Hydroxyapatite deposition on micropore-formed Ti-Ta-Nb alloys by plasma electrolytic oxidation for dental applications

• Microstructure of Ti-35Ta-xNb alloys showed α″and β phases, and the β phase increased with Nb contents.
• For the non-NaOH treated surface, the morphology of HA deposited on the Ti-35Ta-xNb alloys had a plate-like shape.
• The HA particle shape on the micropore-structured Ti-35Ta-xNb alloys was flower-like.
• The pore size and thickness of the surface barrier layer increased as the applied anodizing voltage increased.
• The anatase and rutile phases can be controlled by varying the applied voltage to yield optimum biocompatibility.

Hydroxyapatite deposition on micropore-formed Ti-Ta-Nb alloys by plasma electrolytic oxidation for dental applications was investigated. Ti-35Ta-xNb alloys (x = 0 and 10 wt.%) were prepared with an arc-melting furnace. Micropores were formed on the Ti-35Ta-xNb alloys in 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at 280 V for 3 min. Hydroxyapatite deposition were carried out on the alloy surfaces using cyclic voltammetry in 2.5 mM Ca(NO3)2 ∙ 4H2O + 1.5 mM NH4H2PO4 solution with various deposition cycles. Morphology and structure of the alloy surfaces and hydroxyapatite were investigated by field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction.The microstructure of Ti-35Ta-xNb alloys showed the α″ and β phases, and the XRD peak for the β phase increased with Nb content. For the non-NaOH treated surface, the morphology of HA deposited on Ti-35Ta-xNb alloys showed a plate-like shape, whereas the HA particle shape on the micropore-structured Ti-35Ta-xNb alloys was flower-like. The pore size and thickness of the surface barrier layer increased as the voltage increased. The fraction of rutile also increased as the applied potential increased. The anatase and rutile phases of TiO2 can be controlled by applied voltage for enhanced biocompatibility.