Extrusion-based 3D printing of fully dense zirconia ceramics for dental restorations

Extrusion-based 3D printing using zirconia ceramics shows promising results in biomedical applications, but the challenges in deployment are still significant. In this study, we developed an optimized extrusion-based 3D printing method for fabrication of intricate, fully dense ceramics based on gelled zirconia suspensions. The viscoelastic properties of the suspensions were tailored to facilitate smooth flow through a 150–250 µm nozzle at high solid volume fraction (52%) and produce self-supporting features. Because of the minimal organic content, the as-dried zirconia specimens could be directly sintered without binder-removal steps. The maximum relative density, flexural strength, and hardness of the sintered zirconia ceramics were 99.3%, 1010 MPa, and 15.9 GPa, respectively. Zirconia dental restorations were fabricated, and the occlusal details were preserved by co-printing a novel polyacrylate supporting material which can be removed by cooling owing to its temperature-dependent rheological behavior.