CHANGES IN ELECTRICAL-ACTIVITY OF MASSETER AND TEMPORAL MUSCLES AFTERTEMPOROMANDIBULAR-JOINT SURGERY - A ONE-YEAR FOLLOW-UP

The functioning of the masseter and anterior temporal muscles was reco rded by electromyography (EMG) in 15 patients with disc interference o f the temporomandibular joints, before surgery and three months, six m onths and one year afterwards. EMG recordings were made during maximal bite in intercuspal position and while chewing. The mean electrical a ctivity in the masseter and anterior temporal muscles, both on the ope rated and nonoperated sides, decreased markedly three months after sur gery, especially during maximal bite in intercuspal position, but incr eased to above the preoperative values at the one-year recording in bo th functions. Statistically, significantly lower activities were seen on the operated side in patients with anterior dislocation of the disc without reduction, as compared to patients with reduction df the disc . The EMG activities of the masseter muscles on the nonoperated side w ere significantly lower in women and in older patients, as well as in patients with a longer duration of symptoms than in men and younger pa tients.