| For nearly two decades, alumina ceramics have been
recognized to be useful materials for fabricating substitutes
for parts of human bone. Alumina ceramic was first
applied as a clinical material in 1960s. Subsequently, it was
extensively investigated and at present, it is one of the widely
used biomaterials for bone replacement. Because of their
relatively high strength and good wear resistance, they are good
materials to be used in load bearing devices, particularly as
the ball and socket components of hip prosthesis. They are
also used to develop prosthesis for non-load bearing situations.
Examples are maxillofacial restorations, ossicular
chain replacements, keratoprosthesis and dental implants.
Depending on the nature of the response ceramics elicit
in the body, they are classified into three types, namely
biodegradable, bioinert and bioactive. Each type has its
advantages and disadvantages. In recent years, improvements
have been made in alumina materials by various
structural modifications and by forming composites with
other materials. Depending on the site of application and
mechanical requirements, specific properties of these materials
can be exploited. |
