| Introduction: The purpose of this study was to investigate the antimicrobial effects of a number of Essential Oils (EOs) on Enterococcus faecalis biofilms in a human dentin model. Methods: The Kirby Baur diffusion disc assay was used to determine the antimicrobial properties of 11 EOs against E. faecalis OG1RF. 6% Sodium hypochlorite (NaOCl), 2% Chlorhexidine (CHX) and sterile water were used as positive and negative controls. Thereafter, the Minimum Inhibitory Concentrations (MIC) and the Minimum Bactericidal Concentrations (MBC) of the oils possessing antimicrobial properties against E. faecalis was determined. Dentin discs were sterilized and inoculated with E. faecalis and cultured for 3 weeks. Subsequently the discs were treated with 1% EOs, 6% NaOCl and 2% CHX respectively for 10 minutes. The proportion of live and dead cells was determined by Confocal Laser Scanning Microscopy (CLSM). Results: We identified 3 EOs, Cinnamon bark, Thyme and Oregano, that exhibited significant zones of inhibition against E. faecalis. Furthermore, we determined the MIC for these 3 oils to be 0.01%, 0.8% and 0.2% respectivley, while the MBC for all three EOs were 1%. In the dentin model we observed significant reduction in the number of live bacteria in the oil treated samples (P<0.0001) compared to the untreated sample. Further we observed the antimicrobial activities of Thyme and Oregano were comparable to the 6% NaOCl and 2% CHX treated samples. Conclusions: The EOs of Cinnamon bark, Thyme and Oregano possessed antimicrobial properties against E. faecalis biofilms grown in dentin. |
