Dynamic properties of the human temporomandibular joint disc

The cartilaginous intra-articular disc of the human temporomandibular joint shows clear anteroposterior variations in its morphology. However, anterop osterior variations in its tissue behavior have not been investigated thoro ughly. To test the hypothesis that the mechanical properties of fresh human temporomandibular joint discs vary in anteroposterior direction, we perfor med dynamic indentation tests at three anteroposteriorly different location s. The disc showed strong viscoelastic behavior dependent on the amplitude and frequency of the indentation, the location, and time. The resistance ag ainst deformations and the shock absorbing capabilities were larger in the intermediate zone than in regions located more anteriorly and posteriorly. Because several studies have predicted that the intermediate zone is the pr edominantly loaded region of the disc, it can be concluded that the topolog ical variations in its tissue behavior enable the disc to combine the funct ions of load distribution and shock absorption effectively.