Amplification of Oral Streptococcal DNA from Human Incisors and Bite Marks

Challenges to the evidentiary value of morphometric determinations have led to a requirement for scientifically substantiated approaches to the forensic analysis of bite marks. Human teeth support genotypically distinctive populations of bacteria that could be exploited for forensic purposes. This study explored the feasibility of directly amplifying bacterial DNA from bite marks for comparison with that from teeth. Samples from self-inflicted experimental bite marks (n = 24) and human incisors were amplified by PCR using primers specific for streptococcal 16S ribosomal DNA. Amplicon profiles (resolved by denaturing gradient gel electrophoresis) from bite mark samples aligned significantly more closely with profiles generated from the teeth responsible than with those from other teeth. Streptococcal amplicons were generated from dental samples applied to excised porcine skin for up to 48 h. These findings indicate that streptococcal DNA can be amplified directly from bite marks, and have potential application in bite mark analysis.