Linear dimensional changes of denture base and hard chair‐side reline resins after disinfection

Objectives This study evaluated the effect of disinfection by immersion in sodium perborate (50°C/10 min) or microwave irradiation (650 W/6 min) on the linear dimensional change (LDC) of four reline resins (Kooliner‐K, New Truliner‐N, Tokuso Rebase Fast‐T, Ufi Gel Hard‐U) and one heat‐polymerizing denture base resin (Lucitone 550‐L). Methods Specimens (50.0 mm diameter, 0.5 mm thickness) were made using a split mold with reference points, and divided into two controls and four test groups (n = 8). The distances between the points were measured on the mold (baseline readings), and compared to those obtained from the specimens after: polymerization or immersion in water (37°C) for 7 days (controls); 2 or 7 cycles of disinfection by immersion or microwave irradiation. Results The two‐way ANOVA and Tukey's test (α = 0.05) showed that microwave disinfection significantly increased the mean LDC of materials L (−1.43%), N (−1.27%) and K (−1.06%). Material N also exhibited a significant increase in LDC after two cycles of chemical disinfection (−0.73%). For U (−0.47%) and T (−0.21%) materials, no significant changes in LDC were found. Conclusions Microwave disinfection increases the shrinkage of materials L, N, and K. The dimensional stability of resins U and T was not affected by the disinfection methods evaluated.