Antifungal Efficacy of Aqueous and Gaseous Ozone in Root Canals Infected by Candida albicans

Background: Candida albicans is one of the important microorganism which can be isolated from normal flora in the mouth. The resistance of C. albicans against disinfectants like ozone can reduce success rate of root canal treatments. Objectives: The current study aimed to investigate the antifungal efficacy of aqueous and gaseous ozone in human root canals infected by C. albicans. Materials and Methods: Fifty single-root mandibular premolar teeth were selected. The teeth were prepared and sterilized. C. albicans were incubated in root canals and kept at 37 degrees C for 24 h. The teeth were divided into one positive, one negative control, and three experimental groups (n = 10). Group 1, saline (positive control); Group 2, sodium hypochlorite (NaOCl) (negative control); Group 3, aqueous ozone with manual technique (4 mg/L); Group 4, aqueous ozone with ultrasonic technique (4 mg/L) and Group 5, gaseous ozone. Disinfection procedures were performed during 300 s to ensure standardization among all the working groups. Paper points, placed in the root canals before and after disinfection procedures, were transferred in Eppendorf tubes containing 0.5 ml of brain heart infusion broth. Then 50-mu L suspension was inoculated onto Sabouraud dextrose agar. Microbial colonies were counted and data were evaluated statistically with using one-way ANOVA and Tukey's tests. Results: A statistically significant difference was found between antifungal activities of gaseous ozone group and NaOCl group (P < 0.05). Additionally, although no statistically significant differences were found among aqueous ozone groups (manual and ultrasonic techniques) and the NaOCl group (P > 0.05), few fungi were found in the aqueous ozone with manual technique group. Conclusions: When gaseous ozone was used alone in root canals, its antifungal effect was not sufficient. However, applying aqueous ozone with ultrasonic technique showed stronger antifungal effects than aqueous ozone with manual technique in root canals.