SEM observations of porcelain Y-TZP interface

ObjectivesThe metastability of the tetragonal phase of yttria tetragonal zirconia polycrystalline (Y-TZP) ceramics is a cause for concern in dental crown and bridge applications. One specific problematic area is the nature of the interface between the veneering porcelain and the Y-TZP framework and whether the associated preparation procedures and reactions result in a reduction of the stability of the zirconia.MethodsTo investigate this aspect, high-resolution SEM observations were made of polished and etched (HF content gel) cross-sections of the interface area. Dry and moist veneering porcelain powders were built up on the zirconia base.ResultsIn some instances the zirconia grains at the interface appear to show multiplicity of subgrain faceting whereas in other instances they do not. The latter indicate destabilisation of the tetragonal phase occurs and in addition that the porcelain veneering material wets and some dissolution of the Y-TZP occurs.SignificanceThese results and their relevance to the long-term stability of the interface adhesion to the veneering porcelain as well as possible tetragonal to monoclinic crystal transformations at the interface are discussed.