engleski

Factors influencing the final color of lithium- disilicate restorations

Objectives: The aim of the study was to evaluate the effect of different substrate colors, cement colors and thicknesses, different thicknesses and translucency levels of core ceramics, and different thicknesses of veneering ceramics on the final color of a model representing lithium- disilicate restorations. Materials and methods: Cylindrical specimen of Natural Die material (11 x 5 mm) were prepared in the colors ND1, ND3, ND5, ND7 and ND9 – 11 of each color. Disc specimen of IPS e.max Press LiS2 ceramics in 4 thicknesses (0.5, 0.7, 1.0, 1.2 mm) and 3 translucency levels (HT, LT, MO), and IPS e.max Ceram veneering ceramics in 3 thicknesses (0.3, 0.5, 0.8 mm) were prepared. That resulted in a total of 120 LiS2 specimen (n = 10/group), 30 e.max Ceram specimen (n = 10/group), and 55 ND specimen (n = 11/color). One ND disc of each color served as control, while on the other 10 a layer of Variolink II resin cement was applied in 5 colors (transparent, white, white opaque, yellow and brown) and two thicknesses (80 or 150 μm). Core discs with and without veneering ceramics were overlapped with the background discs to measure L*a*b* values by means of a spectrophotometer. Color differences ΔE* were calculated and data was statistically analyzed using ANOVA (STATISTICA 10.0. Results: A significant influence of supstrate color, thickness and translucency level of LiS2 ceramics, color and thickness of luting agent, and the thickness of veneering ceramics (p < 0, 001 each factor) on the color parameters was found. Although the color and thickness of the cement had a statistically significant effect, only the white opaque cement caused clinically significant, i.e. visible color shifts. Veneering ceramics of varying thickness had a statistically significant impact on the color parameters of the model which simulated an all- ceramic restoration, whereby, besides increasing lightness of the samples, a decrease of the clinical impact of underlying colors (substrate and cement) was noticed. Conclusion: For optimum color-matching results the thickness of the restoration, substrate, and conditionally luting agent color need to be taken into account.

lithium-disilicate ; color matching ; influence of substrate color ; influence of luting agent

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