Available online 11 June 2013
The aim of this study was to assess the effect of different resin cement shades on the opacity and color difference of ceramics and to determine the polymerization efficiency of the resin cement at different shades after curing through ceramics.
Two different ceramics (IPSe.maxPress, and IPSEmpress®CAD, Ivoclar Vivadent) were used for this study. A light-cured veneer luting resin (Variolink Veneer, Ivoclar Vivadent) in four different shades of HV + 1, HV + 3, LV-1, and LV-3 was used for the colorimetric measurements. The colour and spectral reflectance of the ceramics were measured according to the CIELab colour scale relative to the standard illuminant D65 on a reflection spectrophotometer (ColorEye7000A,USA). Colour differences (ΔE values) and the contrast ratios (CR) of the different groups of samples were calculated. In order to analyse the polymerisation efficiency of the resin cements, the micromechanical properties of the resins were measured with an automatic microhardness indenter (Fisherscope H100 C, Germany). The results were analysed using one-way ANOVA and Tukey's HSD post-hoc tests (SPSS 18.0).
The one-way ANOVA test showed that the values of ΔE and CR of the different specimen groups were significantly different (p < 0.05). Group 1 (20.7 ± 0.5) (IPS-CAD without resin cement) exhibited the highest and group 10 (14.8 ± 0.5)(e.max:HV + 3) exhibited the lowest ΔE value. Significant differences in the micromechanical properties were identified among the tested resin cements in different shades (p < 0.05).
Resin cement shade is an important factor for the opacity of a restoration. Furthermore, the resin shade affects the micromechanical properties of the underlying resin cement.