Distinct Cell Functions of Osteoblasts on UV-Functionalized Titanium- and Zirconia-Based Implant Materials Are Modulated by Surface Topography

Though recent studies report decisive positive effects on cells, elicited by ultraviolet (UV)-induced bioactivation of biomaterial implant surfaces, they frequently employ cells other than of human origin or cells not representing oral implant targets. Therefore, the present study aims at exploring distinct cell functions of primary human alveolar bone osteoblasts (PHABO) in response to bioactivated microstructured titanium and zirconia implant surfaces with matched controls. UV-treatment significantly reduced surface carbon, while concomitantly increasing wettability. In case of titanium or zirconia biomaterial source of equal roughness, bioactivation did not significantly improve cell functions, including initial cell attachment, morphogenesis, proliferation, and gene expression of osteogenic biomarkers osteocalcin, alkaline phosphatase and collagen type I. However, cell functions discriminated surface roughness by either comparing titanium and zirconia or interindividual zirconia surfaces. While rough surfaces primarily favored primary adhesion, proliferation appeared improved on smooth surfaces, and gene expression seemed to be stronger modulated on the smoothest biomaterial. Our results show for the first time that bioactivation appears to be not the main causative for the observed modulation of the distinct cell functions analyzed in PHABO, but add to the body of evidence that they were more governed by surface architecture rather than by bioactivation.