下颌第二磨牙长距离近中移动牙根吸收的研究

目的:探究下颌第二磨牙长距离(≥5 mm)近中移动后牙根吸收情况。方法:回顾性分析了36例完成病例,共45颗下颌第二磨牙。采用直接数字化全景片测量正畸前后磨牙牙根长度及轴倾角度变化。根据磨牙初始轴倾度分为A组(轴倾度<86.42°)、B组(轴倾度≥86.42°);根据轴倾度改变量分为C组(变化<10°)、D组(变化≥10°)。计算牙根吸收量并分析轴倾度对其的影响。结果:正畸前后下颌第二磨牙牙根长度缩短(P<0.01);近中、远中牙根吸收量接近(P>0.05);平均牙根吸收量为(0.97±0.40)mm。A组、B组牙根吸收量组间对比无统计学意义(P>0.05);C组、D组仅在远中牙根吸收量上对比有统计学意义(P<0.05)。结论:下颌第二磨牙长距离近中移动后牙根吸收量较小,一般不具有临床意义。磨牙轴倾度改变量对远中牙根吸收存在一定影响,磨牙缺失后应尽早开始正畸治疗。

Study on Root Resorption of Mandibular Second Molars with Long Distance Mesialization

Objective:To explore the root resorption of mandibular second molars after long distance(≥5mm)mesialization.Methods:A total of 45 mandibular second molars in 36 completed cases were retrospectively analyzed.The root length and axis inclination angle of the orthodontic molars were measured by direct digital panorama.According to the initial axial inclination of the molars,they were divided into group A(axial inclination<86.42°)and group B(axial inclination≥86.42°).According to the change of axial inclination,they were divided into group C(change<10°)and group D(change≥10°).The root resorption was calculated and the effect of axis inclination on root resorption was analyzed.Results:The root length was shortened(P<0.01).The mesial and distal root resorption values were approximately(P>0.05).The average root resorption was(0.97±0.40)mm.There was no significant difference between group A and group B in root resorption(P>0.05).Group C and group D had statistical significance only in the amount of distal root resorption(P<0.05).Conclusion:The root resorption of mandibular second molars after long distance mesialization is small and generally has no clinical significance.The change of axial inclination of the molars has a certain effect on the root resorption of the distal root.Orthodontic treatment should be started as soon as possible after the molar loss.