IN-VIVO BEHAVIOR OF 3 CALCIUM-PHOSPHATE CEMENTS AND A MAGNESIUM PHOSPHATE CEMENT

Three types of calcium phosphate cements and one magnesium phosphate c ement were implanted subcutaneously in rats under exclusion of direct cellular contact. Retrieval times were either 1, 2, 4 or 8 weeks. Befo re and after retrieval the compressive strength, the diametral tensile strength, the quantitative chemical composition, the qualitative phas e composition, the FTIR spectrum and the microstructure were determine d. The three calcium phosphate cements maintained their strength durin g implantation. The phase DCPD was completely transformed into a Na- a nd CO3-containing apatite, the phases DCP and CDHA only partially. It could not be ruled out that OCP is also transformed into a bone-minera l-like apatite to a certain extent. That this latter process occurs mu ch faster during the turn-over of living bone, is probably due to the very small crystal size of the OCP particles in bone.