Effects of Different Irrigation Solutions and Protocols on Mineral Content and Ultrastructure of Root Canal Dentine

The aim of this study was to evaluate the effect of different irrigating solutions and irrigation protocols on the chemical and physical structure of root dentin.

Thirty extracted single-rooted human teeth were selected and then distributed into the following treatment groups (n=10): G1, saline solution (0.9% NaCl); G2, 2.5% NaOCl + 17% EDTA + 2.5% NaOCl; G3, 2.5% NaOCl + 9% Etidronate (HEBP) + 2.5% NaOCl; G4, mixture of 5% NaOCl + 18% HEBP; G5, 2.5% NaOCl + 17% EDTA + 0.9% NaCl, and G6, 2.5% NaOCl + 9% HEBP + 0.9% NaCl. The ultrastructure of dentin was characterized through scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS) determined the chemical composition in terms of the calcium (Ca), phosphorus (P), magnesium (Mg) and potassium (K) content and the Ca/P ratio; and the crystalline phase was analyzed by x-ray diffraction (XRD). A descriptive analysis was performed on the ultrastructure and the crystallography data of dentin. Data analysis included a chemical composition analysis of variance (one-way ANOVA) and a subsequent multiple comparison test (Tukey's test).

Except for the control group, all groups showed morphological changes upon visualization with SEM. For EDS, G2 and G5 showed significant mineral loss and changes in the Ca/P ratio (P<0.05); the highest values of Ca and P were observed in G3, G4 and G6.

All the irrigating solutions and irrigation protocols tested promoted changes in the morphology and physical and chemical composition of the dentin. However, no significant differences were observed crystallographically.