Effect of food-simulating solvents on flexural properties of bulk-fill resin composites

This study evaluated the flexural strength of bulk-fills after immersion in food-simulating solvents.

Four overlapping segments along both sides of bar-shaped specimens (25 × 2 × 2 mm) made from bulk-fill composite were irradiated with an Elipar LED light-curing (1,200 mW/cm² for 20 s) device. The specimens were then divided into four groups (n = 20), according to storage media-namely, distilled water, 99% ethanol, heptane, and methyl ethyl ketone-at 37^oC for 4 weeks. Flexural testing was done with a universal testing machine at a crosshead speed of 1 mm/min.

Data were analyzed with the two-way and one-way ANOVA and post-hoc Tukey (HSD) tests (P < 0.05), along with the Weibull statistic. Flexural properties significantly differed in relation to the bulk-fill and solvent used. The flexural properties of bulk-fills decreased in solvents. SonicFill in distilled water had the highest values for flexural properties (σ_f = 165.77 MPa; E_f = 10.3 GPa), followed by the values for SonicFill in ethanol and those for X-tra base and everX Posterior in water. Venus Bulk Fill in methyl ethyl ketone yielded the lowest values (σ_f = 74.11 MPa; E_f = 3.06 GPa).

The flexural properties of bulk-fills are affected by the food-simulating solvent used and by the filler content, type, and resin component.