Development of graded hydroxyapatite/CaCO(3) composite structures for bone ingrowth.

Ceramic composites composed of constituents with different bone cell reactions present an interesting consideration for a new bone replacement material. The first component of the composite used in this study, hydroxyapatite, is known to be replaced by natural tissue significantly slower than the second, calcium carbonate, which has limited structural stability. A graded hydroxyapatite/calcium carbonate composite with bimodal component distribution was developed using a combined slip infiltration and dip-coating technique from a porous polyurethane sponge replica. A graded hydroxyapatite scaffold with porosities from 5 to 90% was produced and then infiltrated with a calcium carbonate slip and sintered. The resultant composite had improved mechanical properties compared with the monolith as measured by crushing and moduli tests.