An electromyographic study of the immediate effect of an occlusal splint on the postural activity of the anterior temporal and masseter muscles in different body positions with and without visual input

Abstract

With the mandible at rest, the clinical postural position was measured and electromyographic recordings (in seated and supine position, eyes open and eyes closed, before as well as 15 min after insertion of an occlusal splint) were from the anterior temporal and masseter muscles in thirty-one patients with signs and symptoms of mandibular dysfunction and nocturnal bruxism. The results indicated that when the patients were seated upright, there was a distinct postural activity in the anterior temporal and in some patients also in the masseter muscles. This postural activity decreased significantly with closure of the eyes and in supine position. Fifteen minutes after insertion of an occlusal splint, the postural activity in the temporal muscles decreased in 52%, increased in 22% and remained unchanged in 26% of the patients. Moreover, the postural activity reached its lowest level in supine position. The results indicate that the supine position is the body position to be preferred for centric relation recording as well as for occlusal and splint adjustment.