Abstract
Electrochemical characterization of titanium alloys with different levels of boron was carried out in phosphate buffered saline (PBS) at body temperature and in 0.9 wt% sodium chloride (saline) at room temperature. Two types of cyclic potentiodynamic polarization tests were conducted - one based on ASTM F 2129-08 and the other with a broader voltage scan with higher peak potentials that further distinguished the behavior of the different titanium alloys. Break-down (pitting) potentials for the alloys in the latter test were in the 4.9 – 6.5 V range.
The susceptibility of osteoblast cells to the titanium (IV) ions released from the different alloys during exposure to cyclic polarization tests was analyzed. The ion levels from the alloys, adjusted to synovial tissue levels, were not high enough to induce osteoblasts to undergo a destructive increase in apoptosis (programmed cell death). Additionally, the titanium alloys containing boron, induced the expression of the protein - receptor activator of nuclear factor kappa-B ligand (RANKL) - more than the alloys without boron. However, the critical level of RANKL expression necessary to activate osteoclast activity is still to be determined.
