Excitatory response of jaw elevators associated with sudden discomfort during chewing.

Abnormalities associated with the chewing contraction of the masseteric and anterior temporal muscles were evaluated in patients who sensed pain in the area of the temporomandibular joint during mandibular movement. The patients were instructed in the use of an electronic switch to mark any event of discomfort/pain during natural chewing. Individual stimulus to response reaction-times were determined. The electromyographic pattern of the jaw elevators was quantified by root mean square (r.m.s.) peak voltage and contraction time. The statistical analysis of group data showed significantly prolonged contraction times and greater r.m.s. amplitudes for chewing cycles with, compared to cycles without, indication of pain. Also, individual data showed statistically significant differences between painful and non-painful cycles in some cases. It is concluded, that the conscious perception of nociception during the closing phase of chewing is associated with an excitatory response of jaw elevators.