拔牙与非拔牙矫治对下颌第二磨牙位置的改变

Position change of the mandibular second molar by extraction and none extraction treatment

目的:研究生长发育完成期患者采取拔牙与非拔牙矫治方法后下颌第二磨牙位置的改变。方法:选择两组患者各40例。第一组采取拔除下颌第二前磨牙矫治方案,第二组采取非拔牙矫治方案。术前、术后常规拍摄头颅侧位定位片测量下颌第二磨牙近远中间隙改变。根据治疗记录和X线片选取46例患者确证下颌第三磨牙是否拔除或保留。结果:拔牙组较非拔牙组均显示下颌第二磨牙远中至Xi点间间隙显著增加(P<0.05)。下颌第三磨牙在非拔牙组中较拔牙组最终更易拔除(P<0.05)。结论:第二前磨牙拔除患者可发生第二磨牙近中移动,导致磨牙后间隙增加。

Objective This study examined position changes occurring the Mandibular second molar in adult patients treated with extraction and none extraction treatment. Methods Two groups of 40 patients were selected for the study. The patients in group Ⅰ were treated with the extraction of Mandibular second premolars, while those in group Ⅱ were treated without extractions, Lateral cephalograms taken before and after treatment were used to measure position changes of the Mandibular second molar, Follow-up written treatment records and radiographs of 46 patients were examined to ascertain whether the Mandibular third molars were ultimately extracted or retained, Results The greater mean space increased in the groups treated with second premolar extractions than in the groups without extractions （P〈0.05）. The Mandibular third molars were ultimately more likely to have been extracted in the groups without extractions than in the second premolar extraction groups in this sample （P〈0.05）. Conclusion This reflects that the second molars could move mesially during treatment in the second premolars extraction subjects, which can lead to the increase of the retromolar space.