Optical properties of CAD–CAM ceramic systems

AbstractObjectives luate the direct transmittance (T%), translucency, opacity and opalescence of CAD–CAM ceramic systems and the correlation between the translucency parameter (TP) and the contrast ratio (CR). s ens of shades A1, A2 and A3 (n = 5) were fabricated from CAD–CAM ceramic blocks (IPS e.max® CAD HT and LT, IPS Empress® CAD HT and LT, Paradigm™ C, and VITABLOCS® Mark II) and polished to 1.0 ± 0.01 mm in thickness. A spectrophotometer (Lambda 20) was used to measure T% on the wavelength range of 400–780 nm. Another spectrophotometer (VITA Easyshade® Advance) was used to measure the CIE L*a*b* coordinates and the reflectance value (Y) of samples on white and black backgrounds. TP, CR and the opalescence parameter (OP) were calculated. Data were statistically analysed using VAF (variance accounting for) coefficient with Cauchy–Schwarz inequality, one-way ANOVA, Tukeyʹs test, Bonferroni correction and Pearsonʹs correlation. s some ceramic systems is dependent on the wavelength. The spectral behaviour showed a slight and constant increase in T% up to approximately 550 nm, then some ceramics changed the behaviour as the wavelength gets longer. TP and CR values ranged, respectively, from 16.79 to 21.69 and from 0.52 to 0.64 (r2 = −0.97). OP values ranged from 3.01 to 7.64. sions crostructure of CAD–CAM ceramic systems influenced the optical properties. TP and CR showed a strong correlation for all ceramic systems evaluated. Yet, all ceramics showed some degree of light transmittance. icance ition to shade, this study showed that other optical properties influence on the natural appearance of dental ceramics.