Abstract
The purpose of this study was to investigate adaptation of the masticatory muscles to the altered jaw relationship that had been brought by orthognathic surgeryin patients with jaw deformities.
The subjects were 5 patients with jaw deformities, and the control group was 19 people with normal occlusion. The masseter and the anterior temporal muscle activities at the maximum clenching were measured at the initial examination, 6 months, and 1 year after operation by electromyography. The activity index of relating masseter muscle to temporal muscle was calculated.
The results were as follows:
1. The activity index increased 1 year after orthognathic surgery. This result showed that the masetter muscles had beengetting work more active than temporal muscles like the control group.
2. The patterns of the increase in the activity index of jaw deformity cases varied individually.
