Analysis of the TMJ intraarticular space variation: a non-invasive insight during mastication

The analysis of the loading of the temporomandibular joint (TMJ) appears important for the study of joint failure. Reconstruction and animation of the TMJ with real anatomic and kinematic data is currently the only method allowing a non invasive, in vivo, three-dimensional, dynamic, real-time quantitative insight into the relationship between the articulating surfaces of a joint. It consists of the software reconstruction of the joint anatomy from tomography data and the application to it of the corresponding real movement data recorded with a tracking device. Because of the physical properties of the TMJ soft tissues, the reduction of the joint space can indicate compressive loads during function. Analyses of the variation of the TMJ space in ten asymptomatic subjects during unilateral mastication showed a TMJ space that was significantly smaller during closing than during opening (p<0.05) and significantly smaller on the balancing than on the working joint (p<0.05). This occurs especially in the medial part of the posterior slope of the articular eminence at the end of the closing phase (p<0.01). Furthermore, the minimum TMJ space at the end of closing increased from the beginning to the end of food comminution (p<0.01).