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KMID : 0355219990240040421
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Journal of Korean Academy Oral Medicine
1999 Volume.24 No. 4 p.421 ~ p.438
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Electromyographic Activity, Firing Time and Sequence of the Anterior Temporalis and the Masseter on Chewing Stroke
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12허문일/12Moon Il Her
12한경수/12Kyung Soo Han
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Abstract
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-Abstract-
This study was performed to investigate the electromyographic(EMG) activity, firing
time and sequence of the mandibular elevator muscle on gum chewing. For this study,
28 patients with temporomandibular disorders(TMD), especially internal derangement of
TM joint, and 16 dental students without any signs and symptoms in the masticatory
system were selected as the patients group and as the normal group, respectively. The
patients group was composed of 14 right and 14 left side affected patients. For
recording of EMG activity(μV) of the anterior temporalis(TA) and the masseter
muscle(MM), and measuring of firing time(millisecond) from the start of mandibular
opening movement to the firing of the muscles, BioEMG, BioEGN, and Combo program
integrated in the Biopak system(Bioresearch Inc., Milwaukee, USA) were used.
Gum chewing stroke was performed in both right and left side for several times, and
the first and the second chewing strokes were analysed and compared with regard to
EMG activity, firing time, firing sequence, correlation between EMG activity and firing
time.
The data obtained were analysed by SPSS windows program and the results of this
study were as follows :
1. In the patients group, chewing on the affected side showed higher EMG activities in
the masseter of the side than those of the contralateral side, but chewing on the unaffected side showed higher EMG activity in the masseter and in the anterior temporalis of the side than those of the contralateral side.
2. There were no difference of firing time between both sides on chewing on the affected side, but firing time in the chewing side were earlier than that of contralateral side on chewing on the unaffected side in
patients
group.
3. In the normal group, EMG activities in the masseter and in the anterior temporalis in
the chewing side were always higher than those of the contralateral side, and there
were no difference of firing time between the two sides.
4. In general, firing sequence of four muscles of both sides were ipsilateral TA, ipsilateral MM, contralateral TA, and contralateral MM in earlier order of time in both groups. Correlation coefficients between EMG
activity
and
firing time were negative value, and more significant correlation were appeared in the normal group
than in the patients group.
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KEYWORD
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