Bilateral coordination pattern of masticatory muscle activities during chewing in normal subjects.

F ollowing studies reported by Moyers,‘,2 electromyographic (EMG) coordination patterns among the synergists during natural chewing have become of major interest in evaluating jaw functions.3,4 It may be fairly asserted that the posterior fibers of the temporal muscles act as principal stabilizers of the mandible and the masseter muscles serve as workers during natural chewing.s--. Recently, it has been suggested that EMG feedback technique may be useful in the conscious control of skeletal muscles and in treating bruxism and myofacial pain dysfunction (MPD) syndrome.*-” Despite analysis with statistically quantitative methods of evaluating the EMG activities of skeletal musc1es,12-14 the typical coordination pattern of the jaw muscles during natural chewing in normal subjects has not been well standardized. The purpose of this study was to standardize and classify the power coordination pattern among the left and right masseter and posterior temporal muscles, in terms of integrated EMG potentials per stroke during gum chewing in normal subjects.