Anticandidal Activity of Cajuput and Lemongrass Essential Oils Supplemented in Alcohol-Free Mouthwash Against Candida albicans Biofilm Formation on 96-Well Plate and Acrylic Surfaces

The present study aimed to evaluate the efficacy of alcohol-free mouthwash containing cajuput and lemongrass essential oils and their synergistic effect on eliminating Candida albicans biofilm formation, the most common causative agent of denture stomatitis. The inhibitory activity against C. albicans ATCC10231 biofilm formation on 96-well plate and acrylic surfaces of this formula was significantly different from 0.12% chlorhexidine solution at 20 minutes (P < 0.0001). At one hour and eight hours of immersion, the activity of this formula was similar to the activity of 0.12% chlorhexidine mouthwash. After treatment with this formula, there were less densely active cells and biofilm compared to the negative control, and the action was close to that of 0.12% chlorhexidine mouthwash. The minimal inhibitory concentrations of cajuput and lemongrass essential oils were 2 and 4 µL/mL (for 0.2% and 0.4% v/v, respectively). For chequerboard assays, the fractional inhibitory concentrations of these oils were 0.5 and 0.25 µL/mL, respectively. The combination of cajuput and lemongrass oils in this formula exhibited partial synergism against C. albicans ATCC10231 biofilm formation with a fractional inhibitory concentration index of 0.75. This study demonstrated the inhibitory activity of this formula against C. albicans biofilm formation on 96-well plate and acrylic surfaces after quantitated by colony enumeration and the XTT reduction assay resembled 0.12% chlorhexidine mouthwash. In conclusion, that C. albicans could be inhibited by the partial synergism of these essential oils in this mouthwash formula. Keywords: Inhibitory activity, Natural essential oils, Candida albicans, Microbial biofilm, Solid surface