Partially resorbable acrylic bone cements based on self-curing acrylic/phosphate glass formulations.

Partially resorbable self-curing cements based on poly(methyl methacrylate)/phosphate glasses were prepared by mixing methyl methacrylate monomer with poly(methyl methacrylate) powder in different proportions (20-60 wt-%) of phosphate glass (BV11) in the system 44.5-P2 O5 , 44.5-CaO, 11-Na2 O (mol-%). The curing of these formulations showed a reduction of 10 degrees C in the maximum temperature and an increase of 10 minutes in the setting time although the content of residual monomer in the cured materials was unaltered. The presence of the inorganic particles did not significantly change the glass transition temperature of the cement. Static mechanical properties were evaluated in compression. The compressive yield strength of PM-MA/BV11 cements were in the range 110-118 MPa, superior to those of the control for dry specimens. When the test was conducted with wet specimens, a decrease in strength was observed due to the dissolution of the glasses in the medium, but the composites prepared with 20 or 40 wt-% BV11 had the compressive yield strengths required by the international standard for acrylic bone cements (ISO 5833). The dynamic mechanical properties of the formulation containing 60 wt-% BV11 and the corresponding control were evaluated through a fatigue crack propagation test. The results showed that both formulations followed a Paris-Erdogan model in the stable crack propagation, with no significant differences in the value of the exponent m of the mentioned law. Finally, the presence of the phosphate glasses in the acrylic composite did not change the wear damage of the pair UHMWPE/Ti6Al4V produced by the PMMA formulations. (Journal of Applied Biomaterials & Biomechanics 2003; 1: 48-57).