Hygroscopic expansion kinetics of dental resin-composites

AbstractObjective luate the extent and rate of hygroscopic expansion of resin composites at 37 °C. s resin composites were examined: 1 micro-hybrid (Bright Light®), 5 nano-hybrids (Experimental Vertise™; Nanoceram-Bright®; Tetric EvoCeram®; Grandio® SO; Ceram X™ duo) and 2 flowables (X-tra base; Venus® Diamond Flow). Five disks (15 mm × 2 mm) of each material were prepared. The mean change in specimen diameter was recorded by a custom-built non-contact laser micrometer. Specimens were initially measured dry and then at fixed time intervals, over 150 days, after storage in distilled water at 37 ± 1 °C. Data were re-expressed in volumetric terms and analysed by repeated measures ANOVA, one-way ANOVA and Tukeyʹs post hoc test (α = 0.05). s lumetric hygroscopic expansion ranged from 0.58 to 2.26 and can be considered in three bands. First, Experimental Vertise had the highest expansion (p < 0.001). Venus Diamond Flow, Tetric EvoCeram and Ceram X duo were the second band. The third band, with still lower expansion, consisted of Bright light, Grandio So, Nanoceram-Bright and X-tra base, with no significant difference between them. sion e size (2 mm thickness) and shape of specimen measured, equilibrium was attained in all cases by 60 days. Within this set of resin-composites the equilibrium expansion varied by almost 400% of the lowest material.