The influence of hydroxyapatite: zinc oxide ratio on the setting behavior and mechanical properties of polyalkenoate cements

The influence of hydroxyapatite (HA) content on the setting behavior and mechanical properties of hydroxyapatite-zinc oxide-poly(acrylic acid) (HA-ZnO-PAA) composite cements were investigated as a function of HA content. The working time increased with HA content up to 45 wt % HA and then decreased whilst the setting time increased with increasing HA content. Mechanical properties were determined after storage in water at 37 degrees C for 1, 7 and 28 days. Young's moduli and compressive strength go through a maximum at approximately 30 and 45 wt % HA. Young's modulus increases with time, which is consistent with an ongoing crosslinking reaction.