[Orthodontic surgical treatment of class III--the electromyographic effects on the masticatory and facial musculatures].

22 adult class-III patients, partly with considerable vertical excess, who required combined orthodontic-surgical treatment were investigated at the end of preoperative orthodontic treatment and six months postoperative. EMG activity was recorded for the m. temporalis, m. masseter, perioral and the floor of the mouth muscles during rest position and in six different active functions. Postoperative activities revealed a significant reduction for most muscles in almost all functions. Additionally right-left differences were reduced. This effect is regarded to be a sign of more efficient muscular action due to improved biomechanical and occlusal conditions so that defined functions can be exerted by less muscular activation.