Effectiveness of microwave irradiation on the disinfection of complete dentures.
OBJECTIVE
The purpose of this study was to evaluate the effectiveness of microwave irradiation on the disinfection of simulated complete dentures.


METHODS
Eighty dentures were fabricated in a standardized procedure and subjected to ethylene oxide sterilization. The dentures were individually inoculated (10(7) cfu/mL) with tryptic soy broth (TSB) media containing one of the tested microorganisms (Candida albicans, Streptoccus aureus, Bacillus subtilis, and Pseudomonas aeruginosa). After 48 hours of incubation at 37 degrees C, 40 dentures were individually immersed in 200 mL of water and submitted to microwave irradiation at 650 W for 6 minutes. Forty nonirradiated dentures were used as positive controls. Replicate aliquots (25 microL) of suspensions were plated at dilutions of 10(-3) to 10(-6) on plates of selective media appropriate for each organism. All plates were incubated at 37 degrees C for 48 hours. TSB beakers with the microwaved dentures were incubated at 37 degrees C for 7 more days. After incubation, the number of colony-forming units was counted and the data were statistically analyzed by Kruskal-Wallis test (alpha = .05).


RESULTS
No evidence of growth was observed at 48 hours for S. aureus, B. subtilis, and C. albicans. Dentures contaminated with P. aeruginosa showed small growth on 2 plates. After 7 days incubation at 37 degrees C, no growth was visible in the TSB beakers of S. aureus and C. albicans. Turbidity was observed in 3 broth beakers, 2 from P. aeruginosa and 1 from B. subtilis.


CONCLUSIONS
Microwave irradiation for 6 minutes at 650 W produced sterilization of complete dentures contaminated with S. aureus and C. albicans and disinfection of those contaminated with P. aeruginosa and B. subtilis.
Silva
Mariana Montenegro
MM
Department of Dental Materials and Prosthodontics, Araraquara Dental School, São Paulo State University, Brazil.
Vergani
Carlos Eduardo
CE
Giampaolo
Eunice Teresinha
ET
Neppelenbroek
Karin Hermana
KH
Spolidorio
Denise Madalena Palomari
DM
Machado
Ana Lúcia
AL
D000180:Acrylic Resins / Q000737:chemistry; D001412:Bacillus subtilis / Q000528:radiation effects; D002176:Candida albicans / Q000528:radiation effects; D015169:Colony Count, Microbial; D003470:Culture Media; D003819:Denture Bases / Q000382:microbiology; D003824:Denture, Complete / Q000382:microbiology*; D004202:Disinfectants / Q000737:chemistry; D004203:Disinfection / Q000379:methods*; D005027:Ethylene Oxide / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008872:Microwaves / Q000627:therapeutic use*; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011550:Pseudomonas aeruginosa / Q000528:radiation effects; D013211:Staphylococcus aureus / Q000528:radiation effects; D013242:Sterilization / Q000379:methods; D013997:Time Factors
D000180:Acrylic Resins; D003470:Culture Media; D004202:Disinfectants; C040291:Lucitone; D019904:Polymethyl Methacrylate; D005027:Ethylene Oxide