Jaw muscle silent periods by tooth tap and chin tap.

Electromyographic silent periods from jaw closing muscles were elicited during a clench by tapping on the chin and on selected teeth both in asymptomatic subjects and in subjects reporting symptoms of temporomandibular joint dysfunction. The mean duration in response to a chin tap was significantly shorter in the asymptomatic group than in the dysfunction group. No significant differences in mean duration elicited by tooth taps were found between groups. Other comparisons of mean durations such as among muscles, among teeth, or between chin taps and tooth taps failed to achieve statistical significance.