Background and objective Human teeth have a significant forensic importance. As they are the hardest of all human tissues, they are not just chemically stable but also their characteristics are maintained for a long time after death even in the most harsh environmental conditions. Despite the advances made in DNA analysis, fingerprinting, etc., ABO blood grouping still plays a significant role in the forensic practice in the field of personal identification, paternity disputes, and several other scenarios including the identification of mass disaster victims. The term blood groups refers to inherited antigens on the surface of red blood cells (RBCs) detected by specific antibodies. Since tooth pulp contains numerous blood vessels, blood group antigens are most certainly bound to be present in tooth pulp. Various studies have shown that blood group antigens in the pulp and dentin are preserved as long as up to two years after the demise of an individual. Absorption-elution technique has been proven to be the most sensitive, reliable, and consistent method to determine the ABO blood group from both the pulp and dentine. This study aimed to ascertain the ABO blood group from both the hard (dentin) as well as the soft tissue (pulp) of the tooth by using the absorption-elution (AE) technique and also to determine if there are any variations in identifying the blood groups from the teeth based on age and gender. Material and methods After obtaining due consent, we included patients of both genders aged between 16-60 years visiting the outpatient department (OPD) clinics at the College of Dentistry for periodontal or orthodontic extractions. One patient\'s blood type was determined by using the slide agglutination technique before any capillary blood extraction was performed; this patient served as a control. For this investigation, we used the pulp and powdered dentin samples taken from the dental extractions to test for the presence of ABO and Rhesus (Rh) factor antigens by using the AE method. The study samples were compared with the control for blood group determination. Statistical analysis was carried out using the chi-square test with Monte Carlo (MC) simulation to check for any correlation of blood grouping with age and gender. Results The dentin and pulp were shown to have positive blood group antigens for the ABO and Rh factors. While neither pulp nor dentin performed significantly differently in identifying the blood group antigens, pulp showed marginally higher accuracy. There was no discernible difference regarding gender or age in the dentin or pulp of any of the 45 samples studied. Conclusions For determining an individual\'s blood type and Rh factor, both the hard (dentin) and soft (pulp) tissues of a tooth are valid sources. This is particularly helpful in forensic medicine cases where teeth are the only remains that can be viably used to find out a person\'s identity.

Introduction Collection of blood samples from mass disaster victims and blood grouping is a challenging task. This can be attributed to various reasons. From the forensic odontology perspective, teeth and bones are one of the noteworthy remains that can be derived from such sites. Aims and objectives The aim of our study is to detect ABO blood groups and Rhesus (Rh) factor from extirpated pulp tissue of the extracted teeth at zero, three, and six months\' time interval by absorption-elution technique. Materials and methods The study consisted of 90 freshly extracted teeth as suggested by a biostatistician. Thirty teeth were analyzed immediately and 60 teeth were stored in vials without any preservative at room temperature. The pulp tissue was extirpated and studied at zero months, three months, and six months to determine blood groups and Rh factors. The extraction socket blood was tested to identify the blood group of that patient and used as a control reference. The blood grouping was done at respective time periods through the absorption-elution method and matched with the control. Data were analyzed using Statistical Package for the Social Sciences (SPSS) version 24 software (IBM Corp., Armonk, NY). The chi-square test and Kruskal-Wallis test were done. A p-value < 0.05 was considered statistically significant. Results Pulp showed the highest sensitivity for blood groups at zero months but it could be identified up to six months, although the sensitivity and specificity gradually decreased. ABO blood grouping showed higher sensitivity than the Rh factor as time progressed. Conclusion In cases where teeth are the only remains in a forensic condition, the dental pulp can be an authentic source for blood group detection.