Short-term effect of the stabilization appliance on masticatory muscle activity in myogenous craniomandibular disorder patients.

The short-term effect (4 to 6 weeks) of a stabilization appliance on masticatory muscle activity was investigated in 26 myogenous craniomandibular disorder patients. The patients were instructed to clench at 10% and 50% of their maximum clenching effort in the intercuspal position and on the appliance. Recordings were made before and immediately after appliance delivery, and 2 and 4 weeks after delivery. The average EMG activity of the masseter muscles remained the same during the period of appliance use, whereas the anterior temporal muscles showed an immediate and long-lasting reduction in activity. The appliance also resulted in an improvement in the balance of left and right masseter muscle activity. There was a minor improvement in temporal muscle symmetry at the 50% clenching level and after 4 weeks of appliance use.