Influence of the changes in the UV component of illumination on the color of composite resins

Abstract

Daylight illumination varies during the day due to weather or other conditions which change the amount of the UV component in daylight. The level of the UV component in daylight may influence the color of fluorescent composite resins used for anterior restorations. The purpose of this study was to measure the fluorescence emission and the corresponding color change of dental composite resins as affected by the included percentage of the UV component of a daylight simulator (pulsed-xenon source simulating the CIE standard illuminant D65). Spectral reflectance and color of 4 brands of composite resins (Filtek Supreme, Estelite Sigma, Point 4, and Vit-l-escence) were measured over a white tile according to the CIELAB color scale relative to the UV adjusted illuminant D65. A UV filter of a spectrophotometer was adjusted to change the UV component of the illuminant D65. From the spectral reflectance values, subtraction spectra between the spectra in UV-included conditions (20, 40, 60, 80, and 100%) and that in the 0% UV condition of the illuminant D65 were calculated. Color difference (DeltaE*(ab)) between each of the UV-included conditions and the 0% UV condition was also calculated. Color difference caused by the included percentage of the UV component, compared with the 0% UV condition, was analyzed with 2-way ANOVA (alpha=.05). Three of the 4 composite resins tested showed fluorescence peaks at approximately 440 nm. Peak height based on subtraction spectra was in the range of 0.39 to 2.42. Color difference (range = 0.32 to 2.72 DeltaE*(ab) units) was influenced by the included percentage of the UV component and the brand of composite resin (P<.001). Color difference caused by the included percentage of the UV component was as high as 2.72. The percentage of the UV component of the daylight simulator influenced the color of composite resins.