The aim of this study was to analyze the optical properties of current CAD/CAM silicate glass-ceramics and the context of their structural properties. Different glass-ceramics (VITABLOCS Mark II, Nice, Celtra Duo, IPS e. max CAD) were prepared at the manufacturer-specific translucency level (LT/MT/HT/O2/O1) in disc form (0. 5/1. 0/1. 5 mm thickness) and examined via a benchtop spectrophotometer (X-Rite Ci76000). TPab, TP00 (translucency), the CR (contrast ratio), ΔE00 (masking ability), OPRT (opalescence) and FL (fluorescence) were calculated. The microstructure was analyzed via powder X-ray diffraction (XRD) with Rietveld refinement and scanning electron microscopy (SEM). With increasing sample thickness, TPab and TP00 decreased, and the CR increased. IPS e. max CAD showed the highest (EmaxO1) and lowest (EmaxLT) translucencies. Thickness had no clear effect on ΔE00, OPRT or FL. EmaxO1/O2 generally presented very high OPRT and FL values. All the ceramics had different phase components and glass contents. The glass content of MarkII was the highest, and that of NiceLT/HT was the lowest. The translucency increased within a particular product line (Nice, Celtra or Emax) with increasing glass content. No correlation between the glass content and optical properties was observed between the different glass-ceramics MarkII, Nice, Celtra and Emax. Furthermore, no correlation was found between the crystallite shape/size and optical properties. To match dental restorations with the aesthetics of natural teeth, knowledge of the optical properties of glass-ceramics is important.
Dettlinger et al. (Fri,) studied this question.