Effect of initiation chemistry on the fracture toughness, fatigue strength, and residual monomer content of a novel high‐viscosity, two‐solution acrylic bone cement

Abstract

Porous-free, two-solution bone cements have been developed in our laboratory as an alternative to commercial powder/liquid formulations. Each pair of solutions consist of poly(methyl methacrylate) (PMMA) powder dissolved in methyl methacrylate (MMA) monomer, with benzoyl peroxide (BPO) added to one solution as the initiator and N,N-dimethyl-p-toluidine (DMPT) added to the other as the activator. When mixed, the solutions polymerize via a free radical reaction, which is governed by the concentrations of initiator and activator and their molar stoichiometry. Previous work by the authors has demonstrated that these two-solution cement compositions are comparable to Simplex P bone cement in polymerization exotherm, setting time, and flexural mechanical properties. This study was designed to evaluate the effect of BPO and DMPT concentrations, along with their molar ratio, on the fracture toughness, fatigue strength, and residual monomer content of the experimental compositions. The results showed that fracture toughness and fatigue strength for the solution cements were comparable to Simplex P and were not significantly affected by the BPO concentration or the BPO:DMPT molar ratio; however, the highest DMPT concentration yielded significantly lower values for both variables. Residual monomer content was significantly affected by both the individual concentrations of BPO and DMPT and their molar ratios. The two-solution cements had significantly higher residual monomer contents versus Simplex P; however, this can be attributed to their higher initial monomer concentration rather than a lower degree of conversion.

Fatigue testing and performance of acrylic bone‐cement materials: State‐of‐the‐art review

“…An example of this flaw in study design is seen in studies that compare Simplex P [in which the powder beads are a mixture of PMMA and P(MMA, S) and the radiopacifier is BaSO 4 ], on the one hand, and either Palacos R or Osteopal (in which the polymerized polymer powder beads and radiopacifier are PMMA and ZrO 2 , respectively), on the other. 31,32,62,74,84 In other words, in these studies, the cements compared have differences in more than one basic constituent; thus, no clear conclusion may be drawn regarding the role of basic composition. In a few literature studies 60,65,75 the cements that were compared have the same basic constituents; this ensured that any differences in fatigue performance of these cements is not likely to be due to differences in their basic compositions.…”

“…Based on the results of this one study, 84 it appears that a cement's fatigue life is, by and large, insensitive to its initiator/activator ratio.…”

“…Only Hasenwinkel et al 84 have reported on the issue of the influence of the relative amounts of initiator and accelerator in the cement on its fatigue life. These workers determined the flexural fatigue lives of 12 compositional variants of an experimental two-composition high-viscosity (2CHV) cement, each being distinguished by its BPO:DMPT molar ratio (M r ).…”

Optimisation of a two-liquid component pre-filled acrylic bone cement system: a design of experiments approach to optimise cement final properties

“…The presence of initiation chemistry within the cement will have an effect on the final properties; the significance of the effect will depend on the BPO: DmpT ratio [6] [27]. The results from this study have shown that the presence of initiation chemistry had a significant effect on the mechanical properties.…”

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

“…Small amounts of unpolymerized monomers, residual monomers, leach out from the polymerized cement. There are many reports on the determination of the residual monomer in a PMMA matrix [7][8][9][10][11][12][13][14].…”