Dental Zirconia Fabricated By Stereolithography: Accuracy, Translucency And Mechanical Properties In Different Build Orientations

Additive manufacturing (AM) zirconia shows excellent prospects for use in clinical applications. In this work, AM zirconia samples were fabricated in horizontal (H) and upright (U) fashion using a stereolithography appearance (SLA) system. The dimensional accuracy, density, translucency, surface quality, flexural strength and fracture toughness (K-Ic) of the samples were then assessed. AM zirconia fabricated in a H fashion shows excellent dimensional accuracy. Samples fabricated in a U fashion exhibit a higher density (relative density 95.4%) and translucency (4.393), but H group samples exhibit a higher K-Ic value (12.635 +/- 1.372 MPa m(1/2)). The flexural strengths of the samples were measured and the values were compared according to their different build orientations, surface quality and fracture modes. Manual defects that arose in the samples as a result of their separation from the build platform in which they were made were found to lead to samples with irregular surface morphologies and increased surface roughness. However, this type of defect does not affect the flexural strength of samples fabricated in a H fashion. Polished-H samples that fracture from the stress concentration area exhibit the highest flexural strength (1151.08 +/- 166.41 MPa) amongst all the samples prepared in this work. However, the flexural strength of the samples prepared in a U fashion is obviously low, even after polishing (225.44 +/- 46.10 MPa). The Weibull characteristic strengths and Weibull moduli of the as-sintered samples are 920.22 MPa and 6.50 for H and 219.59 MPa and 7.99 for U, respectively. Overall, it was found that the dimensional accuracy, density, translucency, surface quality and mechanical properties of materials vary according to their different build orientations.