Color matching and metameric behavior of composite resins applied on anodized titanium surfaces: an in vitro spectrophotometric study

Background The aim of this study was to evaluate the color matching and metameric behavior of two different composite resins applied to titanium surfaces anodized to yellow and pink colors. The study aimed to determine the effects of anodization color and composite resin type on color performance in hybrid prosthesis and screw access hole closure applications. Materials and methods A total of 72 Grade 5 titanium discs (10 mm diameter × 2 mm thickness) were allocated to three anodization conditions: nonanodized/gray (0 V, n = 24), yellow (55 V, n = 24), and pink (80 V, n = 24). Each anodization group was subdivided into two subgroups: 3 M Filtek Z250 (microhybrid) and Tokuyama Estelite Sigma Quick (supra-nano hybrid) composite resins (A2 shade, 2 mm thickness; n = 12 per subgroup). Gray titanium + composite specimens were used as the reference for ΔE₀₀ calculations; yellow and pink anodization groups constituted the experimental groups. Color measurements were performed using a spectrophotometer (Konica Minolta CM-3700 A) under four light sources (D65, D50, incandescent A, and F11). Data were analyzed using mixed-design repeated-measures ANOVA, Bonferroni post hoc test, and independent samples t-test (α = 0.05). Results Anodization color (η² = 0.941) and composite type (η² = 0.952) demonstrated strong effects on ΔE₀₀ values (both p < 0.001). Light source showed statistically significant but clinically negligible effect (η² = 0.521, mean difference < 0.1 ΔE₀₀). Pink anodization exhibited higher color differences than yellow (2.84–2.99 vs. 1.53–1.62), and Tokuyama composite higher than 3 M (2.89–3.12 vs. 1.41–1.54) (both p < 0.001). Yellow+3 M combination showed lowest values (0.91–0.97), while Pink+Tokuyama showed highest (3.68–3.97). Metamerism index remained minimal (MI < 0.21). Conclusions Careful material selection is essential for optimal esthetics in anodized titanium-composite systems. Yellow anodization combined with a microhybrid composite demonstrated the most favorable color matching performance under