Evaluation of the effect of heat damage on DNA extracted from the dental pulp of restored teeth

We evaluate structural damage effects of heat on DNA obtained from the dental pulp of restored premolars. We studied three groups (A, B and C) each group comprised twenty premolars extracted from five patients. Three of the four premolars of each donator were restored with different materials: amalgam, glass ionomer and resin, and one unrestored premolar was used as control. The group A was not exposed to heat, while B and C groups were exposed to 100 °C and 300 °C, respectively. The DNA damage was evaluated as percentage of genotyping of 15 Short Tandem Repeats (STRs) and amelogenin and by Fourier-transform infrared spectroscopy (FTIR). The results showed 100% genotyping in all unheated premolars; however, the increase in heat decreased genotyping percentage due to DNA degradation. The amplifications from the premolars restored with glass ionomer and those unrestored were less affected, amplifying by approximately 80% at 300 °C. FTIR revealed that DNA structural damage occurred in the phosphate region, and changes in ribose were also shown; in addition, we detected presence of β- three-calcium-phosphate (β – TCP) due to heat treatment. Moreover, the phosphate region of DNA was a good indicator of DNA integrity related to the ratio of 1230/1085 cm ⁻¹ in the second derivative (asymmetric/symmetric PO2), which was major in premolars restored with glass ionomer heated at 100 °C, and this ratio is related to less DNA alterations and better genotyping; however this changes only were detected at 100 °C, suggesting that dental restoration with this material only protects dental pulp at temperatures below 300 °C.