Development of a glass reinforced hydroxyapatite with enhanced mechanical properties. The effect of glass composition on mechanical properties and its relationship to phase changes.

Utilizing glasses of the types xNa2O-(1-x)P2O5 and xCaO-(1-x)P2O5 (where x = 0.2, 0.3, and 0.5), a systematic study of the effect of increasing network modifying oxides in glasses was made on the mechanical properties of a glass reinforced hydroxyapatite, at glass additions of 2.5 and 5 wt%. For the soda type glass, phase changes were promoted much more readily compared to the lime type glass. This was true for both 2.5 and 5 wt% additions of glass. For the lime type glass, considerable differences between the effects of 2.5 and 5 wt% additions were seen. At 5 wt%, the increased amount of liquid phase present promotes an increased level of phase inversion to alpha and beta tricalcium phosphate. At 2.5 wt%, a larger percentage of the HA remains stable at higher temperatures. Furthermore, the effect of the composition may be seen. As the mol% of network forming oxide increases, (i.e., the Ca/P ratio moves towards 1.67, (the ratio for HA) the HA remains more stable. This is seen in the maintenance of both the HA phase and also the enhanced mechanical properties.