Antibiofilm Efficacy of Positively Charged Imidazolium-Based Silver Nanoparticles in Enterococcus faecalis Using Quantitative Real-Time PCR

Background: Nanoparticles are made by different methodologies, which can affect the particle’s features. Recently, imidazoliumcoated silver nanoparticles with a positive surface charge (PC Im-based AgNPs) have revealed favorable results as a root canal disinfectant. However, the antibacterial potency of these particles against biofilm form of Enterococcus faecalis, as the most resistant organism to eliminate in endodontic treatment, has not been investigated. It can be noted that removing this microorganism is associated with extremely effective disinfection. Objectives: This study investigated the antibacterial efficacy of PC Im-based AgNPs at 5.7 × 10^-8 mol L^-1 in comparison with 2.5% sodium hypochlorite (NaOCl) and 2% chlorhexidine as the two broadly used endodontic irrigation solutions against biofilm E. faecalis using quantitative real-time polymerase chain reaction. Methods: In total, 48 premolar teeth with a single root were infected with E. faecalis and then prepared with ProTaper rotary instru- ments. The samples were randomly allocated into 4 groups of 12 samples. Sterile saline, PC Im-based AgNPs, NaOCl, and chlorhexidine were used as irrigants. Sampling the root canals was implemented with paper points and GatesGlidden drills. The reduction in E. faecalis counts was calculated and statistically analyzed by means of the Kruskal-Wallis and Mann-Whitney U tests. Results: Irrigation with PC Im-based AgNPs or NaOCl was significantly more effective in bacterial count reduction compared to irrigation with chlorhexidine or sterile saline (P 0.05). There was no significant difference between PC Im-based AgNPs and NaOCl irrigants when either Gates-Glidden drills (P = 0.751) or paper points (P = 0.488) were employed. Chlorhexidine was significantly less efficient than PC Im-based AgNPs and NaOCl solutions (P 0.001); however, it was significantly better than sterile saline in both sampling approaches (P 0.001). -8 Conclusions: The PC Im-based AgNP solution revealed promising results as a root canal irrigant. This solution at 5.7 × 10^-8 mol L^-1was effectively able to eliminate biofilm E. faecalis and this was not significantly different from that of 2.5% NaOCl.