446名大学生下颌第三磨牙阻生情况的CBCT研究

A CBCT study of the impacted mandibular third molars among 446 college students

目的研究下颌第三磨牙阻生情况及其与周围解剖结构的位置关系。方法本研究于2020年应用CBCT观察本院2018级446名大学生下颌第三磨牙牙体形态,比较阻生类型与性别、侧别、邻牙远中牙槽骨的丧失情况、颊舌侧骨板骨密质的厚度以及牙根尖与下颌神经管的位置关系是否具有统计学意义。结果下颌第三磨牙阻生率73.77%,近中阻生率78.88%,水平阻生率11.09%,垂直阻生率4.56%。牙体形态中近远中径大于颊舌径,并与性别有统计学差异(P<0.05)。下颌阻生第三磨牙造成邻牙远中牙槽骨丧失的发生率为62.11%,丧失情况与阻生类型、牙体形态有统计学意义(P<0.05);下颌神经管的位置关系与阻生类型、性别及侧别,均无统计学差异(P>0.05);下颌近中阻生第三磨牙颊侧骨板骨密质厚度与性别、侧别无统计学差异(P>0.05),舌侧骨板骨密质厚度与性别有统计学差异(P<0.05),与侧别无统计学差异(P>0.05)。结论当前大学生群体中普遍存在下颌第三磨牙阻生的情况,且以近中阻生为主,造成邻牙远中牙槽骨丧失的比例较高。女性舌侧骨板骨密质厚度较薄,临床拔除时需注意。

Objective To study the impacted growth of mandibular third molar and its positional relationship with the surrounding anatomical structures.Methods CBCT was applied to observe the morphology of mandibular third molars among 446 college students of grade 2018 in 2020,and compared whether the type of impaction was statistically significant in relation to gender,laterality,loss of distal mesial alveolar bone of adjacent teeth,thickness of compact bone substance in the buccolingual bone plate,and the position of the root tip in relation to the mandibular nerve canal.Results The rate of mandibular third molar impaction was 73.77%,mesial impaction rate was 78.88%,horizontal impaction rate was 11.09%,and vertical impaction rate was 4.56%.The proximal and distal mesial diameters were longer than the buccolingual diameters in tooth morphology and were statistically different between genders(P<0.05).The incidence of loss of distal alveolar bone in the adjacent teeth due to impacted mandibular third molars was 62.11%,and the loss was statistically significant with respect to the type of blockage and tooth morphology(P<0.05).The position of mandibular nerve canal was not statistically different with respect to the type of impaction,gender and laterality(P>0.05).The thickness of compact bone substance in the buccal osteone of the mandibular mesial third molar was not statistically different with respect to gender and laterality(P>0.05),and the thickness of compact bone substance in the lingual-side osteone was statistically different with respect to gender(P<0.05),and no statistical difference between the thickness of lingual-side bone osteone and laterality(P>0.05).Conclusions At present,impacted mandibular third molars are common in college students,which is mainly mesial impacted mandibular third molars,resulting in a high proportion of distal alveolar bone loss in adjacent teeth.The thickness of the compact bone substance of lingual side osteone among the female is thin,which should be paid attention to in clinical extraction.