Fluorescent emission of varied shades of resin composites

The objectives of this study were to measure the fluorescent emission and the corresponding color difference by the inclusion and exclusion of the UV component of the standard illuminant D65 of varied shades of commercial resin composites, and to determine the influence of the color parameters and difference in color parameters by the UV component on the color difference caused by the fluorescent emission.

Eight light-curing resin composites, a total of 41 shades, were studied. Color and spectral reflectance of specimens, 12 mm in diameter and 1mm in thickness, were measured on a reflection spectrophotometer. An UV filter was adjusted to 100% or 0% location to include or exclude the UV component of the standard illuminant D65. From the spectral reflectance values, subtraction spectrum by the inclusion or exclusion of the UV component was calculated, and fluorescence peak height was determined. Color difference caused by the inclusion or exclusion of the UV component (DeltaE*(ab)-FL) was calculated. Differences in color coordinates (DeltaL*, Deltaa* and Deltab*) by the inclusion or the exclusion of the UV component were calculated.

Fluorescence peak height and DeltaE*(ab)-FL were influenced by the brand and the shade of resin composites and there was a significant interaction between the variables based on two-way ANOVA (p<0.05). DeltaE*(ab)-FL was correlated with the chroma component of the shade, and also with Deltab* [standardized partial correlation coefficient (beta)=-0.699], DeltaL* (beta=0.464) and Deltaa* (beta=0.105) based on multiple regression analyses (p<0.05).

Fluorescent emission was influenced by the brand and the shade of resin composites. Fluorescent resin composites showed color shift to blue direction and increased lightness under the UV included illumination.