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Influence of the amount of UV component in daylight simulator on the color of dental composite resins.Lu H, Lee YK, Villalta P, Powers JM, Garcia-Godoy F Assistant Professor, Department of Restorative Dentistry; Director, Biomaterials Research Laboratory, Center for Dental Research, Loma Linda University School of Dentistry. STATEMENT OF PROBLEM: Color of fluorescent substances is influenced by the amount of ultraviolet (UV) component in the illumination. Color of fluorescent dental composite resins may change by the amount of UV component in the ambient light, but there have been few studies on this subject. PURPOSE: The purpose of this study was to determine the differences in color and color parameters such as lightness, chroma, and hue of composite resins created by varying the amount of UV component of a pulsed-xenon source that is conditioned to approximate the Commission Internationale de l'Eclairage (CIE) standard illuminant D65. MATERIAL AND METHODS: A spectrophotometer, in which the UV component of a daylight simulator could be adjusted, was developed. Eight light-polymerized dental composite resins, A3 shade, were studied. Five disk-shaped specimens, 10 x 3 mm, were prepared for each material. Color of specimens was measured on a reflection spectrophotometer over a white background relative to 3 illuminations, which had the same spectral power distribution of the CIE standard illuminant D65 in visible range, but different UV component. D(65) indicated the illumination in which the UV component of the pulsed-xenon source was adjusted to the CIE standard illuminant D65 using a UV adjustment tile. UV-EXC indicated the illumination in which the UV component of the source was excluded with a UV filter. UV-INC indicated the illumination in which the UV component was included. Differences in color parameters by the illumination were analyzed with repeated-measures 1-way analysis of variance (ANOVA) by the brand of composite resins. Differences in color (DeltaE( *)(ab)) and color parameters such as lightness (DeltaL( *)), chroma (DeltaC( *)(ab)), and hue angle (Deltah) were analyzed with 3-way ANOVA, with the independent variables of brand of composite resin, combination of illuminations, and type of color parameters (alpha=.05). RESULTS: Color differences (DeltaE( *)(ab)) by the amount of UV component in the illuminations ranged between 0.3 and 1.4 for D(65) and UV-EXC, between 0.3 and 0.5 for D(65) and UV-INC, and between 0.2 and 1.6 for UV-EXC and UV-INC. Based on the repeated-measures ANOVA, lightness was not influenced by the amount of the UV component in the illumination, however, chroma and hue angle were influenced by the amount of UV component. Based on the 3-way ANOVA, differences in color and color parameters (DeltaE( *)(ab), DeltaL( *), DeltaC( *)(ab), and Deltah) by the amount of the UV component were influenced by all of the 3 factors, and there were significant interactions between all the combinations of factors (P<.05). CONCLUSION: Though there were significant differences in color and color parameters by the amount of the UV component in the D65-simulated xenon source, color difference caused by the UV component was lower than 1.6, which is in the visually acceptable range. Published 13 November 2006 in J Prosthet Dent, 96(5): 322-7.
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