An in Vitro Comparison of Antimicrobial Efficacy and Residual Antimicrobial Activity of Root Canal Irrigants Qmix, 3% Sodium Hypochlorite, 2% Chlorhexidine against Enterococcus Faecalis

AIM: To evaluate the antimicrobial activity and the residual antimicrobial activity of Qmix, 3 % NaOCl and 2 % chlorhexidine (CHX) against E. faecalis in human root dentin in vitro. METHOD: Assessment of antimicrobial activity was done with a dentin disk put into 2 ml Eppendorf tube containing 200μl E. faecalis suspension in BHI broth. The tubes were incubated under anaerobic conditions at 37°C for 3 weeks. The different root canal irrigants of 200 μl each was put in each tubes. After 2 min incubation, the dentin blocks were removed and dried with absorbent paper. The biofilm biomass was measured by crystal violet (CV) staining and the absorbance measurement values were obtained by spectrophotometry at 600 nm. Assessment of residual antimicrobial activity of different groups was done by measuring the absorbance values at different intervals of 0 h, 24 h and 48 h by spectrophotometry at 600nm. RESULTS: Qmix showed highest antimicrobial activity followed by 3 % NaOCl and 2 % CHX against E. faecalis biofilm. The residual antimicrobial activities of the irrigants 2 % CHX showed maximum reduction in E. faecalis biofilm at 0 hr. CHX residual antimicrobial activity became significant at 48 h. Qmix showed reduction in E. faecalis biofilm at the end of 48 h NaOCl did not show any residual antimicrobial activity CONCLUSION: In conclusion, our study showed that 3 % NaOCl, 2 % CHX and Qmix could kill E. faecalis in matured biofilm. The antibacterial activity of QMix excelled among the irrigants included in the study and the residual antimicrobial activity of 2 % CHX was better than QMix at 24h and 48h respectively. Clinical Significance: Antibacterial activity and residual antimicrobial activity are important properties of root canal irrigants against persistent microorganisms like E. Faecalis