Overview

When a metallic material is implanted into a human body, immediate reaction occurs between its surface and the living tissues. In other words, immediate reaction at this initial stage straightaway determines and defines a metallic material s tissue compatibility. Since conventional metallic biomaterials are usually covered with metal oxides, surface oxide films on metallic materials play an important role not only against corrosion but also in tissue compatibility. Surface properties of a metallic material may be controlled with surface modification techniques. To develop and apply the appropriate surface modification technique, knowledge of the material s surface composition is absolutely necessary. This is because surface modification is a process that improves surface property by changing the composition and structure, while leaving the mechanical properties of the material intact. Since surface properties are critically important in biomaterials, issues closely related to this aspect of metallic biomaterials are discussed here: Surface compositions of metallic biomaterials; How surface compositions change due to interaction with human tissues; and How to control surface compositions and morphologies using surface modification techniques.

4.1 Surface of Metals

The definition of surface varies in situations. In this section, only the general concept will be explained.

Atoms in metallic materials located at the surface are considered partly reactive to the environment because atomic configuration terminates at the surface. The surface represents a property different from that inside the material. Due to high surface...