Extraction Method of Dental DNA by Using whole Tooth Sections : Application to Forensic Odontology

我之前曾报道过牙齿作为基因分析DNA来源的法医价值。牙齿DNA通常是从牙髓中提取的。这样得到的DNA通常含有高分子量的DNA，适用于多位点DNA探针分析。在法医实践中看到的大多数情况下，牙齿样本被留在潮湿的环境中，牙髓被内切酶降解，因此其条件太差而无法进行分析。我有时发现从整个牙齿切片中获得的牙齿DNA被严重降解，只适用于聚合酶链反应（PCR）。此外，在一些情况下，即使琼脂糖凝胶电泳证实有足够的DNA用于PCR，也不能通过PCR技术扩增。因此，我怀疑牙齿切片中被污染的一些阳离子可能在提取作为PCR源材料的牙齿DNA过程中污染了牙齿DNA，并在PCR过程中作为Taq DNA聚合酶的抑制剂。在这项研究中，我最终证明了基于chelex的程序提供了从整个牙齿切片获得的DNA，适合PCR扩增，以及使用纯化的牙齿DNA进行法医DNA分析的可能性。牙科鉴定传统上是基于死前与死后牙科图表和x射线的比较。在不可能的情况下，染色体高变位点扩增和线粒体DNA测序的有用性是无可争议的，它应该用作法医齿科实践的辅助手段。

I have previously reported the forensic value of teeth as a source of DNA for genetic analysis. Commonly, dental DNA has been obtained from dental pulp. The DNA thus obtained usually contains high-molecular-weight DNA and is suitable for multilocus DNA probe analysis. In most cases seen in forensic practice, sample teeth have been left in humid conditions and the dental pulp has been degraded by endonucleases, so that its condition is too poor for analysis. I have sometimes found that dental DNA obtained from a whole tooth section is badly degraded, and suitable only for polymerase chain reaction (PCR). Moreover, on several occasions, it is not amplified by the PCR technique even though it has been confirmed by agarose gel electrophoresis that there is enough DNA for the PCR.Therefore, I suspected that some cations contaminated in tooth sections might contaminate dental DNA during its extraction as a source material for PCR,and act as a inhibitor of Taq DNA polymerase during the PCR procedure.In this study, I demonstrated conclusively that the Chelex-based procedure tenders DNAs obtained from a whole tooth section suitable for PCR amplification, and the possibility of forensic DNA analysis using those of purified dental DNA.Dental identification is traditionally based on a comparison of antemortem with postmortem dental charts and X-rays. In cases where this is impossible the usefulness of the amplification of chromosal hypervariable loci and mitochondrial DNA sequencing are undisputed and it should use as an adjunct in forensic odontological practice.