This study identifies the conditions for preparation of stable submicrometer zirconia slurries with a high solids content for the production of aqueous gel-casting fixed partial denture (FPD) framework with improved rheological properties. The effects of the powder and dispersant on the rheological properties were investigated. The results indicated that a polyelectrolyte dispersant had a significant effect on the surface charge of the zirconia powder and the rheological behavior of the suspension. In the optimal range for each factor, a low viscosity was achieved for a slurry of high solids loading. The optimal content of the dispersant is about 0.15 wt.%, based on zirconia. The rheological character of high solids slurries approximates non- Newtonian flow, with a 'shear-thinning' character changes as the shear rate is increased. The viscosity of the 80 wt.% powder slurry with 0.15 wt.% polyelectrolyte (based on the powder) was less than 3 Pa s−1 at a shear rate of 191 s−1. Under these optimal conditions, a slurry met the demands of an aqueous-gel-casting process.

Keywords: rheology, submicrometer tetragonal polycrystalline zirconia, polyelectrolyte dispersant, aqueous gel-casting process, fixed partial denture, framework.