Automatic dental superimposition of 3D intraorals and 2D photographs for human identification

2026-04-07

AI Summary

This study addresses the challenge of human identification in scenarios lacking antemortem dental records—such as deaths among undocumented migrants at borders—by proposing an automated method that matches postmortem 3D intraoral scans with 2D dental photographs sourced from social media. The approach estimates camera parameters either through paired anatomical landmarks or tooth-region segmentation, then integrates 3D-to-2D projection optimization with image registration to reconstruct the original photographic viewpoint and achieve precise morphological alignment of dentition. Innovatively, it introduces an interpretable mechanism for generating superimposed images automatically, effectively mitigating inaccuracies due to inadequate perspective distortion modeling and yielding objective, quantifiable matching scores. Evaluated on 142 subjects with 20,164 cross-comparisons, the two variants of the method achieved average ranks of 1.6 and 1.5, significantly outperforming conventional automated dental chart comparison techniques.

Abstract

Dental comparison is considered a primary identification method, at the level of fingerprints and DNA profiling. One crucial but time-consuming step of this method is the morphological comparison. One of the main challenges to apply this method is the lack of ante-mortem medical records, specially on scenarios such as migrant death at the border and/or in countries where there is no universal healthcare. The availability of photos on social media where teeth are visible has led many odontologists to consider morphological comparison using them. However, state-of-the-art proposals have significant limitations, including the lack of proper modeling of perspective distortion and the absence of objective approaches that quantify morphological differences. Our proposal involves a 3D (post-mortem scan) - 2D (ante-mortem photos) approach. Using computer vision and optimization techniques, we replicate the ante-mortem image with the 3D model to perform the morphological comparison. Two automatic approaches have been developed: i) using paired landmarks and ii) using a segmentation of the teeth region to estimate camera parameters. Both are capable of obtaining very promising results over 20,164 cross comparisons from 142 samples, obtaining mean ranking values of 1.6 and 1.5, respectively. These results clearly outperform filtering capabilities of automatic dental chart comparison approaches, while providing an automatic, objective and quantitative score of the morphological correspondence, easily to interpret and analyze by visualizing superimposed images.

Problem

• dental identification
• 3D-2D superimposition
• morphological comparison
• perspective distortion
• human identification

Innovation

• 3D-2D dental superimposition
• perspective distortion modeling
• automatic morphological comparison
• camera parameter estimation
• forensic odontology