Additive Manufacturing of Zirconia-Based Pastes for Dental Prosthesis Via Robocasting Method

The main goal of this study is to develop zirconia-based pastes that are well-suited for the robocasting process, with the purpose of manufacturing dental prostheses. This study involved examination of the rheological properties of several zirconia-based pastes with different colors/shade and organic additives, as well as microstructural analysis (using XRD, SEM) and physical-mechanical characterization (through micro and nano-examination) of the printed and sintered material, after the application of different firing cycles (1400, 1450, 1540, and 1580 degrees C), in accordance with the ISO 6872 specifications for "Dental-Ceramic materials". Generally, homogeneous, and dense tetragonal yttria-stabilized zirconia specimens with fine microstructure, were produced. The mechanical properties increased as the firing cycle temperature increased. Results revealed that firing cycle of 1540 degrees C achieved the best balance regarding microstructure, physical, and mechanical strength of the specimens. The flexural strength ranged from 504 to 823 MPa, modulus of elasticity varied between 171 and 192 GPa, hardness and fracture toughness values ranged from 10.6 to 11.5 GPa and from 4.2 to 5.3 MPa m(0.5), respectively. Nanoindentation experiments showed hardness values from 11.7 to 14.1 GPa and modulus of elasticity from 239 to 316 GPa. The zirconia ceramics met ISO 6872 standards for dental prostheses, indicating suitability for oral use.