Abstract
Metallic materials with high fracture toughness are clinically utilized for bone repair under load-bearing conditions. Their problem is that they do not possess ability of bone-bonding, i.e. bioactivity. The prerequisite for artificial materials to show bioactivity is formation of bone-like apatite layer on their surfaces in body environment. We previously found that apatite was deposited on titanium and tantalum metals in a simulated body fluid (Kokubo solution), when they were subjected to chemical modification using alkali solution and subsequent firing. This means that bioactivity can be induced on these metals by the modification. In this study, we precisely observed interface between the apatite layer and the bioactive metals. Both the titanium and tantalum metals after the apatite deposition showed graded structure, where the apatite gradually changed from the surface to the interior metal. This type of specific structure would lead to tight bonding of the apatite layer to the metals.
