Introduction: Under well-defined experimental conditions, and in the presence of hydrogen peroxide, lactoperoxidase produces stable iodine-thiocyanate complexes that have antimicrobial properties. A novel process was developed to short circuit the consumption of hydrogen peroxide by microbial catalases by producing iodine-thiocyanate complexes prior to contact with microorganisms, with the aim of being able to decontaminate the ex vivo dentures colonized by yeasts.

Materials and methods: Teabags containing lactoperoxidase adsorbed on inert clay beads were immersed for 1 minute in phosphate buffer solution (0.1 M pH 7.4) containing 5.2 mM potassium iodide, 1.2 mM potassium thiocyanate, and 5.5 mM hydrogen peroxide. After removing the adsorbed lactoperoxidase, the stability and efficacy of iodine-thiocyanate complexes for Candida -colonized denture decontamination were verified. Investigations were performed in vitro on Candida albicans ATCC 10231 and on clinical isolates from 46 dentures. A Candida plate count was performed after a 24-hour incubation at 37°C on Sabouraud-chloramphenicol or CHROMagar solid media; then, the yeast growth was evaluated in Sabouraud broth by turbidimetry and biofilm biomass by crystal violet staining.

Results: In vitro tests demonstrated the effectiveness of the oxidant solution in sterilizing a suspension of 10⁶ Candida cells per milliliter after a 5-minute incubation. A single ex vivo immersion of contaminated dentures in a solution of iodine-thiocyanate complexes led to a decrease of at least 1 log unit in the number of colony-forming units in 58.3% of the tested dentures, while immersing in water alone had no effect on denture colonization (significant c 2: p = 0.0006).

Conclusion: These data suggest a promising new strategy for decontamination of dentures.