正常咬合小兒와 下顎前突小兒 咀嚼筋의 筋電圖 分析

Abstract

[한글]

[영문]

Ten children with normal occlusion and another thn children with mandibular prognathosis were selected. They range in age from 6 to 12 years. The electromyographic study was limited to the anterior inferior part and posterior superior part of masseter muscle and the posterior and anterior part of the temporal muscle. The electromyogram was taken on a 4 channel Grass Polygraph Wodel VII electroencephalograph modified for electromyograph. Four pairs of surface electrodes were used exclusively, with the ear lobe as reference point. The contraction patterns of the masticatory muscles was observed in rest position, centric occlusion, mandibular protrusive and retrusive positions. In rest position electrical silences or little electrical potentials were found in four muscles in

children with normal occlusion. In centric occlusion all four muscles showed almost the same electrical activity and displayed synchoronous activity. Whe the mandible comes forward into protrusive occlusion then the activity of the temporal muscles

dropped considerably while the activity of the masseter muscles was greator than that of the temporal muscle. Coolusion in forced retruded position showed high activity of temporal muscle but the greatest changes in activity were seen in the masseter muscle. The aotivity of this muscle droped. In mandibular prognathous

children it was impossible to obtain a balanced rest position recording and electrical silence of all four muscles. The uneven contraction and electrical potential of four muscles showed in centric occlusion. An irregular action potential of all four muscles during mandibular protrusive retrusive movement was

found in mandibular prognathous children. Unfortunately in mandibular prognathous patients, although clinically normal in appearence, normal electromyography has not been achieved yet. The primary pur pose of the research reported in this paper is

to analyse the muscles contraction patterns of Korean normal occlusion children, and mandibular proganthous children, so that these comparative electromyographic studies may help in diagnosis and treatment planning for mandibular prognathosis.