Comparison of tooth nuclear DNA preservation between cementum and other dental tissues

For the genetic identification of skeletal remains, teeth can be used since they contain well-preserved DNA, which is present in various dental tissues, including dental pulp, dentin, and cementum. In forensics, the standard extraction method utilizes the whole tooth and destructive grinding. In our previous study, a highly effective non-destructive method was introduced to extract DNA from tooth cementum, bypassing whole tooth destruction. An analysis was performed on sixty-two canines obtained from adult skeletons from two archaeological cemeteries. After tooth cementum DNA extraction, teeth were stored in the freezer, and later used for destructive DNA extraction, grinding the entire tooth left after non-destructive extraction. The purpose of this study was to compare the preservation of DNA in tooth cementum and other tooth tissues. To extract the DNA from the stored teeth, they were pulverized, and DNA was obtained using the full demineralization method. Real-time PCR was employed to evaluate the quality and quantity of DNA, followed by STR typing. The amount of DNA, degradation rate, and success of STR typing were compared between DNA retrieved from tooth cementum and DNA extracted from the other tooth tissues. The results showed no successful STR typing in most stored teeth, and only five of them produced full or almost full profiles. Comparison to tooth root cementum, where 46 out of 62 teeth generated highly informative STR profiles, indicates that in the aged canines analysed, DNA preservation is strongest in tooth root cementum, while other tooth tissues generally yield little or no recoverable DNA. In five teeth that generated informative STR profiles, we assume that not all the tooth root cementum was decalcified using a non-destructive extraction method, and after grinding the whole tooth, some cementum tissue remained, contributing to successful genetic typing. In this study, the importance of tooth root cementum in archaeological samples is emphasized while exploring the forensic relevance of various tooth tissues. It highlights the notably poorer DNA preservation in dental pulp and dentin compared to cementum in the context of aged teeth.