Twin-block矫治器治疗下颌后缩安氏Ⅱ~1类错儿童咬肌厚度变化

Masseter muscle thickness changes with twin-block appliance in children with class II division 1 malocclusion and mandibular retrusion

目的研究Twin-block矫治器(TB)治疗下颌后缩安氏Ⅱ1类错儿童咬肌(masseter muscle,MM)厚度变化。方法选取下颌后缩安氏Ⅱ1类错儿童15例,分为TB治疗组和对照组。采用超声成像技术测量0、1、3、6个月两组受试者姿势位及紧咬位MM厚度,计算各指标均值和厚度不对称性指数,并比较组间及组内在不同时间相应指标的差异。结果①TB治疗过程中,MM在姿势位及紧咬位厚度先减小后增大,具有统计学意义;②MM厚度不对称性指数显著性下降,肌肉不平衡性改善。结论TB能消除异常肌功能状态,去除错形成的不利因素,改善口颌肌肉协调性,是一种良好的肌肉训练装置。

Objectives To evaluate the change of thickness of masseter muscle （MM） before and after treatment with Twin-block （TB） appliance in children with Class Ⅱ division 1 malocclusion and mandibular retrusion. Methods Fifteen children with Class Ⅱ malocclusion and retruded mandible were selected and divided into the TB treatment group and the control group. By using uhrasonography, the thickness of bilateral masseter muscles was measured at mandibular postural position （MPP） and at maximal voluntary clenching position （MCP） after 0,1,3,6 months for both groups respectively. Statistical analysis was performed to compare the means of the corresponding parameters and the AILCSD （asymmetry index of local cross-sectional dimension） of masseter muscles between groups, as well as the parameters among O, 1,3,6 months in each group. Results ①MM thickness at MPP and MCP during the treatment decreased first and then increased with statistical significance;②AILCSD of MM decreased significantly and compensated the imbalance of MM. Conclusions TB appliance is a muscular training device to eliminate the muscular abnormal function and disadvantage of malocclusion, which improves the coordination of the oral-maxillofacial muscles.