Post-curing effects on mechanical properties staining resistance of a 3D-printed resin versus a direct composite for...

This study evaluated the mechanical performance and staining resistance of a three-dimensional (3D)-printed resin (VarseoSmile Crown Plus) subjected to different post-curing times (0, 5, 10, 15, and 20 min), compared with a conventional nanofilled resin composite (Filtek Z350XT). Specimens of both materials were fabricated and tested for flexural strength and flexural modulus using a three-point bending test, whereas cohesive strength (CS) was assessed by microtensile testing. For color analysis, disk specimens were immersed in artificial saliva, Coca-Cola, or red wine (RW) for 7 days, followed by polishing and whitening procedures. Color change (ΔE₀₀) and whiteness index (ΔWI_D) were recorded. Data were analyzed using a generalized linear model and Bonferroni tests (α = 5%). The direct composite showed higher flexural and CS than the 3D-printed resin. Post-curing improved the mechanical properties of the printed material, although values remained inferior to those of the composite. Both materials exhibited color changes after staining, with RW causing the greatest discoloration. Polishing and whitening reduced staining but did not always restore baseline values. Although post-curing enhances 3D-printed resin performance, its mechanical behavior and color stability remain inferior to those of conventional composites, indicating the need for further optimization before clinical use as definitive restorations.