Effect of different exposure times on microwave irradiation on the disinfection of a hard chairside reline resin.
OBJECTIVE
This study evaluated the effectiveness of different exposure times of microwave irradiation on the disinfection of a hard chairside reline resin.


METHODS
Sterile specimens were individually inoculated with one of the tested microorganisms (Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, and Bacillus subtilis) and incubated for 24 hours at 37 degrees C. For each microorganism, 10 specimens were not microwaved (control), and 50 specimens were microwaved. Control specimens were individually immersed in sterile saline, and replicate aliquots of serial dilutions were plated on selective media appropriate for each organism. Irradiated specimens were immersed in water and microwaved at 650 W for 1, 2, 3, 4, or 5 minutes before serial dilutions and platings. After 48 hours of incubation, colonies on plates were counted. Irradiated specimens were also incubated for 7 days. Some specimens were prepared for scanning electron microscopic (SEM) analysis.


RESULTS
Specimens irradiated for 3, 4, and 5 minutes showed sterilization. After 2 minutes of irradiation, specimens inoculated with C. albicans were sterilized, whereas those inoculated with bacteria were disinfected. One minute of irradiation resulted in growth of all microorganisms. SEM examination indicated alteration in cell morphology of sterilized specimens. The effectiveness of microwave irradiation was improved as the exposure time increased.


CONCLUSIONS
This study suggests that 3 minutes of microwave irradiation can be used for acrylic resin sterilization, thus preventing cross-contamination.
Mima
Ewerton G
EG
Department of Dental Materials and Prosthodontics, Araquara Dental School, Sao Paulo State University, Sao Paulo, Brazil.
Pavarina
Ana Claudia
AC
Neppelenbroek
Karin Hermana
KH
Vergani
Carlos Eduardo
CE
Spolidorio
Denise Madalena P
DM
Machado
Ana Lucia
AL
D000180:Acrylic Resins / Q000528:radiation effects*; D001412:Bacillus subtilis / Q000528:radiation effects; D002176:Candida albicans / Q000528:radiation effects; D015169:Colony Count, Microbial; D003764:Dental Materials / Q000528:radiation effects*; D003822:Denture Liners / Q000382:microbiology*; D003823:Denture Rebasing; D004203:Disinfection / Q000379:methods*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008872:Microwaves / Q000627:therapeutic use*; D011550:Pseudomonas aeruginosa / Q000528:radiation effects; D011829:Radiation Dosage; D013211:Staphylococcus aureus / Q000528:radiation effects; D013242:Sterilization / Q000379:methods; D013696:Temperature; D013997:Time Factors
D000180:Acrylic Resins; D003764:Dental Materials; D008689:Methacrylates; C503430:Tokuso Rebase Fast