Comparing the accuracy of Demirjian and Nolla methods and establishing a new method for dental age estimation in northeastern Chinese children

Abstract

Dental age estimation plays an important role in the field of clinic medicine and forensic medicine. The Demirjian and Nolla methods are common scoring methods for dental age estimation but there was no research about the comparison of accuracy of these two methods in northeastern Chinese children. Hence, in this study, we compared the accuracy of these two methods to explore more suitable method for our studied population. We collected 535 orthopantomograms from northern Chinese children aged from 6 to 15 years and divided them into training dataset and testing dataset according to the ratio of 7:3. The dental age of training dataset were estimated using Demirjian and Nolla methods, respectively. The results suggested that the mean differences of these two methods were 0.24 and −0.40 years, and mean absolute difference were 0.65 and 0.59 years. Then to further improve the accuracy of dental age assessment, the new improved formulas and dental age conversion tables were established after analyzing the relationship between the sum scores based on Nolla method and chronology age in training dataset. According to the new method used in testing dataset, the minimum value of mean difference (0.00) and mean absolute difference (0.49) were obtained, which are largely smaller than that of Demirjian and Nolla methods. The new developed method and dental age conversion scales may be more suitable dental age estimation method for northeastern Chinese children.

Key points

• We collected 535 orthopantomograms from northern Chinese children aged from 6 to 15 years and divided them into training dataset and testing dataset according to the ratio of 7:3.

• The mean differences of Demirjian and Nolla methods in training dataset were 0.24 and −0.40 years, and mean absolute difference were 0.65 and 0.59 years.

• The new improved formulas and dental age conversion tables were established after analyzing the relationship between the sum score based on Nolla method and chronology age in training dataset.

• According to the new method used in testing dataset, the minimum value of mean difference (0.00) and mean absolute difference (0.49) were obtained, which are largely smaller than that of Demirjian and Nolla methods.

Keywords:

• Forensic science
• forensic odontology
• dental age estimation
• Demirjian method
• Nolla method
• northeastern Chinese children

Authors’ contributions

Ying Liu and Lagabaiyila Zha designed the experiments and revised the manuscript; Dan Wen and Zhiyu Ding performed the experiments, analyzed the data, and drafted the manuscript; Zhikai Tian and Wenshuang Wu collected the data; Weifeng Qu, Wei He, Chudong Wang, and Jienan Li participated in the experiments and data analyses. All authors contributed to the final manuscript and approved it.

Compliance of ethical standards

Written informed consent was obtained from parents or guardians of all participants in this study. Ethical approval was obtained from the Ethics Committee of Xiangya Hospital of Central South University.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This project was supported by the National Natural Science Foundation of China [grant number 81871533 and 82002005], Natural Science Foundation of Hunan Province [grant number 2020JJ4779 and 2020JJ5787].