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.

翻译：牙科比对被视为与指纹和DNA分析同级的主要身份识别方法，其中关键且耗时的步骤之一是形态学比对。该方法面临的主要挑战在于缺乏生前医疗记录，尤其是在边境移民死亡或未实行全民医保的国家等场景。社交媒体上可见牙齿的照片日益普及，促使多位齿科法医考虑利用此类照片进行形态学比对。然而，现有方法存在显著局限性，包括未恰当建模透视畸变、缺乏量化形态差异的客观手段等。本方案采用三维（死后扫描）-二维（生前照片）联合方法，运用计算机视觉与优化技术，以三维模型复现生前影像进行形态学比对。我们开发了两种自动化方法：i）基于成对标记点法；ii）基于牙齿区域分割的相机参数估计法。两种方法在142个样本的20,164次交叉比对中均取得极具前景的结果，平均排名值分别为1.6和1.5。这些结果显著优于自动牙科图表比对方法的过滤性能，同时提供了可自动生成、客观量化形态匹配度的评分，便于通过叠加影像可视化进行解读与分析。