Preparation of zirconia dental crowns via electrophoretic deposition

Tetragonally stabilized, polycrystalline zirconia (TZP) is an interesting material for dental applications due to the tooth-like appearance, biocompatibility and, compared with other advanced ceramics, high bending and tensile strength. At present fully sintered TZP dental crowns or bridges can only be made via CAD-CAM supported mechanical milling processes, but the high costs and long processing times are disadvantageous. In contrast to this process a less expensive preparation is possible via near net-shape electrophoretic shaping from aqueous suspensions and consecutive sintering. As the deposition rate for electrophoretic deposition (EPD) is independent of particle size, bimodal starting powders can be used for optimizing the green density of the compact. Thus the shrinkage during sintering can be minimized. Furthermore, the pore structure can be controlled. In this paper the preparation of dental crowns via EPD is shown. With a combination of commercially available micron-sized Ce-stabilized zirconia (Ce-ZrO2) powder, nanosized zirconia powder (nano-ZrO2), and a submicron alumina powder (Al2O3) compacts with relative green densities up to 78% could be achieved. These compacts could be completely sintered at 1,600 degrees C with a linear shrinkage of less than 9%.