COMPARISON OF REACTIVITY OF SYNTHETIC AND BOVINE HYDROXYAPATITE IN VITRO UNDER DYNAMIC CONDITIONS

Hydroxyapatite materials prepared using synthetic (HA-S) or bovine (HA-B) granules were exposed to a long-term in-vitro test under dynamic conditions. Testing cells, filled up to one quarter of their volume with the tested material, were exposed to continuous flow of simulated body fluid (SBF) for 56 days. The objective was to determine whether the reactivity of the biomaterials (hydroxyapatites), prepared by different methods but identical in terms of their chemical and phase composition, in SBF were comparable. Analyses of the solutions proved that both materials were highly reactive from the very start of interaction with SBF (significant decrease of Ca2+ and (PO4)3- concentrations in the leachate). SEM/EDS images showed that the surface of bovine HA-B was covered with a new hydroxyapatite (HAp) phase in the first two weeks of the test while synthetic HA-S was covered after two weeks immersion in SBF. At the end of the test, day 56, both materials were completely covered with well developed porous HAp phase in the form of nano-plates. A calculation of the rate of HAp formation from the concentration of (PO4)3- ions in SBF leachates confirmed that all removed ions were consumed for the formation of the HAp phase throughout the entire testing time for bovine HA-B and only during the second half of the testing time for synthetic HA-S.