이악물기 양태, 머리자세, 하악위 등의 변화가 저작근 활성과 절치부 교합력의 크기에 미치는 영향
Effects of Clenching Mode, Head Posture, and Mandibular Position on the Magnitude of Masticatory Muscle Activity and Incisal Bite Force
소속 상세정보
문성진
한경수/여인식
KMID : 0355220040290010051
Abstract
This study was performed to investigate the electromyographic(EMG) activity and bite force according to head posture and clenching mode. Twenty four male dental students were selected for this study. They were healthy and had no masticatory problems. To reduce the subjects´ fear of dental damage and to deliver the bite force to several teeth on hard biting of the metallic sensory element of the bite force recorder, acrylic full arch wafers were adapted on both of dental arches. Surface EMG electrodes were placed over the light and the left anterior temporalis(TA), the superficial masseter(MM), and the anterior belly of digastic muscles(DA). Subjects were asked to sit upright with relaxed habitual or natural head posture, and to keep their eyes open. The sensory element was located on the incisal area and subjects were asked to bite according to instruction.
Measurements of the EMG activity and bite force were simultaneously carried out in the three head postures. natural(NHP). 45˚ upward(UHP), and 30˚ downward(DHP), and in the two clenching levels, namely, maximal voluntary contraction(MVC) and 70% EMG activity of MVC, and in two mandibular positions. The two mandibular positions were habitual and forward biting positions and two clenching modes applied here for the clenching of 70% EMG activity of MVC were controlled and voluntary contraction. Data were recorded and processed with SPSS windows® (ver. 10.0) and the results obtained were as follows:
1. In case of the anterior temporalis, there was a tendency showing increased EMG activity at forward biting positions than habitual biting positions by controlled 70% activity of MVC, but the tendency was not seen by MVC.
2. There were no significant change of the EMG activity both of the anterior temporalis and the superficial masseter by head posture. but the EMG activity of the anterior belly of the digastric muscles was significantly increased in DHP by voluntary 70% activity of MVC. Balance index(BI) and bite force also did not change according to head posture.
3. The BI of the TA and the DA were higher than that of MM by controlled 70% activity of MVC. There were no significant difference of the EMG activity bet ween controlled and voluntary contraction, on the other hand, the bite force was allowed to show a increasing tendency in voluntary contraction.
4. Bite force at incisal area were not generally correlated with the recorded value and the m of the EMG activity, and the correlationship between the bite force of incisal and molar region were significant in NHP and DHP by 100% of MVC.
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