Dental Casting Properties of Ti-15Zr-4Nb-4Ta Alloy

Abstract

The dental casting properties of the Ti–15Zr–4Nb–4Ta alloy were compared with those of commercial pure Ti grade 2 and Ti–6Al–V alloy. Ti–15Zr–4Nb–4Ta dental castings were also surface-coated by TiN ion plating. Metal plates for complete and partial dentures, crowns and bridges were experimentally fabricated using the Ti–15Zr–4Nb–4Ta alloy. The cast surface down to a depth of about 200 µm had a highhardness layer due to the reaction with the dental investment. Also, there was no sharp increase in the current density caused by the breakdown of the passive film starting from the layer that reacted with the dental investment. The 0.2% proof strength, ultimate tensile strength, total elongation and Young’s modulus of the Ti–15Zr–4Nb–4Ta castings, which were chemically polished by acid treatment after sandblasting, were 761 ± 33 MPa, 970± 31 MPa, 6 ± 4% and 90± 2 GPa, respectively. The micro-Vickers hardness of the TiN coated-surface was 740. The effect of TiN surface coating on the mechanical properties of the Ti–15Zr–4Nb–4Ta castings was negligible. The Ti–15Zr–4Nb–4Ta alloy exhibited a lower release of metal ions into the artificial saliva and 1% lactic acid solution than the Ti–6Al–4V alloy, and the quantity of metal ions released was less than 20% of that of titanium ions released from the Ti–6Al–4V alloy. The quantities of the titanium, zirconium and niobium ions released from TiN-coated Ti–15Zr–4Nb–4Ta casting into the artificial saliva were smaller than those released from the Ti–15Zr–4Nb–4Ta casting that was only chemically polished. Metal plates for complete and partial dentures, crowns and bridges were successfully fabricated using the Ti–15Zr–4Nb–4Ta alloy. A TiN-coated partial denture was also successfully fabricated using this alloy. The Ti–15Zr–4Nb–4Ta alloy with its excellent corrosion resistance and mechanical properties is expected to be used for dental prostheses in the future.