[Optical properties of computer aided design and computer aided manufactured materials for veneer restorations]

Objective: To investigate the translucency parameters (TP) and the color parameters of computer-aided design and computer-aided manufacturing (CAD/CAM) materials for veneer restorations in order to guide clinical practice. Methods: Eleven groups of CAD/CAM materials (A2 shade) were included in this study: IPS e.max CAD HT/LT, IPS Empress CAD HT/LT, Lava(TM) Ultimate HT/LT, VITA SUPRINITY HT/T, VITA ENAMIC HT/T, VITABLOCS Mark Ⅱ, and were named as Group A, B, C, D, E, F, G, H, I, J, K. Each material was designed and milled to disk-shaped specimens (10.0 mm×8.0 mm×0.7 mm) (n=6). The specimens were polished with silicon carbide paper and the thickness of specimens were adjusted into (0.60±0.03) mm. The color parameters of specimens were individually measured with the colorimeter against black and white ceramic tiles background to obtain the TP values. The color parameters of the specimens against the composite resin background were also measured and the color differences (ΔE values) between specimens and the A2 shade tab were calculated. Results: One-way ANOVA showed that the translucency parameters of the 11 groups of materials were statistically significant (F=253.69, P<0.05). The ΔE values of CAD/CAM material groups ranged from 1.78 to 4.12 (ΔE values<5.5). Conclusions: The microstructure of CAD/CAM materials and the types of material translucency influence the optical properties. The CAD/CAM materials in this experiment have achieved color matching with the A2 shade tab.