NCJ Number
138344
Journal
Journal of Forensic Sciences Volume: 37 Issue: 4 Dated: (July 1992) Pages: 1061-1067
Date Published
1992
Length
7 pages
Annotation
The accuracy of data from enamel and dentin in the same tooth was compared in this study of age estimation from teeth by measuring the racemization of aspartic acid, a representative amino acid.
Abstract
All teeth were extracted from living subjects; they showed no macroscopically severe cavities and were stored in 10 percent formalin. The samples for age estimation included 16 upper central incisors. After each sample was sliced into 1 mm thick longitudinal sections, enamel and dentin chips were isolated with a cutter. These chips were washed, dried, and powdered, and 5 mg of each was used as a specimen. Gas chromatograms of amino acids obtained by hydrolyzing enamel and dentin at 100 degrees C for 6 hours showed that glycine, proline, alanine, and hydroxyproline were detected and had the same proportion of amino acids as collagen. The fact that hydroxyproline was detected in enamel suggested the possibility that substances stemming from dentin collagen may have been included. The amount of amino acids in whole enamel, however, was scarce in comparison with dentin. The difference in ages between one estimated by the D/L ratio and the actual one was within plus or minus 3 years in dentin; an error of from 2 years to 11 years was observed in enamel. Reaction rate constants of racemization in a dry postmortem state (15 degrees C) were calculated. Compared to rates determined from teeth recently extracted from living subjects, the reaction rate was higher in dentin than in enamel. Study data confirm that dentin is superior to enamel in making exact age estimations from teeth. 8 references and 5 figures