Age estimation using third molars in forced migrant populations: Determining age and probability

Background: Accurate age estimation is a critical component of forensic assessment in undocumented forced migrants, as it directly influences legal protection, social support, and immigration procedures. Objectives: To develop and validate a statistical model for estimating chronological age and its probability distribution based on third molar maturity index values in forced migrants. Material and Methods: In this observational study, we employed a Bayesian Calibration approach utilizing a Normal density and an expected value modeled by a Segmented function. The model underwent calibration using a training sample consisting of 481 orthopantomographs of healthy males, gathered during routine visits spanning from 2012 to 2017. A testing sample comprising 45 forced migrant males recruited from four Italian hosting centers in 2018 was utilized to validate the model. Results: The two samples exhibited similar distributions in terms of age and dental maturity index. The model's breakpoint age was estimated at 18.6 years, suggesting a sharp decline in dental maturity rate beyond this threshold. For instance, the probability of a forced migrant being 18 years or older with a dental maturity index of 0.15 was 0.75. The mean error in age estimation was 1.57 years, with a variability of 2 years, and demonstrated a statistically significant increasing trend of 0.3 years. Discussion: The model offers, in addition to estimated age, the likelihood that an individual is of a specific age or older, taking into account their dental maturity. This provides valuable supplementary information to authorities during the age assessment procedure. A web application has been launched to facilitate the retrieval of age estimates and associated probabilities when inputting the dental maturity index value.