Masseter and temporal muscle electromyographic activity change in patients after orthognathic surgery

Jaw size and position abnormalities are a widespread pathology of the maxillofacial region. Orthognathic surgery is in many cases the only and/or optimal treatment method in such patients. Surgical intervention aimed at changing the spatial relationships of the jaws changes the functioning of the entire stomatognathic system, primarily affects the masticatory muscle group. Functional state of masseter and temporal muscles can be objectively assessed by superficial electromyography. Materials and methods. A total of 29 patients with skeletal abnormalities of the jaws (skeletal classes II and III) were included in the study. The control group consisted of 30 healthy volunteers. Superficial electromyography was performed in patients before surgery, 3 and 6 months after. Results. In the postoperative period, an increase in the EMG activity of the temporal muscles was found at 3 and 6 months after surgery compared to the values before surgery. A decrease in the activity of the masticatory muscles proper was also found at a period of 3 months after surgery with a gradual increase in activity after 6 months (however, the values did not reach the indicators before surgery). Conclusion. Orthognathic surgery has a significant impact on the functioning of the masticatory muscle group. Longer follow-up is required to assess the long-term effect of surgical treatment of jaw abnormalities in size and position on the masseter muscle group.