A multi technique study of a new lithium disilicate glass-ceramic spray-coated on ZrO2 substrate for dental restoration

An alkali niobate-silicate veneer ceramic for ZrO2-based dental restoration was developed and characterized for its physical properties and structure. The properties were adjusted for dental applications. The new lithium disilicate glass-ceramic VBK (sold as cerafusion or LiSi) can easily be applied by spray coating to any individually formed ZrO2-matrix and needs only one final tempering treatment. The surface of the glass-ceramic is very smooth. The color of the already translucent glass-ceramic can be adjusted to that of individual natural teeth. The structure of the glass-ceramicwas studied by XRD and Ramanspectroscopy as a function of heat-treatment and of spatial variations within the material and at its interfaces. ToF SIMS, SEM and thermal analysis techniques were applied to investigate the crystallization behavior and surface-interface reactions. XRD and Raman spectroscopy identified different crystalline phases in the amorphous glass matrix including Li2Si2O5, Li2SiO3, NaxLi(1−x)NbO3 and Na3NbO4. The Raman spectrum of the amorphous matrix is dominated by the vibrational activity of the highly polarizable niobate units with a prominent feature at 865 cm−1, assigned to Nb-O stretching in NbO6 octahedra, which have non-bridging oxygen atoms and are connected to the silicate matrix rather than to other niobate polyhedra.