title: Effect of microwave disinfection on the flexural strength of hard chairside reline resins.
abstract: OBJECTIVE
  This study investigated the effect of microwave disinfection (650W/6 min) on the flexural strength of five hard chairside reline resins (Kooliner, Duraliner II, Tokuso Rebase Fast, Ufi Gel Hard, New Truliner) and one denture base resin (Lucitone 550).
  
  
  METHODS
  Thirty-two specimens (3.3x10x64 mm) from each acrylic resin were produced and divided into four groups of eight specimens each. The flexural test was performed after polymerization (G1), after two cycles of microwave disinfection (G2), after 7 days storage in water at 37 degrees C (G3) and after seven cycles of microwave disinfection (G4). Specimens from group G4 were microwaved daily being stored in water at 37 degrees C between exposures. The specimens were placed in three-point bend fixture in a MTS machine and loaded until failure. The flexural values (MPa) were submitted to ANOVA and Tukey's test (p=0.05).
  
  
  RESULTS
  Two cycles of microwave disinfection promoted a significant increase in flexural strength for materials Kooliner and Lucitone 550. After seven cycles of microwave disinfection, materials Kooliner and New Truliner showed a significant increase (p<0.05) in flexural values. The flexural strength of the material Tokuso Rebase was not significantly affected by microwave irradiation. Seven cycles of microwave disinfection resulted in a significant decrease in the flexural strength of material Duraliner II. Material Ufi Gel Hard was the only resin detrimentally affected by microwave disinfection after two and seven cycles.
  
  
  CONCLUSIONS
  Microwave disinfection did not adversely affect the flexural strength of all tested materials with the exception of material Ufi Gel Hard.
authors.affiliation: Department of Dental Materials and Prosthodontics, São Paulo State University-UNESP, Araraquara Dental School, Araraquara, São Paulo, Brazil. pavarina@foar.unesp.br
authors.forename: Ana Cláudia
authors.initials: AC
authors.lastname: Pavarina
authors.forename: Karin Hermana
authors.initials: KH
authors.lastname: Neppelenbroek
authors.forename: Adriana Simionatto
authors.initials: AS
authors.lastname: Guinesi
authors.forename: Carlos Eduardo
authors.initials: CE
authors.lastname: Vergani
authors.forename: Ana Lúcia
authors.initials: AL
authors.lastname: Machado
authors.forename: Eunice Teresinha
authors.initials: ET
authors.lastname: Giampaolo
mesh_terms: D000180:Acrylic Resins / Q000528:radiation effects*; D004203:Disinfection / Q000379:methods*; D004548:Elasticity / Q000528:radiation effects; D008422:Materials Testing; D008872:Microwaves / Q000009:adverse effects*
chemical_list: D000180:Acrylic Resins