Effect of water treatment on the apatite-forming ability of NaOH-treated titanium metal.

NaOH and heat treatments of titanium metal induce an apatite-forming ability on the metal by producing a bioactive graded sodium titanate structure on its surface. An enhancement of the apatite-forming ability of titanium metal induced by the NaOH treatment was attempted by conjoining the water and heat treatments. These treatments are assumed to convert the sodium titanate into anatase, which is presumed to be more effective for apatite nucleation. The sodium titanate gel on the metal formed from the NaOH treatment was shown to transform into anatase by a simple immersion in pure water, with subsequent heat treatments. Forming anatase on the metal significantly improved the apatite-forming ability of the metal in a simulated body fluid (SBF). The apatite-forming ability correlated directly with the amount of anatase on the metal. It is therefore expected that bioactive titanium metal and its alloys with a higher bone-bonding ability can be obtained with the use of the water and subsequent heat treatments after the NaOH treatment. Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 522-530, 2002