ABSTRACT
The term “bioactive” has been used with different definitions in different scientific fields. In the biochemistry field, for example, the bioactive component of an enzyme refers to its biochemically reactive part. In the field of biomaterials, bioactive often refers to a material, which upon being placed within the human body interacts with the surrounding tissue [1,2]. According to the aforementioned definition, bioactive is restricted to surface bioactive materials, as opposed to bulk bioresorbable materials. Surface bioactive ceramics are virtually nonresorbable in the body but exhibit an ability to bond with the bone. Surface-erodible and surface-bioactive are often used interchangeably. There are three types of surface bioactive ceramics:
1. Hydroxyapatite and related calcium phosphates 2. Bioactive glasses 3. Glass-ceramics
Most surface bioactive ceramics can, however, be tuned to become bulk biodegradable via the alteration of crystallinity and/or composition. In general, crystalline ceramics are more stable in aqueous environments than their amorphous counterparts of the same compositions, and many glass bioceramics (e.g., amorphous calcium phosphates) are biodegradable.
