Aim to analyze the impact of various irrigating solutions on the superficial chemical structure and microhardness of the root dentine.

Methodology Fifty-two dentin half discs were distributed randomly into four groups (n=13); Control groups: distilled water was used to treat the samples, NaOCl/EDTA group: 2.6% NaOCl was applied to the samples, followed by distilled water and then 17% EDTA, NaOCl/Dual Rinse group : was irrigated with 2.6% NaOCl/9% Dual Rinse, NaOCl/Glycolic acid group : 2.6% NaOCl was applied to the samples, followed by distilled water and then 17% glycolic acid (PH 2). Utilizing Fourier Transform Infrared Spectroscopy (FTIR), the ratio of phosphate to amide I ratio was calculated, and then Vickers hardness test was employed to gauge the microhardness of the dentine. One-way ANOVA was used to compare between groups, followed by Tukey post-hoc analysis.

Results: Phosphate/Amide ratio and microhardness evaluation revealed statistically significant differences (p<0.05) among groups, with no difference demonstrated between the Control, NaOCl/Dual Rinse or NaOCl/Glycolic acid groups (p>0.05).

Conclusion: Date revealed that sequential treatment of dentine with NaOCl and different decalcifying affected the chemical composition and microhardness, where NaOCl/Dual Rinse and NaOCl/Glycolic acid caused less depletion of the apatite and changes in dentine microhardness compared to NaOCl/EDTA group.