Mechanical properties, corrosion behaviour and biocompatibility of TiNbTaSn for dentistry

Abstract

Titanium and the alloy Ti-6Al-4V are standard in implantology, despite the fact that the alloys may suffer from biomechanical incompatibility. The appropriate solution is the use of titanium β-alloys with a low modulus of elasticity and high strength. An additional advantage of these alloys is improved corrosion behaviour in environments that may contain fluoride ions, i.e. the oral cavity. Ti-25Nb-4Ta-(X)Sn alloys, where X is 4, 6, 8 and 10 weight per cent, were prepared. The phase composition, ultimate tensile strength, yield strength, Young modulus, elongation and hardness were measured. The corrosion behaviour in physiological saline, acidified physiological saline with and without the fluoride ions, was determined using, potentiodynamic polarization and electrochemical impedance spectroscopy. Bioactivity was predicted on the base of exposure in the simulated body fluid extended by impedance detection of the Ca/P layer formation. From the point of view of mechanical properties, alloys with a higher tin content are ideal for load-bearing applications. The corrosion resistance of these alloys in physiological saline is similar to titanium and significantly higher in the fluoride ions containing environment. The bioactivity test -exposure in SBF has shown quite identical results of the studied alloys and titanium, both in terms of kinetics and total composition of precipitated calciumphosphate layer. Possible cytotoxicity effects were excluded by the exposure with murine fibroblasts. This study describes the mechanical properties and corrosion resistance in non-fluoride and fluoride containing media, predicts bioactivity and verifies non-cytotoxicity of new titanium alloys and demonstrates that they are a suitable substitute for currently the most widely used alloys (Ti-6Al-4V, Ti-6Al-7Nb) in terms of both mechanical properties and corrosion resistance for dental implants.