Search

Zirconia ceramic is a widely used material for dental restoration. Stabilized zirconia all-ceramic teeth have excellent mechanical properties, biocompatibility, and aesthetic properties. At present, the CAD/CAM technique for zirconia all-ceramic dental prosthesis leads to low material efficiency and high tool wear. Although restorations fabricated using additive manufacturing are gaining attention, it is still very challenging to obtain accurate shapes and proper mechanical properties in zirconia restorations. In this investigation, a type of three-part auxiliary support was adopted and added to the occlusal surface to fabricate a typical molar crown bridge. A ceramic solid content of 40 vol% acrylic-based slurry was prepared, and a molar crown bridge was fabricated using mask projection stereolithography. The experimental results showed that the average dimensional error of the printed green body was ±150 μm. The density of the sintered ceramic parts was 6.026 g/cm3, and the three-point bending strength was 541 ± 160 MPa, which is higher than that of human dentin (160 MPa), but lower than that of CAD/CAM zirconia (900–1200 MPa). Although the proposed process still needs to be optimized to improve the mechanical properties and reliability of the crown bridge, the mask projection process combined with the adopted three-part auxiliary supports are capable of individualized manufacturing of complex zirconia crown bridges.

Mask projection stereolithography can be used to fabricate complex ceramic parts layer by layer through the photopolymerisation of ceramic suspensions. The broadening or lateral overcure of the curing shape occurs because of light scattering effects. Achieving a better dimension and strength quality by adjusting light energy delivery in the boundary mask area has been insufficiently investigated thus far. In this study, the conventional mask was segmented into boundary and interior masks. The exposure time and power of the boundary mask (two pixels wide) were varied to investigate the effects of segmented exposure. The segmented exposure constrained the dimension errors to a width of within two pixels for a feature dimension of less than 1200 µm. It further smoothed the lateral surface of the green part to achieve Ra values of below 6 µm. Moreover, enhancing the boundary mask increased the flexural strength and Weibull modulus to 248 MPa and 11.1, respectively. The results indicate that segmented exposure can potentially be used in complex lattice ceramic structures.