Charakterisierung des in-vitro-Resorptionsverhaltens von plasmagespritzten Hydroxylapatit-Schichten

Long-term incubation (up to 56 days) of plasma-sprayed hydroxyapati te coatings in protein-free simulated body fluid (pf-SBF) was performed to predict the in vivo behaviour of bioceramic coatings for endoprosthetic implants. Pure hydroxyapatite coatings and hydroxyapati te coatings doped with manganese (180 ppm) were deposited by atmospheric plasma spraying onto Ti6Al4V targets. The manganese was used as a tracer to investigate by cathodoluminescence (CL) microscopy the interaction of the coating with the simulated body fluid and to monitor possible structural changes within the coatings. Differently luminescing zones and growth of secondary crystals at the surface were observed in Mndoped hydroxyapati te coatings after 28 days of incubation. Additional results from SEM and XRD studies indicate changes in the microstructure of the coatings due to dissolution and reprecipitation processes in contact with the simulated body fluid. The crystallisation of Ca-deficient hydroxyapat ite with a Ca/P ratio of about 1.4 (probably „bone-like" apatite according to Weng et al. [16]) onto the coating surface is remarkable and can probably improve the in-growth of living bone cells.