Demonstration and semi-quantification of mtDNA from human dentine and its relation to age

In order to study if mitochondrial DNA (mtDNA) could be retrieved from isolated human dentine, small pieces of dentine were cut out from the central part of the apical half of wisdom teeth from 21 individuals aged 15 to 85 years. The dental pulp was used as a control. After extraction, amplification and agarose gel electrophoresis the amount of mtDNA was semi-quantified from the intensity of the stained bands in the gel. Mitochondrial DNA was retrieved from all samples and the sequences were identical in pulp and dentine from each individual. There was a clear age-dependent decrease in the amount of amplified mtDNA. Since the odontoblastic processes in the apical dentine undergo degeneration with age and the dentinal tubules subsequently become occluded with calcium phosphate crystals, the conclusion was drawn that even after dissolution of the odontoblastic processes, at least remains of the mtDNA are trapped in the dentine. This well protected mtDNA could thus be regarded a good source of DNA in identification cases with severe degradation.