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目的调查蚌埠市18岁青少年下颌第三磨牙根部发育及近、远中倾斜情况,为预防青少年磨牙的阻生和提前拔出提供参考。方法随机选取2011年1月至2014年10月在蚌埠三院放射科拍摄的18岁青少年的上下颌骨全景片,观察根部发育情况并进行近、远中倾斜度的对比。结果男生第三磨牙发育29.6%在Ⅳ级,Ⅴ级占27.1%,Ⅵ级占19.9%,Ⅲ级占16.5%,Ⅱ级占6.9%;女生Ⅳ级占29.4%,Ⅴ级占28.0%,Ⅵ级占27.5%,Ⅲ级占9.6%,Ⅱ级占5.5%。在牙体长轴生长方向上,男、女生第三磨牙近中向生长所占比例分别为63.9%,65.1%;牙根发育情况男女生比较,采用确切概率法差异有统计学意义(P<0.05)。结论蚌埠地区18岁青少年下颌第三磨牙牙根的发育绝大多数尚未完成,而且多数近中倾斜,女生牙根发育较男生略早。拍摄全景片对牙根发育的了解和提前预防性拔除具有重要的参考价值。
Objective To investigate the root development of the mandibular third molars of 18-year-old adolescents in Bengbu, and to provide a reference for prevention of premature abruption and premature withdrawal of adolescent molars. Methods The panoramic images of the maxilla and mandible of 18-year-old adolescents from January 2011 to October 2014 in Bengbu Hospital were randomly selected to observe the development of the root and to compare the near-far and far-away inclinations. Results The incidence of the third molars was 29.6% in grade Ⅳ and grade Ⅴ, 19.9% in grade Ⅵ, 16.5% in grade Ⅲ and 6.9% in grade Ⅱ, while 29.4% in grade Ⅳ and 28.0% in grade Ⅴ. Grade 27.5%, Grade III 9.6%, Grade II 5.5%. In the long axis growth direction of the tooth, the third and fourth molar growth rate of male and female was 63.9% and 65.1% respectively. There was significant difference between boys and girls in root development (P <0.05) ). Conclusion The majority of mandibular third molar root development in 18-year-old adolescents in Bengbu is not yet completed, and most of them are near-mid-tilt. The root development of girls is slightly earlier than that of boys. Panoramic film photography on the root development and understanding of premature erection has important reference value.