Frictional Coefficient of TMJ Disc and Condylar Cartilage

Temporomandibular joint (TMJ), the only diarthrodial joint in human head, is composed of two articulating bones covered by cartilage with an extra disc between the two cartilage surfaces. The rotation and gliding motions of TMJ allow us to talk, chew, and yawn. Dislocation of the disc or degeneration of the cartilage can severely ruin the congruity and integrality of TMJ and further leads to TMJ disorders (TMD). Histology studies showed that the composition and structure of condylar cartilage do not resemble any other fibrocartilages [1], our recent study also found that the condylar cartilage is much softer than cartilage in other joints [2]. The condyle is fully covered by the disc, which glides on the condyle cartilage during daily activities [3]. Little is known about the frictional coefficients of these cartilaginous tissues in TMJ. In this study, using a novel custom-built tribometer, we propose to investigate: 1) the frictional coefficients of condylar cartilage and disc at five different regions, and 2) the dependency of frictional coefficient on sliding speed and loading magnitude.