Antibacterial Properties of Chitosan Nanoparticles and Propolis Associated with Calcium Hydroxide against Single- and Multispecies Biofilms: An In Vitro and In Situ Study

Abstract Introduction The aim of this study was to evaluate the efficacy of chitosan nanoparticles (CNPs) and ethanolic propolis extract (EPE) incorporated into a calcium hydroxide paste (Ca[OH]2 ) to kill bacterial biofilms. Methods Human root canal dentin was infected with Enterococcus faecalis for 21 days and also intraorally for 48 hours followed by incubation in brain-heart infusion for 48 hours to standardize biofilm growth. Ca(OH)2 pastes associated or not with CNPs or EPE were tested on biofilms for 7 and 14 days. Distilled water was used for control purposes. After the treatment procedures, microbiological analysis was performed to determine the reduction in E. faecalis colonies. Confocal microscopy was used to determine the percentage of cell viability in polymicrobial biofilms before and after the exposure to the experimental intracanal medications. Results All experimental pastes were able to significantly reduce the E. faecalis colony-forming units (CFU) after 7 or 14 days ( P