Formation of a bioactive calcium titanate layer on gum metal by chemical treatment.

The so-called gum metal with the composition Ti-36Nb-2Ta-3Zr-0.3O is free from cytotoxic elements and exhibits a low elastic modulus as well as high mechanical strength. In the present study, it was shown that this alloy exhibited a high capacity for apatite formation in a simulated body fluid when subjected to 1 M NaOH treatment, 100 mM CaCl(2) treatment, heat treatment at 700°C, and then hot water treatment. The high apatite formation was attributed to the CaTi(2)O(5) which was precipitated on its surface, and found to be maintained even in a humid environment over a long period. The treated surface exhibited high scratch resistance, which is likely to be useful in clinical applications. The surface treatment had little effect on the unique mechanical properties described above. These results show that gum metal subjected to the present surface treatments exhibits a high potential for bone-bonding, which will be useful in orthopedic and dental implants.