Effect of Fluoride Modified Titanium Surfaces on Osteoblast Responses

Objectives: The responses of human embryonic palatal mesenchymal (HEPM) cells on a fluoride modified titanium surface (Osseospeed^TM Astra Tech, Mölndal, Sweden) were compared to two other surfaces: TiOblast^TM, Astra Tech, and a titanium surface prepared by blasting with the same sized titanium dioxide particles without the fluoride modification, creating a rough blasted surface (RB). Methods: HEPM cells were plated at micromass density (50,000 cells/10µL droplet) on each surface for 1, 3 and 7 days followed by analysis for cell proliferation, alkaline phosphatase specific activity and mRNA steady state expression for bone related genes (Alkaline phosphatase, Collagen Type I, Osteocalcin, BSP II, Cbfa1 and Osterix) by real-time PCR. Results: The different surfaces did not alter the mRNA expression for alkaline phosphatase, BSP II and Osterix. Expression of type I Collagen and osteocalcin were significantly higher (p<0.05) with time of culture, although there was no significant difference in the gene expression among the titanium surfaces. By day 7, Cbfa1 expression on the Osseospeed surface was significantly higher than on the other two implant surfaces (expression on RB surface, the least, p<0.001), although the cell number on the Osseospeed surface was reduced by 20% as compared to the TiOblast and TCP surfaces, and not significantly different from that on the RB surface. Cells grown on all the titanium surfaces expressed similar levels of alkaline phosphatase activity. Conclusions: The results indicate that the chemistry of the fluoride modified surface in synergy with the surface roughness may have a greater influence on the level of Cbfa1 (the key regulator for osteogenesis) expression than the unmodified titanium surfaces studied. This suggests that the Osseospeed surface may be better than TiOblast and RB surfaces for the growth and differentiation of osteoblast-like cells in vitro. Supported by: NIH R03DE014269, P60DE13076, R21DE016677 and Astra Tech.