Impact of acidic pH and sealer thickness on the physical behavior of endodontic sealers: a micro-CT study

The aim of this study was to evaluate the effect of immersion in an acidic (butyric acid - BA; pH 4.1) or neutral (phosphate-buffered saline - PBS; pH 7.0) environment on the physical behavior of Bio-C Sealer (BCS) or AH Plus Jet (AHPJ) after filling oval root canals with different thicknesses of sealer. Thirty-two oval root canals were prepared and filled with BCS or AHPJ (n = 16), using the single-cone technique. Greater, middle, and smaller thicknesses of sealer were established in the cervical, middle, and apical thirds of the root canals, respectively. Then, the samples were immersed in BA or PBS (n = 8) for time intervals of 7 and 30 days. Micro-CT scans were performed after the materials set and after the experimental time intervals ended. Volumetric change and the percentage of voids and gaps at the material/dentin interface were evaluated. Kruskal-Wallis and Dunn, Friedman, Wilcoxon paired, and ANOVA/Tukey tests were performed (α = 0.05). Significant volumetric change and percentage of voids and gaps at the interface of BCS and AHPJ were observed in BA after 30 days (p < 0.05). Both materials showed a higher percentage of voids and volumetric loss in the greater sealer thickness (p < 0.05). Baseline showed a lower percentage of voids and gaps at the interface when compared with the experimental periods (p < 0.05). An acidic environment harms the properties of endodontic sealers after 30 days. The greater sealer thickness negatively affected the volumetric change and presence of voids in oval root canals.