目的 通过全景片分析成都地区12 岁青少年第三磨牙(M3)的发育情况.方法 随机抽取四川大学华西口腔医院影像资料库12岁青少年的全景片449张,根据观察的结果将M3 的发育状况进行分级统计,分析不同性别以及上下颌骨和两侧颌骨M3 的发育情况.结果 12 岁青少年M3 的发育情况为:大部分牙冠已钙化,牙冠呈帽状,而且男性与女性的发育情况差别不明显.大部分下颌M3较上颌M3 发育得更早,左右两侧M3 分别占60.69%和64.25%.上颌M3 以垂直向生长为主,下颌M3 以近中向生长为主.结论 12 岁青少年M3 牙冠大部分已经钙化,下颌发育早于上颌.%Objective To investigate the development of third molars of twelve years old teenagers in Chengdu through X -ray films. Methods Randomly selected 449 panoramic radiographs of twelve -year -olds from the database of West China Hospital of Stomatology, Sichuan University, and divided the development degree of third molars into several phrases to analysed the development status according to different genders, the left and right sides, the maxilla and the mandible. Results Most part of the crowns of the third molars of the twelve years old teenagers were mineralized. There was no significant differences between male and female about the development degree of third molars. Mostly, the development of third molars appeared earlier in the mandible than that in the maxillary. The occurrence ratio was 60.69% on the left side and 64.25% on the right side. The abnormal development direction of third molar in the maxillary appeared vertical tilting and in the mandible appeared mesial tilting more frequently. Conclusion The crowns of the twelve-year-olds' third molars were mostly mineralized. The mandible third molars appeared earlier than maxillary ones.
展开▼
