Exothermal Characteristics and Release of Residual Monomers from Fiber-reinforced Oligomer-modified Acrylic Bone Cement

The aim of this study is to determine the peak temperature of polymerization, the setting time and the release of residual monomers of a modified acrylic bone cement. Palacos®R, a commercial bone cement, is used as the main component. The cement is modified by adding short glass fibers and resorbable oligomer fillers, and an additional cross-linking monomer. The test specimens are classified according to the composition of the bone cement matrix (i.e., oligomer-filler, glass-fiber reinforcement, and/or cross-linking monomer). The exothermal characteristics during autopolymerization are analyzed using a transducer connected with a computer. The quantities of residual monomers were analyzed from different test groups using high performance liquid chromatography (HPLC). The ΔT value for the oligomer filler and the glass-fiber-containing acrylic bone cement is lower than that for the unmodified bone cement (2.1±0.8 vs. 23.5±4.2°C). The addition of a cross-linking monomer, EGDMA, shortens the setting time of the autopolymerization of the unmodified bone cement (7.1±0.9min vs. 3.3 ±0.3min). The quantity of the residual monomers released is higher in the modified bone cement than that in the unmodified cement. The cement that contains glass fibers and oligomer fillers has a considerably lower exothermal peak, whereas the total quantity of residual monomers released is increased.