拔除第二双尖牙矫正病例(牙合)颌面的垂直向变化

目的　评价安氏 I类错畸形患者,特别是下颌平面角较大的患者拔除第二双尖牙矫正后颌面的垂直向变化,尤其是下颌平面的旋转变化。方法　24 例覆正常或较浅且下颌平面角大于均值的安氏 I类错患者(骨性与牙性均为 I类)拔除第二双尖牙,应用直丝弓技术完成矫治,25 例符合同样标准的患者由不拔牙矫正完成。对所有病例治疗前后的头颅侧位片进行描图和手工测量,比较拔牙组与非拔牙组颌面垂直向的变化。结果　对拔牙和非拔牙两组患者的头影测量结果进行的统计学比较发现,除下磨牙的伸长量拔牙组大于非拔牙组外,两组患者间颌面垂直向的变化并无统计学意义的差别。结论　第二双尖牙的拔除并不一定意味着下颌平面角的减小,对于高角前牙开倾向病例选择拔除第二双尖牙后,在矫正过程中仍需注意对后牙的垂直向控制。

The effect of second premolar extraction on vertical dimension

Objective The purpose of this study was to assess the vertical changes occurring in Class I patients treated orthodontically with second premolar extraction and to compare these changes with those occurring in Class I patients treated orthodontically without extractions.Methods 24 Class I maxillary and mandibular second premolar extraction cases and 25 class I non-extraction cases were obtained, and all of them have a larger mandibular plane angle(large than mean value) and normal overbite or open bite tendency. The pretreatment and posttreatment cephalograms of all samples were digitized, and several cephalometric variables were examined to evaluate the vertical changes occurring as a result of orthodontic treatment.Results No statistical difference in vertical changes was found between second premolar extraction and non-extraction cases.Conclusions Second premolar extraction treatment does not certainly result in counterclockwise rotation of mandible.