Corrosion behaviour of Ti-15Mo alloy for dental implant applications

The corrosion behaviour of Ti-15Mo alloy in 0.15 M NaCl solution containing varying concentrations of fluoride ions (190, 570, 1140 and 9500 ppm) is evaluated using potentio-dynamic polarization, electrochemical impedance spectroscopy (EIS) and chronoamperometric/current-time transient (CTT) studies to ascertain its suitability for dental implant applications. The study reveals that there is a strong dependence of the corrosion resistance of Ti-15Mo alloy on the concentration of fluoride ions in the electrolyte medium. Increase in fluoride ion concentration from 0 to 9500 ppm shifts the corrosion potential (E-corr) from -275 to -457 mV vs. SCE, increases the corrosion current density (i(corr)) from 0.31 to 2.30 mu A/cm(2), the passive current density (i(pass)) from 0.07 to 7.32 mA/cm(2) and the double-layer capacitance (C-d1) from 9.63 x 10(-5) to 1.79 x 10(-4) F and reduces the charge transfer resistance (R,,) from 6.58 x 10(4) to 6.64 x 10(3) Omega cm(2). In spite of the active dissolution, the Ti-15Mo alloy exhibit passivity at anodic potentials at all concentrations of the fluoride ions studied. In dental implants since the exposure of the alloy will be limited only to its 'neck', the amount of Mo ions released from Ti-15Mo alloy is not likely to have an adverse and hence, in terms of biocompatibility this alloy seems to be acceptable for dental implant applications. The results of the study suggest that Ti-15Mo alloy can be a suitable alternative for dental implant applications. (C) 2008 Elsevier Ltd. All rights reserved.