Fracture evaluation of acrylic bone cements modi®ed with hydroxyapatite: in¯uence of the storage conditions

P. MONTEMARTINI; T. CUADRADO; P. FRONTINI

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE

SPRINGER

Lugar: Berlin; Año: 1999 p. 309 - 317

0957-4530

Fracture and mechanical characterization of bone composite composed of polymethylmethacrylateand hydroxyapatite (HA) at different contents was carried out. Hydroxyapatiteis added in order to improve cement biocompatibility, but it is expected that it also affectsmechanical properties. Specimens were either stored in air at 37 C for 120 h or inphysiological solution (PhS-37), in order to establish the in¯uence of storage conditionsupon mechanical behavior. One set of specimens was also postcured at 120 C for 4 h to takeinto account the in¯uence of free monomer. Fracture experiments revealed some nonlinearityin load±displacement records and differences in trends between initiation andpropagation values of the fracture surface energies. The trends in the data shows that HAacts as a rigid ®ller enhancing fracture resistance, ¯exural modules and yield stress, up to acertain content. Beyond the latter limit, properties suffer a deterioration because the additionof HA also affects the cement porosity. Absorbed water acts as plasticizer leading to adecrease in mechanical properties. The highest propagation strain energies were exhibitedby materials aged in PhS-37.