• 作者： 蕭裕源; 張心涪; 陳坤智
• 作者服務機構： 國立臺灣大學醫學院牙醫學系
• 中文摘要： 咀嚼肌在緊咬時的肌電圖靜止期，近10年來屢為許多學者用為診斷顎肌機能障礙症之重要根據，認為顎肌障礙會使靜止期變長。然而靜止期變長之因素不止一端，咬合穩定與否即為重要影響因素之一。顎肌症之症狀亦頗複雜，經常與咬合不良有關聯，靜止期之變化是否來自症狀，或者因咬合不穩而致則尚未清楚。為澄清此問題，特選用不具顎肌症狀，而有不良咬合狀態之青少年31名（男19人女12人，年齡自9歲至18歲）為檢查對象，觀察其顳肌與咬肌肌電圖靜止期變化與咬合壓力強度之關係。肌電圖靜止期之測取乃於受檢者緊咬之時輕敲頦部而得，並依肌電活動靜止狀態之不同區分為純靜止（SSP），壓抑活動（DP）及二次、三次靜止期（2SP，3SP）。咬合壓力則以咬合薄膜置於上下牙間緊咬10秒後以咬合顯像器觀測其壓陷強度而得各牙之壓力百分值，並以之與肌電圖平均振幅及靜止期數據做相關比較。結果發現，SSP平均為34毫秒，而加上其他種變化，靜止期分別成為40毫秒（顳肌）及44毫秒（咬肌）。每個受檢者皆可於10次敲擊中出現一次以上之DP，18人曾顯示2SP或3SP。肌電圖之平均振幅與同側之咬合壓力或總咬合壓力之相關性甚低，而與肌電圖靜止期之壓抑活動出現次數有相當之負相關，與純靜止期，總靜止期之相關性則甚低。肌電圖之SSP+DP，SSP+2SP3SP及SSP+DP+2SP3SP與總咬壓百分值及前後牙咬壓差異之相關性亦甚低，但與左右側咬壓大小差異則相關性甚高。由此可見咬合狀態可影響肌電圖靜止期之長度及性質，但最重要的影響來自兩側咬力的不平均，而非總咬力之大小，或前後咬壓之不平均。
• 英文摘要： Electromyographic silent periods (EMG SP) and occlusal contact intensity were studied in 31 youngpatients (9-I8 years of age) having different types of malocclusion. EMG SP was induced from bilateraltemporalis and masseter muscles by chin tapping during isometric contraction. The simple silent period(SSP), depressed activity (DP) and double silent period (2SP or 3SP) were classified according to the charac-ter of silence. The occlusal contact intensity was obtained by using a polymer wafer for clenching and wasanalysed with a photocclusion analyser. It was found that the average amplitude of temporalis and massetermuscles during clenching was about 400 μV. The mean SSP was around 34 msec. The total SP was around40 msec in temporalis and 44 msec in masseter. All of the subjects demonstrated one or more DP in tentaps while 18 of them had 2SP or 3SP. The difference in contact intensity between right and left had astrong correlation with the EMG SSP+DP, SSP+2SP3SP and total SP. Anterior-posterior difference was notas strongly related to SP parameters. Less significant correlation was found between SSP and occlusal inten-sity. It is concluded that the influence of occlusion on EMG SP is basically related to the uneven occlusalcontact between the two sides rather than the total occlusal contact intensity or the difference in intensityanterior-posteriorly.
• 中文關鍵字： malocclusion; EMG silent period; occlusal contact
• 英文關鍵字： --