Osteoblast mechanoresponses on Ti with different surface topographies.

During implant healing, mechanical force is transmitted to osteogenic cells via implant surfaces with various topographies. This study tested a hypothesis that osteoblasts respond to mechanical stimulation differently on titanium with different surface topographies. Rat bone-marrow-derived osteoblastic cells were cultured on titanium disks with machined or acid-etched surfaces. A loading session consisted of a 3-minute application of a 10- or 20-mum-amplitude vibration. Alkaline phosphatase activity and gene expression increased only when the cells were loaded in 3 sessions/day on machined surfaces, regardless of the vibration amplitude, whereas they were increased with 1 loading session/day on the acid-etched surface. The loading did not affect the osteoblast proliferation on either surface, but selectively enhanced the cell spreading on the machined surface. Analysis of the data suggests that osteoblastic differentiation is promoted by mechanical stimulation on titanium, and that the promotion is disproportionate, depending on the titanium surface topography. The frequency of mechanical stimulation, rather than its amplitude, seemed to have a key role.