The effectiveness of 4.0% sodium hypochlorite (NaOCl) used with three irrigation methods in the elimination of Enterococcus faecalis from the root canal was tested in vitro. Root canals contaminated with E. faecalis were treated as follows: (i) irrigation with 2 mL of NaOCl solution and agitation with hand files; (ii) irrigation with 2 mL of NaOCl solution and ultrasonic agitation; (iii) irrigation with NaOCl alternated with hydrogen peroxide. Contaminated canals irrigated with sterile saline solution served as the control. Paper points used to sample bacteria from the root canals were transferred to tubes containing 5 mL of brain heart infusion (BHI) broth. Tubes were incubated and the appearance of broth turbidity was indicative of bacteria remaining in the root canal. There were no statistically significant differences between the experimental groups. However, NaOCl applied by the three methods tested, was significantly more effective than the saline solution (control group) in disinfecting the root canal.

Aim To compare the effects of three instrumentation systems, and a supplementary approach with a finishing instrument, on filling material removal during retreatment of mandibular molar canals. Methods Sixty mesial canals from mandibular molars (Vertucci's type IV anatomy) were instrumented, filled and subjected to retreatment. After initial removal of the root canal filling material using the D‐RaCe system, the canals were randomly distributed into three groups (n = 20) according to the instrument system used for preparation: the Self‐Adjusting File (SAF), TRUShape or XP‐endo Shaper. The filling material volume in the apical 5 mm of the canals was assessed by means of micro‐computed tomography (micro‐CT) before and after retreatment. All specimens with residual filling material were subjected to a supplementary approach with the XP‐endo Finisher R instrument and another micro‐CT scan was taken. Data on the volumes of filling material and incidence of total removal were compared between groups by the general linear model for paired data and the Fisher's exact test. The effects of the refinement step were evaluated by the Wilcoxon Signed Ranks test. Results The amount of removed material was 92.4%, 96.9% and 96.9% for the SAF, TRUShape and XP‐endo Shaper, respectively. There were no significant differences between them (P > 0.05). Canals were completely cleaned of filling material in 70% of the specimens for XP‐endo Shaper, 55% for SAF and 30% for TRUShape; the difference between XP‐endo Shaper and TRUShape was significant (P = 0.03). The supplementary step with the XP‐endo Finisher R instrument was associated with additional filling material removal of 38% (P < 0.001). Six more canals were rendered free of filling material after using this finishing instrument. Conclusions The tested systems were equally effective in removing the mass of filling material from the apical 5 mm of molar canals. The supplementary step with the XP‐endo Finisher R instrument enhanced filling material removal.

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This study compared the efficacy of XP‐Endo Finisher R and R1‐Clearsonic insert in removing filling material remnants from oval canals. Twelve pairs of contralateral premolars were treated and subsequently retreated with Reciproc 50. A supplementary procedure with XP‐Endo Finisher R or R1‐Clearsonic was performed. Micro‐computed tomography was used to quantify the filling material volume in the full canal and apical segment lengths. Intragroup analyses revealed significant reduction of filling material after both procedures, not only in the full canal but also in the apical segment (P < 0.05). The amount of filling material removed with XP‐Endo Finisher R and R1‐Clearsonic was 47.9% and 52.2% in the apical segment (P > 0.05), and 82.1% and 64.6% in the full canal (P < 0.05). None of the instruments was effective in completely removing the filling material from the apical canal, but better results were obtained with XP‐Endo Finisher R in the total canal length.