Statement of the Problem: Matching adjacent anterior all-ceramic restorations supported by natural teeth and implants to adjacent natural teeth or all-ceramic restoration is a demanding task for both clinicians and dental technician, especially when cemented to natural teeth and/or implant-supported abutments with different stump shades.
Aim: To compare the optical effect of dissimilar background and cement shades in terms of color differences (DE) after cementation to low-translucency lithium-disilicate glass-ceramic (LT-LDGC).
Material and Methods: Sixty LT-LDGC specimens were sectioned from CAD/CAM block with a standard thickness of (1.5 ± 0.2) mm. Four background materials (zirconia (white), nano-ceramic filled composite resin (shade A2), dual-cure composite core build-up (shades light opaque and A3) were used to fabricate rectangular square discs (n=15). Ceramic and background specimens were cemented with three shades of dual-cure self-adhesive resin cement (clear, white, and yellow). The 3 coordinates of the CIELAB system were measured using a spectrophotometer (Vita Easyshade Advance, Vita Zahnfabrik) twice (at baseline for the ceramic alone and after cementation). Then, color difference (DE00) values were calculated for each sample with the baseline measurement as control. Two-way ANOVA was used to analyze the effect of the background and cement shade on the color difference at a significant level (0.05).
Results: Two-way ANOVA revealed a significant effect of the background shade, but not for the cement shade and their interaction on the color difference. The reported DE00 values ranged between 2 to 8.5. Majority of the groups showed DE00 values higher than clinically acceptable level (DE00>2.25). Only one group of the combination of zirconia background and yellow cement showed means DE00 values within the clinically acceptable level (1.3 < DE00 ≤ 2.25).
Conclusion: This study demonstrated that the underlying background color influences the final color of the LT-LDGC restorations. Using variable cement shades failed in decreasing the color difference to a clinically acceptable level.
