Evaluation of modified dental composites as an alternative to Poly(methyl methacrylate) bone cement

Conventional PMMA bone cement, and more lately BisGMA (bisphenol A-glycidyl methacrylate) composite bone cement, is employed in various bone augmentation procedures such as vertebroplasty. Problems with these materials include high curing exotherm and shrinkage, leakage of toxic components after insertion and exhibition of a modulus mismatch between bone cement and weak bone. A novel high molecular weight dimethacrylate, polypropylene glycol dimethacrylate (PPG), was used in combination with urethane dimethacrylate, hydroxyethyl methacrylate, silica glass particles and fibres to create PPG fibre composite (PFC) dual paste materials. This study was designed to ascertain whether PFCs are a viable alternative to Cortoss™ composite bone void filler and Simplex P™ PMMA bone cement for osteoporotic vertebroplasty and fracture fixation applications. The degree of monomer conversion and curing kinetics of the PFCs and commercial bone cements were found using FTIR, while the mechanical properties were found through biaxial flexural testing. An equation was derived to describe the curing profiles of the PFCs and commercial bone cements. The curing profiles and equations and mechanical properties of the PFCs, Cortoss™ and Simplex P™ bone cements were compared. It was found that PFC materials had more complete monomer conversion, and faster cure than Cortoss™ and Simplex P. The flexural strength of some of the PFC materials was comparable to Cortoss™ and Simplex P. Incorporating fibres into the PFC materials prevented brittle fracture exhibited by Cortoss™ and mimicking the fracture behaviour of Simplex P.