Influence of Microwave Disinfection on the Dimensional Stability of Denture Reline Polymers

Purpose: The purpose of this study was to evaluate the effect of microwave disinfection (3 minutes at 650 W) on the dimensional stability of hard chairside reline resins (Kooliner, Tokuyama Rebase II, Ufi Gel hard, New Truliner) and one heat-polymerizing denture base resin (Lucitone 550). Materials and Methods: A split mold with reference points was used to make specimens (50.0-mm diameter, 0.5-mm thick) from each material, divided into five test groups (n = 8). The distances between the points on the mold were measured (gold standard), and compared with those obtained from the specimens after polymerization (baseline readings) after one, two, three, and four cycles of disinfection by microwave irradiation. Results: ANOVA and Tukey tests (alpha = 0.05) showed that Kooliner was significantly affected by all disinfection cycles (p < 0.05) when compared with baseline measurements. New Truliner resin was significantly affected by three and four cycles of microwave disinfection when compared with baseline measurements (p < 0.05). For Tokuyama Rebase II, Ufi Gel hard, and Lucitone 550, no significant dimensional changes were found. Conclusions: Microwave disinfection promoted shrinkage of Kooliner and New Truliner. The dimensional stability of Tokuyama Rebase II, Ufi Gel Hard, and Lucitone 550 was not affected by microwave disinfection.