Liu Chufeng, Cao Yang, Zhao Zhihe
Department of Orthodontics, West China College of Stomatology, Sichuan University, Chengdu 610041, China.
Hua Xi Kou Qiang Yi Xue Za Zhi. 2003 Jun;21(3):208-10.
To investigate the development of third molar embryo and establish the normal value of posterior arch length of adolescence in Chengdu.
The samples consisted of 40 males and 41 females with Class 1 dentitions, normal second molar occlusion, no history of orthodontic treatment, and good facial balance. Cephalometry and statistic analysis were conducted for all the subject.
The normal value of posterior arch length of maxilla in male was(16.52 +/- 2.35) mm and in female was(16.42 +/- 2.55) mm. The normal length of mandible was(13.00 +/- 2.44) mm in male and(12.43 +/- 2.18) mm in female. But statistic analysis showed no gender difference. Most of the third molar embryo had been formed and their tooth crowns had been calcified, the occurrence ratio was 84.0% in maxilla and 85.2% in mandible. Most of them located in the middle and inclined mesially.
The data obtained in this study will be valuable for our clinical practice and be helpful for the study concerning dento-facial growth and development.
研究第三磨牙胚的发育情况，建立成都地区青少年后牙弓长度的正常值。
样本包括40名男性和41名女性，均为安氏Ⅰ类牙合、第二磨牙咬合正常、无正畸治疗史且面部比例协调。对所有受试者进行头影测量和统计分析。
男性上颌后牙弓长度正常值为(16.52±2.35)mm，女性为(16.42±2.55)mm。男性下颌后牙弓长度正常值为(13.00±2.44)mm，女性为(12.43±2.18)mm。但统计分析显示无性别差异。大多数第三磨牙胚已形成，牙冠已钙化，上颌发生率为84.0%，下颌为85.2%。大多数位于中部且近中倾斜。
本研究所得数据对临床实践有重要价值，有助于牙颌面生长发育的研究。
