Modification of Acrylic Bone Cements with Oxygen Plasma and Additives

Acrylic bone cements which are commonly used for the fixation of orthopedic prostheses, were prepared at different formulations, by using either ground poly(methyl methacrylate) (PMMA) particles or homogeneously synthesized PMMA microspheres with application of plasma and addition of various ingredients in order to improve mechanical and thermal properties. PMMA powders having three different particle size (ground and sieved particles with 0-50 mu m (BC1 group, average particle size: 21 mu m) and 50-150 mu m (BC2 group, average particle size: 77 mu m) and microspheres with 1 mu m (BC3 group) size) with addition of methyl methacrylate (MMA) monomer, radiopaque agent of barium sulphate (BaSO4), hydroxyapatite (HAp) and an initiator as well as other additives such as 1-dodecyl mercaptan (DDM), ammonium nitrate (AN) or zeolite particles. Among three bone cement groups, compositions prepared with PMMA particles having 50-150 mu m particle size had better handling properties and lower maximum curing temperatures. Oxygen plasma application and zeolite addition caused an increase in tensile and compressive strength and also curing temperature in all groups, while DDM and AN reduced maximum curing temperature.