The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)


Assessing damages: Testing the assumptions of a non-destructive protocol for DNA extraction from modern human teeth

CHRISTOPHER BOWERS1, BRIDGET F.B. ALGEE-HEWITT2 and GRACIELA S. CABANA2.

1Department of Engineering, University of Michigan, Ann Arbor, 2Department of Anthropology, University of Tennessee, Knoxville, 3Department of Anthropology, University of Tennessee, Knoxville

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For skeletal biologists, the use of destructive DNA extraction methods on teeth result in the loss of information on morphology, wear patterns and age. Similarly, these methods affect molecular anthropologists, who may be denied research requests when samples are limited. As an alternative, we are testing a recently published “non-destructive” method (Bolnick et al. 2011) for use in modern DNA, and especially forensic, contexts. Here, we report on our investigations into chemical alterations of the tooth surface and the effects of multiple tooth “soaking” steps. As tooth enamel is composed primarily of hydroxyapatite, our concern is with the use of EDTA, a strong chelating agent that may bond with calcium. Five pigs’ teeth were soaked first to test the effects of the soaking solution (with controlled repeat-soaking) on the enamel of different teeth. Six dry human molars were subsequently soaked, two of which were treated with lower concentrations of EDTA. For all samples, damage was quantified in terms of the change in mass and calcium. Preliminary findings indicate that all teeth were damaged. The effect was much greater on the pig teeth. Cracking and surface erosion were observed for the human teeth, but these effects may be exacerbated by preexisting defects. Further, the human teeth subjected to lower concentrations of EDTA were largely undamaged. These results suggest the possibility of fine-tuning the protocol to be less destructive and to accommodate forensic casework, when pristine samples are not recoverable. Recommendations will be provided on method improvement for contemporary sample analysis.

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