Multiple forensic insights for human identification using single teeth with applicability to advanced postmortem remains

Prolonged postmortem intervals cause soft tissue loss, complicating identification in disasters and criminal investigations. We used a single mandibular first premolar from bodies ( n = 15) with a long postmortem interval for simultaneous 14 C and δ 13 C isotope analysis, amino acid racemization analysis, DNA profiling, and toxicological analysis. 14 C analysis gave multiple estimated birth years, including actual birth year, in 14 of 15 cases, and amino acid racemization analysis estimated ages at death within a margin of mean error of − 5.82 ± 6.87 years (mean absolute error (MAE) = 7.93, r = 0.86). Integrating both results increased the year of birth estimation accuracy (0.57 ± 6.36 years, MAE = 5.01, r = 0.95). Estimated region based on δ 13 C analysis did not contradict known individual information. DNA analysis estimated sex in all cases, and a sufficient number of autosomal short tandem repeat (STR) loci for individual identification was detected in 12 cases. Mitochondrial DNA typing and Y-STR analysis were also successful. Toxicological analysis of dental pulp detected drugs consistent with autopsy screening results and drug use information. The findings suggest that various identifying information can be obtained from a single tooth, representing a novel, useful strategy for rapidly narrowing potential individuals.