This study investigated the effectiveness of XP-Endo Finisher (XPF) associated with XP-Endo Shaper (XPS) or Reciproc Blue (RB) files in reducing bacterial load in oval-shaped root canals (RC) during chemomechanical preparation (CMP) using 0.9% saline solution (NaCl) or 2.5% sodium hypochlorite (NaOCl). Eighty mandibular incisors with single oval-shaped RC were contaminated with Enterococcus faecalis. The teeth were randomly assigned to eight experimental groups (n = 10) according to the CMP, as follows: G1: XPS, G2: XPS + XPF, G3: RB, and G4: RB + XPF. CMP was performed with NaCl or NaOCl. The reduction of bacterial load was assessed by colony-forming unit count before (S1) and after (S2) CMP. Data normality was verified by using Shapiro-Wilk test. ANOVA, Tukey's test, and Bonferroni post-hoc test were used at a 5% significance level. Culturable bacteria were present in all S1 samples (p>0.05). All instrumentation techniques were effective in reducing bacterial load, irrespective of the irrigating solution (p < 0.05). With the use of NaCl, RB was more effective than XPS (p = 0.035). With the use of NaOCl, XPS and RB presented similar effectiveness (p = 0.779). XPF enhanced the bacterial reduction of both systems tested (p < 0.05). The use of NaOCl improved the CMP, irrespective of the instrumentation technique used (p < 0.05). In conclusion, XPS and RB files are effective in reducing bacterial levels in oval-shaped RC. The use of XPF as a method of agitation of the irrigating solution improved the cleaning efficiency of both file systems tested. Mechanical preparation performed with saline solution decreased culturable bacteria from the root canal, but antimicrobial substances such as NaOCl should be used to achieve a significantly better disinfection.

This study evaluated the amount of apically extruded debris after chemo-mechanical preparation (CMP) using positive and negative pressure irrigation systems [Conventional irrigation (CI) and EndoVac (EV)] in association with different irrigants [6% Sodium Hypochlorite (NaOCl), 2% Chlorhexidine gel + saline solution (CHXg + SS), 2% Chlorhexidine solution (CHXs) or Saline solution (SS)]. Eighty mandibular premolars with single root canals were selected and randomly assigned into 8 groups (n = 10) according to the irrigation system and the irrigant used during CMP: G1 (EV + NaOCl), G2 (EV + CHXg + SS), G3 (EV + CHXs), G4 (EV + SS), G5 (CI + NaOCl), G6 (CI + CHXg + SS), G7 (CI + CHXs) and G8 (CI + SS). Reciproc® R25 files (25/.08) were used during the CMP and the extruded debris from each tooth was collected in pre-weighted Eppendorf tubes and dried. The average weight of debris was assessed using a microbalance, and the data were statistically analyzed using ANOVA and the post hoc Tukey’s test (a = 0.05). All groups were associated with debris extrusion. EV was the irrigation system with less extruded debris (p < 0.05). No differences were observed regarding the irrigant when EV was used. When CI was used, CHXg + SS were associated with lower debris extrusion (p < 0.05). It was concluded that no irrigation protocol succeeded in preventing debris extrusion. EV resulted in lower levels of debris extrusion than CI. The use of CHXg + SS resulted in lower debris extrusion.

The present study evaluated the amount of apically extruded debris after chemo-mechanical preparation (CMP) associated with passive ultrasonic irrigation (PUI) using four different root canal irrigants, namely, 6% sodium hypochlorite (NaOCl), 2% chlorhexidine gel + saline solution (2% CHXg+SS), 2% chlorhexidine solution (2% CHXs) and SS alone. Sixty mandibular premolars with single straight root canals were selected and randomly assigned into 4 groups (n=15) according to the root canal irrigant used as follows: G1 (PUI + NaOCl), G2 (PUI + CHXg+SS), G3 (PUI+CHXs) and G4 (PUI+SS). Reciproc® R25 files (25/.08) were used during CMP and the debris extruded from each tooth were collected in pre-weighted Eppendorf tubes and dried. The average weight of debris was assessed by using an analytical microbalance. Data were statistically analysed by using ANOVA and post-hoc Tukey’s test (a=0.05). Debris extrusion was observed in all groups, irrespective of the root canal irrigating, with 2% CHXg + SS being associated with lower debris extrusion compared to other irrigants (p<0.05). No significant differences were observed between 6% NaOCl, 2% CHXs and SS. In conclusion, passive ultrasonic irrigation did not completely prevent apically extrusion of debris. PUI performed with 2% chlorhexidine gel + saline solution significantly minimized debris extrusion compared to 6% sodium hypochlorite, chlorhexidine solution and saline solution.