Characteristics of mentalis muscle activity during chewing

Purpose: Contraction of the mentalis muscle is known topull up the skin and alter the space of the oral vestibule. The purpose of this investigation was to study the characteristics of the surface electromyographic (EMG) activity of the mentalis muscle during chewing. Materials and Methods: Six healthy dentate subjects were directed to chew the test food, peanuts, and swallow them. A digital EMG recording device (Muscle Tester ME3000P, Mega Electronics Ltd, Kuopio, Finland) and bipolar electrodes (Blue sensor, type-N-00-S) were used to record the surface EMG from the masseter muscle, anterior belly of the digastric muscle and the mentalis muscle during chewing. Result: The EMG activity of the mentalis showed different patterns during jaw opening and closing strokes and clenching in each subjects, but the onset of mentalis activity coincided with the onset of activity of the anterior belly of the digastric muscle during chewing activity in all subjects. It was recognized that the activity of the mentalis and anterior belly of the digastric muscle began at the end of the activity of the masseter muscle. The results showed coordination between mentalis activity and the activity of the masseter muscle and anterior belly of the digastric muscle during chewing. Conclusion: These results clarify the coordination pattern of mentalis and masticatory muscle activity during chewing although individual difference was found out the subjects' characteristics of EMG patterns of mentalis and masticatory muscle during jawopening and closing movement and clenching.