A novel high-viscosity, two-solution acrylic bone cement: Effect of chemical composition on properties

Solutions of poly(methyl methacrylate) (PMMA) powder predissolved in methyl methacrylate (MMA) have been developed as an alternative to current powder /liquid bone cements. They utilize the same addition polymerization chemist ry as commercial cements, but in mixing and delivering via a closed system, porosity is eliminated and the dependence of material properties on the su rgical technique is decreased. Twelve different sets of compositions were p repared, with two solutions of constant polymer-to-monomer ratio (80 g of P MMA/100 mL of MMA) and all combinations of four benzoyl peroxide (BPO) init iator levels added to the first solution and three N,N-dimethyl-p-toluidine (DMPT) activator levels added to the second. These compositions were teste d, along with Simplex-P bone cement, for effects of BPO and DMPT concentrat ions on polymerization exotherm, setting time, flexural strength, modulus, and maximum strain. The results show that each of these dependent variables was affected significantly by the individual concentrations of BPO and DMP T and their interactions. The flexural strength, modulus, and polymerizatio n exotherm reached their maximums at about a 1:1 molar ratio of BPO to DMPT . Most compositions had exotherms, setting times, and maximum strains withi n the range of commercial cements and flexural strengths and moduli up to 5 4 and 43% higher than Simplex-P, respectively. (C) 1999 John Wiley & Sons, Inc.