Quantification of jaw reflexes evoked by natural tooth contact in human subjects

The Neurophysiology of Jaw-Closing Kinematics – a Mandible-Meets-Maxilla Narrative

“…Following the instant of the occluding tooth-contacts of deliberate, empty mouth jaw-closures (as verified by a microphone collecting the sound of collision) the EMG-activity of the masseter muscles goes first inactive, and then resumes the activity again [ [26][27][28]]. A purposedly brisk jaw closure starting from the maximal opening position to the "median occlusal position" causes a stall of 20-30 ms duration in the masseteric activity [ [29,30]].…”

“…Studies examining the duration of masseteric silent period employ pre-existing masseteric activity before the controlled tap-or push-stimulus [35,36] produced consistent and repeatable measurements of the duration of the silent period. In contrast, more variable durations of the silent period have been obtained in studies employing natural jaw-closingstimuli (almost all teeth are each sending the contact-stimulus almost simultaneously) [26][27][28][29][30]. The relatively short duration of masseteric silent periods in an experiment setting mimicking a natural jaw-closure stimulus (20-30 ms, for study [30]) could possibly be explained by the natural abundance of excitatory BAT-PMR neurons firing in the jaw-closed situation, as compared to the experiments where the inhibitory silent periods are elicited by the firing of ANT-PMRs of a single incisor tooth (44 ms, for study [36]).…”