Can we use the translucency parameter to predict the CAD/CAM ceramic restoration aesthetic?

OBJECTIVES: To evaluate the effects of background color, ceramic type and coping thickness on masking ability (DeltaE) and translucency parameter (TP) of CAD/CAM lithium disilicate glass-ceramic/monolithic zirconia and, to determine the correlations between coping thickness, TP and DeltaE. METHODS: A total of 120 ceramic specimens (2 mm, 1 mm and 0.5 mm thickness; n = 10) of four CAD/CAM ceramics: IPS e.max, IPS ZirCAD, Upcera Li CAD and Upcera TT CAD, were studied. Specimens were tested over nine fabricated backgrounds: A1, A2, A3.5, ND2 and ND7 shade resin-based composites, cobalt-chromium alloy (CC), medium precious alloy (MPA), black (B) and white (W). CIELab values (L*, a* and b*), color difference (DeltaE) and translucency parameter (TP) were measured and calculated using a digital spectrophotometer (color i7, X-Rite, Pantone(R)). Data were analyzed using the Shapiro-Wilk test, one-way ANOVA, three-way ANOVA, independent t-tests and Tukey post-hoc tests (p < 0.05). RESULTS: 2 mm CAD/CAM ceramics showed ideal color matching (DeltaE<2.6) over different backgrounds, except for CC, B and W backgrounds. Monolithic zirconia had lower DeltaE values than lithium disilicate glass-ceramics. DeltaE and TP values significantly reduced with the increased coping thickness (p < 0.05). Regardless of ceramic type and thickness, a strong TP-SD of DeltaE correlation was observed. SIGNIFICANCE: CAD/CAM ceramic restoration color was significantly affected by background color, ceramic type and coping thickness. TP is a promising predictor for appropriate ceramic selection to receive an acceptable CAD/CAM ceramic restoration aesthetic.