Effect of color and tranclucency of ceramics and color of resin cements on the final color of laminate veneers

With the increasing popularity of minimal invasive dentistry, removal of tooth structure, especially enamel, has started to be reduced. For this reason, thinner laminate veneers are required. When the thickness of veneers with high translucency is decreased, properties of tooth and resin cement color become more important. The purpose of this study was to evaluate the effect of abutment tooth color, ceramics and resin cements with different translucencies on the final color of laminate restorations, and also to evaluate the interactions between these materials. Five hundred and four (N=504) smooth-surfaced framework specimens (5 x 5 x 2) were prepared using the resin die material (Natural Die Material, ND1, ND2, ND3, ND8, Ivoclar Vivadent, Schaan, Lichtenstein) to simulate prepared tooth surfaces (N=504). Six ceramic blanks with different translucencies were used to prepare ceramic laminate specimens: leucite-reinforced glass-ceramic (Empress Cad, Ivoclar Vivadent), polymer-infiltrated-ceramic network material (Vita Enamic, Vita Zahnfabrik, Germany) and lithium disilicate glass-ceramic (E.max Cad Opal, E.max CAD Value, E.max CAD LT, Ivoclar Vivadent). A precision diamond saw (Isomet 1000, Buehler, Lake Bluff, IL, ABD) was used to section the ceramic blanks under water cooling to yield 5x5 mm diameter and 0,5 mm thick ceramic slices (N=504; n=84/ceramic group). Ceramic slices were bonded to framework specimens with three adhesive cements with different tranclucencies (0, +1, +3 color, Variolink Veneer, Ivoclar Vivadent) under a constant load. L*a*b values of each specimen were measured on a white background with a digital spectrophotometer (VITA Easyshade Advance, VITA Zahnfabrik, Bad Säckingen, Germany) and these values were recorded. Also L*a*b* values of A1 shade were recorded. The values were calculated as ∆E and the data were statistically analyzed (One-way ANOVA, Shapiro-Wilk; α=0.05). Mean ∆E values between ceramic types, resin cements and abutment tooth colors were statistically significant (p=0.000). Mean ∆E values (∆E=1,08) were the lowest when the specimens were cemented with the resin cement of 0 color and ceramic type of IPS e.max CAD Value in ND1 grup. Although all mean ∆E values were significant in all combinations with resin cement, tooth color and ceramic type, for ND2, ND3, ND8 groups, ∆E values which were > 3.5 were recorded as clinically unacceptable. The color of A1 in ND2, ND3, ND8 groups could not be detected. Within the limitations of this in-vitro study it can be concluded that, laminate veneers with the thickness of 0.5 mm were affected significantly by the ceramic type, tooth color and resin cement. Changing the underlying color of abutment tooth from a lighter color to a darker color results in increased ∆E values. Appropriate material selection plays an essential role for color matching of laminate venners. The thickness of the ceramic material should be increased when the abutment tooth is too dark and its colour should be masked.