Antimicrobial and biofilm anti-adhesion activities of silver nanoparticles and farnesol against endodontic microorganisms for possible application in root canal treatment

Objective: This study aimed to evaluate the antimicrobial and biofilm anti-adhesion activities of poly(vinyl alcohol)-coated silver nanoparticles (AgNPs-PVA) and farnesol against Enterococcus faecalis, Candida albicans or Pseudomonas aeruginosa. Design: Minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) of the solutions, as well as the effect on the biofilm biomass were evaluated. The biofilm anti-adhesion activity was evaluated using bovine root dentine treated with the solutions after 3 min of contact and analyzed by scanning electron microscopy (SEM) and by colony-forming units per milliliter (CFU mL(-1)) counting. Data were analyzed using ANOVA and Tukey's, the paired Student's t-test or Kruskal-Wallis and Dunn's tests (alpha = 0.05). Results: The MIC and MMC values (MIC/MMC) of the AgNPs-PVA and farnesol against E. faecalis were 42.5/50 mu M and 0.85/1.0%, respectively. For C. albicans, the values were 27.5/37.5 mu M and 1.75/2.5%; and for P. aeruginosa, 32.5/32.5 pM and 2.5/2.75%, respectively. Both solutions showed reduced biofilm biomass (p < 0.05). SEM analysis showed that dentine blocks treated with both solutions had lower biofilm formation than the control (saline), except for C. albicans. In the CFU mL(-1) counting, biofilm cells were viable in the all groups in comparison with control (p > 0.05). Conclusions: AgNPs-PVA and farnesol showed antimicrobial and biofilm anti-adhesion activities, as well as potential for use as coadjuvant in endodontic treatment, and may be an option as auxiliary procedure for root canal disinfection or to inhibit biofilm formation.