smaller, even when the condyles re-mained in a posterior position (retrusion). These find-ings were confirmed by statistical analysis, which dem-onstrated that the mean values of condylar positionsincreased (condyles moved to a more anterior position)when a mandibular stabilizing base was added to theexisting complete denture before treatment. The in-crease was even more pronounced after prosthetic reha-bilitation with a new maxillary complete denture and amandibular RPD.

A larger incidence of concentricity was found on theleft side, confirming the results of other studies.6,13 Con-dylar asymmetry may be an indication of osseous unbal-ance caused by different growth patterns or differentremodeling effects as a result of occlusal disturbance.12

It was not the aim of this study to analyze the occur-rence of unilateral chewers among the subjects evalu-ated. Future studies should attempt to verify the possiblerelationship between the asymmetry of the condylar po-sition and the incidence of unilateral chewing. It is fur-ther recommended that long-term follow-up controlsbe established to assess whether the condylar positionafter prosthetic rehabilitation is maintained.

Statistical analysis revealed no significant differencebetween the methods (A and B) used to evaluate theposition of the condyle. Method A is recommendedbecause it is easier and does not require drawings ortracings.

CONCLUSIONS

Within the limitations of this study, subjects with amaxillary complete denture but no RPD for the partiallyedentulous mandibular arch showed a predominance ofposterior condylar positions in maximal intercuspal po-sition. Also, when mandibular stabilizing bases wereused during tomographic examination with the existingmaxillary complete dentures in maximal intercuspal po-sition, a decrease in posterior condylar positions and anincrease in condylar concentricity were observed. Afterprosthetic rehabilitation, more pronounced decreases inposterior condylar positions and increases in concentriccondylar positions were observed in the maximal inter-cuspal position. Regardless of when the condylar posi-tions were analyzed (before or after rehabilitation), theTMJ on the left side displayed a higher frequency of

concentric condylar positions than its counterpart onthe right side.

We thank Prof Israel Chilvarquer, for his encouragement, supportand valuable collaboration with the tomograms, and Dr Luiz PauloRestiffe de Carvalho, for his large contribution to this work.

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Noteworthy Abstractsof theCurrent Literature

An in vitro study to investigate the load at fracture of ProceraAllCeram crowns with various thickness of occlusal veneerporcelainHarrington Z, McDonald A, Knowles J. Int J Prosthodont2003;16:54-8.

Purpose. The aim of this study was to investigate the effect of occlusal veneer porcelain thicknesson the load at fracture of Procera AllCeram crowns.Materials and Methods. Fifty resin dies were manufactured to incorporate the features of anall-ceramic crown preparation on a premolar tooth. Fifty corresponding crowns were constructedand divided into five groups. Groups 1, 2, 3, and 4 were crowns with 0.6-mm-thick Procera coresand 0.4-mm-thick axial veneer porcelain and occlusal veneer porcelain thicknesses of 0.0 mm, 0.4mm, 0.9 mm, and 1.4 mm, respectively. Group 5 specimens consisted of 0.6-mm–thick In-Ceramcores with 0.4 mm of axial porcelain and 0.4 mm of occlusal porcelain. The crowns were cementedonto their respective dies with a resin luting agent. Specimens were stored in distilled water at 37°Cfor 24 hours prior to placing them in a universal testing machine and applying a controlledcompressive load at a cross-head speed of 0.1 mm/min until fracture occurred.Results. The mean loads at fracture were 419 N (group 1), 702 N (group 2), 1,142 N (group 3),1,297 N (group 4), and 732 N (group 5). Statistical analysis revealed significant differences (P�.05) in the load at fracture between the groups, except for between groups 2 and 5.Conclusion. Increasing the thickness of the occlusal veneer porcelain increased the load at fracturefor Procera AllCeram crowns. There was no significant difference in load at fracture between theProcera and In-Ceram crowns.—Reprinted with permission of Quintessence Publishing.



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Condyl Fossa