A quantitative method for comparing human dentition with tooth marks using three-dimensional technology and geometric morphometric analysis

Abstract

Objective. To develop a quantitative method to compare 3D overlays from dental casts with experimental bitemarks by using geometric morphometric analysis. Materials and methods. Thirteen upper and lower dental casts and corresponding simulated bitemarks were 3D-scanned to generate comparison overlays with DentalPrint software^©. This study considered the inter-canine distance and four incisal angles. A matrix was created to compare all possible combinations of matches and non-matches between models and bites, i.e. 169 combinations (13 models × 13 bites), of which 13 were true matches. For each combination, the percentage difference was calculated between the variables in the model and the same variables in the bitemark. Logistic regression was used to obtain a predictive model (algorithm) for a match, calculating the discriminative values (area under the ROC curve, sensitivity and specificity) for each measure and for the logistic model. Results. Statistically significant discriminative power was found for all single (angle or distance) and combined (logistic model) variables, with lower 95% CI limits > 0.50 for areas under the ROC curves and sensitivity/specificity values > 50% in both maxilla and mandible. Conclusions. This quantitative method has sufficient discriminative power to be utilized in forensic cases.

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