Glass reinforced hydroxyapatite for hard tissue surgery--part 1: Mechanical properties.

Commercial hydroxyapatite (HA) was reinforced by adding 2.5 and 5 wt% of a Na2O-CaO-P2O5 glass and then sintered. The resulting composites have chemical compositions that are similar to the inorganic constituent of the mineral part of bone, and are closely related to the trace elements that are present, in this case Na. X-ray diffraction showed no decomposition of HA to secondary phases; however, the glass reinforced-HA composites contained a HA phase and variable amounts of tricalcium phosphate phase, depending on the sintering temperature and the amount of glass added. The HA-composite material exhibited higher flexural strength overall compared to sintered HA. The presence of secondary phases beta- and alpha-tricalcium phosphate in the microstructure of the composites has a major influence on the mechanical properties. Additionally, the presence of porosity also has a bearing on the mechanical properties of the material.