In vitro measurement of the frictional properties of the temporomandibular joint disc.

The integrity of the articulating surfaces of the temporomandibular joint (TMJ) is likely to be promoted by the control of stresses due to frictional forces between moving joint surfaces. Using a pendulum designed to measure the friction on the surface of the pig TMJ disc, factors such as duration of loading and degree of hydration of the disc were found to influence the amount of friction and the time-dependent changes in friction on the disc surface. The tests provide evidence in support of the hypothesis of 'weeping lubrication' on the surface of the TMJ disc.