Bijtsporen en tandheelkunde

Voor het opsporen en identificeren van mogelijke daders van misdrijven met dodelijke afloop wordt nogal eens de hulp ingeroepen van tandartsen die verbonden zijn aan rechtbanken. Bij bijtsporen kan aan de tandarts worden gevraagd gebitsafdrukken van de verdachte te nemen. In een enkele moordzaak bleek deze identificatiemethode van doorslaggevend belang in het bewijsmateriaal. DNA-onderzoek en de verbeterde methoden voor speekselanalyse kunnen de mogelijkheden van het forensische tandheelkundige onderzoek aanzienlijk uitbreiden in de toekomst.

Bite mark injuries often feature in violent crimes. Conventional morphometric methods for the forensic analysis of bite marks involve elements of subjective interpretation that threaten the credibility of this field. Human DNA recovered from bite marks has the highest evidentiary value, however recovery can be compromised by salivary components. This study assessed the feasibility of matching bacterial DNA sequences amplified from experimental bite marks to those obtained from the teeth responsible, with the aim of evaluating the capability of three genomic regions of streptococcal DNA to discriminate between participant samples. Bite mark and teeth swabs were collected from 16 participants. Bacterial DNA was extracted to provide the template for PCR primers specific for streptococcal 16S ribosomal RNA (16S rRNA) gene, 16S-23S intergenic spacer (ITS) and RNA polymerase beta subunit (rpoB). High throughput sequencing (GS FLX 454), followed by stringent quality filtering, generated reads from bite marks for comparison to those generated from teeth samples. For all three regions, the greatest overlaps of identical reads were between bite mark samples and the corresponding teeth samples. The average proportions of reads identical between bite mark and corresponding teeth samples were 0.31, 0.41 and 0.31, and for non-corresponding samples were 0.11, 0.20 and 0.016, for 16S rRNA, ITS and rpoB, respectively. The probabilities of correctly distinguishing matching and non-matching teeth samples were 0.92 for ITS, 0.99 for 16S rRNA and 1.0 for rpoB. These findings strongly support the tenet that bacterial DNA amplified from bite marks and teeth can provide corroborating information in the identification of assailants

Bron
Kennedy DM, Stanton JA, García JA, et al. Microbial analysis of bite marks by sequence comparison of streptococcal DNA. PLoS One 2012; 7: e51757. doi: 10.1371/journal.pone.0051757. Epub 2012 Dec 19.