The influence of irrigation solutions in the inorganic and organic radicular dentine composition

The aim of this study was to analyse changes in radicular dentine composition after different irrigation regimes using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). Dentine slices from human single-root teeth were immersed in: (i) 5.25% sodium hypochlorite (NaOCl) for 1, 5 and 20 min; (ii) 17% EDTA for 1 min; and (iii) 5.25% NaOCl for 20 min, and 17% EDTA and 5.25% NaOCl, both for 1 min. Carbonate/mineral, Amide I/mineral and Amide III/CH₂ ratios were determined using ATR-FTIR before and after immersion in the irrigation solutions tested. Results showed that 5.25% NaOCl significantly decreased carbonate/mineral, Amide I/mineral and Amide III/CH₂ ratios (P < 0.05). Application of 17% EDTA produced no change in carbonate/mineral ratio (P = 0.120), while an increase in Amide I/mineral in apical third (P = 0.002) and Amide III/CH₂ (P < 0.001) was observed. The combination of NaOCl, EDTA and NaOCl increased carbonate/mineral ratio in coronal third (P = 0.037), and Amide I/mineral (P = 0.003) and Amide III/CH₂ (P = 0.001) ratios. In conclusion, irrigation solutions tested significantly affected radicular dentine composition.