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

OBJECTIVES

The 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.

METHODS

Eight 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 (DeltaEab*) 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).

RESULTS

The range of DeltaL* between the same shade-designated resin composites by the brand was 0.1-10.2 (mean: 2.9), that of Deltaa* was 0.0-2.4 (mean: 0.9), that of Deltab* was 0.1-7.0 (mean: 2.0) and that of DeltaEab* was 0.7-11.0 (mean: 4.2). DeltaL* and Deltaa* were not influenced by the shade designation; however, Deltab* and DeltaEab* were influenced by the shade designation based on one-way ANOVA (alpha=0.05). Half of the color difference values between the same shade-designated resin composites were perceptible (42 pairs among 83 pairs, DeltaEab*>3.7).

SIGNIFICANCE

Since 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 (DeltaEab*>3.7), optical properties of resin composites should be considered differently by the shade designation and brand when selecting these materials.