Mechanical characterization of brushite and hydroxyapatite cements

Compression, tension and torsion tests were designed and completed successf ully on a brushite and a precipitated hydroxyapatite cement in moist condit ion. Elastic and strength properties were measured for these three loading cases. For each cement, the full set of strength data was fitted to an isot ropic Tsai-Wu criterion and the associated coefficients identified. Since t he compressive Young's moduli were about 10% larger than the tensile moduli , the full set of elastic data of each cement was fitted to a conewise line ar elastic model. Hysteresis of the stress-strain curves was also observed, indicating dissipation mechanisms within these cement microstructures. A c omparison of the measured mechanical properties with human cancellous bone confirmed the indication of brushite as a bone filling material and the pot ential of the hydroxyapatite cement as a structural biomaterial. (C) 2001 E lsevier Science Ltd. All rights reserved.