[Influence of the implant surface on the early phase of osteogenesis in vitro]

The specific structure of a dental implant's surface is often used as an argument for a better overall performance and durability. Nonetheless, it is not yet fully clear to what extent an implant's material or surface structure improves its performance. For a better understanding of the early integration-related processes, growth and initiation of mineralization of human MG-63 osteoblasts grown on glass slides or on polished (MS: machine-surfaced) or structured (SB: deep-structured) titanium surfaces were monitored. Cells were cultured under non-confluent conditions in absence and presence of osteogenic medium (OS). The 3D-architecture of growing cells was documented by confocal laser scanning microscopy (CLSM) upon fluorescently labeling for collagen I. Collagen I distribution was found comparable under all conditions. In control cultures on glass, MS and SB, cells had grown as multilayered but not yet confluent networks, which additionally comprised dome-like structures on the two Ti-surfaces. While on glass and SB cells essentially maintained this architecture also in presence of OS, three-dimensional structures on MS were--if at all--only barely visible. This was reflected also in the protein content of the cultures that was significantly lower under OS in the case of MS only. The activity of the early mineralization marker alkaline phosphatase (ALP) was higher in the controls on glass than on MS or SB. In presence of OS it was significantly higher on MS and SB than in the controls, yet not on glass. Obviously both, the surface material and the surface structure contribute--possibly synergistically--to early processes of implant integration, such as matrix formation and mineralization. The impact of such effects is discussed, in relation to implant loading and implant durability.