Electromyographic evaluation of the masseter and temporal muscles activity in volunteers submitted to acupuncture

To assess the effect of acupuncture on the temporal and masseter muscles activity employing surface electromyography.

Thirty volunteers were evaluated according to three groups of acupuncture application: selected local points, selected points at distance and association of local and distant points. Bipolar surface electrodes were positioned bilaterally on the anterior portion of temporal muscle, as well as in the median region of masseter muscle. An electromyograph connected to a computer and a specific software registered the muscular activity before and after acupuncture, in the following experimental conditions: 1- Rest Position (RP); 2- Maximum Intercuspation Clenching (MIC); 3- Bilateral Molar Clenching with Cotton Rolls (BMCCR). The mean values obtained for the activities of the studied muscles were submitted to Analysis of Variance and Tukey complementary test.

The electromyographic activity of the studied muscles was lower after the application of the methods of acupuncture in the Rest, and higher after the application of the acupuncture in the Maximum Intercuspation Clenching; the electromyographic activity of the temporal muscle was higher than the masseter muscle in the Rest and lower in the Bilateral molar clenching with cotton rolls; the electromyographic activity showed to be modified after the three used methods of acupuncture in the Maximum Intercuspation Clenching. In this clinical condition, the method of long-distance acupuncture was higher than the application of local needles and the associated method.

Acupuncture provided alterations in the activity of the studied muscles, favoring conditions of rest and muscular tightness.