Journal of Oral Medicine and Pain

Korean Academy of Orofacial Pain and Oral Medicine (대한안면통증구강내과학회)
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Effects of Mandibular Midline Shift and Difference of Mandibular Height on the Masticatory Muscle Activity

하악 정중선의 편위와 하악골의 높이차가 저작근 활성에 미치는 영향

  • Jung, Dae-Yeon (Department of Oral Diagnosis and Oral Medicine, Wonkwang University School of Dentistry and Wonkwang Dental Research Institute) ;
  • Han, Kyung-Soo (Department of Oral Diagnosis and Oral Medicine, Wonkwang University School of Dentistry and Wonkwang Dental Research Institute) ;
  • Hyun, Tae-Yeon (Department of Oral Diagnosis and Oral Medicine, Wonkwang University School of Dentistry and Wonkwang Dental Research Institute) ;
  • Kwag, Dong-Kon (Department of Oral Diagnosis and Oral Medicine, Wonkwang University School of Dentistry and Wonkwang Dental Research Institute)
  • 정대연 (원광대학교 치과대학 구강진단.구강내과학 교실, 원광치의학연구소) ;
  • 한경수 (원광대학교 치과대학 구강진단.구강내과학 교실, 원광치의학연구소) ;
  • 현태연 (원광대학교 치과대학 구강진단.구강내과학 교실, 원광치의학연구소) ;
  • 곽동곤 (원광대학교 치과대학 구강진단.구강내과학 교실, 원광치의학연구소)
  • Published : 2001.03.30
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Abstract

This study was performed to investigate the effect of mandibular midline shift and difference of mandibular height between both sides on the electromyo- graphic(EMG) activity of the masticatory muscles on clenching or gum chewing movement. For this study, 105 patients with temporomandibular disorders(TMD) were selected and panoramic radiograph were taken. Amount and side of the midline shift and height of the mandible from antegonial notch to the top of the condylar head were measured on panoramic view. $BioEMG^{(R)}$ (Bioresearch Inc., Milwaukee, USA) was used for recording of EMG activity(${\mu}V$) of the anterior temporalis and the superficial masseter on clenching or gum chewing movement. EMG activity on clenching during 533msec period were measured for activity of the starting point and the one second-after activity as the early EMG and the maximum EMG, respectively. EMG activity on gum chewing movement were measured for activity of the first and the second chewing stroke. The data collected were analysed by SPSS windows program, and the results of this study were as follows : 1. Height of the mandible was 8.06cm on right side and 8.03cm on left side, and showed no difference by age, but significantly differed by sex with higher in male subjects. 2. Mean value of the midline shift was 0.1mm with range of 0~5mm on both sides. The amount and side of the midline shift did not related with height difference of the mandible and/or the EMG activity of the masticatory muscles on clenching. 3. Prevalence of higher right side and higher left side of the mandible were almost same, and the EMG activity of higher side was not higher than that of the other side. 4. In the subjects with height difference of more than 5mm between both sides of the mandible, the early EMG activity on clenching were differed for the anterior temporalis, but the maximum activity were differed for the superficial masseter. 5. In the subjects with height difference of more than 5mm between both sides of the mandible, EMG activity of the anterior temporalis of the gum chewing side was not higher than that of the other side when chewing on the side of lower height, but in the subjects with height difference of less than 5mm, the EMG activity was higher than that of the other side.

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