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KMID : 0376319900020010145
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Dental Journal of CNU
1990 Volume.2 No. 1 p.145 ~ p.152
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AN ELECTROMYOGRAPHIC ANALYSIS OF SOME MASTICATORY MUSCLES IN ANGLE’S CLASS Ⅲ MALOCCLUSION WITH ACTIVATOR
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Kim Yeong-Seog
Yang Kyu-Ho
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Abstract
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The purpose of the present study was to investigate the influence of activator on EMG activity of some masticatory muscles in Angle Class Ⅲ malocclusion. The subjects were consisted of 23 children with Class Ⅲ malocclusion, 13 boys and 10 girls, ranging in age from 7 to 12 years(mean 8.9 years).
The EMG activity from the anterior temporal and masseter muscles was recorded during maximal biting in centric occlusion before, immediately after, twenty days and three months after wearing the activator.
The following results were obtained ;
1. Before wearing the activator, there was no significant difference in EMG activity between the masseter and anterior temporal muscles.
2. Immediately after wearing the activator, the EMG activity in the masseter and temporal muscles was markedly reduced.
3. Twenty days after wearing the activator, the EMG activity in the masseter and temporal muscles was markedly increased compared to that obtained immediately after wearing the activator and was not significantly different from that obtained before wearing the activator.
4. Three months after wearing the activator, the EMG activity in the masseter and temporal muscles was markedly increased compared to that obtained before wearing the activator ＆ twenty days after wearing the activator.
5. The significant difference appeared in EMG activity between the masseter and anterior temporal muscles after twenty days of wearing the activator, but disappeared after three months of wearing the activator.
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