中国北方青少年下颌第二磨牙的矿化进程与年龄的相关性
Chronology of mineralization of permanent mandibular second molar teeth and age estimation in northern Chinese children

摘要：目的 通过建立中国北方青少年第二磨牙矿化进程与年龄的线性关系推断个体年龄，并验证其在推断个体年龄是否满14周岁的准确性。方法 选取862例年龄介于8～18岁的中国北方青少年的口腔曲面断层片(OPG)，并记录所有受试者的编号、性别、出生日期、OPG拍摄日期，按照国内外应用广泛的Demirjian法评估右侧下颌第二磨牙矿化阶段。将研究对象随机分为实验组和验证组，通过Logistic回归法分析实验组数据并得出符合中国北方青少年发育规律的年龄推断公式，并通过配对卡方检验，利用验证组数据评价构建的年龄推断公式在实际应用中的准确性。结果 采用Logistic回归法得出的年龄推断公式为：Age=-17.153－0.668g+2.646S。其中g为性别，男性记为1，女性记为2；S代表右侧下颌第二磨牙的矿化程度。将数据带入方程，如果得出的年龄值<1，则推断个体年龄小于14岁；若得出的年龄值≥1，则推断个体年龄大于或等于14岁。通过对验证组数据采用配对卡方检验评价推断年龄和实际年龄的一致性，得出该公式应用于男性的准确率为92.7%，女性的准确率为88.9%。结论 基于下颌第二磨牙的矿化程度建立的年龄推断公式在判断个体年龄是否满14周岁时具有较高的准确性和应用价值，但仍需要与其他年龄推断方法相结合以进一步提高其准确性。
ABSTRACT: Objective To study the relationship between age and mineralization of permanent mandibular second molar teeth so as to validate the accuracy of the formula in estimating whether the age of the individual is over 14 years old. Methods A sample of 862 orthopantograms (OPGs) of northern Chinese children aged between 8 and 18 years was selected. All the subjects were recorded for the number, sex, date of birth, examination date and mandibular second molar development stage. The mineralization status of the second molars was assessed using the formation stages described by Demirjian et al. The sample was randomly divided into a training dataset and a test dataset. The test dataset was used to verify the accuracy of constructed age estimation formula by using paired chi-square test. Results By using Logistic regression, the age estimation formula was as follows: Age=－17.153－0.668g+2.646S, with g coded as 1 for males and 2 for females, and S as the mineralization status of second molars. If the number obtained is <1, the estimated age is under 14 years. If the number obtained is ≥1, the estimated age is ≥14 years. The paired chi-square test was used to compare the consistency between chronology age and estimated age. The accuracy rate in estimating ages was 92.7% in males and 88.9% in females, respectively. Conclusion The age estimation formula based on the development of mandibular second molars has an important value in judging whether the individual is over 14 years of age. However, it is necessary to further improve the accuracy in estimating age by combing other methods