The influence of mechanical input parameters on the duration of the mandibular joint electromyographic silent period in man.

The duration of the electromyographic silent period following a tap to the menton has been reported to be clinically useful in the diagnosis of mandibular joint dysfunction but not the influence of details of the tap. Using a solenoid-driven mechanical tapper, the following were investigated: in patients with joint dysfunction, effect on single muscles and position of the tap in a sequence of taps, in normal subjects, force of the tap, degree of opening of the jaw, angle of tap, and the biting force; all on the duration of the resulting silent period. No significant changes could be ascribed to any of these variables. The introduction between the teeth of wooden shims or a bite-force transducer were the only factors to change the duration. The dysfunction group had significantly longer silent periods than the normal group. It is concluded that, provided nothing is introduced between the teeth, the input parameters investigated do not influence the duration of the silent period.