Development of free binder zirconia-based pastes for the production of dental pieces by robocasting

摘要

The current work aims to develop high solid load zirconia pastes without organic binder additives, for the robocasting of dental structures. The effect of the amount of Dolapix CE64 dispersant on the stabilisation of zirconia aqueous suspensions was first tested. The determined optimal amount of dispersant was then used to produce pastes with zirconia concentration in the 80-90 wt% range. Pastes were further studied regarding rheological behaviour and printability. The most printable were used to produce parallelepiped blocks by robocasting; slip casting samples were also produced for comparison. Density, surface roughness, porosity, hardness and toughness of both types of samples were assessed after sintering. Finally, a model molar tooth was produced by robocasting and sintered.The most encouraging robocasting results were obtained using a paste with 0.5 wt% Dolapix CE64 and 88 wt % zirconia. The produced samples displayed 97.1 % of theoretical density, Vickers hardness of 1485 +/- 32 and fracture toughness of 4.11 +/- 0.09 MPa.m(1/2) after sintering. Similar values were obtained for slip casting parts. A model molar tooth with adequate surface finishing was successfully obtained using the described processing parameters, together with a brushing treatment carried out in the green state.Attained results show that it is possible to build zirconia prosthetic dental structures with adequate morphological and mechanical properties by robocasting of binder free pastes. This opens an opportunity window for the cost-effective and environmentally friendly customized production of prosthetic dental structures by additive manufacturing.