Original Article Condylar displacement between centric relation and maximum intercuspation in symptomatic and asymptomatic individuals Soo Young Kim Wefforta; Solange Mongelli de Fantinib ABSTRACT Objective: To measure condylar displacement between centric relation (CR) and maximum intercuspation (MIC) in symptomatic and asymptomatic subjects. Materials and Methods: The sample comprised 70 non-deprogrammed individuals, divided equally into two groups, one symptomatic and the other asymptomatic, grouped according to the research diagnostic criteria for temporomandibular disorders (RDC/TMD). Condylar displacement was measured in three dimensions with the condylar position indicator (CPI) device. Dahlberg’s index, intraclass correlation coefficient, repeated measures analysis of variance, analysis of variance, and generalized estimating equations were used for statistical analysis. Results: A greater magnitude of difference was observed on the vertical plane on the left side in both symptomatic and asymptomatic individuals (P 5 .033). The symptomatic group presented higher measurements on the transverse plane (P 5 .015). The percentage of displacement in the mesial direction was significantly higher in the asymptomatic group than in the symptomatic one (P 5 .049). Both groups presented a significantly higher percentage of mesial direction on the right side than on the left (P 5 .036). The presence of bilateral condylar displacement (left and right sides) in an inferior and distal direction was significantly greater in symptomatic individuals (P 5 .012). However, no statistical difference was noted between genders. Conclusion: Statistically significant differences between CR and MIC were quantifiable at the condylar level in asymptomatic and symptomatic individuals. (Angle Orthod. 2010;80:835–842.) KEY WORDS: Condylar displacement; Centric relation; Maximum intercuspation INTRODUCTION the fossa, seated against the articular disc at the posterior slope of the eminence, centered transversely Regarding dental procedures, the mandible can by coordinated masticatory muscles.7,20 It has also assume two well-known positions as a reference for been described as the most stable and comfortable treatment: centric relation (CR) and maximum inter- position of the mandible in which the joints can be cuspation (MIC).1 These usually are not coincident in loaded without discomfort.20 the general population.1–20 The MIC position refers to Controversy continues about what is considered an the occlusal relationship in which the teeth of both ideal condyle-fossa relationship when the teeth estab- arches are mostly interposed. In this case, the lish MIC.1–4 If any premature occlusal contact changes mandible generates a joint position dictated by the the jaw closing arc, the condyles might be displaced to teeth. On the other side, CR is defined as the most achieve a maxillomandibular relationship in MIC, thus anterior-superior position the condyles can achieve in avoiding premature contact. It is not clear how occlusal changes (natural dentition development, occlusal treat- a PhD Graduate Student, Department of Orthodontics and Dental Pediatrics, Faculty of Dentistry, University of Sa˜o Paulo, ments, or restoration procedures) affect the function of Brazil. the temporomandibular joint.21,22 Several studies have b Professor of Department of Orthodontics and Dental shown that in most cases the neuromusculature places Pediatrics, Faculty of Dentistry, University of Sa˜o Paulo, Brazil. the mandible in such a position that the highest number Corresponding author: Dr Soo Young Kim Weffort, Depart- of occlusal contacts is established without taking into ment of Orthodontics and Dental Pediatrics, Faculty of Dentistry, 1–4,13,23–26 Av Prof Lineu Prestes, 2227, University of Sa˜o Paulo, Brazil account the final condylar position. (e-mail: [email protected]) However, the role of condylar displacement in the Accepted: December 2009. Submitted: September 2009. context of morphologic and functional occlusion as a G 2010 by The EH Angle Education and Research Foundation, risk factor in temporomandibular disorder (TMD) Inc. development has not been clearly elucidated. For this DOI: 10.2319/090909-510.1 835 Angle Orthodontist, Vol 80, No 5, 2010 836 WEFFORT, DE FANTINI Figure 1. Maximal intercuspation (MIC) wax bite registration was Figure 2. For the centric relation (CR) bite record, Blue Bite taken with one sheet only of Beauty Pink Wax (Moyco Inc, Registration Delar Wax (Delar Corp, Lake Oswego, Ore) was used in Philadelphia, Pa). two sections according to Roth’s power centric technique. reason, assessment of articulated models in CR and patients of the Orthodontic Department at Sa˜o should not be ignored because the malocclusion could Paulo Dental