title: Effectiveness of microwave sterilization on three hard chairside reline resins.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effectiveness of microwave irradiation sterilization on hard chairside reline resins.
  
  
  METHODS
  Specimens of three reline resins (Kooliner, Tokuso Rebase, and Ufi Gel Hard) were fabricated and subjected to ethylene oxide sterilization. The specimens were then individually inoculated (10(7) cfu/mL) with Tryptic Soy Broth media containing one of the tested microorganisms (C albicans, S aureus, B subtilis, and P aeruginosa). After 48 hours at 37 degrees C, the samples were vortexed for 1 minute and allowed to stand for 9 minutes, followed by a short vortex to resuspend any organisms present. After inoculation, 40 specimens of each material were immersed in 200 mL of water and subjected to microwave irradiation at 650 W for 6 minutes. Forty non-irradiated specimens were used as positive controls. Replicate specimens (25 microL) of suspension 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. After incubation, colonies were counted, and the data were statistically analyzed by the Kruskal-Wallis test. Twelve specimens of each material were prepared for SEM.
  
  
  RESULTS
  All immersed specimens showed consistent sterilization of all the individual organisms after microwave irradiation. SEM examination indicated an alteration in cell morphology after microwave irradiation.
  
  
  CONCLUSIONS
  Microwave sterilization for 6 minutes at 650 W proved to be effective for the sterilization of hard chairside reline resins.
authors.affiliation: Department of Dental Materials and Prosthodontics, São Paulo State University, Araraquara Dental School, São Paulo, Brazil.
authors.forename: Karin Hermana
authors.initials: KH
authors.lastname: Neppelenbroek
authors.forename: Ana Cláudia
authors.initials: AC
authors.lastname: Pavarina
authors.forename: Denise Madalena Palomari
authors.initials: DM
authors.lastname: Spolidorio
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Vergani
authors.forename: Ewerton Garcia de Oliveira
authors.initials: EG
authors.lastname: Mima
authors.forename: Ana Lúcia
authors.initials: AL
authors.lastname: Machado
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry / Q000528:radiation effects*; D001412:Bacillus subtilis / Q000254:growth & development / Q000528:radiation effects; D002176:Candida albicans / Q000254:growth & development / Q000528:radiation effects; D015169:Colony Count, Microbial; D003764:Dental Materials / Q000528:radiation effects*; D003819:Denture Bases / Q000382:microbiology; D003823:Denture Rebasing; D004202:Disinfectants / Q000627:therapeutic use; D005027:Ethylene Oxide / Q000627:therapeutic use; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008872:Microwaves / Q000627:therapeutic use*; D011550:Pseudomonas aeruginosa / Q000254:growth & development / Q000528:radiation effects; D013211:Staphylococcus aureus / Q000254:growth & development / Q000528:radiation effects; D018709:Statistics, Nonparametric; D013242:Sterilization / Q000379:methods*; D013499:Surface Properties; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; D004202:Disinfectants; D008689:Methacrylates; C437925:Tokuso rebase normal-set; C103363:kooliner; D005027:Ethylene Oxide