Smile selfie image analysis for forensic dental identification: protocol proposal

Portrait photographs showing a person’s smile, widely available on smartphones and social media, are increasingly used as ante-mortem (AM) data in missing person investigations, particularly when conventional dental records are unavailable. Previous case reports and methodological studies have demonstrated that smile images may support human identification; however, existing approaches are heterogeneous, largely case-dependent, and often developed for controlled photographic material. To date, no consensus-based and reproducible protocol specifically designed for the forensic analysis of smile selfie images has been established. This study aimed to evaluate the reliability of smile selfies for AM–post-mortem (PM) dental comparison and to propose a structured protocol adapted to non-clinical smile images. Results A total of 253 volunteers provided smile selfies showing the maxillary anterior teeth, simulating AM portrait images. Among them, 71 participants also produced intraoral photographs simulating PM documentation. Four experienced forensic odontologists independently compared the 71 PM images with the full set of 253 AM selfies using predefined dental criteria, including axial inclination, incisal edge morphology, incisor proportions, and anterior dental anomalies. Recognition accuracy ranged from 63.38% to 70.42%, with a mean of 67.25%. The incisal edge morphology of the maxillary central incisors showed the highest inter-operator agreement (95%), whereas the relative position of the upper lateral incisors demonstrated the lowest reliability (25–30%). Statistical analyses confirmed consistent recognition patterns among evaluators. Conclusions Smile selfie images can provide useful supplementary AM information for the preliminary sorting of compatible and incompatible dental profiles when dental records are absent or unavailable. Although the recognition rates observed in this exploratory study indicate that selfie-based comparison should be applied conservatively and in conjunction with other identification methods, the findings confirm that specific anterior dental traits may meaningfully contribute to forensic decision-making. The proposed protocol offers a structured framework for the forensic evaluation of smile selfies. Further validation on larger and more diverse populations is needed to enhance standardization and refine criteria for the use of photographic material in forensic odontology.