青少年下颌第三磨牙生长发育的锥形束CT研究

Cone-beam CT study on the growth and development of mandibular third molar in adolescents

目的基于锥形束CT(cone-beam CT,CBCT)分析随年龄增长下颌第三磨牙生长发育的变化,为临床判断是否需要预防性拔除第三磨牙提供一定参考。方法选取2015年10月至2017年10月于吉林大学口腔医院就诊的15～20周岁患者CBCT数字影像资料,采用分层抽样调查法筛选符合纳入标准的患者96例,其中男44例,女52例。共计下颌第三磨牙192颗。运用Invivo 5.4.5软件测量下颌第二磨牙与第三磨牙长轴之间的角度、下颌第二磨牙后间隙以及下颌第三磨牙牙根长度,并对下颌第三磨牙生长情况进行分类。结果不同性别患者下颌第三磨牙生长类型分布的差异有统计学意义(χ~2=14.794,P <0.05);不同年龄患者下颌第三磨牙生长类型与生长位置分布的差异均有统计学意义(χ~2=28.269、80.501,均P <0.05),其中垂直生长所占比例随年龄增长大致呈增加趋势;不同年龄患者下颌第二磨牙后间隙及下颌第三磨牙牙根长度比较,差异无统计学意义(均P> 0.05)。结论通过CBCT测量青少年下颌第三磨牙阻生角度等,为临床医生预测下颌第三磨牙生长发育的变化提供参考。

Objective To analyze the changes of growth and development of mandibular third molars with age by conebeam CT(CBCT),in order to provide a reference for clinical judgment whether it is necessary to preventively extract the third molar.Methods CBCT digital images of 96 patients(44 male and 22 female)aged 15 to 20 in the Stomatological Hospital of Jilin University from October 2015 to October 2017 were chosen.Totally there were 192 mandibular third molars.Invivo 5.4.5 software was used to measure the angle between the long axis of mandibular second molar and the third molars,the second molar posterior space,and the mandibular third molar root length.The growth situation of mandibular third molar was classified.Results There was significant statistical difference in the growth of mandibular third molars between males and females(χ~2=14.794,P<0.05).There was significant difference in the growth types and the positions of mandibular third molars between different ages(χ~2=28.269,80.501,P<0.05).The ratio of vertical growth of mandibular third molars increased roughly with age.There was no significant difference in the posterior space of mandibular second molar or the root length of mandibular third molar in patients of different ages(P>0.05).Conclusion The CBCT measurement of the impact angle of the mandibular third molar in adolescents provides a reference for clinicians to predict the growth and development of the third molar.