Chemical-Assisted Microwave Disinfection Used to Eradicate Candida albicans from Acrylic Resin Surfaces

Microwave radiation is a potential alternative to conventional disinfection of acrylic resin, but exposure time must be minimized, e.g., by combining it with chemical agents, due to its effects on material properties. This study aimed to microbiologically evaluate the antifungal activity of microwave disinfection performed in distilled water, sodium hypochlorite (NaOCl), chlorhexidine (CHX), hydrogen peroxide (H2O2), or without immersion. Thermally polymerized PMMA samples colonized with Candida albicans ATCC 14053 were exposed to microwaves for 1 or 3 min in an unmodified microwave oven. Disinfection effectiveness was assessed by colony counting after 48 h of culture and absorbance after crystal violet staining. All microwave treatments significantly reduced fungal counts compared with the control (5360.00 ± 1663.09 CFU/mL). Complete inhibition of colony growth occurred only after 3 min exposure in distilled water, NaOCl, or CHX. One-minute exposure in these liquids reduced but did not eliminate fungi. The least effective method was disinfection without immersion, yielding 1040.00 ± 169.71 CFU/mL after 1 min and 560.00 ± 108.32 CFU/mL after 3 min. None of the tested conditions fully removed biofilms, although microwaves combined with NaOCl produced the best results. Overall, it was found that the presence of a liquid itself, rather than the type of chemical used, was the key factor in effective microwave-assisted disinfection. Microwave disinfection without the addition of chemicals does not remove biofilms.