Influence of the color of composite resin foundation and luting cement on the final color of lithium disilicate ceramic systems

Abstract

Statement of problem. Lithium disilicate restorations are commonly used, particularly in the anterior region. The color of the underlying composite resin foundation (CRF) and luting cement may negatively affect the color of lithium disilicate ceramic restorations. Purpose. The purpose of this in vitro study was to investigate the effect of CRF and resin cement materials on the color of lithium disilicate ceramics in 2 different translucencies. Material and methods. Twenty disks (11x1.5 mm, shade A2) were fabricated from medium-opacity (mo) (n=10) and high-translucency (ht) (n=10) lithium disilicate (Lds) blocks (IPS e.max Press). Five CRF disks (11x3 mm) were fabricated in 5 different shades (A1, A2, A3, B2, C2) and 30 resin cement disks (11x0.2 mm) in the shades of translucent (Tr), universal (Un=A2), and white-opaque (Wo). Ceramic specimens were placed on each CRF, and the resin cement combination and color was measured with a spectrophotometer. CIELAB color coordinates were recorded, and the color coordinates of both ceramics on the shades of the A2 CRF and resin cement were saved as the control. Color differences (Delta E-00) between the control and test groups were calculated. Data were analyzed with 3-way analysis ANOVA and compared with the Tukey HSD test (alpha=.05). Results. The Delta E-00 values were influenced by the shades of the CRF, resin cement materials, and also their interactions (P<.05). The Delta E-00 values were not affected by the ceramic type. The Delta E-00 values of the Wo cement groups (1.73 to 2.96) were significantly higher than those of the other cement shades (0.88 to 1.29) for each ceramic type and CRF shade (P<.05). Conclusions. Lithium disilicate ceramics in 2 different translucencies were similarly influenced by the color of the underlying cement and CRF. When translucent and universal cement shades were used, the core shade did not affect the final color of the ceramics. White opaque cement caused clinically unacceptable color changes in both ceramics on all shades of CRFs except the C2 CRF and when high translucency ceramic was used on the A2 CRF. These changes were clinically acceptable, but perceptible.