Abstract: The purpose of this study was to determine the effect of TMJ dysfunction on the recording of centric relation. Centric relation was recorded using an anterior occlusal stop and by bimanual manipulation. Changes in occlusal contacts were recorded before and after occlusal splint therapy in six subjects with TMJ dysfunction. The pantographic reproducibility index and clinical signs and symptoms were used to determine the presence or absence of dysfunction. Use of the anterior occlusal stop resulted in a more posterior, superior initial tooth contact position when compared with bimanual manipulation. Occlusal contact positions were less consistent in TMJ dysfunction subjects than in control subjects. Initial occlusal contacts changed toward centric relation as the dysfunction disappeared. Final occlusal contact was found on the side where clinical signs and symptoms occurred. The condyle on the affected side appeared to be repositioned posteriorly and superiorly in most instances. Occlusal splint therapy was more effective when the splint was adjusted weekly. This study indicates the need to eliminate TMJ dysfunction before recording centric relation or adjusting the occlusion. Occlusal interferences found with TMJ dysfunction are not the same as occlusal interferences found when TMJ dysfunction is absent. Abnormal features on pantographic tracings may aid in indicating the presence of occlusal interferences. Occlusal adjustment in the presence of TMJ dysfunction would result in erroneous occlusal reduction.

Abstract: Repeatability of the centric jaw relation recorded with the one-handed push-back technique was tested on six subjects. Condylar positions were radiographically recorded using cold cure acrylic indices to lock the jaws in centric. This was done on two occasions with an interval of 1 week between recordings. Utilizing the subtraction technique, the radiographs of these condylar positions were compared. Intra-individual differences were not found to be significant and it may be concluded that centric relation registered with the push-back technique results in accurate and consistent repositioning of the condyles in the glenoid fossa.

Abstract: An indirect method to locate the first tooth contacts in centric relation was described in this study. Mounted casts with an associated table and styli were used to locate the position of contact points in three planes. The method was tested using the anterior occlusal stop with chin point guidance and bimanual manipulation for recording centric relation. Ten records from one subject were analyzed statistically for each method. At the p less than .05 level of significance, the anterior occlusal stop produced a centric relation position more posterior than that found with bimanual manipulation. There was no statistically significant difference in the vertical and mediolateral planes. The anterior occlusal stop method produced more consistent tooth contacts in all three planes. The centric relation points found on the recording plates correlated well with the initial tooth contacts marked on the cast. This indirect method is an accurate means of recording and reevaluating changes in tooth contact positions in three planes.

Abstract: A new method for analyzing centric interocclusal records is easily adapted to a Whip-Mix (Whip-Mix Co., Louisville, Ky.) articulator using items available in dental supply catalogs and flags readily cast in any dental laboratory. If a constant vertical dimension of occlusion is used or a hinge axis point is accurately located, the instrument can verify that two centric relation records are identical. The importance of accurate centric interocclusal records when preparing a reconstruction or making a diagnostic mounting cannot be overstated. Centric interocclusal records are made of many different materials, and the literature is replete with information regarding the importance of accuracy in centric interocclusal records.‘-4 There are several methods in current use to verify or evaluate centric interocclusal records, but none is as easy or accurate as the method presented in this article.‘-* This new device for analyzing centric interocclusal records, easily made for a Whip-Mix or Stuart (Stuart Instrument and Pantograph Co., Ventura, Calif.) articulator, will determine the accuracy of centric interocclusal records by permitting evaluation of the position of the mandible in relation to the maxillae in three planes. The direction of the error in record making can be determined, the accuracy of the hinge axis location can be evaluated, the changes in the hinge axis during temporomandibular joint resolution can be recorded, and the differences in materials used to make interocclusal records can be evaluated. In addition, the analyzer can be used as a teaching aid to analyze operator variability in making centric relation records.