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目的:调查第三磨牙的发生和发育情况。方法:对870名8～18岁青少年全牙列曲面断层片进行统计分析。结果:第三磨牙牙胚发生率趋于稳定的时间下颌早于上颌约1年;男14岁,女13岁起第三磨牙的发生率趋于稳定;上颌第三磨牙缺失率约为17%,下颌约为12%;个体缺失4个、3个、个和1个第三磨牙的比例分别是5.06%、23.86%、8.92%和10.84%;上颌第三磨牙与第二磨牙的牙冠近远中宽度比主要集中在0.9+0.1,而下颌集中在1.0+0.1的范围内;第三磨牙的发育阶段个体年龄差异较大。结论:对第三磨牙的发生、发育及牙冠大小的评估对于口腔各专业学科均有参考价值。
Objective: To investigate the occurrence and development of the third molars. Methods: Eighty-eight adolescents aged 8 to 18 years with total dentition surface were collected for statistical analysis. Results: The incidence of the third molar tooth germ tended to be stable at about one year earlier than the maxillary mandibular. The incidence of third molars from the age of 14 and 13 years old was stable. The maxillary third molar loss rate was about 17% , The mandible was about 12%; the proportions of 4, 3, and 3 third molars missing were 5.06%, 23.86%, 8.92% and 10.84% respectively; the crowns of the maxillary third molars and the second molars The ratio of distance to center was mainly in the range of 0.9 + 0.1, while the mandible was in the range of 1.0 + 0.1. The age of the third molars was significantly different among individuals. Conclusion: The evaluation of the occurrence and development of the third molars and the size of the crowns is of reference value to all major disciplines in oral cavity.