Yang Lian-Yi, Lai Guang-Yun, Wang Jun
Department of Pediatric Dentistry, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine; National Clinical Research Center for Oral Diseases; Shanghai Key Laboratory of Stomatology and Shanghai Research Institute of Stomatology. Shanghai 200011, China. E-mail:
Shanghai Kou Qiang Yi Xue. 2020 Apr;29(2):183-186.
To determine the age medians for crown and root length completion stages of permanent teeth (except for the third molars) and to study gender differences in crown and root length completion stages by radiographic examinations.
The development of permanent teeth (except for the third molars) was evaluated from 3304 panoramic radiographs of children aged between 3 and 18 years by Haavikko's method. Statistical analysis was performed using SPSS 25.0 software package. Age medians for crown and root length completion stages of permanent teeth were calculated. Gender differences were analyzed by Mann-Whitney U test.
There were no significant gender differences in crown completion stages of central incisor and first molar, of which P values were 0.143 (for maxillary central incisor), 0.122 (for maxillary first molar), 0.191 (for mandibular central incisor) and 0.558 (for mandibular first molar), while girls were found to be ahead of boys for crown completion stages of other teeth. In maxilla, girls were found to be ahead of boys for root length completion stages except for lateral incisor, second premolar and second molar, of which P values were 0.057, 0.130 and 0.294; in mandible, except for second premolar and second molar, girls were observed to be ahead of boys for root length completion stages, of which P values were 0.428 and 0.057.
It is concluded that girls are advanced than boys for crown and root length completion stages in most teeth. There is a similarity in gender differences for crown and root length completion stages between maxilla and mandible.
确定恒牙（第三磨牙除外）牙冠和牙根长度完成阶段的年龄中位数，并通过影像学检查研究牙冠和牙根长度完成阶段的性别差异。
采用哈维科（Haavikko）法，从3304张3至18岁儿童的全景X线片评估恒牙（第三磨牙除外）的发育情况。使用SPSS 25.0软件包进行统计分析。计算恒牙牙冠和牙根长度完成阶段的年龄中位数。采用曼-惠特尼U检验分析性别差异。
中切牙和第一磨牙牙冠完成阶段无显著性别差异，上颌中切牙P值为0.143，上颌第一磨牙为0.122，下颌中切牙为0.191，下颌第一磨牙为0.558，而其他牙齿牙冠完成阶段女孩比男孩提前。在上颌，除侧切牙、第二前磨牙和第二磨牙外，女孩牙根长度完成阶段比男孩提前，其P值分别为0.057、0.130和0.294；在下颌，除第二前磨牙和第二磨牙外，女孩牙根长度完成阶段比男孩提前，其P值分别为0.428和0.057。
得出结论，大多数牙齿的牙冠和牙根长度完成阶段女孩比男孩提前。上颌和下颌在牙冠和牙根长度完成阶段的性别差异具有相似性。
