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目的    探讨拔除下颌第二磨牙结合多曲唇弓（MEAW）技术矫治恒牙期骨性Ⅲ类错牙合的疗效。方法    选择2005年1月至2008年2月黑龙江省口腔病防治院正畸科就诊的7例恒牙期骨性Ⅲ类错牙合非手术患者，男3例，女4例；年龄13～16岁，平均14.3岁。所有患者均采用拔除下颌第二磨牙结合MEAW技术进行矫治，对比分析矫治前后的头影测量数据。结果    矫治后所有患者磨牙关系及尖牙关系均达到中性，前牙反牙合解除，达到正常覆牙合和覆盖关系，所有患者的软组织侧貌得到改善。下颌第一磨牙平均向远中移动3.1 mm，下颌切牙平均舌向移动2.8 mm，上齿槽座点、鼻根点与下齿槽座点构成的角（ANB角）平均增加1.2°，差异均有统计学意义（P < 0.05）。结论    拔除下颌第二磨牙结合MEAW技术矫治，适用于下颌第三磨牙牙胚正常，下颌牙弓有拥挤需要拔牙且有开牙合倾向的恒牙期骨性Ⅲ类错牙合非手术患者。

Clinical application of lower second molar extraction to correction of skeletal Class Ⅲ malocclusion

Objective To study the clinical application of lower second molars extraction and treatment using MEAW in non-surgical patients with skeletal Class Ⅲ malocclusion. Methods Seven non-surgical patients of skeletal Class Ⅲ malocculsion（ male 3,female 4,age ranging 13 ～16 years old,mean age 14.3）were included in the study. They were treated by MEAW technique after extraction of lower second molars;cephalometric films at the beginning and end of treatment were analyzed using cephalometric analysis. Results After treatment,all the patients reached normal occlusion relationship,the cross bite of anterior tooth was corrected,and reached the normal overbite and overjet. The lower first molars was moved 3.1 mm posteriorly ,the lower incisors were moved 2.8 mm lingually,and the angle of ANB were increased 1.2 degree. The difference was of statistical significance. Conclusions The treatment of MEAW technique after extraction of lower second molars is suitable for the non-surgical patients of skeletal Class Ⅲ malocclusion in the period of permanent teeth,whose dental germs of lower third molar are normal,and whose dentition is crowded in the mandible,and has a tendency of openbite.