Synergistic bactericidal activity of chlorhexidine loaded on positively charged ionic liquid-protected silver nanoparticles as a root canal disinfectant against Enterococcus faecalis: An ex vivo study

• Chlorhexidine is effectively loaded onto positively charged silver nanoparticles (CHX@AgNPs⁺). • CHX@AgNPs⁺ demonstrates significant antibacterial efficacy against Enterococcus faecalis . • CHX@AgNPs⁺ shows strong potential as a root canal disinfectant. • The antibacterial effect of CHX@AgNPs⁺ is comparable to that of 2.5 % NaOCl. • CHX@AgNPs⁺ exhibits enhanced antibacterial activity compared to chlorhexidine alone. The advancement of nanotechnology and the development of nanocomplexes offer promising solutions to address the limitations in biofilm management within endodontics. Current cleaning and disinfection methods often fail to completely eliminate bacterial biofilms from the complex anatomical structures of root canals, making the invention of new disinfectants or disinfection methods highly relevant. Previously, chlorhexidine-loaded positively charged ionic liquid-protected silver nanoparticles (CHX@AgNPs⁺) were introduced as an innovative root canal irrigation solution, demonstrating significant antibacterial efficacy against Enterococcus faecalis in vitro. This study aimed to further evaluate the antibiofilm activity of CHX@AgNPs⁺ in the root canals of extracted human teeth contaminated with E. faecalis biofilm. Fifty single-rooted human teeth with mature apices were randomly assigned to five experimental groups based on the irrigants used: CHX@AgNPs⁺, AgNPs⁺, 2.5 % NaOCl, 2 % CHX, and normal saline ( n = 10 per group). The root canals were contaminated with E. faecalis , and biofilm formation was confirmed. Initial sampling (S1) was performed, followed by mechanical preparation of the root canals using ProTaper F3 files and irrigation with the respective test solutions. Post-instrumentation sampling (S2) was then conducted. The results demonstrated that CHX@AgNPs⁺ exhibited antibiofilm properties comparable to 2.5 % NaOCl, with no significant difference between them. Additionally, CHX@AgNPs⁺ significantly enhanced antimicrobial efficacy compared to CHX alone ( P < 0.05), highlighting its potential as an effective root canal disinfectant.