下顎門牙傾斜度與咬肌活性之相關性

Relationship between the Inclination of Lower Incisors and Human Masseter Muscle Activity

蔡吉陽(Chi-Yang Tsai) ； 陳玉玲(Yu-Ling Chen)

《中華牙醫學雜誌》 23卷6期 (2004/12) Pp. 464-470

https://doi.org/10.7105/CDJ.200412.0464

摘要

1954年Dr. Tweed在符合顏面美觀的條件下提出了齒顎矯正界著名的診斷三角，在測顱片上，他認為下顎門齒長軸、下顎平面及法蘭克福平面所形成的三角形為臨床上擬定治療計畫的重要依據：其中下顎門齒長軸必須和下顎平面成90度的直角，這個角度至今仍為許多矯正醫師所遵循。但這樣的角度在功能上是否恰當，必須經由驗證才可知道。本研究的目的是探討下顎門齒長軸對下顎平面夾角(IMPA)對人類最大緊咬時咬肌活性的影響。藉由表面肌電圖數值的變化，比較IMPA角較直立與較前傾時是否對咬肌活性產生影響。本研究選取20名成年正常齒列受測者用最大力氣緊咬，同時記錄咬肌表面肌電圖振幅，統計結果後，發現IMPA較直立及較前傾的兩組人，其咬肌肌電圖振幅並無統計學上的差異。由功能的觀點看，IMPA需較直立的目標並無實質意義。

關鍵字

下顎門牙角度 ； 咬肌活性 ； 肌電圖

並列摘要

Tweed reported the presently well-known diagnostic triangle in 1954. He thought that the triangle formed by the incisor axis, mandibular plane and Frankfort-horizontal plane should be the basis of making clinical treatment plans, i.e., the angle formed by the lower incisor axis and mandibular plane (IMPA) must be a right angle. This norm is still used at present by many orthodontists. His main idea was to establish normal references chosen by facial esthetics. But whether this right angle functions properly or not needs to be proven. The aim of this study was to investigate the influence of the IMPA on human masseter muscle activity. By observing changes in electromyographic (EMG) data, we were able to determine whether or not the lower incisor being upright or proclined influences masseter muscle activity. The main observation in this study was the EMG maximum clenching value (amplitude) when the overall and anterior teeth were in contact with the custom-made bite registration material. We found that the EMG amplitude in the IMPA upright group and proclination group showed no statistical differences. The results of this study suggest that masseter muscle function is not influenced by whether the IMPA angle is upright or not.

並列關鍵字

IMPA ； masseter muscle activity ； surface electromyography