Jaw muscle activity patterns in women with chronic TMD myalgia during standardized clenching and chewing tasks.

Objective

To examine jaw muscle activity of women with chronic temporomandibular myalgia (mTMD). It was hypothesized that mTMD patients had a different masticatory muscle activity, increased work during isometric clenching, and a reduced chewing frequency as compared to TMD-free subjects.

Methods

The electromyographic (EMG) activity of temporalis anterior (TA) and masseter (MM) of 27 women with mTMD and 18 TMD-free women was recorded during clenching tasks and while chewing. EMG indices comparing the activity of paired jaw muscles were computed.

Results

Women with TMD myalgia had greater muscular work than controls (p = 0.025). The activity of TA and MM were similar between right and left sides in both groups. mTMD patients had a greater activity of MM than TA (p = 0.028). No between-groups differences were found in chewing rate.

Conclusion

Women with mTMD showed an abnormal recruitment of the jaw-closing muscles during functional tasks, which may predispose to further tissue injury.