In Vitro Behavior of Heat-treated Hydroxyapatite-based Dental Implants

In Vitro Behavior of Heat-treated Hydroxyapatite-based Dental Implants
13 March 2004
S.-J. DING, Chung Shan Medical University, Taiwan, Taiwan
IADR
Objectives: Plasma-sprayed hydroxyapatite (HA) based implants on metallic substrates have been widely used as load-bearing applications. To improve the performance of HA, incorporating bioactive glass (BG) into HA has been proven a potential alternative. Methods: Hydroxyapatite-bioactive glass (HA-BG) coatings were plasma-sprayed on Ti6Al4V substrates. The in vitro behavior of bioactive glass-containing HA coatings with or without heat treatment in a simulated body fluid has been performed by means of electrochemical techniques and immersion tests. Results: X-ray diffraction patterns showed that the presence of 5 wt% BG enhanced the decomposition of HA structure during fabrication of the powder. The plasma spray process itself also enhanced the decomposition of apatite. Annealing of the coatings in air at 650oC led to recrystallization of amorphous calcium phosphate and effectively increased the conversion of non-apatite phase (TCP) into apatite. The heat treatment also resulted in a reduction of flake-type structures associated with plasma-sprayed coatings. The heat-treated coatings show a higher corrosion resistance, significantly reducing the corrosion rate by approximately two times. Conclusion: The heat-treated coatings in in-vitro testing present a better behavior than as-sprayed coatings. Supported by Taiwan grant NSC 91-2213-E-040-002. sjding@csmu.edu.tw