Effect of calcium hypochlorite and sodium thiosulfate on the bond strength to pulp chamber dentin: A laboratory investigation

This study aimed to compare the effect of sodium hypochlorite (NaOCl) and calcium hypochlorite [Ca(OCl)2] on the bond strength to pulp chamber dentin when followed or not by the use of sodium thiosulfate (Na2S2O3). The pulp chamber of fifty human molars were divided into five groups (n = 10) according to the immersion protocol: 2.5% NaOCl; 2.5% NaOCl + 5% Na2S2O3; 2.5% Ca(OCl)2; 2.5% Ca(OCl)2 + 5% Na2S2O3; and 0.9% sodium chloride (NaCl; control). Subsequently, the samples were restored with resin composite. Three sticks each were obtained and subjected to microtensile testing. SEM/EDS analyses of the pulp chamber roof (n = 8) were carried out for mineral quantification. Elemental analysis data were investigated via one‐way ANOVA and Tukey's post hoc, and bond strength data by post hoc pairwise comparisons using the Kruskal–Wallis test. Use of 2.5% NaOCl was associated with the lowest value of bond strength, while 2.5% Ca(OCl)2 had similar bond strength to that of the 0.9% NaCl control. Using 5% Na2S2O3 was able to increase the bond strength after 2.5% NaOCl, but not after 2.5% Ca(OCl)2. The group treated only with 2.5% Ca(OCl)2 had a higher Ca/P ratio on the dentin surface. Dentin treated with Ca(OCl)2 was not affected by Na2S2O3 and showed bond strength similar to the 0.9% NaCl.