Effects of surface treatments on Y-TZP phase stability, microstructure and osteoblast cell response

The effects of hydrothermal and phosphoric acid treatments on the tetragonal ZrO2 stability and surface microstructure were determined for 3 mol% yttria- partially stabilized zirconia (Y-TZP) and Al2O3 doped Y-TZP (Y-TZPA). Y-TZP slip cast compacts were sintered at 1300–1500 °C to achieve fully dense samples. The increase in the sintering temperature enhanced the hydrothermal degradation of Y-TZP. Although the average grain size of Y-TZPA sintered at 1500 °C was lower than that of Y-TZP, no significant difference in the ageing behavior between these two ceramics was found. For Y-TZP sintered at 1500 °C, the volume fraction of monoclinic ZrO2 induced by acid treatment was higher than that obtained after 10 h of hydrothermal treatment. The Al2O3 doping of Y-TZP improved the acid degradation resistance. Osteoblast cell culture studies on the Y-TZP surface confirmed its biocompatibility. The Y-TZP surface supported a higher cell proliferation compared to Y-TZPA. The less degradation on the 1 day acid-treated Y-TZPA surface stimulated cell proliferation, whereas a longer acid treatment reduced cell survival.