Influence different polishing systems on roughness and colour stability of chairside CAD/CAM blocks with laminate...

The aim of this study was to evaluate the effect of different polishing systems on the colour stability of different laminate veneer blocks for chair-side CAD-CAM after ultraviolet (UV) ageing.

About 240 sample (13 × 13 × 0.7) were prepared from four different CAD-CAM blocks IPS e.max CAD (IP), IPS Empress CAD (IE), Mark II (M) and Lava Ultimate (LU)) with A1 shade. Each group was divided into five subgroups (n = 12) according to the control (C) and four different polishing system: Sof-Lex (S), Edenta (E), Identoflex (I) and Zircon Brite (Z). Surface roughnesses (Ra) were measured by a profilometer before and after polishing. The baseline colour values were recorded according to the CIELab system. The colour coordinates (L*, a* and b*) of the samples were measured before and after UV ageing, and colour differences (ΔE₀₀) were calculated by using the CIEDE2000 colour difference formula. A two-way ANOVA and Tukey test methods were used to analyse the data (α = 0.05).

A significant interaction was observed between CAD-CAM blocks and polishing system (p < 0.001). The higher Ra and colour difference was calculated in LU in the Z group after polished and the lower Ra and colour difference was calculated in the IP in the S group after polished. For the IP group, the glazing procedure showed higher Ra and ΔE values with Z group than polished S system, whereas there is no statistical differences.

It is concluded that polishing with the Sof-Lex system improves significantly smoothness and colour stability. However, there is no success in using the Zircon Brite polishing system.