Reproducibility of 2 methods to locate centric relation in healthy individuals and TMD patients

No conclusive evidence exists for any maxillomandibular relationship as the preferable treatment position. Measurement reliability of 2 different methods to attempt to locate centric relation in control and TMD patients was assessed to determine if both methods lead to the same position. A group of 27 controls and 91 TMD patients were examined using the Research Diagnostic Criteria for TMD (RDC/TMD). Three patient groups were recruited: 27 patients with myofascial pain (MYO), 34 patients with disc displacement without reduction (ID), and 30 patients with osteoarthritis (OA). For each study participant centric relation was located with chinpoint guidance and a technique with a leaf gauge, for the controls once, for all TMD patients before and after stabilization splint treatment. The mixed model procedure revealed no significant differences between the methods, the patient groups and the time interval. However the patient groups at baseline and conclusion of treatment differed significantly from the controls. The percentage of patients (15.9%) having a coincident split-cast result for both methods was significantly smaller (P < 0.001) than the corresponding percentage (85.2%) of controls. After splint treatment, the percentage of coincident split-casts increased from 15.9% to 76.8%. Both methods are reproducible techniques to locate centric relation for control and TMD patients. However, the leaf gauge provides the clinician a different centric relation position in TMD patients than chinpoint guidance does.