The arrangement, size and alignment of the human teeth are accepted as being unique to each person. When a biting incident occurs involving the human dentition, those unique characteristics of the biter's teeth are transferred to the object or person bitten. Using the bite mark, which transferred those unique qualities to the object being bitten when the bite occurred, it is sometimes possible to establish the identity of the person responsible for the biting.
Bite marks can occur in inanimate objects such as cheese, chocolate and fruit, as well as wood and Styrofoam. Most times, the bite mark is associated with one human biting another intentionally. These types of cases are usually sexual assault, violent homicide and assault cases. Many times, the bite marks associated with the case are of such poor quality that they are of no evidentiary value. Care must be exercised when evaluating a suspected bite mark so that no over-interpretation occurs which could invalidate the results.
By establishing the uniqueness of the biter's teeth and then applying those unique properties to the bite pattern, a degree of confidence relating the biter's teeth to the injury pattern is described. This opinion can range for excluded ( the suspect did not do the biting) to indeed and without a doubt (the bite was witnessed and there is not question the suspected biter inflicted the bite). Because of the unique nature of the position and arrangement of the human teeth, it is usually easier to rule out a suspect as a potential biter than it is to include a suspect as a potential biter.
In those cases when a high quality bite mark injury has occurred and been successfully recorded, scientific testing is undertaken to attempt to determine if a suspect biter can be scientifically identified. This usually involves the application of scientific methodology via multiple testing in the position and arrangement of the suspect's teeth and the actual bite mark injury. This testing can involve the use of clear acetate overlays of the biter's teeth on a life sized photograph of the bite mark injury, test bites in wax, Styrofoam or skin, a metric analysis of the bite mark injury and the biter's dental arch(es), digital analysis of bite mark injury and the biter's teeth, scanning electron microscope studies, resection and transillumination of the bite as it relates to the biter's teeth and other types of two dimensional and three dimensional analyses. Once all testing is completed, a review of the test results is completed and an opinion of the relationship of the bite mark injury and the biter's teeth is reached, validated and verified. The use of independent second opinions in bite mark cases is a frequent method of verification and validation. Finally, a written report is delivered summarizing the findings of the testing methodology.
Bite mark cases will challenge the forensic dental capabilities of the investigator. Involvement in these types of cases is not advised for the unprepared or untrained forensic dentist. Because most bite mark case analyses utilize photographs of the injuries, some knowledge in the recording of the bite mark patterns with photography is necessary. High quality photographs are absolutely necessary. ( Dr. Wright does research on photography of patterned injuries and has published in textbooks and journals on the subject. Specific questions about the photography of patterned injuries can be directed to Dr. Wright through email from this web site.)
To view the case examples, click on the link below.
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