Effects of Cement Shade, Cementation, and Thermocycling on the Color Parameters and the Final Color of the SLA-Printed Photopolymer Resins

This study investigated the effects of resin cement shade and thermocycling on the color parameters and final appearance of SLA-printed photopolymer resins. Specimens with a thickness of 1 mm were fabricated and categorized into eight groups based on four different cement shades (universal-A2, clear, white, and opaque) and two applications (cementation and thermal aging). Differences in color parameters (ΔL*, Δa*, and Δb*) were measured after cement polymerization and thermocycling, and overall color differences (ΔE₀₀-1 and ΔE₀₀-2) were calculated. Two-way ANOVA revealed significant interactions between cement shade and thermocycling for ΔL*, Δa*, and Δb* (<i>p</i> < 0.05). After cementation, L* decreased for universal-A2, clear, and white cements, but increased for opaque cement. Furthermore, thermocycling altered L*, a*, and b* values differently among the experimental groups. Cement shade significantly influenced ΔE₀₀, with universal-A2 and clear cements showing higher values than white and opaque cements (<i>p</i> < 0.05). All ΔE₀₀ values exceeded the clinically acceptable limit (>1.8). The findings suggest that careful selection of the cement shade is therefore critical to achieving optimal esthetic outcomes with the tested 3D-printed resin. Formlabs SLA-printed permanent resin, although labeled as an A2 shade, behaves more like white or opaque shades, highlighting inconsistencies between labeled and actual color.