Evaluation of Photodynamic Therapy with 660 nm Diode Laser and Different Concentrations of Methylene Blue on Candida Albicans growth on Denture(laboratory study)

Background and Aim: Candida has an important role in denture-dependent stomatitis. The use of lasers and light-absorbing materials to act against this fungus has been suggested in some studies. In this study, the antifungal effects of 660 nm diode laser with different concentrations of methylene blue as a light absorbing agent against Candida albicans grown on dentures was investigated. Materials and methods: In this laboratory study, 26 similar dentures were prepared. Suspension (0.5 McFarland) of candida albicans was inoculated on the dentures. The samples were selected into three similar seven groups with different concentrations of methylene blue (0.1, 0.01, 0.001 g / l) and a 660 nm diode laser (200 mW,0 Hz,3.25 J/cm2  )was applied. Five control samples including 1 untreated, 1 laser alone and 3 different concentration of methylene blue alone were considered. The number of colonies was counted using non automatic and by eye methods. Data were analyzed using SPSS version 22 by using one way t-test and ANOVA. Results: The mean number of Candida albicans grown on denture after photodynamic therapy and different concentrations of methylene blue was significantly different from controls (P <0.001). The mean number of Candida albicans grown was significantly different between the three concentrations of methylene blue (P <0.001) and the efficiency of methylene blue with a concentration of 0.001 was significantly higher than the other two concentrations (P <0.001), but between the two Concentrations of 0.1 and 0.01 showed no significant difference in efficacy (P = 0.96). Conclusion: Photodynamic therapy with 660 nm laser and methylene blue with a concentration of 0.001 had the highest efficiency in reducing Candida albicans.