title: Comparative analysis of aspartic acid racemization methods using whole-tooth and dentin samples.
abstract: One way to estimate biological age is to use the aspartic acid (Asp) racemization method. Although this method has been performed mostly using enamel and dentin, we investigated whether an entire tooth can be used for age estimation. This study used 12 pairs of canines extracted from both sides of the mandible of 12 individuals of known age. From each pair, one tooth was used as a dentin sample and the other as a whole-tooth sample. Amino acids were extracted from each sample, and the integrated peak areas of D-Asp and L-Asp were determined using a gas chromatograph/mass spectrometer. Statistical analysis was performed using the D/L-Asp ratio. Furthermore, teeth from two unidentified bodies, later identified as Japanese and Brazilian, were examined in the same manner. Results showed that the D/L ratios of whole-tooth samples were higher overall than those of dentin samples. The correlation coefficient between the D/L ratios of dentin samples and their age was r=0.98, and that of the whole-tooth samples was r=0.93. The difference between estimated age and actual chronological age was -0.116 and -6.86 years in the Japanese and Brazilian cases, respectively. The use of whole teeth makes the racemization technique easier and can standardize the sampling site. Additionally, using only a few tooth samples per analysis made it possible to reanalyze known-age samples. Although the difficulty in obtaining a proper control sample has prevented racemization from being widely used, the method described here not only ensures the availability of a control tooth, but also enables the teeth to be used for other purposes such as DNA analysis. The use of a whole tooth will increase the application of the racemization technique for age determination.
authors.affiliation: Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba 260-8670, Japan. a.sakuma@chiba-u.jp
authors.forename: Ayaka
authors.initials: A
authors.lastname: Sakuma
authors.forename: Susumu
authors.initials: S
authors.lastname: Ohtani
authors.forename: Hisako
authors.initials: H
authors.lastname: Saitoh
authors.forename: Hirotaro
authors.initials: H
authors.lastname: Iwase
mesh_terms: D000328:Adult; D000366:Age Determination by Teeth / Q000379:methods*; D001224:Aspartic Acid / Q000737:chemistry*; D003481:Cuspid / Q000737:chemistry*; D003804:Dentin / Q000737:chemistry*; D005260:Female; D005553:Forensic Dentistry; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D013237:Stereoisomerism
chemical_list: D001224:Aspartic Acid