Effect of MgO-P2O5 Sintering Additive on Microstructure of SinteredHydroxyapatite (HAp) Bodies and Their In-Vitro Study

Abstract

The effects of <TEX>$MgO-P_2O_5$</TEX> based sintering additive on the microstructure and material and biological properties of hydroxyapatite <TEX>$(HAp,\;Ca_{10}(PO_4)_6(OH)_2)$</TEX> ceramic were investigated using XRD, SEM and TEM techniques. The <TEX>$MgO-P_2O_5$</TEX> sintering additive improved the material properties and increased the grain size in the sintered HAp bodies. As the content of sintering additive increased over 4 wt%, a small amount of the HAp phase was decomposed and transformed to <TEX>${\beta}-TCP$</TEX>. In the 2 wt% <TEX>$MgO-P_2O_5$</TEX> content HAp sintered body, the maximum values of density and hardness were respectively about 3.10 gm/cc and 657 HV. However, the maximum fracture toughness in the HAp body containing 8 wt% <TEX>$MgO-P_{2}O_{5}$</TEX> was about <TEX>$1.02MPa{\cdot}m^{1/2}$</TEX> due to the crack deflection effect. Human osteoblast like MG-63 cells and osteoclast like raw 264.7 cells were well grown and fully covered all of the HAp sintered bodies. The osteoblast cells were grown with spindle-shaped and the osteoclast cells had a grape-like round shape.