악기능장치 사용 전후 제 Ⅱ급 부정교합자의 근육활성도 변화에 관한 연구

Abstract

The pattern of EMG activity and the adaptation of muscles were investigated with Class 11 malocclusion treated with an j I functional appliance. The experimental group consisted of 15 growing children with skeletal Class II malocclusion who were being treated with an activator, and the control group were 15 growing children with Class I malocclusion and normal skeletal relationship. i A quantitative analysis of EMG activity from the anterior temporalis, masseten- posterior temporalis; anterior belly of digastric muscles was made before treatment, and after 1 week, 3 months, 6 months of treatment. 1 For the EMG recordings, the Biopak program was used and the bipolar hook electrodes were placed bilaterally on the four muscles. The EMG activity was registered during resting, swallowing: and clenching positions. The results of the investigation revealed the following: (1) In the comparison of EMG activity between the normal group and the skeletal Class II malocclusion group before treatment, after {! 1 week, 3 months, and 6 months of treatment when the appliance was removed, there was no statistically significant difference in the EMG activity during resting and swallowing positions. During clenching, however, there was significant difference in the EMG activity from the masseter and posterior temporalis muslces according to the phase of activator treatment. (2) In the comparison of EMG activity before and after treatment, during clenching, there was no statistically significant i difference for the anterior temporalis and anterior belly of digastric muscles, but the EMG activity had increased significantly for the masseter muscles while the EMG activity had decreased significantly for the posterior temporalis muscles. ; The rusults of this investigation suggest that the activity of the masseter and posterior temporalis muscles during clenching was influenced by the occlusal instability created during the course of treatment.