Human dental age estimation using third molar developmental stages: does a Bayesian approach outperform regression models to discriminate between juveniles and adults?

Abstract

Dental age estimation methods based on the radiologically detected third molar developmental stages are implemented in forensic age assessments to discriminate between juveniles and adults considering the judgment of young unaccompanied asylum seekers. Accurate and unbiased age estimates combined with appropriate quantified uncertainties are the required properties for accurate forensic reporting. In this study, a subset of 910 individuals uniformly distributed in age between 16 and 22 years was selected from an existing dataset collected by Gunst et al. containing 2,513 panoramic radiographs with known third molar developmental stages of Belgian Caucasian men and women. This subset was randomly split in a training set to develop a classical regression analysis and a Bayesian model for the multivariate distribution of the third molar developmental stages conditional on age and in a test set to assess the performance of both models. The aim of this study was to verify if the Bayesian approach differentiates the age of maturity more precisely and removes the bias, which disadvantages the systematically overestimated young individuals. The Bayesian model offers the discrimination of subjects being older than 18 years more appropriate and produces more meaningful prediction intervals but does not strongly outperform the classical approaches.

Estimating age and the likelihood of having attained 18 years of age using mandibular third molars

“…An over-estimation at early root stages and under-estimation at late root stages was noted by Thevissen et al using a sample of 780 aged 16-22. 38 Our considerably smaller sample also showed this pattern. Thorson and Hägg 39 found a systematic bias, under-estimating age that increased with age from a sample of 375 aged 14-25.…”

“…Previous reports are 1.3 and 1.5 years in males and females respectively 7 and 1.13 years using a polynomial and Bayesian approach. 38 It is unclear if these studies used independent target and reference samples. Mean absolute difference using M3 to estimate age differed considerably to the value of 0.66 year using earlier developing teeth and the method of Willems et al 41 (n = 827 developing teeth, n = 946 age 3-16 years).…”

Human age estimation from lower-canine pulp volume ratio based on Bayes’ theorem with modern Japanese population as prior distribution

“…As mentioned above, inverse regression is not appropriate for age estimation unless the age distribution of the target sample is same as that of the reference sample. Since the critique by Bocquet-Appel and Masset (1982) of the conventional regression approach (inverse regression), the Bayesian approach has been a promising methodology for a new ageestimation scheme (Lucy et al, 1996;Buckberry and Chamberlain, 2002;Gowland and Chamberlain, 2002;Storey, 2007;Kimmerle et al, 2008;Konigsberg et al, 2008;Nagaoka et al, 2008;Coqueugniot et al, 2010;LangleyShirley and Jantz, 2010;Thevissen et al, 2010;Nagaoka et al, 2012a, b). The Bayesian approach takes the age distribution of the target population (referred to as prior distribution) into the probability calculation and, therefore, the answer (referred to as posterior distribution) circumvents the above-mentioned problem as it is customized to the target population.…”

Statistical methods to assess the reliability of measurements in the procedures for forensic age estimation

“…In forensic science, anthropology, and archaeology, many studies deal with the estimation of chronological age in humans, but few are devoted to studying the accuracy and reliability of the results. The most widespread methods for age estimation are based on skeletal indicators such as epiphysial fusion [1][2][3], hand-wrist bones [4][5][6][7][8], changes in the pubic symphysis [9][10][11][12], fusion of cranial sutures [12,13], dental maturation [14][15][16][17][18][19][20][21][22], and combined method [23].…”