A comparison of the efficacy of mechanical, chemical, and microwave radiation methods in disinfecting complete dentures

BACKGROUND Poor denture hygiene can be a potential source of pathogens. The aim of this study was to compare the efficacy of microwave radiation with that of chemical and mechanical techniques in disinfecting complete dentures contaminated with Staphylococcus aureus and Pseudomonas aeruginosa. MATERIALS AND METHODS Seventy-two sterilized mandibular dentures were separately contaminated with S. aureus (n = 32) and P. aeruginosa (n = 32) and then incubated at 37°C for 48 h. The contaminated dentures were disinfected as follows: chemical disinfection with Corega tablets; chemical disinfection with 2% glutaraldehyde; mechanical disinfection by brushing the denture; and physical disinfection by 650-W microwaves irradiation for 3 min with six samples in each subgroup. Six dentures served as negative control group, and six contaminated dentures with no disinfection served as the positive control group. 10-3-10-6 dilutions were cultured in the nutrient agar, and the colonies were counted after incubation at 37°C for 48 h. To evaluate the lasting time of disinfection, the containers with nutrient agar and dentures were stored for 7 days at 37°C to evaluate turbidity. Data were analyzed using Kruskal-Wallis and Mann-Whitney U-test (α = 0.05). RESULTS There was no evidence of bacterial growth in 48 h and turbidity after 7 days of incubation of dentures disinfected by microwaves, glutaraldehyde, and Corega tablets, which was statistically significant compared to the positive controls (P < 0.001). In mechanically disinfected dentures (brushing), bacterial growth was detected after 48 h which was statistically significant compared to the positive controls (P < 0.001) and turbidity was seen in all the nutrient agar plates. CONCLUSION Microwave iradiation, 2% glutaraldehyde, and Corega tablets disinfected complete dentures contaminated with S. aureus and P. aeruginosa which lasted for a long and a short terms.