Forensic age assessment in Finland, and dental development of Somalis

Assessment of an individual’s age has important applications in forensics. From developing countries, the possibility to gather reliable reference data for forensic age estimation may be difficult. The aim was 1) to analyse the validity of the Greulich and Pyle method (1959), and other skeletal and dental methods; 2) to analyse forensic age assessments of asylum seekers in Finland, and the Finnish legislation; 3) to compare a created Somali dental development model (SM) on lower left permanent teeth (PT) from 31 to 37 with the Willems et al. model (WM; 2001); and 4) to study whether the addition of information on the development of third molars (TM) with PT increases the accuracy of age assessment of young Somalis. Dental and skeletal radiographic age-assessment methods were compared using Finnish child victim data (N=47). Information on forensic age assessment was collected from Finnish legislation texts, EU statistics, and public statistics by Immigration Authorities on asylum seekers in Finland. Analysis was made of forensic age assessments in Finland in 2015. The dental development of Somalis, born and living in Finland, was analysed, staging the PT according to Demirjian et al. (1973) and TM according to Köhler et al. (1994). First, both SM and WM on PT were validated on 635 Somalis, aged 4–18 years. Secondly, the age prediction performances of PT and TM development were tested separately and combined on 803 Somalis, aged 3–23 years, using a Bayesian approach. Of the compared dental and skeletal methods, development of PT showed the smallest deviation from the chronological age. In 2015, 149 asylum seekers, originating most often from Afghanistan, Iraq, and Somalia, were assessed for age using methods authorised by the Finnish legislation. Comparing the performances of the WM and SM, small but statistically significant differences in mean error were detected: -0.07 years in males and 0.16 years in females. The approach combining PT and TM predicted the age with the highest accuracy. In conclusion, dental methods, except using only TM, override skeletal methods in accuracy. The current Finnish legislation on forensic age assessment has been successfully implemented in Finland. In age assessment, the WM performs well for Somali children. The age prediction performance improves by combining the information of PT and TM, especially in 12- to 15-year-olds, when both PT and TM are still developing.