When adsorbed to implant surfaces, osteogenic proteins such as fibronectin induce bone cell adhesion, growth, maturation and the formation of a mineralized matrix. Therefore, such proteins may be useful in accelerating osseointegration of dental and orthopedic implants and prolong their longevity. Studies of nteractions between fibronectin and titanium materials suggest that the negative charge of the surface oxide modulates the structure of the protein to increase the functional presentation of its cell binding domain to osteoblast integrin receptors. Furthermore, the biological potency of fibronectin as a bone cell adhesive protein may be increased by the use of surface treatments such as thermal oxidation and radiofrequency glow discharge which increase the concentration and negative charge of surface oxides. It is our hypothesis that this latter oxide property is uniquely capable of inducing adsorbed fibronectin to bind with higher affinity to functional bone cell receptors and thereby attach to more cells, stimulate cell spreading and accelerate and strengthen implant integration. To test this hypothesis we will address the following aims:
Aim I. To demonstrate that negatively charged metallic surface oxides increase the number of bone cells that attach to preadsorbed fibronectin and exhibit a spreading response associated with cell adhesion ;
Aim II. To demonstrate that negatively charged metallic surface oxides induce adsorbed fibronectin to bind with higher affinity to functional bone receptors and promote osteogenesis ;
Aim III. To demonstrate that negatively charged metallic surface oxides enhance the ability of adsorbed fibronectin to accelerate and strengthen implant bonding to bone in an animal model. This proposal intends to validate our strategy of forming a more highly charged implant surface oxide followed by fibronectin coating to achieve a more robust fixation in less time. Therefore, the implant's longevity may be enhanced by using this simple and relatively inexpensive preparative procedure. ? ? ?
