Monotonic and Fatigue Strength of 3D-Printed Partially Stabilized Zirconia for Monolithic Restorations
Yuqing Lu1, Li Wang2, João Paulo Mendes Tribst3
1Department of Dental Materials Science, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, The Netherlands; Department of Reconstructive Oral Care, Academic Centre for Dentistry Amsterdam (ACTA), Universiteit van Amsterdam and Vrije Universiteit, Amsterdam, The Netherlands.
Objectives:
To investigate the monotonic and fatigue strength of 3D-printed 5 mol% yttria partially stabilized zirconia (5Y-PSZ) and the influences of printing layer orientation and finishing protocol.
Methods:
Bar-shaped 5Y-PSZ specimens (1.0 mm x 1.0 mm x 12.0 mm) were 3D-printed via stereolithography, followed by debinding and sintering. The specimens were randomly divided into 2 groups according to printing layer orientations: parallel or perpendicular to the tensile surface of a 3-point bending test. The specimens of each printing layer orientation were subsequently submitted to different surface finishing protocols: as-sintered, polished, and glazed. The monotonic strength of each group was determined using a ball-in-hole device. A step-wise fatigue test was conducted for the polished and glazed specimens.
Results:
For monotonic strength, the parallel specimens (640 ± 99 MPa) were stronger than the perpendicular (507 ± 48 MPa); polishing generated higher strength for both parallel (782 ± 134 MPa) and perpendicular (645 ± 160 MPa) orientations; while the effect of glazing was not significant, the glazed perpendicular specimen (623 ± 97 MPa) presented similar strength to the glazed parallel specimens (581 ± 117 MPa). However, the fatigue strength was similar in the evaluated groups (parallel and polished: 418 ± 115 MPa; perpendicular and polished: 404 ± 55 MPa; parallel and glazed: 406 ± 41 MPa; perpendicular and glazed: 371 ± 86 MPa).
Conclusion:
Both printing layer orientation and surface finishing influenced the monotonic strength of 3D-printed 5Y-PSZ, while fatigue strength did not differ significantly among polished and glazed specimens with different orientations.
