Q. Relate the oxide layer and biocompatibility of titanium?

The compatibility of a metal with its host environment depends on its resistance to biodegradation and on the degree of cytotoxicity of its products of corrosion. Surface properties of a biomaterial are an extremely critical aspect of biocompatibility. Passive reactions on metals possessing a high reactive surface energy that interacts with oxygen, forms passivated surface oxides. Titanium on exposure to air forms several oxides, such as TiO, TiO2, Ti2O3, with three different crystal structures (anastase, rutile, and brookite). Mainly it forms a surface coating of titanium oxide (TiO2) which is about 10 to 100 Å, thus providing a stable ceramic interface on which mineralizing bone matrix is deposited. This oxide surface provides an initial 5200 Armstrong reactive surface that becomes coated by plasma proteins (especially fibro nectin and vitronectin) at the time of implant placement.It is from the biological inertness of this oxide surface that implant derive the important property of biocompatibility.