Influence of the shade designation on the color difference between the same shade-designated resin composites by the brand

ObjectivesThe objectives were to measure the difference in color and color coordinates between the same shade-designated resin composites from different brands, and to determine the influence of shade designation on the difference in color and color coordinates between them.MethodsEight light-curing resin composites, a total of 32 shades, were investigated. Color of specimens (1 mm in thickness) was measured on a reflection spectrophotometer over a white background. Differences in color (ΔEab*) and color coordinates such as CIE L* (lightness), a* (red–green coordinate) and b* (yellow–blue coordinate) between each pair of the same shade-designated resin composites were calculated. The influence of the shade designation on these differences was analyzed with one-way analysis of variance (p < 0.05).ResultsThe range of ΔL* between the same shade-designated resin composites by the brand was 0.1–10.2 (mean: 2.9), that of Δa* was 0.0–2.4 (mean: 0.9), that of Δb  * was 0.1–7.0 (mean: 2.0) and that of ΔEab* was 0.7–11.0 (mean: 4.2). ΔL* and Δa* were not influenced by the shade designation; however, Δb  * and ΔEab* were influenced by the shade designation based on one-way ANOVA (α = 0.05). Half of the color difference values between the same shade-designated resin composites were perceptible (42 pairs among 83 pairs, ΔEab*>3.7).SignificanceSince the color difference between the same shade-designated resin composite from different brands varied by the shade designation and was perceptible in more than half of the compared pairs (ΔEab*>3.7), optical properties of resin composites should be considered differently by the shade designation and brand when selecting these materials.