Surface electromyography of masticatory muscles in individuals with temporomandibular disorder submitted to acupuncture Avaliação eletromiográfica dos músculos da mastigação de indivíduos com desordem temporomandibular submetidos a acupuntura

Purpose: To assess the effect of acupuncture on the electromyographic activity of masticatory muscles in patients with temporomandibular disorder (TMD). Methods: Forty women, from 20 to 40 years old, with TMD diagnosis were assessed using the electromyography of the masseter and temporal (anterior fascicle) muscles. Participants were distributed into study group (SG), which received acupuncture treatment soon after the first assessment, and control group (CG), which received the treatment five weeks after this assessment. The electromyography was accomplished at the first evaluation (Av), immediately after one session of acupuncture (R1), and after ten sessions (R10) in the SG. The CG was evaluated at the beginning (Av) and after five weeks (R10), while waiting for the treatment. The acupuncture was carried out twice a week, for five uninterrupted weeks. Results were statistically analyzed. Results: At the rest mandibular position, the SG showed a significant decrease in the left temporal muscle activity in R1, and in the right and left temporal muscles in R10. In the CG, the activity increased in the left temporal muscle after five weeks (R10). During chewing, the activity decreased in the right masseter in the SG. Conclusion: Acupuncture reduced the temporal muscles activity at rest mandibular position, providing better muscular balance between these and masseter muscles. There was not a uniform effect of the acupuncture on the assessed muscles assessed during maximal intercuspal position and chewing, showing no improvement in the quality of their activity.