A Time Interval Based Forensic Study on Estimation of ABO Blood Group & Rh Typing From Dental Pulp: An Aid in Personal Identification

To assess the viability of pulp tissue in identifying the ABO blood group of an individual at various time intervals (same day, after one week and six months of extraction) and assess its reliability by comparing with the routine capillary agglutination method.

The study was conducted on 75 patients. The capillary blood samples were obtained by finger prick method, the blood grouping and rhesus typing was done by slide agglutination method for each of the 75 patients and considered as controls. The pulp obtained from the extracted teeth of the same 75 patients was considered as case. The cases were divided into 3 groups based on the time interval of pulp extirpation and examination for blood grouping & rhesus typing after extraction. Group I (pulp extirpation on day of extraction), Group II (pulp extirpation after one week of extraction) and Group III (pulp extirpation after six months of extraction). Blood grouping, Rhesus typing for extirpated dental pulp was done by modified absorption elution method. The results of the cases were compared with the respective controls to arrive at conclusions.

In Group I (n = 25) and Group III (n = 25), the results of blood group estimation by both the methods matched completely and showed 100% sensitivity. In Group II (n = 25), 24 teeth samples showed consistent results with only one case being non confirmatory and hence a sensitivity of 96%.

Teeth are hard structures and resist adverse environmental conditions. The pulp tissue within the tooth is well protected and remains stable retaining the viability of the blood group antigen for at least up to 6 months. Thus, it could be concluded from the present study that the dental pulp tissue can be used with good reliability in person identification.