In vitro and in vivo studies on the thin and defect-free calcium phosphate films formed by electron-beam evaporation

The thin and defect-free calcium phosphate film deposited to a thickness of 1 mum by electron beam evaporation was characterized in vivo and in vitro. For the in vivo study, as-machined, as-blasted, and calcium phosphate coating on machined surface of commercially pure titanium screw implants were inserted in the rabbit tibiae. Twelve screws of each condition were implanted, and the total of 144 implants were evaluated. The various Ca/P ratios of calcium phosphate films were formed by e-beam evaporation without simultaneous Ar ion bombardment. The as-deposited films had the average bonding strengths of 64.8 MPa to metal implant and different dissolution rates with the Ca/P ratio. After a healing period of 12-week, at the day of sacrifice, the implants were unscrewed with a torque gauge instrument. The coated sample showed the highest removal torque in both normal and ovariectomized group, indicating direct chemical bond with bone tissues.