拔除磨牙矫治对青少年第三磨牙牙根发育的影响

The effect on the root formation of third molars in adolescent by orthodontic molar extraction

目的:探讨发育期第三磨牙牙根在正畸拔除前方磨牙矫治后第三磨牙牙根生长特点及意义。方法:研究组32例下颌第三磨牙牙根未发育完成前接受拔除下颌第一或第二磨牙正畸治疗的青少年,追踪调查其下颌第三磨牙牙根发育完成后全颌曲面断层片上的牙根融合率、根分叉程度及根长,并与对照组35例牙根发育完成后进行拔除磨牙矫治的成人患者的下颌第三磨牙进行比较。结果:研究组牙根分叉率、分叉程度均高于对照组,差异有显著性;牙根长度两者相仿。结论:下颌第三磨牙牙根分叉不足、融合可能是因空间不足受挤压所致,在牙根发育完成前获得充足的空间,牙根将发育得更充分;正畸利用、保留第三磨牙宜选择在第三磨牙牙根未发育完成前进行。

Objective：To investigate the characteristic of the root formation of mandibular third molars by orthodontic treatment with molar extraction in developing stage.Method：The study group consisted of 32 orthodontic cases by extraction of first or second molars prior to the completeness of the root formation of mandibular third molars.35 orthodontic cases with naturally complete root formation served as control.After the completeness of root formation of the study group,the ratio and degree of separate root and the length of root of mandibular third molars were compared with the control group by the orthopantomography.Result：The ratio and degree of separate root of mandibular third molars in the study group were significantly higher than those in the control group,while the length of root was similar.Conclusion：The fused root of mandibular third molars might be caused by being impacted in the insufficient space.With abundant space prior to the completeness of root formation,roots can fully develop.Treatment of the reservation of third molars should be carried out before the completeness of root formation of third molars.