Process of apatite formation induced by anatase on titanium metal in simulated body fluid

Mechanism of apatite formation on the NaOH-, hot-water- and heat-treated titanium metal in simulated body fluid (SBF) was investigated using TEM-EDX. The NaOH, hot-water, and heat treatments gave an anatase layer on the metal. This anatase was found to combine first with the calcium ions in SBF to form an amorphous calcium titanate within 0.5 h, and then, after a period as long as 30 h, to combine with the phosphate ions in SBF to form an amorphous calcium phosphate with a low Ca/P ratio of 1.43. The calcium phosphate gradually increased Ca/P ratio up to 1.63, to eventually transform into crystalline apatite incorporating minor ions such as magnesium, similar to the bone mineral.