The off-season of dental cementum investigations. A critical appraisal of season-of-death prediction in medico-legal investigations

• Dental cementum-based methods are increasingly considered in forensic anthropology. • The season-of-death can be estimated based on the outermost cementum deposit. • Estimating season-of-death aids connecting with missing persons’ disappearance date. • Estimating death seasonality requires further research to meet forensic requirements. It has been suggested that death seasonality could be estimated based on the dark/bright appearance of the outermost dental cementum deposit. The few existing studies show variable accuracy rates. The question whether estimating season-of-death based on dental cementum represents a realistic and achievable goal can arise. This work, based on a software-assisted procedure and direct human observation, aims to critically evaluate the applicability of dental cementum to estimate the season-of-death in forensic anthropology. The sample consists of 20 canines from individuals belonging to the 21st century Identified Skeletal Collection, University of Coimbra, Portugal, and with documented biodemographic data. Fifty percent of the individuals died during the summer and 50% during the winter. Five non-decalcified 100 μm cross-sections per tooth were prepared, using a standardized protocol. Images of the region of interest, with the acellular cementum, were captured, and imported into FIJI/ImageJ software. Performance of the season-of-death predictions was very low, with 50% accuracy, score of 0.0000 for Matthews Correlation Coefficient, and F1-score of 61.5% for Summer and 28.6% for Winter, were obtained for the observer assessment. For the software model, performance was equally poor, with 52.6% accuracy, score of 0.0272 for Matthews Correlation Coefficient, and F1-score of 30.8% for Summer and 64.0% for Winter. This work is of relevance to the forensic science community by demonstrating the prospects and limitations of dental cementum as a method for estimating seasonality of death.