安氏Ⅱ类1分类下颌后缩儿童的肌电研究

An electromyographic study of masticatory muscles in growing children with Class Ⅱ Division 1 malocclusion and mandibular retrusion

目的 研究安氏Ⅱ类 1分类下颌后缩儿童在姿势位 ,紧咬位及前后向运动及咀嚼运动中 ,双侧颞肌前束 (TA)、咬肌(MM)、二腹肌前腹 (DA)的肌电活动规律 ,以探讨该类错牙合畸形的发生机制。方法 采用美国Myotronic公司研制的K6 I型肌电仪及双极表面电极同步记录 19名安氏Ⅱ类 1分类下颌后缩儿童上述各肌的肌电活动 ,并以同年龄段的 16名正常儿童作为对照。结果 ①姿势位时 ,后缩组DA的肌电幅值显著高于对照组 (P <0 .0 1) ;②前伸运动时 ,后缩组 3组肌群的肌电活动均显著高于对照组 ;后退运动时 ,后缩组MM、TA的肌电幅值均高于对照组 ;③ICP最大紧咬位及咀嚼运动中 ,后缩组MM低于对照组 ,DA显著高于对照组 (P <0 .0 5 )。结论 安氏Ⅱ类 1分类下颌后缩儿童与发育正常儿童相比 ,下颌后缩对升降颌肌活动能力不产生明显影响 ,但对其功能具有明显影响。

Objective To investigate the bilateral electromyographic (EMG) activity of anterior temporalis muscle (TA), masseter muscle (MM), anterior diagastric (DA) at postural position, maximum clench and during various mandibular movements in growing children with mandibular retrusion. Methods A computer integrated K6 I Diagnostic System with surface electrode was used to synchronously record the EMG activities of the 19 mandibular retrusion children and 16 healthy children with normal occlusion. Results There was a wider variation of EMG activities in retrusion children compared with normal control. In postural position, myo muscular activity of DA showed move active in the mandibular retrusion group. In maximum clench, MM showed lower activity with respect to normal group: DA showed higher activity than that of normal controls. During protrusive movement, activity in all muscle groups in the retrusion group were beyond that of control subjects. During retrusive movement, both MM and TA's activities were higher than control levels. In the chewing gum movement, MM showed lower activity but DA showed higher activity than that of normal group. Conclusion Children with mandibular retrusion have different muscle recruitment patterns from those of normal subjects at postural position and during mandibular movement. It could be concluded that mandibular retrusion does not affect the ability of mandibular movement, but affect the oral function, eg. decrease of chewing function. It demonstrates the necessity and importance of improving muscular balance in treating mandibular deformity in the early time.