Mechanical Properties and Bond Strength of Additively Manufactured and Milled Dental Zirconia: A Pilot Study.

PURPOSE: To evaluate and compare the mechanical properties and ceramic bond of additively manufactured and milled dental zirconia materials. MATERIALS AND METHODS: Disc (r = 10 mm, h = 2 mm) and bar (25 x 4 x 1. 2 mm) shaped milled (M group) (Nacera Pearl; Doceram) and additively manufactured (AM group) (NanoParticle Jetting; XJet, Carmel 1400) zirconia specimens were prepared for 2 experimental groups. Ceramic was applied to the disc specimens (h = 4 mm, r = 6 mm) (n = 9) and their shear bond strength (SBS) was measured. The surface morphology of disc specimens was analyzed with a scanning electron microscope (SEM). The Vickers microhardness (Vh), surface roughness (Ra), and three-point flexural strength (FS) of bar specimens (n = 9) were measured. Results were statistically analyzed with Mann-Whitney U-test (alpha = 0.05). RESULTS: Significant differences were found in FS and Vh values of the M and AM groups. M group (1501.4 +/- 60.1 HV1) showed a significantly higher Vh value than the AM group (1169.2 +/- 48.4 HV1) (p < 0.001). FS of the M group (1287.5 +/- 115.2 MPa) exhibited significantly high value than the AM (1030.0 +/- 29.2 Mpa) group (p < 0.001). Statistically, no significant differences were seen in SBS and Ra values of the M and AM groups. CONCLUSION: Within the limitations of this in vitro study, the manufacturing technique affected the mechanical properties of the zirconia materials. AM zirconia material showed lower Vh and FS values than M zirconia. Additionally AM zirconia demonstrated adequate bond strength with dental ceramic.