Analysis of C concentration in teeth to estimate the year of birth in the Mexican population.

The C analysis of permanent teeth employing nuclear techniques has a direct application in Forensic Sciences since teeth are the hardest part of the human body and can survive natural decay or extreme conditions. After the first Accelerator Mass Spectrometry Laboratory AMS-LEMA at UNAM, our research group is interested in reproducing C analysis on teeth as other countries to estimate age in the Mexican population samples. One of the main goals of this exploratory study is to know the best methodology considering relevant biological factors based on differences in tissues (enamel and dentin) that allows us to know the year of birth through the C concentration comparing the yield between C analyses from carbonate in enamel and collagen in dentin. In this study, Accelerator Mass Spectrometry (AMS) has been performed in 22 contemporary teeth samples (each one donated from 1 different adult), participating 22 individuals by informed consent to enable a new tool and improve forensic practices in Mexico. Carbon is extracted, converted to graphite, and pressed into a cathode. The sample is taken to an AMS system, where carbon isotopes are separated, counted, and the C/C and C/C ratios determined. Our results for standards and teeth samples from Mexican people are in good agreement with the expected values; they are also useful to set up the best conditions for studies in dentin and enamel. However, this is a destructive technique for dental organs; it is not suitable for individuals born previous 1950. New challenges in sample preparation processes are to be solved to take advantage of the nuclear techniques developed in the last 50 years and make new contributions to society.