Effect of Composite Thickness and Dimensions of Class IV Restorations on Color Match of Omnichroma Single-Shade Composite Resin

Objectives: This study aimed to investigate the effect of composite thickness and dimensions of Class IV restorations on color match of Omnichroma single-shade composite resin. Materials and Methods: In this in vitro study, 48 composite discs were fabricated from A2 shade of Estelite Sigma Quick composite resin. The specimens were randomly assigned to three groups based on restoration width (2mm, 3mm, and 4mm), while preparation depth was standardized at 1.5mm. Each group was further subdivided according to Omnichroma blocker thickness (0.5mm or 0.8mm). Restorations were completed using Omnichroma layered over the blocker material. Color difference (ΔE00) was determined using the CIEDE2000 formula with a non-contact spectrophotometer. Statistical analysis was conducted using two-way ANOVA with a significance level set at 0.05. Results: A significant reduction in ΔE00 values was observed with increasing restoration width (P<0.0001). Blocker thickness did not have a statistically significant effect on ΔE00 (P=0.92). No significant interaction was found between restoration width and blocker thickness in terms of lightness change (ΔL00). Conclusion: The color match of Omnichroma was found to be clinically unacceptable in simulated anterior restorations; however, its performance improved as restoration width increased. Variations in blocker thickness did not significantly influence the color match.