Three-dimensional analysis of bitemarks: A validation study using an intraoral scanner

Conservation of the three-dimensional aspect of bitemarks optimizes their analysis. Although bitemarks could be recorded with a surface scanner, in clinical dentistry, intraoral scanners are used as an alternative to conventional dental impressions. Here we assess the reproducibility and the reliability of a three-dimensional bitemark analysis protocol using an intraoral scanner. Twenty-seven volunteers bit on different materials: dental wax, hard cheese, chocolate and apple. Then, bitemarks and dentitions were scanned with the PlanMeca® Emerald intraoral scanner and the scans obtained were exported into the mesh comparison software, CloudCompare®, which can generate overlays automatically. For this purpose, dentitions were aligned and compared with the indentations. The meshing and non-meshing areas were visualized using a colorimetric scale. First, the same blinded observer compared the bitten materials by analyzing 256 meshing areas for each. Secondly, comparisons of bitemarks from wax were analyzed in a randomized blinded study involving four observers (dentist, dental student, forensic scientist and police officer) and predictive values were calculated. The wax support obtained the best result and apple the worst. The rate of correct classifications was high and misclassification was rare. For the all observers, negative predictive values were near 100%. Positive predictive values were more variable. Moreover, the work clearly highlighted the importance of experience in odontology.