A quantitative analysis of subtraction images based on bite-wing radiographs for simulated victim identification in...

The comparison between ante- and post-mortem radiographs constitutes an important basis for victim identification in forensic dentistry. Due to the decline in dental caries among children that has occurred in Western countries over the last 20 years, the number of restorations in future populations will be limited. It is likely that this will impede successful victim identification in the future. It was the aim of this study to evaluate a new radiographic technique, subtraction radiography based on bitewing radiographs and determine whether it could provide an objective quantitative measure for victim identification. Bite-wings randomly sampled from a large population of adolescents (13-19 yrs) were video-camera-recorded and digitized. Subtraction images were performed of pairs of bite-wings originating from the same individual (identical images) and from different individuals (non-identical images). The images were separated into two groups, one without fillings (12 identical and 48 non-identical) and one with simple amalgam fillings (15 identical and 60 non-identical). The distribution of grey shades in the subtraction image was used as the parameter for evaluation of homogeneity in the images. Subtraction images derived from identical radiographs were significantly more homogeneous than those derived from non-identical radiographs (p < 0.001) in both group with and without fillings. Although the difference was statistically highly significant, the distribution of grey shades in the two groups overlapped. Thus, the grey shades in the subtraction image cannot per se unequivocally establish the identity of a victim, but may add to the subjective comparison of two radiographs in victim identification.