An electromyographic investigation of patients with a normal jaw relationship and a Class III jaw relationship

Abstract

The method of analyzing the electromyographic data from patients has been described, and the results of the investigation of twenty adult patients with normal occlusion, twenty children with normal occlusion, fifteen patients with skeletal Class III malocclusion, and fifteen patients with postural Class III malocclusion have been presented. Each patient was recorded in the protruded contact, retruded contact and intercuspal positions. A group of Class III patients who had received orthodontic treatment were recorded after treatment and out of retention, and this group was also investigated. The results showed that the best jaw position for discrimination between the groups was the intercuspal position and that, following orthodontic treatment, the muscle activity returned to a more normal pattern of activity.