Influence of Backgrounds on Spectral Reflectance and Color of CAD-CAM Ceramic Systems

Objectives: To evaluate the influence of different standard backgrounds on spectral reflectance and color parameters of CAD-CAM ceramic systems.
Methods: Four ceramic systems were evaluated: emLT- IPS e.max^® CAD LT, emHT- IPS e.max^® CAD HT, EmpLT- IPS Empress^® CAD LT and EmpHT- IPS Empress^® CAD HT (Ivoclar Vivadent, Schaan, Liechtenstein). Ceramic specimens (10mm x 20mm x 1mm) from shades A1, A2 and A3 (n=5) were fabricated according to manufacturers’ instructions. Spectral reflectance (R) of all samples was measured using a spectroradiometer (PR 704, Color Research, USA) over a B- black (L*=3.10, a*=0.27, b*=0.44) and a W- white (L*=97.44, a*=-0.40, b*=3.64) backgrounds inside a viewing booth (CAC D60, VeriVide, UK), under D65 illuminant and optical geometry of 0/45º. Color coordinates CIE L* (lightness) a* (red-green axis) and b* (yellow-blue axis), over B and W, were calculated according to the CIE D65 illuminant and the CIE 2° Supplementary Standard Observer. C* (chroma) and hº (hue) were determined from a* and b* color coordinates. R, which is wavelength-dependent, will be represented by its average (sum of values at each wavelength divided by number of data points). R and L*, C* and hº were correlated using Pearson correlation coefficient (r) with α= 0.05.
Results: Pearson correlation coefficients are presented in the Table. L* coordinate showed a strong correlation using B and W backgrounds for each ceramic systems. When all systems were evaluated together, the strongest correlations between R and color coordinates were obtained using a white background.
Conclusions: Lightness of CAD-CAM ceramic systems was not influenced by the reflectance obtained by different standard backgrounds.