关闭下颌第一磨牙失牙间隙对下颌第二磨牙牙根及牙槽骨的影响

The evaluation of the root resorption and alveolar bone loss of the mandibular second molar after closing the mandibular first molar space

目的研究关闭下颌第一磨牙失牙间隙对下颌第二磨牙牙根及牙槽骨的影响。方法回顾性分析需正畸治疗近中移动下颌第二磨牙关闭下颌第一磨牙失牙间隙的病例20例,根据失牙间隙的类型分为拔除组(10例)和陈旧组(10例)。所有病例均采用直丝弓矫治技术矫治,对下颌第二磨牙牙根长度及牙槽骨高度的变化进行测量分析。结果拔除组近远中根分别吸收(0.96±0.30)、(0.82±0.30)mm,陈旧组近远中根分别吸收(1.82±0.91)、(1.77±0.84)mm,与治疗前相比具有统计学意义(P<0.05),且牙根吸收的量与磨牙近中移动的距离呈正相关(P<0.05)。两组牙治疗前后牙槽嵴高度的变化无统计学意义(P>0.05),与磨牙近中移动的距离未见明显相关性(P>0.05)。结论在关闭下颌第一磨牙失牙间隙尤其是长距离陈旧性间隙时,要特别注意对下颌第二磨牙移动方式的控制,以减小发生牙根吸收和牙槽骨吸收的风险。

Objective To investigate apical root resorption(ARR) and alveolar bone loss(ABL) of the mandibular second molar after closing the mandibular first molar missing space.Methods Twenty patients who needed to close the mandibular first molar area were included in the study, and they were divided into extracted group(10 patients) and missing group(10 patients) according to the types of the molar area. Pre-and Posttreatment panoramic radiographs were used to measure root length and alveolar bone height of the mandibular second molar.Results The mesial and distal root length of the extracted group decreased significantly by(0.96±0.30)mm and(0.82±0.30)mm(P<0.05), and The missing group decreased significantly by(1.82±0.91)mm and (1.77±0.84)mm (P<0.05). There was a positive correlation between the EARR and the second molar mesial moving distance(P<0.05). There was no statistic difference in the changes of the alveolar bone height(P>0.05), and the tooth moving distance was not significantly correlated with ABL(P>0.05).Conclusion Space closure of missing mandibular fist molars caused EARR at the mandibular second molars. Orthodontists should control the types of tooth movement especially in closing long-distance edentulous spaces in order to reduce ARR and ABL of the mandibular second molars.