Comparative Evaluation of Calcium Hypochlorite and Sodium Hypochlorite Associated with Passive Ultrasonic Irrigation on Antimicrobial Activity of a Root Canal System Infected with Enterococcus faecalis: An In Vitro Study

Introduction

The purpose of this study was to compare in vitro the effectiveness of calcium hypochlorite (Ca[OCl]₂) and sodium hypochlorite (NaOCl) associated with passive ultrasonic irrigation in root canals of bovine teeth infected with Enterococcus faecalis.

Methods

The root canals of 60 single-rooted bovine extracted teeth were enlarged up to a file 45, autoclaved, inoculated with Enterococcus faecalis, and incubated for 30 days. The samples were divided into 6 groups (n = 10) according to the protocol for decontamination: G1: no treatment; G2: distilled water; G3: 2.5% NaOCl; G4: 2.5% Ca(OCl)₂; G5: 2.5% NaOCl with ultrasonic activation; and G6: 2.5% Ca(OCl)₂ with ultrasonic activation (US). Microbiological testing (colony-forming unit [CFU] counting) was performed to evaluate and show, respectively, the effectiveness of the proposed treatments. Data were subjected to 1-way analysis of variance followed by the post hoc Tukey test (α = 0.05).

Results

Groups 1 and 2 showed the highest mean contamination (3.26 log₁₀ CFU/mL and 2.69 log₁₀ CFU/mL, respectively), which was statistically different from all other groups (P < .05). Group 6 (Ca[OCl]₂ + US) showed the lowest mean contamination (1.00 log₁₀ CFU/mL), with no statistically significant difference found in groups 3 (NaOCl), 4 (Ca[OCl]₂), and 5 (NaOCl + US) (P < .05).

Conclusions

Ca(OCl)₂ as well as passive ultrasonic irrigation can aid in chemomechanical preparation, contributing in a significant way to the reduction of microbial content during root canal treatment.