Effect of Thickness and Shade of Resin and Ceramic- Based Hybrid Materials on Color Masking Abilities and Optical Performance of CAD/CAM Materials.

Scientific data analysing color masking abilities of chairside CAD/CAM materials is lacking. The purpose of this in-vitro study was to evaluate the thickness and shade influence of three materials on their optical behaviour. Three materials: a) LD: Lithium disilicate glass ceramic (Emax, Ivoclar Vivadent), b) LDS: Lithium-disilicate-strengthened aluminosilicate glass ceramic (N!ce, Straumann) and c) RNC: Resin Nanoceramic (Lava Ultimate, 3M ESPE) were polished in different shades (A1,A2,A3) and thicknesses (0.1- 1.2mm). Specimens (N=108; n=36 per group) (12x12x1mm3) were positioned on resin composite base (Clearfil AP-X, Kuraray) in shade A3. Spectrophotometric measurements were performed and the parameters thickness, shade and material were analysed using three-way ANOVA, and pairwise T-tests (P-values ⟨ 0.05). Both the shade (p⟨0.001) and the interaction of material in correlation to thickness (p⟨0.001) were significant. Shade value A1-A3 comparisons were significant A1 vs. A2 (p=0.045); A2 vs. A3 (p=0.002); A1 vs. A3 (p⟨0.001)). A significant correlation of the material and thickness was observed when comparing LD and LDS (p=0.007) at the thickness of 0.1-0.4 mm. Masking abilities were influenced by material and thickness choice. Reinforced glass ceramics showed the best results in the smallest thickness tested (0.1-0.4 mm). LDS could be considered as an advantageous alternative in minimal-invasive cases