This is a duplicate of my comments in the rating section, so ignore if you read that already. Overall I begin by saying that I think this is a fantastic and simple approach for minimising lab contamination in teeth-bacterial assays. However I would caution that DNA recovery from teeth is likely to be extremely complicated, and that readers might wish to consider the following.

Firstly, the methods use may in some situations not be applicable with regards to the extraction of endogenous human DNA. In recent years several studies have demonstrated that contaminant DNA derived from unprotected handling or washing of old material can permeate deep into teeth samples, and in some cases this can likely only be removed by direct application of bleach to the powdered tooth (c.f. Malmstrom et al. 2005, Malmstrom et al. 2007). Bleaching may not be viable in conjunction with the method published here, unless the bleach can first be injected into the cavity, then removed and effectively rinsed, prior to digestion as described. It would be very interesting to demonstrate how easy this is.

Having said that however, I am not aware of any published study that has proven where the contaminant DNA is within the tooth. It may be that it does not reach the pulp cavity, in which case the above would be irrelevant.

Furthermore, I acknowledge that bleaching of the powder and cavity would be disasterous if the aim of the analysis was to recover bacteria that dwell within the pulp cavity, as they would be unlikely to be protected in such a way as the endogenous host DNA. Thus for the stated and tested, bacterial related application, this method is of great interest.