FTIR/ATR study of human dentin subjected to hydrogen peroxide

Objective: To investigate the effects of 30% hydrogen peroxide on the organic and mineral components of human dentin. Methods: Ten freshly extracted human premolars were sectioned and fabricated into approximately 4×6×2 mm slabs. These specimens were randomly assigned to two groups and treated either with 30% hydrogen peroxide (Group 1) or Hanks' balanced salt solution (Group 2) for 24h. Fourier transform infrared attenuated total reflection (FTIR/ATR) spectroscopy was used to measure the specimens before and after treatment. The spectroscopic parameters calculated were mineral to matrix ratio and carbonate to mineral ratio. And the mineral crystallinity investigations were focused essentially on the v1, v3 phosphate region. Statistical analyses of the mineral to matrix ratio and the carbonate to mineral ratio were carried out using mixed model ANOVA. Results: After treatment, great changes were observed in the spectra of Group 1, while the changes were rather slight in Group 2. The mineral to matrix ratios increased dramatically in Group 1 but slightly in Group 2. The carbonate to mineral ratios decreased in Group 1 whereas they increased in Group 2. Statistical analyses revealed that there were significant differences in the mineral to matrix ratios (p=0.000) and the carbonate to mineral ratios (p=0.000) between two groups. Moreover, the contour in the v1, v3 phosphate region became sharpened in Group 1 while it slightly widened in Group 2. Conclusions: Hydrogen peroxide mainly attacks the organic component of superficial human dentin and also has effects on the mineral components.