青少年下颌第三磨牙生长发育与下颌骨相关变量的分析

Analysis of the Relationship between the Growth of the Mandibular Third Molar and Some Relative Indices in Teenagers

目的分析青少年第三磨牙的生长发育与下颌骨相关变量的关系,为临床和基础研究提供参考依据。方法随机抽取全景片1177张,通过相关指标的测量分析,研究下颌骨第三磨牙的生长发育规律。结果牙齿先天缺失率为12.02%;第二磨牙后间隙BX和第三磨牙牙冠宽度比值与磨牙后间隙长度(MD/BX)12岁组、13岁组、14岁组和20岁组都与下一年龄组有显著性差异;下颌第三磨牙倾斜角男女之间,各年龄组之间均无统计学差异。结论青少年下颌骨第二磨牙后间隙会不断地增长,其中12~14岁生长显著。第三磨牙倾斜角随着年龄的增长由正态分布变为一部分倾向直立,另一部分更加倾斜的偏态分布。

Objective Analysisof the relationship between the growth of the mandibular third molar and some relative indices in teenagers, and to provide reference for clinical and basic research.Methods Randomly select 1177 panoramic radiographs, then, study the growth and development of the mandibular third molar through measuring relative indices.Results The frequency of congenital missing mandibular third molar is 12.02%.There are statistically change in BX and MD/BX between the 12, 13, 14, 20 years old group and the right after group.There was no statistically change in the mandibular third molar angle of inclination in all groups.The comparison between male and female also like this.Conclusion The mandibular third molar eruption space is increasing at the period of 12-22.Moreover, the obviously increasing age is 12-14.The angle of inclination changes were normal distribution at first.According to the growth, some became up-right, the other became more inclined.