Age estimation in northern Chinese children by measurement of open apices in tooth roots.

The aim of this study was to assess the accuracy of Cameriere's methods on dental age estimation in the northern Chinese population. A sample of orthopantomographs of 785 healthy children (397 girls and 388 boys) aged between 5 and 15 years was collected. The seven left permanent mandibular teeth were evaluated with Cameriere's method. The sample was split into a training set to develop a Chinese-specific prediction formula and a test set to validate this novel developed formula. Following the training dataset study, the variables gender (g), x 3 (canine teeth), x 4 (first premolar), x 7 (second molar), N 0, and the first-order interaction between s and N 0 contributed significantly to the fit, yielding the following linear regression formula: Age = 10.202 + 0.826 g - 4.068x 3 - 1.536x 4 - 1.959x 7 + 0.536 N 0 - 0.219 s [Symbol: see text] N 0, where g is a variable, 1 for boys and 0 for girls. The equation explained 91.2 % (R (2) = 0.912) of the total deviance. By analyzing the test dataset, the accuracy of the European formula and Chinese formula was determined by the difference between the estimated dental age (DA) and chronological age (CA). The European formula verified on the collected Chinese children underestimated chronological age with a mean difference of around -0.23 year, while the Chinese formula underestimated the chronological age with a mean difference of -0.04 year. Significant differences in mean differences in years (DA - CA) and absolute difference (AD) between the Chinese-specific prediction formula and Cameriere's European formula were observed. In conclusion, a Chinese-specific prediction formula based on a large Chinese reference sample could ameliorate the age prediction accuracy in the age group of children.

Studies of the chronological course of third molars eruption in a northern Chinese population.

Dental age estimation is of great importance for individual identification in forensic medicine and many other fields of study. Among them, tooth eruption is a parameter developmental morphology that can be determined by clinical examinations or by dental X-rays. The purpose of present research is to study the chronological course of third molars eruption in a Chinese population and compare that with other ethnic population for age estimation. A total of 1135 conventional orthopantomograms from 506 male and 629 female northern Chinese subjects aged between 11 and 26 years were analyzed. The eruption status of the third molars was assessed using the developmental stages described by Olze et al. Results showed that the third molars 18, 28, 38 and 48 in the stage A showed significant younger average age in males than in females. The Olze's stage A could be used as a reference stage to determine whether a male or female northern Chinese is likely to be equal or above age 16, with 99.6-100% and 97.4-98.1% of correct predictions, respectively. The stage D was found to be a useful marker for diagnosing age under 16 years, with 98.9-100% and 100% of correct predictions in males and females, respectively. There were some significant differences of the chronological course of the third molars eruption in different ethnic groups, which indicated that population-specific standards could enhance the accuracy of forensic age estimation based on third molar eruption.

The influence of impaction to the third molar mineralization in northwestern Chinese population.

Age estimation by third molar mineralization has been developed for a period of time. Recent studies showed that impaction status has an influence on the rate of the third molar mineralization in Europids and male Black African populations. In this regard, the present study was conducted to determine whether the impaction status could delay the chronological process of third molar mineralization in northwestern Chinese population too. A total of 3,512 digital orthopantomograms of 1,255 male and 2,257 female northwestern Chinese subjects aged from 11 to 26 years were assessed based on the formation stages described by Demirjian et al. with two modifications. Mineralization stage and impaction status were determined for all third molars. Statistical measures were calculated at stages C-H in the male and female gender for both impacted and non-impacted third molars. It was ascertained that the mean ages with impacted third molars at stages C-H were 0.02-1.42 years higher in males and 0.04-1.52 years higher in females than those with non-impacted third molars, but statistical differences were only found at stages C, D, and E in males and stages D and E in females. The probabilities of being under 14, 16, or 18 years of age with non-impacted third molars were all higher than those with impacted third molars. The results prove that impacted third molars show significant slower mineralization than non-impacted ones at stages D and E in both males and females of northwestern Chinese population. It is recommended to consider the influence of impaction on the rate of third molar mineralization for dental age estimation.