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目的:观察上颌第一磨牙拔除后正畸近中移动第二磨牙对牙根吸收的影响。方法:选取正畸拔除上颌第一磨牙病例17例,通过头颅定位侧位片测量第二磨牙近中移动的距离,应用头影测量软件分析矫治前后上颌第二磨牙的冠根比,确定牙根吸收的量,对17例病例治疗前后第二磨牙冠根比做t检验,对上颌第二磨牙近中移动距离和冠根比进行相关分析。结果:治疗前后上颌第二磨牙的冠根比差异均有统计学意义(P<0.01),移动距离与冠根比呈正相关。结论:上颌第二磨牙近中移动会造成牙根吸收,但是吸收量较少,在临床上是可以接受的。牙齿的移动距离是影响牙根吸收的重要因素。
OBJECTIVE: To observe the effect of second molars with orthodontic movement on root resorption after maxillary first molar removal. Methods: Seventeen cases of maxillary first molar removal were selected by orthodontic extraction. The distance of the second molars moving proximally and centrally was measured by cephalometric lateral projection. The crown-root ratio of the second molar before and after orthodontic treatment was analyzed by cephalometric software to determine the root resorption The t test was performed on the crown-root ratio of the second molar before and after treatment in 17 cases. Correlation analysis was made between the maxillary second molar molar distance and the crown-root ratio. Results: Before and after treatment, the crown-root ratio of the maxillary second molar was significantly different (P <0.01). The moving distance was positively correlated with the ratio of crown-root. Conclusion: The maxillary second molars can cause root resorption but less absorption, which is clinically acceptable. Teeth movement distance is an important factor affecting root resorption.