Wang Yun, Teng Chen, Wang Meng-Ya
Department of Orthodontics of Wannan Medical College, Wuhu 241002, China. E-mail:
Nan Fang Yi Ke Da Xue Xue Bao. 2015 Apr;35(4):536-9.
To explore the effect of intervention with unilateral mastication on masseter muscle asymmetry.
Forty-three subjects (19 males and 24 females, mean age 20.0∓0.5 years) with unilateral chewing were divided into group A0 with motivation and without intervention, group A1 with motivation and intervention, group B0 without motivation or intervention, and group B1 without motivation but with intervention. In groups A0 and A1, the motivation was removed and groups A1 and group B1 received interventions. Surface electromyography was recorded using surface electromyography in all the subjects in mandible postural position (MPP), with maximum clenching in intercuspal position (ICP) and during chewing. The sEMG of the left and right masseter muscle were separately recorded to assess the asymmetry index of the masseter muscles (ASMM) and its changes after intervention.
In groupA0, the ASMM at MPP, during maximum clenching and chewing had no obvious changes after removal of the motivation. In group A1, the ASMM at MPP, during maximum clenching and chewing were obviously decreased after intervention. In group B0, the ASMM at MPP and during maximum clenching showed no obvious changes but ASMM during chewing significantly increased after removal of the motivation. In group B1, the ASMM at MPP, during maximum clenching and chewing all decreased obviously after intervention.
Interventions can significantly improve the bilateral symmetry of the masseter muscles in subjects with unilateral chewing, and the motivation for unilateral chewing should be removed before intervention.
探讨单侧咀嚼干预对咬肌不对称的影响。
43例单侧咀嚼受试者（19例男性，24例女性，平均年龄20.0±0.5岁）分为有动机未干预的A0组、有动机且干预的A1组、无动机无干预的B0组和无动机但有干预的B1组。A0组和A1组去除动机，A1组和B1组接受干预。采用表面肌电图记录所有受试者在下颌姿势位（MPP）、牙尖交错位（ICP）最大紧咬时及咀嚼时的表面肌电图。分别记录左右咬肌的表面肌电图，以评估咬肌不对称指数（ASMM）及其干预后的变化。
A0组去除动机后，MPP位、最大紧咬时及咀嚼时的ASMM无明显变化。A1组干预后，MPP位、最大紧咬时及咀嚼时的ASMM明显降低。B0组去除动机后，MPP位及最大紧咬时的ASMM无明显变化，但咀嚼时的ASMM显著增加。B1组干预后，MPP位、最大紧咬时及咀嚼时的ASMM均明显降低。
干预可显著改善单侧咀嚼受试者咬肌的双侧对称性，且干预前应去除单侧咀嚼的动机。
