Effects of condylar fibrocartilage on the biomechanical loading of the human temporomandibular joint in a three-dimensional, nonlinear finite element model.

The present study was undertaken to test a hypothesis that the addition of articular fibrocartilage in the condyle of the temporomandibular joint reduces three-dimensional stress distribution in the condyle, the disc and articular eminence. A three-dimensional, nonlinear finite-element model was developed for analysis of joint loading before and after the addition of condylar fibrocartilage to the osseous mandibular condyle reconstructed from spiral computer topography data. In the model, each of the disc, condyle and articular eminence was arbitrarily divided into five regions: the anterior, posterior, medial, lateral and central. Von Mises stresses that in virtually all regions of the disc, condyle and articular eminence became lower after the addition of condylar fibrocartilage. Especially remarkable was the approximately four-fold reduction in von Mises stresses in the anterior, central and medial regions of the mandibular condyle. In comparison, only slight to moderate stress reductions occurred in the disc and articular eminence, suggesting that condylar fibrocartilage absorbs considerable stresses and likely dampens more loads than the disc and articular eminence. The mandibular condyle demonstrated the largest total displacement in all directions after the addition of articular fibrocartilage, followed by the disc and articular eminence. We conclude that the addition of articular fibrocartilage primarily reduces loading of the mandibular condyle, rather than the disc and articular eminence. These findings lead to a hypothesis that the mandibular condyle more likely functions as a shock absorber than the disc.