Calcium Carbonate-Calcium Phosphate Mixed Cement Compositions For Bone Reconstruction

摘要

The feasibility of making calcium carbonate-calcium phosphate (CaCO_2-CaP) mixed cements, comprising at least 40 percent (w/w) CaCO_3 in the dry powder ingredients, has been demonstrated. Several original cement compositions were obtained by mixing metastable crystalline CaCO_3 phases with metastable amorphous or crystalline CaP powders in aqueous medium. The cements set within at most 1 h at 37 deg C in atmosphere saturated with water. The hardened cement is microporous and exhibits weak compressive strength. The setting reaction appeared to be essentially related to the formation of a highly carbonated nanocrystalline apatite phase by reaction of the metastable CaP phase with part or almost all of the metastable CaCO_3 phase. The recrystallization of metastable CaP varieties led to a final cement consisting of a highly carbonated poorly crystalline apatite analogous to bone mineral associated with various amounts of vaterite and/or arago-nite. The presence of controlled amounts of CaCO_3 with a higher solubility than that of the apatite formed in the well-developed CaP cements might be of interest to increase resorption rates in biomedical cement and favors its replacement by bone tissue. Cytotoxicity testing revealed excellent cytocompatibility of CaCO_3-CaP mixed cement compositions.