PROPERTIES OF CALCIUM-PHOSPHATE COATINGS BEFORE AND AFTER EXPOSURE TOSIMULATED BIOLOGICAL FLUID

The surface qualities of calcium phosphate (CaP) implants are importan t factors determining the nature and degree of cellular behaviour, esp ecially cellular attachment, proliferation and differentiation. Thus, in this study, the chemical composition and crystallographic propertie s of radiofrequency sputter-deposited CaP coatings prior to and after in vitro immersion in a physiological solution were characterized. Sig nificant differences in crystallite size were observed with different heat treatments, with coatings heat treated at 850 degrees C (CA8) hav ing larger crystallites compared to coatings heat treated at 700 degre es C (CA7). However, no statistical difference in the Ca/P ratio, carb on concentration and surface energy were observed with different heat treatments. After immersion in a physiological solution, the crystalli te size was significantly increased. The crystallite size for the CA8 and CA7 coatings remained statistically different after 1-week immersi on in solution. An increase in carbon concentration was also observed for both samples after 1-week immersion in solution. However, no signi ficant differences in the Ca/P ratio and surface energy were indicated between the two coatings after 1-week immersion in solution. In addit ion, no statistical difference in surface energy was observed for both samples initially and after 1 week. (C) 1997 Elsevier Science Limited . All rights reserved.