School, University of Sa˜o Paulo, Brazil. be different, depending on the mandibular position All individuals signed an informed consent indicating adopted during the orthodontic diagnosis.1–3,25–27 their agreement with the research procedures. Ap- Previous studies1,2,4,24–26,28–30 have shown that CR-MIC proval for the procedures of this research was obtained discrepancies are frequently present in the general from the Ethics Committee of the University of Sa˜o population, in symptomatic as often as in asymptomatic Paulo (Project Number 82/05). All subjects completed subjects, whether they are of a distinct facial pattern or a questionnaire to identify facial pain, joint and muscle not, and whether deprogrammed or not. Differences complaints, problems of mastication, headache, par- between CR and MIC are observed on three spatial afunction, and clenching, grinding, and bite habits. planes, equally at the condylar level, by means of a Subsequent clinical muscle and joint examinations condylar position indicator (CPI), and at the dental level, were performed on each patient. via an interdental relation examination. CR-MIC discrep- On the basis of data collected during anamnesis and ancies observed at the level of the occlusion frequently clinical examination, subjects were divided into two have been shown not to correspond to those measured groups—a symptomatic group and an asymptomatic at the condylar level.1,2,4,24–26,28–31 group—in accordance with the Research Diagnostic The purpose of this cross-sectional study was to Criteria (RDC) for TMD (Axis I group I).32 The measure condylar displacement between CR and MIC temporomandibular joint (TMJ) physical examination in symptomatic and asymptomatic individuals with included measurements of mouth opening, right and TMD. The objectives were as follows: left excursion of the mandible, and protrusion. All these measurements were made on maximum unassisted N Measure the CR-MIC discrepancy in the three extension. The joint noise level was verified by digital dimensions of space palpation during mandibular movements such as N Statistically compare the magnitude, direction, and opening-closing, protrusion-retrusion, and lateral ex- frequency of CPI measurements in both study groups cursion. In the TMJ examination, possible restriction or N Compare condylar displacement among males and deviation of jaw movement was observed. Following females the previous examination, palpation for the reference point of muscle pain and tenderness was analyzed. As pressure was applied, the patient was asked if the MATERIALS AND METHODS palpation was painful, and if the reference point of the The sample comprised 70 non-deprogrammed pain was located away from the palpation site. A individuals, divided equally into two groups: a symp- numeric rating scale (0 to 10) was used to quantify tomatic group (mean age, 22.8 years) and an pain levels experienced by patients. asymptomatic group (mean age, 23.6 years). Each The asymptomatic group had no history of any type group contained 20 females and 15 males, aged 18 to of TMD (ie, absence of the following signs and 30 years. Participants were selected from the students symptoms: facial muscle pain/fatigue, tenderness Angle Orthodontist, Vol 80, No 5, 2010 CONDYLAR DISPLACEMENT BETWEEN CR AND MIC 837 Figure 3. Centric relation (CR) position in condylar position indicator (CPI) instrumentation determined by CR bite record. Figure 5. Centric relation (CR) position was marked in black, and maximal intercuspation (MIC) in red. On the vertical plane, a upon palpation, limited range of motion, pain upon negative sign represents that MIC is dislocated in the superior movement, clicking or locking joint, or TMJ pain). The direction, and on the horizontal plane, in the posterior direction. A positive sign on the vertical plane indicates inferior direction, and on symptomatic group was identified as participants who the horizontal plane, anterior direction. presented with myofascial pain, in whom a click sound could be present or absent. Pain upon palpation at three or more muscular sites had to be present (pain A wax bite registration in MIC was taken for each level $5 on a numeric scale) on masticatory muscles. patient (Figure 1). The CR bite registration (Figure 2) The muscle sites included the origin, body, and was taken according to Roth’s power centric tech- 1,10 33 insertion of the masseter; the deep masseter; the nique modified by Fantini, with the patient in a anterior, medium, and posterior temporalis; the attach- supine position and bimanual mandibular manipulation ment of the temporalis on the coronoid process; and applied to achieve the best CR available that day. No the medial and lateral pterygoid. Muscular spasm, other deprogramming method was used.