A COMPARATIVE ELECTROMYOGRAPHIC STUDY OF TEMPORALAND MASSETER MUSCLE IN CLASS I AND CLASS II DIVISION I CASES

Abstract

Aim- The purpose of this study was to record the electromyographic activity of the temporalis and masseter muscles in normal and Angle's class II division 1 cases in maximal biting in intercuspal position and during chewing and to compare the activities of the two muscles in class II division 1 cases with those of normal occlusion. Materials And Methods- 15 subjects of Angle's class II division 1 malocclusion with deep anterior overbite, skeletal class II pattern with ANB angle greater than 4° and normal mandibular plane angle were selected. The 15 normal occlusion subjects had normal overjet and overbite with class I dental arch and normal mandibular plane angle. All the subjects were male of 9-15 years of age, with full compliment of teeth particular for that age, were free of any temporomandibular joint disorder and had no history of previous orthodontic treatment. Electromyographic activity of the temporal and masseter muscles of both sides were recorded during maximal biting in intercuspal position and during chewing of peanuts. The peak to peak amplitude was obtained from the raw EMG data using the integrated software. The average peak to peak amplitude in uv were used for statistical analyses. Results And Conclusion-The results revealed that there was no statistically signicant differences in activity of the muscles of the right and left sides in both the groups. The activity of the masseter muscle in both maximal biting and chewing was signicantly higher in class I group. In class II division 1 group although the masseteric activity was higher, it was not statistically signicant. Comparison between the groups showed that the masseteric activity was signicantly higher in class 1 group for both chewing and maximal biting. The temporalis activity was also signicantly higher for class I group during chewing, but the difference in temporalis activity during maximal biting, although higher in class I group, was not statistically signicant.