Osteoblast behaviour on zirconia fabricated by additive and subtractive technology

Zirconia is an attractive material for the manufacturing of oral implants and patient-individual barriers for guided bone regeneration. This study compared osteoblast behaviour on additive manufactured and milled 3-mol % yttria-stabilized tetragonal polycrystal zirconia (ZrO2).Two groups of samples (O5 x 2 mm) were manufactured by stereolithography (LithaCon 230, Lithoz, Vienna, Austria) and subsequently heat-treated and sintered. One group remained superficially unmodified (AM-ZrO2unmod.), while the other was polished according to DIN EN ISO 6872 standard using automated grinding (AMZrO2-pol.). For comparison, milled samples (e.max ZirCAD LT, Ivoclar Vivadent, Schaan, Liechtenstein) were sintered and polished similarly (Mil-ZrO2-pol.). Surface roughness was characterized using tactile profilometry. Adhesion, proliferation and coverage of human fetal osteoblasts (hFOB 1.19) as well as expression of osteogenic marker genes ALPL and RUNX2 were determined (and statistically compared using Kruskal-Wallis-analyses and Dunn's Post-hoc-tests).The surface roughness of AM-ZrO2-unmod. Was 45 times higher than that of the polished groups. No significant differences were detected between the three groups regarding cell adhesion and proliferation. With regard to cell coverage, AM-ZrO2-pol. Significantly outperformed the two other groups (p < 0.05). ALPL- and RUNX2mRNA expression was insignificantly superior for AM-ZrO2-unmod. Compared to the two other groups. Therefor no detrimental effect on osteoblast behaviour caused by the investigated, acrylic binder-based 3D printing workflow was observed.

Automated summary

This study compared the behavior of osteoblasts on additive manufactured and milled zirconia materials, and found that the surface roughness of the two groups differed significantly, but there was no significant effect on cell adhesion, proliferation, and coverage. The investigated 3D printing workflow did not have a detrimental effect on osteoblast behavior.