Variation in Biological Properties of Thin Calcium Phosphate Films Formed by e-Beam Evaporation

Calcium phosphate films, which had the identical Ca/P ratio of 1.62 but different I crystallinity, were evaluated in vitro and in vivo. The dissolution rate in isotonic saline solution was 47.5 nm/hr for the as-deposited film, and decreased to 4.6 nm/hr upon heat treatment at 450degreesC for 1 hr. Removal torque force measurements after 6 weeks insertion of screw shaped implants in rabbit tibiae showed the value of 42.2 Ncm for the heat treated calcium phosphate coating layer, whereas it was 34.4 Ncm for the as-blasted Ti implant. The higher bone to implant contact measured by a microtomographic technique was responsible for the higher removal torque force.