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) counting. Data were analyzed using ANOVA and Tukey's, the paired Student's t-test or Kruskal-Wallis and Dunn's tests (α = 0.05).

Results: The MIC and MMC values (MIC/MMC) of the AgNPs-PVA and farnesol against E. faecalis were 42.5/50 μM and 0.85/1.0%, respectively. For C. albicans, the values were 27.5/37.5 μM and 1.75/2.5%; and for P. aeruginosa, 32.5/32.5 μM 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 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.