ABSTRACT

Ceramics are refractory, polycrystalline compounds, usually inorganic, including silicates, metallic oxides, carbides and various refractory hydrides, suldes, and selenides. Ceramics are generally hard; in fact, the measurement of hardness is calibrated against ceramic materials. Ceramics used in fabricating implants can be classified as nonabsorbable, bioactive or surface reactive. American Society for Testing and Materials species that alumina for implant use should contain 99.5% pure alumina and less than 0.1% combined SiO2 and alkali oxides. Alumina is usually a quite hard material with hardness varies from 20 to 30 GPa is high hardness permits its use as an abrasive and as bearings for watch movements. The key for success of any implant, besides the correct surgical implantation, is the highest possible quality control during fabrication of the material and the production of the implant.