Development of mask-less projection slurry stereolithography for the fabrication of zirconia dental coping

Zirconia dental coping (ZDC) has an obvious aesthetic advantage over titanium implants, in that it is pure white, which makes it indistinguishable from the material of natural teeth. Conventional fabrication of ZDC uses CAD/CAM, but surface defects and micro-cracks can result in a decrease in the ultimate strength and compressive resistance. This study proposes the use of mask-less projection slurry stereolithography (MPSS) to fabricate the proposed benchmarks, such as 2.5D model with varying angles and ZDC, and uses two-stage sintering to obtain the sintered parts. The experimental results show that the effective exposure time for the proposed slurry with a minimum particle size of 1.1 μm is 5 seconds, which gives a curing depth of 23.4 μm. The maximum tolerance of the fabricated green body is about 20 μm and linear shrinkage rate, after sintering, is 23.5%. SEM images show that no delamination occurs on the surface of the green body and no cracks are found on sintered parts. The flexural strength and the hardness of the zirconia sintered parts are 539.1 MPa and 13.02 GPa, respectively. Using this MPSS, it is also possible to construct green bodies for customized zirconia dental restoration, as an alternative to CAD/CAM machining.