AN INTEGRATED EMG STUDY OF RELATIONSHIPS BETWEEN PREFERRED CHEWING AND SIDE OF INITIAL MUSCLE PAINS

습관적(習慣的) 저작(咀嚼)과 저작근(咀嚼筋)의 동통유발(疼痛誘發)과의 관계에 대한 근전도학적(筋電圖學的) 연구(硏究)

The purpose of this study was to investigate electromyographically the relationship between preferred chewing side and side of initial muscle pains. In this study, 20 normal healthy subjects were selected , and each subject chewed randomly chewing gum for 20 minutes to establish preferred chewing side. To induce initial muscle pains, biting force of 10Kg on the gnathodynamometer was maintained by the subjects. And the Bioelectric processor EM2(Myo-Ironies Research, Inc. U.S.A.) with the surface electrodes was used to record the EMG activity during all experimental procedures. The results were as follows; 1. A majority of the present subjects (60%) had a preferred chewing side, but with few exceptions, subjects were unable to explain why a given side was preferred; explanations were only 'comfort' and 'habit' 2. The chewing, or working side was determined largely by the mean voltage of the surface electromyogram (EMG); in comparison with EMG from the non-wlring (contralateral) side, the working (ipsilateral) side showed a higher amplitude. 3. After the effort, the right masseter muscle is the most frequent site of pains, followed by the left masseter muscle, the anterior part of the right temporalis muscle and tile anterior part of the left temporalis muscle. 4. After the effort, mean voltages of masseter muscles were slightly increased, but mean voltages of temporalis anterior were slightly decreased at physiologic rest position. 5. No relationships could be established between preferred chewing side and side of initial muscle pains.