正畸拔除下颌前磨牙对第三磨牙萌出影响的测量研究

Effect of the lower premolar extraction on third molar eruption

目的:评价正畸拔除下颌前磨牙对下颌第三磨牙萌出角度和间隙的影响。方法:选取23例正畸非拔牙矫治病例(男性12例,女性11例,平均年龄13.5岁),23例拔除下颌第一前磨牙矫治病例(男性12例,女性11例,平均年龄13岁),21例拔除下颌第二前磨牙矫治病例(男性11例,女性10例,平均年龄14.07岁),在治疗前和治疗后拍摄全颌曲面断层片,测量下颌第三磨牙的轴倾角度和萌出间隙,使用SPSS 17.0软件对3组病例的数据进行配对t检验。结果:拔除下颌第一前磨牙组患者RS,LS,Rratio,Lratio在治疗后显著增大(P<0.01);拔除下颌第二前磨牙组患者RM3,LM3等指标在治疗后增大(P<0.05),RS,LS,Rratio,Lratio等指标在治疗后显著增大(P<0.01)。结论:正畸拔除下颌前磨牙较非拔牙矫治可以增加下颌第三磨牙的萌出间隙;拔除下颌第二前磨牙可以改善第三磨牙的萌出角度。

Objective： To evaluate the eruption of mandible third molar in orthodontic patients with non-extraction or extraction of the lower premolars.Methods： We selected 3 group of the orthodontic patients.One group consisted of 23 subjects（12 males,11 females,average age 13.5 years） with non-extraction.One group consisted of 23 subjects（12 males,11 females,average age 13 years） with lower first premolar extraction.One group consisted of 21 subjects（11 males,10 females,average age 14.07 years） with lower second premolar extraction.The panoramic radiography was taken.The lower third molar angulation and eruption space were measured before and after the orthodontic treatment.The comparison of treatment changes in 3 groups were performed by means of a paired-sample t test using SPSS 17.0 software package.Results： The RS,LS,Rratio and Lratio increased significantly after treatment in patients with lower first premolar extraction（P0.01）.The RM3 and LM3 increased（P0.05） and RS,LS,Rratio and Lratio increased significantly（P0.01） after treatment in patients with lower second premolar extraction（P0.05）.Conclusion： The mandibular third molars show improvement in eruption space and inclination in the orthodontic patients with lower premolar extraction.