The aim of this study was to investigate whether a final rinse with Endosolv R ® solvent and ultrasound resulted in cleaner root canal walls during endodontic retreatment. A total of 56 extracted premolar teeth were manually instrumented using a step-back flare technique and filled with gutta-percha and AH Plus sealer. After 9 months, the canals were retreated by removing the gutta-percha and sealer with ProTaper Universal Retreatment and rotary preparation with ProTaper Universal System up to an F5 file. As a final step, the teeth were randomly divided in 4 groups (n=14) and were subjected to passive ultrasonic irrigation (PUI) with either Endosolv R or distilled water. In the control groups, the irrigants were left undisturbed. Roots were cleaved and examined under scanning electron microscopy (SEM), and the amount of filling remnants on the canal walls was assessed by two calibrated examiners in a blinded fashion. Data were analyzed by the Kruskal-Wallis test and the Student-Newman-Keuls post hoc test (α=0.05). All groups presented filling debris in the three root canal thirds after retreatment. There were no significant differences between the groups or among the root canal thirds within each group (p>0.05). PUI with Endosolv R was not effective in the removal of filling debris from root canal walls.

Aim:The aim of this study was to investigate whether time exposure of resin-based root canal sealers to organic solvents affects their solubility. Materials and methods: Standardized circular silicon moulds (4.47mm wide and 1.5mm high) were filled with four freshly mixed resin-based root canal sealers (Acroseal ® , Epiphany ® , AH Plus ® and Sealer 26 ® ) and stored at 37° for two weeks (n=8). After inspection, each sample was weighted thrice and individually immersed in Citrol ® , Endosolv R ® , 2.5% sodium hypochlorite or distilled water for 10, 120 and 1440 min. In the tested intervals, the mean weight loss of each filling material immersed in solvents was determined.Data were statistically analyzed by Two-way ANOVA, Bonferroni post hoc and Pearson tests (α=0.05). Results: Endosolv ® R was significantly more effective in dissolving Sealer26 ® than distilled water (control group), orange oil and 2.5% sodium hypochlorite. Citrol ® and 2.5% sodium hypochlorite showed the greatest potential to dissolve Sealer26 ® within 24 hours, compared to the control group. The weight losses between sealers immersed in sodium hypochlorite 2.5% were not statistically significant. Solubility was significantly correlated with exposure intervals only when Endosolv R ® (+0,829) or double-distilled water (+0,441) were applied. Conclusion: Dissolution of resin-based root canal sealers was affected by exposure interval and type of organic solvent used. Endosolv R® and longer exposure intervals promoted greater solubilization of the resin-based sealers tested.