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

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=-17.153-0.668 g+2.646 S, 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.