Quantitative assessment of root canal roughness with calcium-based hypochlorite irrigants by 3D CLSM

Chemical solutions play important roles in endodontic treatment and promote ultrastructural changes in dentin surface. The aim of this study was to quantify root canal roughness at different concentrations of calcium hypochlorite (Ca(OCl)2) and sodium hypochlorite (NaOCl) by confocal laser scanning microscopy (CLSM). Fifty-two human mandibular premolars were sectioned and randomly organized into thirteen groups (n=8): saline (control); 1%, 2.5% and 5% NaOCl; 1%, 2.5% and 5% Ca(OCl)2; the hypochlorite groups were further divided into with or without EDTA. The chlorine concentrations of the different solutions were measured by iodine titration (%). The superficial roughness (Sa) was quantified by CLSM. Ca(OCl)2 presented substantial decrease in chlorine concentration that differed from the package indication, but without compromising the dentin ultrastructure changes. There were no significant differences in dentin roughness between Ca(OCl)2 or NaOCl at all studied concentrations. The combination with EDTA provided similar roughness values among the solutions (p>0.05). The 5% Ca(OCl)2 and NaOCl solutions significantly increased dentin roughness and did not differ from the EDTA association (p>0.05). Ca(OCl)2 promoted similar dentin roughness as the NaOCl at the same concentrations and combined with EDTA. It may be concluded that Ca(OCl)2 modified the root canal dentin roughness similarly to NaOCl, at the same concentrations and EDTA combinations used in this study. Ca(OCl)2 and NaOCl, both at 5%, significantly altered dentin roughness, overcoming EDTA association, thus Ca(OCl)2 concentrations ranging from 1% to 2.5% may be suitable solutions for root canal irrigation protocols.