Age Estimation Using the Racemization of Amino Acid on Human Teeth

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An investigation into racemization of aspartic acid in dentin (D/L ratio) was carried out for the realization of a more accurate dental age estimate.1.Influence of pH :The influence of pH (4 and 9) on teeth was investigated by a heating experiment for precise estimation of age at death. The reaction rate was highest in dentin in a pH 9 environment, followed by that in water, that in a pH 4 environment, and that in a dry state.2.Influence of fixative :We investigated and compared the degree of progression of racemization of dentinal aspartic acid in teeth stored in 95% ethanol, 10% formalin, or 10% neutral formalin fixatives. The racemization rate of dentinal aspartic acid in teeth stored in 10% neutral formalin was the highest, followed by that for teeth stored in 10% formalin then that for teeth stored in 95% ethanol. Teeth stored in these fixatives at 15ﾟC showed almost no progression of racemization.3.Influence of pink teeth :Age was estimated from pink teeth utilizing the racemization of dentinal aspartic acid. These results suggest that age estimated from pink teeth are probably underestimated but that a more accurate age estimate can be obtained after adequate washing.4.Age estimation from racemization rate using heated teeth :The ratio was higher in heated than in unheated teeth for total amino acid, but approximately the same for soluble peptide. These results suggest that age calculated from the D/L ratio of dentinal soluble peptide from burned bodies is sufficiently accurate for this parameter to be used to estimate age in teeth from burned bodies.