The objectives of this study were to characterize the thermal decomposition of human teeth and to evaluate the decomposition of organic matter, including DNA, at different temperatures. Eight teeth were chemically characterized by thermogravimetric analysis coupled with mass spectroscopy, conducting evolved gas analyses at temperatures up to 1000 °C and 60-min isothermal assays at 50, 100, 150, 200, 250, 300, 350, and 400 °C. Mass losses (total of 25.2%) were associated with: loss of free water at temperatures between 44 and 210 °C, combustion of organic matter between 211 and 603 °C, and decomposition of inorganic matter between 604 and 940 °C. The first organic fragment detected was sulfur dioxide (linked to protein decomposition), which showed a major peak at around 270 °C, while volatile DNA residues were recorded between 330 and 347 °C. Isothermal assay results showed that carbon dioxide molecules (associated with organic matrix decomposition) were already present between 150 and 200 °C, indicating the start of organic matter degradation and a potential negative effect on DNA integrity at this temperature range. The most severe decomposition of organic matter started between 200 and 250 °C. These data contribute to knowledge on the decomposition of organic matter, particularly DNA, under thermal conditions encountered in forensic scenarios requiring the genetic identification of fire-damaged humans.
Teeth DNA Identification Thermogravimetric analysis Mass spectroscopy
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Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The study and protocols for recruitment were approved by the Human Research Ethics Committee of the University of Malaga (Approval number: CEUMA 2013-0048-H) in accordance with the “Ethical Principles for Medical Research Involving Human Subjects” adopted in the Declaration of Helsinki by the World Medical Association (64th WMA General Assembly, Fortaleza, Brazil, October 2013), Recommendation No. R (97) 5 of the Committee of Ministers to Member States on the Protection of Medical Data (1997), and Spanish Data Protection Act (Ley Orgánica 15/1999 de Protección de Datos, LOPD).
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