正畸治疗中磨牙的拔除和保留(十二)——拔除磨牙与拔除前磨牙矫治牙根吸收的对比研究

目的：通过对磨牙拔除病例与前磨牙拔除病例的牙根吸收情况的对比，探讨关闭磨牙间隙是否加重牙根吸收。方法：将矫治前后下颌第二磨牙的冠根比作为判断牙根吸收程度的指标。其中拔除下颌第一磨牙病例的牙根数为72个，拔除下颌第一前磨牙病例的牙根数为74个。将测量值进行配对t检验。结果：第一磨牙拔除病例与第一前磨牙拔除病例相比，虽然矫治后下颌第二磨牙牙根吸收的程度较大，但两组间比较并无显著性差异。结论：采用拔除第一磨牙后的第二磨牙近中平移技术，并不加重矫治后磨牙牙根的吸收。

A comparision of the effects of molar and premolar extractions on root resorption

Objective:To study if closing molar spaces could cause severe root resorption through comparing the effects of molar and premolar extractions on root resorption.Method:72 roots' crown-root ratio of mandibular first molars extractions and 74 roots' crown-root ratio of mandibular first premolars extractions were analyzed with paired-t tests.Result:Root resorption of molar extractions was more severe than premolar extractions.Statistically there were no significant differences in the extent of root resorption between two groups.Conclusion:The method of mesio-translation of lower second molar couldn't aggravate the root resorption of molars.