Characterization of bone cements prepared with functionalized methacrylates and hydroxyapatite

Bone cements prepared with methyl methacrylate and either methyacrylic acid or diethyl amino ethyl methacrylate as comonomers were characterized by in frared spectroscopy, nuclear magnetic resonance, gel permeation chromatogra phy, dynamic mechanical thermal analysis, and mechanical testing. Selected formulations containing these functionalized methacrylates were filled with hydroxyapatite and studied in terms of their properties in tension, compre ssion and bending, and X-ray diffraction. It was found that residual monomer was not greatly affected by the presence of either acid or basic comonomers in the unfilled bone cements. In contra st, molecular weight, curing times, and glass transition temperature were c omposition dependent. For samples with acidic comonomer, a faster curing ti me, higher molecular weight, and higher glass transition temperatures were observed with respect to those with the basic comonomer. X-ray diffraction revealed that the crystalline structure was not affected by the nature of comonomer in the bone cement while scanning electron micro scopy showed that hydroxyapatite remained as clusters in the bone cement. T he mechanical properties of filled bone cements depended mainly on composit ion and type of testing. Hydroxyapatite-filled bone cements fullfilled the minimum compressive strength (70 MPa) required for bone cement use. However , the minimum tensile strength (30 MPa) was only fullfilled by cements prep ared without comonomer and those containing methacrylic acid, The minimum b ending strength requirement (50 MPa) was not satisfied by any of the formul ations studied.