Evaluation of masticatory muscle activanterior digastric muscle (3·49 mV) on the left side. Overall mean activity during clenching was 66·77 9 ity by surface electromyography (EMG) is a valuable tool for diagnosing dysfunction of the masticatory 35·22 mV, which is about half that observed in healthy subjects (110·30 9 82·97 mV). During leftapparatus. However, controversy exists with regard ward movement of the jaw, activity was on average to the usefulness of the EMG for patients with highest in the left digastric, while during rightward temporomandibular disorders (TMD). Forty patients with TMD were subjected to surface EMG of movement, activity was on average highest in the right anterior temporal (AT). Our results thus indithe masticatory muscles. These patients had concate that patients with temporomandibular joint sulted because of temporomandibular pain and (TMJ) disorder show: (1) a slight increase in basal clicks. In most cases (75%), the symptoms affected tone;(2) a significantly reduced capacity for clenchthe patient's left side. Overall mean resting activity was 2·52 mV91·25 mV (s.d.), which is slightly higher ing; and (3) an apparently paradoxical inhibition of than in comparable healthy subjects (1·92 9 the dysfunctional-side AT during movement of the 1·20 mV). Mean resting activity was highest in the mandible towards that side.

Evaluation of masticatory muscle activity by surface electromyography (EMG) is a valuable tool for diagnosing dysfunction of the masticatory apparatus. However, controversy exists with regard to the usefulness of the EMG for patients with temporomandibular disorders (TMD). Forty patients with TMD were subjected to surface EMG of the masticatory muscles. These patients had consulted because of temporomandibular pain and clicks. In most cases (75%), the symptoms affected the patient's left side. Overall mean resting activity was 2.52 microV+/-1.25 microV (s.d.), which is slightly higher than in comparable healthy subjects (1.92+/-1.20 microV). Mean resting activity was highest in the anterior digastric muscle (3.49 microV) on the left side. Overall mean activity during clenching was 66.77+/-35.22 microV, which is about half that observed in healthy subjects (110.30+/-82.97 microV). During leftward movement of the jaw, activity was on average highest in the left digastric, while during rightward movement, activity was on average highest in the right anterior temporal (AT). Our results thus indicate that patients with temporomandibular joint (TMJ) disorder show: (1) a slight increase in basal tone; (2) a significantly reduced capacity for clenching; and (3) an apparently paradoxical inhibition of the dysfunctional-side AT during movement of the mandible towards that side.