Observation of proportionality of myoelectrical activity of anterior temporalis to masseter muscle during clenching at varied jaw positions.

Abstract

Twelve healthy subjects with an intact permanent dentition and normal occlusion were selected for sampling of myoelectrical activity of their left and right anterior temporal and masseter muscles during habitual clenching level in varied positions. The proportionality of normalized myoelectrical potentials of anterior temporal muscle to masseter muscle at ICP and RCP was greater than one, while the proportionality at PP was less than one. In the lateral position, the proportionality on the working side was approximately equal to that at RCP, while the proportionality on the non-working side was similar to that at PP. These results suggest that temporal muscle contraction can bring the mandible upward and backward whilst the masseter muscle can elevate the mandible upward and forward.