Forensic bitemark analysis lacks scientific research

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Forensic bitemark analysis lacks scientific research, can lead to wrongful convictions

A recent study has reported that forensic bitemark analysis used in court trials is flawed and may lead to wrongful conviction cases. (Image: GOLFX/Shutterstock)

NEW YORK, US: Bitemark analysis is often used as evidence in court. However, a recent study has demonstrated that its use is not backed by scientific research. The researchers hope that the findings will help raise awareness of the unreliability of bitemark evidence and the possible liabilities of testifying on this basis in court.

According to the US National Academy of Sciences, the assertion that dental professionals can identify perpetrators by matching their dental patterns to marks on victims’ bodies has never been supported by any scientific study. According to the authors of the present study, 26 people have been wrongfully convicted and some even given the death penalty as a result of forensic bitemark analysis. This suggests that the forensic dentistry discipline of bitemark analysis is unreliable.

The study included an analysis of current literature and the undertaking of 12 studies to examine the underlying premises of bitemark analysis, namely that human dentition can reliably transfer to skin and that its arrangement is unique. To that end, in one of the studies, the researchers made 23 bites on unembalmed cadavers with the same set of teeth and the same opening diameter and found that none of the bites were identical to each other and that there was dramatic distortion in biting dentition in some cases, mostly arising from the biomechanical properties of the skin.

Demonstration of distortion among bites created with the same set of teeth. Outlines of the biting dentition are displayed above and below the bite, the maxillary and mandibular arches corresponding with the maxillary and mandibular bites, respectively. (Image: © 2023 Bush et al., licensed under CC BY 4.0, no changes)

In another study, the researchers measured the alignment patterns of the six anterior maxillary and mandibular teeth of 1,100 sets of digital 3D dental models and compared them against one another to see how many of them matched. They also took into account the distortion seen in the previous studies.

“We find bitemark transfer to skin is not reliable and found that within a population of 1,100 people, with just 25% distortion, a significant number of the population could have created the bite,” lead author Dr Mary A. Bush, an associate professor in the Department of Restorative Dentistry at the University at Buffalo School of Dental Medicine in New York state, said in a press release. “The scientific community does not uphold the underlying premise that human teeth are unique and their unique features transfer to human skin,” she emphasised.

The findings concur with those of previous studies, including a recently published review by the US National Institute of Standards and Technology, which reported that there is a lack of consensus among practitioners regarding the interpretation of bitemark data. “Our findings are a cautionary tale of how dangerous the consequences can be when [bitemark analysis] is relied on in trials,” Dr Bush concluded.

The study, titled “C.E. credit. Bitemark analysis: The legal vs scientific battle for justice”, was published online on 1 May 2023 in the Journal of the California Dental Association.

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