Isolation of DNA from human teeth exposed to different decalcifying solutions for forensic identification: A study

Background: Teeth are selected as source of DNA material mainly due to the high durability found in its structures (enamel, cementum, and dentin), which often succeeds in preserving the integrity of genetic material. Attempts of perpetrators of crime in the destruction of evidence including dead bodies are on the rise. Hence, the use of advanced techniques such as DNA analysis in such a scenario has been the choice. Aim: The purpose of this study was to evaluate the extraction and amplification of DNA from human teeth exposed to different chemicals Nitric Acid at 25%, Formaldehyde at 25 %, and Acetic Acid at 25 %. Objective: The objective of the study was to determine the intactness of DNA using polymerase chain reaction. Materials and Methods: The experimental study was performed with a sample of 15 subjects who underwent tooth extraction from which 5 samples of oral mucosal cells were taken as controls (reference population). The experimental population was divided into three equal parts, which were exposed to different chemical solutions, namely Nitric Acid 25 %, Formaldehyde at 25 %, and Acetic Acid at 25 % compared with the control group (oral mucosal cells [5 samples]). The silica method was used for the extraction of DNA from teeth and the organic method was used for the extraction of DNA from oral mucosa cells. Results: Estimation of DNA quantity and size distribution was done on an Agrose Gel Electrophorosis. From our study we could observe that the teeth that were immersed in 25% Formaldehyde & 25% Acetic Acid were having intact DNA, which we were able to isolate & amplify. There was degradation of DNA tooth which were immersed in 25% Nitric Acid, thus the identification & amplification was not possible. Conclusion: The present study demonstrated that DNA extraction may be limited under exposure to chemical solutions or bodies that undergo intentional postmortem alterations, such as carbonization and dissolution, hamper the degradation of DNA due to high temperature and acid pH. Therefore, testing the collection of DNA from the human teeth in such conditions could contribute significantly to the field of forensic genetics.