下颌第二磨牙阻生的骨性与牙性指标的三维研究

Three-dimensional bony and dental measurements of mandibular second molar impaction

目的:通过CBCT测量下颌第二磨牙阻生的骨性和牙性指标,探究下颌第二磨牙阻生的机制,为临床治疗提供指导。方法:选取53例下颌第二磨牙阻生与53例下颌第二磨牙正常萌出患者的CBCT为研究对象,使用Mimics 19.0测量一般颌骨指标如SNA、SNB、ANB、Co-Gn、Co-Go、Go-Gn、W、Co-Go-Gn等,磨牙后间隙、牙冠宽度和牙弓后段拥挤度,对两组数据进行独立样本t检验和回归分析阻生相关因素。结果:阻生组与正常组在一般颌骨测量指标没有显著差异(P>0.05)。阻生组的磨牙后间隙小于正常组,下颌第二磨牙冠宽大于正常组,有第三磨牙存在的牙弓后段拥挤度阻生组显著大于正常组(P<0.05)。磨牙后间隙与阻生负相关,下颌第二磨牙冠宽和牙弓后段拥挤度与阻生正相关。结论:下颌第二磨牙的阻生与磨牙后间隙小、下颌第二磨牙冠宽、牙弓后段拥挤有关。

Objective:To evaluate the bony and dental characteristics of mandibular second molar impaction and to provide reference for clinical treatment.Methods:Pretreatment CBCT records of 53 subjects of impacted mandibular second molar were selected as impaction group,and the same number of fully erupted mandibular second molar as eruption group.Mimics 19.0 software was used to observe and measure the indexes like SNA,SNB,ANB,Co-Gn,Co-Go,Go-Gn,W,Co-Go-Gn,retromolar space,tooth size and posterior tooth crowd.Independent t test and binary linear regression were analyzed and significant difference was identified with P<0.05.Results:The impaction and eruption group did not differ significantly in respect to the bony measurements(P>0.05).Retromolar space was significantly shorter,and second molar was wider in the impaction group.Posterior tooth crowd of third molar in impaction group was statistically bigger in the eruption group(P<0.05).Conclusions:Mandibular second molar impaction seemed to be relevant to retromolar space,mesiodistal width of the second molar,and the posterior tooth crowd.