ENVIRONMENTAL-EFFECT ON BOND STRENGTH OF PLASMA-SPRAYED HYDROXYAPATITE BIOACTIVE GLASS COMPOSITE COATINGS

Bond strength of hydroxyapatite (HA) coatings is one of the major concerns of biomaterials scientists and engineers. This study was conducted to determine the effects of environment (particularly humidity and storage time) on bond strength of HA, bioactive glass (BG) and HA/BG (1:1 by weight) composite coatings on Ti6AI4V substrates. Results indicated that the HA coating on Ti6AI4V lost bond strength when exposed to either a high (>95%) or low (<30%) humidity environment. In the high humidity environment, degradation of the coating was quite drastic (nearly 40%). The BG coating was more stable in the low humidity environment but lost much bond strength in the high humidity environment (nearly 40 %). The HA/BG composite coating behaved well in both environments. After 30 d, the HA/BG composite coating retained nearly all of its as-coated bond strength. These results imply that tremendous care BG should be taken in storing and/or shipping HA- or BG-coated Ti6AI4V implants or other components.