A thin bite-force transducer with three-dimensional capabilities reveals a consistent change in bite-force direction during human jaw-muscle endurance tests.

The construction of a 2 mm-thick bite-force transducer, capable of measuring the magnitude and direction of a bite force in three dimensions, is described. The transducer is programmed to display the properties of a bite force on a computer monitor. A preliminary study was designed to test its performance. This took the form of endurance tests on three human subjects: the test was repeated on one subject. The direction of a sustained maximum incisal bite force was monitored while subjects clenched for as long as possible on the transducer. The initial bite force was directed about 10-15 degrees forward of the vertical. During the test the magnitude of the bite force was kept roughly constant but, for all four tests, its direction gradually changed until at the failure point it was nearly vertical. The consistency of the results suggests that the transducer is sufficiently accurate to be a useful tool for studying human jaw mechanics.