Effect of microwave disinfection on the flexural strength of hard chairside reline resins

Objectives: This study investigated the effect of microwave disinfection (650 W/6 min) on the flexural strength of five hard chairside reline resins (Kooliner, Duraliner II, Tokuso Rebase Fast, Ufi Get Hard, New Truliner) and one denture base resin (Lucitone 550).Methods: Thirty-two specimens (3.1x10x64 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