Tooth portion profile in criminology

Abstract

Up to date the mineralized tissue is the only option, in many extreme forensic conditions, to achieve a genetic profile. In several samples, both tooth type and portion were studied in order to optimize the methodology and to reduce time and costs. Results from a wisdom tooth (a natural degraded sample), a case of the National Institute Legal Medicine of Portugal, and the topographic drawings of Gaytmenn and Sweet's study from 2003, are presented. DNA from the root tooth (apical and remaining portions) was extracted by using the ArchivePure DNA Tissue kit (5Prime ®). Total DNA quantification was performed by real time PCR, by using the Human Quantifiler kit (Applied Biosystems ®). Depending on the DNA quantification value, the most relevant polymorphisms for genetic identification, autosomic STRs, were amplified with AmpFℓSTR ® Identifiler™ by Applied Biosystems and PowerPlex ® by Promega. The two root tooth portions (apical and remaining) presented different results (in quantity and quality), with respect DNA quantification and genetic profile. The apical portion allowed an autossomic profile while in the remaining portion was not allowed. Our results can be explained based on the fact that apical canicular obliteration through the formation of terciary dentin can preserve some of the pulpar contents in the topographic region, on the other hand cementogenesis in the apical portion can occur by invagination into the canalicula and canaliculi in a rapid and disorganized fashion enabling the trapping of cementocites in its lacunae. Furthermore we must add that it is the apical portion that through its cellular content potentially presents us with the best results in genetic analysis.