ABSTRACT
This chapter describes the structure and composition of synthetic hydroxyapatite. It discusses the deviations from the ideal structure as a result of ionic substitutions. Studies of the thermal behavior of precipitated tricalcium phosphates using X-ray diffraction, Infrared spectroscopy, thermogravimetric analyses, and differential thermal analysis show that phosphates preserve their normal apatitic structure until 650°C without forming a supplementary phase. Isostatic compaction is the forming technique which is often used to produce dense calcium phosphate ceramics. This results in a greater density and higher compressive strength of unsintered compacts than after uniaxial compression. Calcium phosphate ceramics have low tensile properties. Calcium phosphate ceramics obviously show attractive properties, such as lack of toxicity, absence of intervening fibrous tissue, the possibility of forming a direct bond with bone, and the possibility to stimulate bone growth. Animal experimentation and limited clinical applications confirm the usefulness of calcium phosphate ceramics.
