The Korean Journal of Ceramics

The Korean Ceramic Society (한국세라믹학회)
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Mechanism of Apatite Formation on Bioactive Titanium Metal

  • Kim, Hyun-Min (Department of Material Chemistry, Faculty of Engineering, Kyoto University) ;
  • Takadama, Hiroaki (Department of Material Chemistry, Faculty of Engineering, Kyoto University) ;
  • Miyaji, Fumiaki (Department of Material Chemistry, Faculty of Engineering, Kyoto University) ;
  • Kokubo, Tadashi (Department of Material Chemistry, Faculty of Engineering, Kyoto University) ;
  • Nishiguchi, Shigeru (Department of Orthopaedic Surgery, Faculty of Medicine, Kyoto University) ;
  • Nakamura, Takashi (Department of Orthopaedic Surgery, Faculty of Medicine, Kyoto University)
  • Published : 1998.12.01
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Abstract

Bioactive titanium metal can be prepared by simple 5M-NaOH treatment and subsuquent heat treatment at $600^{\circ}C$ to form an amorphous sodium titanate on its surface. In the present study, mechanism of apatite formation on the titanium metal was investigated by examining its surface compositional and structural changes in a simulated body fluid. The apatite formation on the metal was found to proceed in the sequence of 1)$Na^+$ ion release from the sodium titanate to form hydrated titania abundant in Ti-OH groups, 2) early and selective binding of calcium ions with the Ti-OH groups to form a calcium titanate, and 3) late binding of phosphate ions to make apatite nucleation and growth. This indicates that Ti-OH groups do not directly induce the apatite nucleation, but via formation of a calcium titanate.

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