Investigation on the age estimation from dentin with an amino acid racemization method.

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During the investigation period, following results were obtained. 1. On age estimation, accurate age was able to be estimated by using artificial standard samples that were made by mixtures of L-and D-aspartic acid, instead of a control tooth conventionally required. 2. A special FS column was fabricated for aspartic acid (Asp) that can separate type D and L distinctly within 5 minute. 3. The racemization rates of Asp from the alveolar bone presented extremely lower value than that of the femur previously investigated. This result indicated that the alveolar bone showed more active metabolism than the femur. The gender differences regarding the racemization rates was also observed. 4. The results of comparison between the racemization rates of dentin in humans and mammoths showed that lower values on the latter and both groups showed higher values on the cementum side. 5. The optimum indicator for age estimation using racemization method is considered to be Asp since almost no reports using other amino acids have been found. However, if other amino acids can be exploited, reliability of this method will be increased, therefore; besides Asp, glutamic acid (Glu) and alanine (Ala) were tested. As a result, it was found that Glu and Ala have sufficient potential to be used for age estimation by using soluble components of samples. 6. Examination of the racemization rates of the mandible revealed that the mandibular ramus, the lower part of the mandibular body, and the molar region of the upper part of the mandibular body showed higher rates than the mandibular body, the upper part of the mandibular body, and the anterior region of the upper part of the mandibular body, respectively. From these results, racemization rates were different depending upon the area of bone. 7. According to the result of the heating experiment simulating teeth from a burned body, it was suggested that estimation of age from dark brown teeth is possible by using a colorimeter.