Accuracy of the Demirjian and Willems methods of dental age estimation for children from central southern China.

The aim of this study was to compare the accuracy of the Demirjian method and the Demirjian method as revised by Willems for age estimation based on orthopantomograms from central southern Chinese Han population aged 8-16 years. Discrepancies between chronological and estimated ages were statistically evaluated by analyzing 1249 orthopantomograms from 603 girls and 646 boys. Using the Demirjian method, the mean age estimates underestimated chronological age by 0.03 years (p = 0.48) for girls and overestimated it by 0.03 years (p = 0.59) for boys; these differences with respect to chronological age were not statistically significant. In contrast, the Willems method underestimated chronological age by 0.54 years (p < 0.01) for girls and 0.44 years (p < 0.01) for boys; these differences with respect to chronological age were statistically significant. Compared to the Demirjian method, the overall mean absolute error generated using the Willems method was slightly higher (0.85 and 0.86 years, respectively). Since the Demirjian method was more accurate, we highly recommend that it should be applied when estimating dental age in the Chinese Han population. Further modifications of these two methods for populations from other regions and additional studies of other age groups are warranted.

Combining the third molar mineralization to further improve the accuracy of the Kvaal's method in dental age estimation of subadults in northern China.

The morphological changes based on deposition of secondary dentin and mineralization of the third molar have been proven to be related to chronological age. However, Kvaal's method on the theory of deposition of secondary dentin was controversial with respect to dental age estimation in the recent research. The aim of this study was to combine the parameters of Kvaal's method with relatively high correlation coefficients and mineralization stages of the third molar to improve the accuracy of predicting the dental age of subadults in northern China. A total of 340 digital orthopantomograms of subadults aged from 15 to 21 years were analysed. A training group was used to test the accuracy of the original Kvaal's method and to establish novel methods for subadults in northern China. A testing group was used to compare the accuracy of the newly established methods with the Kvaal's original method and with published method specifically used in northern China. To increase the feasibility of our estimation model, we combined the mineralization of the third molar to build a combined specific formula. The results showed that the combined specific model increased the coefficient of determination to 0.513, and the standard error of the estimate was reduced to 1.482 years. We concluded that the combined specific model based on the deposition of secondary dentin and mineralization of the third molar could improve the accuracy of dental age assessment of subadults in northern China. Key Points: The decrease in the dental pulp cavity based on deposition of secondary dentin is a useful variable for assessing age.A total of 340 orthopantomographs were used in this research, including 278 in training groups and 62 in testing groups.Original Kvaal's method underestimated the dental age for subadults in northern China.The equation of combined specific method constructed in our study was proved more suitable to calculate dental age for subadults in northern China.

Application of Cameriere's method for dental age estimation in children in South China.

The aim of this study was to evaluate the applicability of Cameriere's European formula for age estimation in children in South China and to adapt the formula to establish a more suitable formula for these children. Moreover, the performance of dental age estimation based on Cameriere's method combining the developmental information of permanent teeth (PT) and third molar (TM) was also analysed. Orthopantomographs of 720 healthy children in Group A, and orthopantomographs of 320 children and 280 subadults in Group B were assessed. The samples of Group A were divided into training dataset 1 and test dataset 1, and the samples of Group B were also divided into training dataset 2 and test dataset 2. A South China-specific formula was established based on the training dataset 1, and the comparison of accuracy between the Cameriere's European formula and the South China-specific formula was conducted with the test dataset 1. Additionally, a PT regression model, a TM regression model, and a combined regression model (PT + TM) were established based on the training dataset 2, and the performance of these three models were validated on the test dataset 2. The Cameriere's European formula underestimated chronological age with a mean difference (ME) of -0.47 ± 1.11 years in males and -0.69 ± 1.19 years in females. However, the South China-specific formula underestimated chronological age, with a mean difference (ME) of -0.02 ± 0.71 years in males and -0.14 ± 0.73 years in females. Compared with PT model and TM model, the PT and TM combined model obtained the smallest root mean square error (RMSE) of 1.29 years in males and 0.93 years in females. In conclusion, the South China-specific formula was more suitable for assessing the dental age of children in South China, and the PT and TM combined model can improve the accuracy of dental age estimation in children.Key pointsOrthopantomographs of 720 healthy children in Group A, and orthopantomographs of 320 children and 280 subadults in Group B were assessed.A South China-specific formula was established based on the training dataset 1, and the comparison of accuracy between the Cameriere's European formula and the South China-specific formula was conducted with the test dataset 1.A PT regression model, a TM regression model, and a combined regression model (PT + TM) were established based on the training dataset 2, and the performance of these three models were validated on the test dataset 2.The South China-specific formula was more suitable for assessing the dental age of children in South China, and the PT and TM combined model can improve the accuracy of dental age estimation in children.