Behaviour of Ti6Al4V implant alloy in vitro after plastic deformation by bending

Abstract

Electrochemical and biological tests were used to evaluate in vitro the behaviour of anodised Ti6Al4V ELI samples after plastic deformation by bending. The implant rods of 6 mm diameter, anodised in H3PO4 acid solution, were used. Bending of implant rods was performed according to typical intra-surgical procedure applied during pre-shaping stage of implantation. The electrochemical properties were evaluated on the corrosion potential E corr and the results of the electrochemical impedance spectroscopy tests (EIS) of deformed samples immersed in simulated body fluid (SBF). Biological behaviour was estimated in contact with human osteoblasts. Electrochemical and biological changes demonstrated that mechanically disturbed anodic layer strived to achieve 'the state of balance' during immersion in electrolyte. After ∼6 days in SBF the former bi-layer structure of the anodic surface layer was recovered. Moreover, all samples irrespective of bending angle achieved similar values of Ecorr corresponding to the corrosion potential of the sample deformed at the 20° angle. Biological tests in vitro confirmed that deformation of anodic surface layer on implant titanium alloy also stimulated its bioactivity. The observed higher number of osteoblasts and enzyme level are conducive for the formation of hydroxyapatite crystals (ALP), which stimulate in-growth of bone tissue and accelerate healing process. Copyright © 2008 John Wiley & Sons, Ltd.