In-Vitro Comparative Evaluation of the Physical Properties of Three Dimensional-Printed and Milled High Performance Ceramics

Aim: to investigate the potential role of 3D printing to produce zirconia restorations and to assess the mechanical properties of the 3D printed zirconia. Hypotheses: 1) The flexural strength of 3D printed yttria-stabilized zirconia is comparable or superior to milled yttria-stabilized, isostatic pressed zirconia, and 2) thermocycling and chewing simulation does not affect the flexural strength of 3D printed yttria-stabilized zirconia. Material and methods: 30 bars of printed yttria-stabilized zirconia and 10 bars of milled yttria-stabilized, isostatic pressed zirconia were utilized in this study. Printed zirconia bars were divided in 3 groups (10 bars per group): untreated, thermocycling and chewing simulation. Flexural strength test was performed on all the samples using a three-point bend test. One-way ANOVA analysis compared the 3 groups of printed zirconia samples, and Mann-Whitney test was used to compare the non-treated printed zirconia group to the milled zirconia group. Results: No statistically significant difference between the three groups of printed zirconia samples was found (P = 0.119). No statistically significant difference between the non-treated printed zirconia group and non-treated samples of milled yttria- stabilized, isostatic pressed zirconia was found (P = 0.178). Conclusion: No statistically significant differences in flexural strength were detected between yttria-stabilized printed zirconia and milled yttria-stabilized, isostatic pressed zirconia, and non-treated, thermocycling and chewing simulation tested printed zirconia samples. These results indicate the promising role of 3D printing in the fabrication of zirconia. Additional studies are needed to explore the full potential of this technology