Characterization of bone cements prepared with functionalized methacrylates and hydroxyapatite

Abstract

Bone cements prepared with methyl methacrylate and either methacrylic acid or diethyl amino ethyl methacrylate as comonomers were characterized by infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, 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, compression 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 contrast, molecular weight, curing times, and glass transition temperature were composition dependent. For samples with acidic comonomer, a faster curing time, 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 microscopy showed that hydroxyapatite remained as clusters in the bone cement. The mechanical properties of filled bone cements depended mainly on composition 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 prepared without comonomer and those containing methacrylic acid. The minimum bending strength requirement (50 MPa) was not satisfied by any of the formulations studied.

Dielectric properties of nanotube reinforced butyl elastomer composites

“…However, when the amount of filler is increased to 30% by weight, the tensile modulus increases from 2.2 to 2.8 GPA ( p < 0.05) and ultimate strain ( p < 0.05) is reduced. Islas‐Blancas et al found a decrease in tensile modulus when HA powder was used as a filler, and explained this decrease as a result of poor mixing and poor adhesion between matrix and filler 19. Canul‐Chuil et al also reported that the presence of HA powder in an acrylic bone cement decreased the tensile modulus 18.…”

Towards optimization of the silanization process of hydroxyapatite for its use in bone cement formulations

“…4(b)). Generally, the presence of hydroxyapatite clusters within the polymeric matrix suggests not only poor mixing but also poor adhesion between matrix and fillers [38]. Considering that the hydroxyapatite particles have been treated with a silane coupling agent and, therefore, the adhesion between HA and PMMA was improved as demonstrated by the results in compressive tests, then it is possible to postulate that the surface treatment is mainly improving the interfacial adhesion to the dispersion of particles.…”

Hydroxyapatite-reinforced polymer biocomposites for synthetic bone substitutes

“…For example, the polymer matrix may be nonresorbable and non-injectable (e.g., thermoplastics such as PAEK, [40][41][42][43] UHMWPE, 44 and HDPE 1-6 ), nonresorbable and injectable (e.g., acrylics such as PMMA [45][46][47][48][49][50][51][52] and bis-GMA/TEG-DMA 52-57 ), bioresorbable and non-injectable (e.g., collagen [58][59][60][61] or poly--hydroxy esters such as PLLA and PLGA 62-68 ), or bioresorbable and injectable (e.g., collagen, calcium phosphate cements [68][69][70][71] and various hydrogels [72][73][74][75]. (Collagen may function as either noninjectable or injectable depending on whether it has been cross-linked prior to implantation.…”