Comparative analysis of aspartic acid racemization methods using whole-tooth and dentin samples

Area of Science:

• Forensic Anthropology
• Biogeochronology
• Biomolecular analysis

Background:

• Aspartic acid (Asp) racemization is a method for estimating biological age.
• This technique has primarily used tooth enamel and dentin.
• Challenges in sample standardization and control have limited its widespread application.

Purpose of the Study:

• To investigate the feasibility of using entire teeth for age estimation via Asp racemization.
• To compare the efficacy of whole-tooth samples versus dentin-only samples.
• To simplify and standardize the Asp racemization technique for broader use.

Main Methods:

• 12 pairs of human canine teeth from individuals of known age were analyzed.
• Samples were processed as either dentin-only or whole-tooth specimens.
• D-Asp and L-Asp levels were quantified using gas chromatography/mass spectrometry.
• The D/L-Asp ratio was calculated and correlated with chronological age.

Main Results:

• Whole-tooth samples exhibited higher D/L-Asp ratios compared to dentin samples.
• Strong correlations were observed between D/L-Asp ratios and age (r=0.98 for dentin, r=0.93 for whole tooth).
• Age estimations for unidentified Japanese and Brazilian individuals showed minimal discrepancies.

Conclusions:

• Using whole teeth simplifies the Asp racemization process and standardizes sampling.
• This method enhances the reliability of biological age estimation.
• The whole-tooth approach facilitates additional analyses like DNA profiling from the same sample.