RESUMO
The purpose of this study was to determine the antifungal efficacy of 4% chlorhexidine (CHX) and 2% sodium hypochlorite (NaOCl) on 24-hour Candida albicans biofilms. Candida albicans biofilms were developed on acrylic resin specimens, which were randomly assigned to 1 of 5 groups (n = 3 per group) exposed to 1 mL of 4% CHX for 2, 4, 6, 8, or 10 minutes. Biofilms in contact with 1 mL of distilled water or 2% NaOCl for 10 minutes were used as positive and negative controls (n = 3 per group), respectively. Specimens were analyzed with confocal laser scanning microscopy and a cell viability assay technique. The biovolume of the live subpopulation of the biofilm was calculated with biofilm image analysis software. Statistically significant differences (P < 0.05) in the biovolume of surviving cells were found among the positive control group and the 4-, 6-, 8-, and 10-minute experimental periods. The biovolumes found after 6-10 minutes of exposure to chlorhexidine were significantly different (P < 0.05) from the biovolume after 2 minutes of exposure. The most effective decrease of the biovolume was found after the use of the negative control (sodium hypochlorite) solution. Exposure to 10 minutes of 2% NaOCl removed fungal cells more effectively than all the experimental groups (P < 0.05). The 4% CHX solution showed an antifungal activity against C albicans biofilms but failed to decrease the biovolume to the levels of 2% NaOCl, which eliminated viable cells more effectively and appeared to be more effective in disrupting the attached biofilms.