21 classII malocclusion adolescents (9 boys and 12 girls) were selected as the subjects, aged from 10.6 to 14.5 years, and the initial mean age was 12.8 years. All were treated with the modified Pendulum appli-ance. The duration for distalization of maxillary molars was from 3.2 to 5.7 months (4.3 months on average). Lat-eral cephalograms were obtained before and after distalization. Changes produced by the modified Pendulum appli-ance were analyzed with paired t tests. The mean space opening on lateral cephalograms was 7.31 mm, and maxil-lary first molar distalization accounted for 64.8% of the space,with a mean distal crown tipping of 18.64o. The rate of molar movement was 1.27 mm per month. The maxillary first molars intruded 0.69 mm,and the premolars extru-ded 1.02 mm. Lower anterior facial height increased 2.19 mm. The maxillary incisors had increased 3.39oof labial tipping and 1.13 mm of protrusion.%选择年轻恒牙牙合牙性安氏域类错牙合21例,使用改良pendulum摆型远中移动上颌磨牙3.2~5.7个月,平均4.38个月。改良pendulum摆型远中移动上颌磨牙前后拍摄X线头颅定位侧位片,对于前后的变化采用配对t检验。侧位片上显示每侧平均开出7.31 mm的间隙,上颌第一磨牙后移占间隙的64.8%,牙冠向后倾斜平均为18.64º,平均每月后移率为1.27 mm。上颌第一磨牙平均压低0.69 mm,上颌前磨牙平均伸长1.02 mm,面下1/3平均增加2.19 mm。上颌中切牙平均增加3.39º的唇倾和切端平均增加1.13 mm的唇展。
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