Age Estimation Using the Racemization of Amino Acid on Human Teeth

为了实现更准确的牙龄估计，对牙本质中天冬氨酸的消旋作用(D/L比)进行了研究。1.pH的影响：通过加热实验研究了pH(4和9)对牙齿死亡年龄的影响。2.固定剂的影响：研究比较了牙本质天冬氨酸在95%乙醇、10%福尔马林和10%中性福尔马林溶液中外消旋的进程。用10%中性福尔马林保存的牙齿中，牙本质天冬氨酸的消旋率最高，其次是10%福尔马林保存的牙齿，然后是95%乙醇保存的牙齿。在15ﾟC保存在这些固定剂中的牙齿几乎没有外消旋的进展。3.粉红色牙齿的影响：利用牙本质天冬氨酸的外消旋来估计粉红色牙齿的年龄。这些结果表明，粉色牙齿的年龄估计可能被低估了，但经过充分的洗涤可以得到更准确的年龄估计。4.从加热牙齿的消旋率估计年龄：加热牙齿的总氨基酸比例高于未加热牙齿，但可溶性多肽的比例大致相同。这些结果表明，根据烧伤身体牙本质可溶性多肽的D/L比值计算的年龄是足够准确的，可以用这个参数来估计烧伤身体牙齿的年龄。

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.