Antibacterial Effect of Cannabinoids on Bacteria Associated with Persistent Endodontic Infections

Cannabinoids have been shown to have effective antibacterial applications. With the limitations of current intracanal endodontic medicaments and the rise of bacterial resistance, it is important to investigate novel treatment strategies for endodontic infections. The aim of this study was to test the antibacterial efficacy of cannabinoids on bacteria in persistent endodontic infections: Enterococcus faecalis, Streptococcus mutans, and Fusobacterium nucleatum. Planktonic bacteria were exposed to a negative control (no exposure), a positive control (3% NaOCl), and the experimental groups Cannabidiol (CBD), Cannabinol (CBN), and Tetrahydrocannabinol (THC). The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were also investigated. Biofilms were cultured and treated with cannabinoids. A crystal violet assay (CVA) and live/dead analysis assessed the biofilm degradation and inhibition, respectively. A statistical analysis was performed using an ANOVA. CBD, CBN, and THC reached a MIC for both E. faecalis and S. mutans in planktonic forms. The MBC was found for the tested cannabinoids on planktonic E. faecalis. No MBC was found for S. mutans. The live/dead analysis of E. faecalis and S. mutans biofilms showed a decrease in the viability of the biofilm with an increased cannabinoid concentration. The CVA revealed that cannabinoids only degrade the E. faecalis biofilm. Planktonic F. nucleatum had no MIC for tested cannabinoids. Cannabinoids have inhibitory effects on E. faecalis and S. mutans in the planktonic and biofilm states. No inhibitory effects of F. nucleatum were found at tested concentrations of all three cannabinoids. The findings suggest that cannabinoids have distinct antibacterial effects on certain pathogens associated with persistent endodontic infections.