A new publication has found that the uniqueness of the human dentition remains unproven. Bitemark analysis is based on two predicates; that the human dentition is unique and secondly that this uniqueness is appropriately recorded in the bitten substrate. It is, however, important to note that some will argue against the need for uniqueness - Page for example, and also the ABFO who state that in a "closed" population - uniqueness needs only to exist between those individuals proven to have access to the bitten individual or object. Nonetheless a great deal of research has been undertaken recently to prove or disprove uniqueness. In this recent article; published in the International Journal of Legal Medicine, a systematic review has been undertaken.
Systematic reviews are means of collating, reviewing and critiquing evidence to reach a consensus view. Most often undertaken in medical research, and often restricted to randomised controlled trials, they produce an overview of the current state of the science. The abstract of the review is here:
The uniqueness of human dentition is routinely approached as identification evidence in forensic odontology. Specifically in bitemark and human identification cases, positive identifications are obtained under the hypothesis that two individuals do not have the same dental features. The present study compiles methodological information from articles on the uniqueness of human dentition to support investigations into the mentioned hypothesis. In April 2014, three electronic library databases (SciELO®, MEDLINE®/PubMed®, and LILACS®) were systematically searched. In parallel, reference lists of relevant studies were also screened. From the obtained articles (n = 1235), 13 full-text articles were considered eligible. They were examined according to the studied parameters: the sample size, the number of examined teeth, the registration technique for data collection, the methods for data analysis, and the study outcomes. Six combinations of studied data were detected: (1) dental shape, size, angulation, and position (n = 1); (2) dental shape, size, and angulation (n = 4); (3) dental shape and size (n = 5); (4) dental angulation and position (n = 2); (5) dental shape and angulation (n = 1); and (6) dental shape (n = 1). The sample size ranged between 10 and 1099 human dentitions. Ten articles examined the six anterior teeth, while three articles examined more teeth. Four articles exclusively addressed three-dimensional (3D) data registration, while six articles used two-dimensional (2D) imaging. In three articles, both imaging registrations were combined. Most articles (n = 9) explored the data using landmark placement. The other articles (n = 4) comprised digital comparison of superimposed dental contours. Although there were large methodological variations within the investigated articles, the uniqueness of human dentition remains unproved.
The conclusion, that the uniqueness of the human dentition remains unproven must be considered only in relation to bitemark analysis - the use of the entire dentition, restorations, anomalies etc for the purposes of human identification is well accepted. This work should be commended as it takes a further step towards introducing recognised and robust scientific approaches to forensic research. The question remains that if further research will prove uniqueness or if the odontological community should continue to work on bitemark analysis accepting that uniqueness is not proven but that it is an irrelevance in the assessment of injuries within small populations of potential biters.
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