Evaluation of EMG profiles of masticatory muscles in orthognathic surgery patients with mandibular prognathism using the cross-correlation technique

Abstract

We investigated the EMG profiles of masticatory muscles in orthognathic surgery patients with mandibular prognathism during gum chewing. Vertical jaw movement and EMG activities from the bilateral anterior temporal, the masseter and the anterior belly of the digastric muscles were recorded simultaneously in 12 healthy adults and 12 patients. Normalization was achieved by setting the mean value of each EMG over the chewing cycle to 100%. The degree of similarity and time lag for each EMG profile between normal subjects and patients were investigated using the cross-correlation technique. The EMG profiles for the normal subjects were similar in shape and had little time lag. However, on the working side the profiles for patients were similar in shape but had considerable time lag. On the non-working side, the shape was not similar, but there was no time lag.