Use of sound and jaw movement patterns to characterize patients with temporomandibular disorders

Research diagnostic criteria (RDC) have been proposed to identify subgroups in the patient population suffering from temporomandibular disorders (TMDs). To demonstrate the reliability and validity of the RDC, this study validates clinical examination findings by performing experiments to analyze jaw motion and corresponding sounds. 20 TMD patients participated in a paradigm that captured their motion profiles and temporomandibular joint (TMJ) sound production during three clinically derived movements. Movement patterns were acquired with two orthogonal CCD video cameras that recorded the motion of retro-reflective markers. Sound was recorded bilaterally from Panasonic electret microphones placed in the subject's ear canals. During opening from normal occlusion, clicks occurred predominately in the final 75% of the opening phase. When opening immediately following protrusion, clicks predominately occurred during protrusion prior to opening. Movement profiles were usually significantly altered in the presence of clicks. The reduction of an anteriorly displaced articular disc in the TMJ is proposed as a source of the clicks and can explain the increased percentage of clicks during protrusion and the motion profile changes. Correlation between TMJ sound and jaw motion has been established and is to be employed to classify a larger sample of TMD patients