Effects of Three Types of Veneering Porcelain on Bending Strength of KAVO™ Y-TZP/Porcelain Bilayered Structure

The purpose of this study was to investigate the effect of three types of veneering porcelain on the bending strength of KAVO (TM) Y-TZP/porcelain layered structure. KAVO (TM) zirconia ceramics were selected as substructure. To form Y-TZP/porcelain bilayered structure, a leucite based veneering porcelain was fired on the zirconia substructures by slip-casting technique with dentin washbake, and two nano-fluorapatite based veneering porcelain was fired on the zirconia substructures either by slip-casting or pressed-on technique with or without liner coverage. Bending strength was tested according to ISO 6872 standard, and the veneered surfaces of fracture samples were analyzed by SEM. For covering KAVO (TM) zirconia core material, conventionally applied veneering slurry-porcelain combined with liner or wash firing has significantly higher bending strength than pressed-on porcelain. SEM analyses show that the main failure type at the interface is adhesive. Thin layer sintering as applying washbake program or liner on KAVO (TM) zirconia surface can increase the surface wettability, and this procedure may be indispensable when veneering on the surface of dental zirconia.