Materials and Methods: Reference stains of C. albicans (ATCC 90231), C. glabrata (ATCC 22019), C. krusei (ATCC 6258) and C. parapsilosis (ATCC 90030) were chosen for the study. A total of 160 PMMA samples (40 for each species) were tested. Each sample was immersed in Yeast Nitrogen Broth (YNB) supplemented with 100 mM of Glucose containing 10 7 CFU/ml of yeast cells, for 48 hours. Following biofilm formation, the samples were washed with sterile PBS (pH 7.2), placed in a glass beaker containing 200 ml of water and microwaved individually. The settings used for irradiation were 600, 850 and 1000 watts for 30 seconds, 1 minute, 1 minute 30 seconds and 2 minutes, respectively. Following irradiation, XTT assay was carried out for quantitative assessment of live candidal cells adhered on the samples. The XTT assay results were analyzed using a three-way ANOVA statistical analysis (P value 0.05). The physical properties of the acrylic after microwave irradiation was tested using ISO (20795-1) standards.
Results: Microwave irradiation affected the biofilm formation on the acrylic specimens. The maximum effects for biofilm removal from the samples were seen with 1000 watts at 2 minutes. The amount of disinfection obtained was directly related with the time period and intensity of microwave irradiation.
Conclusions: Candidal biofilm can be removed by microwave irradiation. Therefore, microwave irradiation can provide a simple and effective means for the disinfection of PMMA resin.