Surface characterization of dental Y-TZP ceramic after air abrasion treatment

The aim of this study was to characterize the surface of Y-TZP after abrasion with various airborne particles.

The Y-TZP blanks were cut into 44 discs and sintered according to the manufacturer's instructions. The specimens were treated as follows: (a) control specimens, (b) abraded with 50μm alumina, (c) abraded with 110μm alumina, (d) abraded with 30μm silica-coated alumina, (e) abraded with 110μm silica-coated alumina, (f) abraded with 110μm alumina followed by 110μm silica-coated alumina particles. Airborne abrasion was performed at a pressure of 2.5bar for 15s/cm(2). The Y-TZP was characterized using X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and X-ray diffraction analysis (XRD).

Surface morphology of Y-TZP ceramic was changed after the airborne abrasion process compared to the control specimens. The grain boundaries disappeared and part of the airborne particles are embedded and/or rested on the ceramic surfaces. The elemental composition of the Y-TZP surface after the airborne abrasion process depended on the type and size of these particles. The concentration of Si resulted higher after the airborne abrasion process with 110μm alumina followed by 110μm silica-coated alumina particles in comparison to the specimens abraded with 110μm silica-coated alumina particles. The ratio of elements normalized by yttrium for these specimens was: [Zr]/[Y]/[Al]/[Si]=15.2/1.0/26.0/73.6, respectively.

The change of grain topography occurred during each impact process. Silica nano-particles covered not only loosely the abraded ceramic surface after abrasion process, but the release of kinetic energy in form of thermal energy resulted in melting of the ceramic surface and in the formation of zirconium silicate.