下颌第三磨牙长距离近中移动后牙根吸收的研究

目的 通过对拔除下颌第一磨牙病例的回顾性研究，探讨第三磨牙在长距离近中移动后其牙根的吸收情况，同时比较第三磨牙牙根发育完成与否对牙根吸收的影响。方法 回顾性分析32例拔除下颌第一磨牙的病例，共41颗下颌第三磨牙。根据第三磨牙牙根的发育情况，分为A组(发育完成组)和B组(未发育完成组),采用直接数字化全景片测量矫治前后下颌第三磨牙牙根的长度，研究不同发育阶段的第三磨牙在长距离近中移动后其牙根的变化。结果 A组第三磨牙在长距离近中移动后，近远中牙根分别吸收(0.07±0.66) mm、(0.09±0.62) mm,差异没有统计学意义(P>0.05);B组第三磨牙牙根继续发育，矫治结束后长度增加，差异具有统计学意义(P<0.05);B组较A组下颌磨牙近中移动距离大，差异具有统计学意义(P<0.05)。矫治结束后A组、B组近中牙根长度差异没有统计学意义(P>0.05),但远中牙根B组较A组长，差异具有统计学意义(P<0.05)。结论 下颌第三磨牙长距离近中移动后，其牙根的吸收量较小，不具备临床意义，牙根发育情况对远中牙根存在一定影响，提示临床中磨牙缺失后要在第三磨...

Study on root resorption of mandibular third molars after long distance mesial movement

Objective To explore root resorption of third molars after long-distance mesial movement through retrospective study on mandibular first molar extraction cases and to compare the effect of root development of the third molars on root resorption. Methods Thirty-two cases of mandibular first molar extraction were analyzed retrospectively, and 41 mandibular third molars were included in the study. According to root development of the third molars, they were divided into group A (root development completed) and group B (root development not completed). Length of the root was measured by direct digital panorama before and after treatment. Changes of the root at different development stages were studied after long-distance mesial movement. Results In group A, the mesial and distal roots absorbed (0.07±0.66) mm and (0.09±0.62) mm respectively, and the difference was not statistically significant (P>0.05). In group B, the third molars continued to develop and the length increased after correction,and the difference was statistically significant (P<0.05). The distance of mesial movement of mandibular molars in group B was greater than that in group A (P<0.05). There was no significant difference in the length of mesial roots between group A and group B (P>0.05) after treatment. The length of distal root in group B was longer than that in group A, and the difference was statistically significant (P<0.05). Conclusion The root resorption of mandibular third molars after long distance mesial movement is small and generally has no clinical significance. Root development has a certain impact on the distal root, suggesting that loss of mandibular first molars should be treated before the completion of root development of mandibular third molars.