Researchers from the University at Buffalo’s (UB) Laboratory for Forensic Odontology Research in the School of Dental Medicine have published a landmark paper on the controversial topic of bitemark analysis. The UB study published in the Journal of Forensic Sciences challenges the commonly held belief that every bitemark can be perpetrator identified. “Bitemark identification is not as reliable as DNA identification,” explains the study’s lead author, Raymond G. Miller, DDS. “With DNA, the probability of an individual not matching another can be calculated,” he says. “In bitemark analysis, there have been few studies that looked at how many people’s teeth could have made the bite.” The study investigated 3 areas: determining biter identity among people with similarly aligned teeth; determining how many individuals from a larger sample might also be considered as the biter; and determining if bite pattern distortion is enough to rule out a specific biter while still including a nonbiter. The researchers used 100 stone dental models that were measured and divided into 10 groups based upon the misalignment patterns of the teeth. After randomly selecting one model from each of the 10 groups, the researchers impressed bitemarks on cadaver skin, which were then photographed and the indentations compared to the dentitions using overlays created with photographic software. The authors are one of the first to use a human skin model rather than animal models or nonelastic biting substrates such as wax or Styrofoam. Current human subject restrictions limit experimentation on living subjects. The results indicated that when dental alignments were similar, it was difficult to distinguish which set of teeth made the bites. Distortion in the bitemarks allowed matches even from different alignment groups. Therefore, the researchers concluded that bitemarks should be very carefully evaluated in criminal investigations where perpetrator identity is the focus of a case. As Dr. Miller notes, “In the past 10 years, the number of court cases involving bitemark evidence that have been overturned led us to question the reasons for the erroneous bitemark identification. It’s important to recognize the serious consequences of a misidentification for the accused, the victim, the families involved, the justice system and the possibility that the perpetrator is still at large.”
(Source: Science Daily, September 17, 2009; adapted from materials provided by UB)
