Evaluation of Calcium Phosphate-Collagen Bone Cement: A Preliminary Study

In recent years, calcium phosphate ceramics have been explored also as injectable materials for bone repair, due to their advantageous properties including moldability, biocompatibility, bioactivity and osteoconduction. Therefore, new formulations have been developed for calcium phosphate cements (CPCs) as injectable ceramics enable minimally invasive application. In the present study, a calcium phosphate cement with and without collagen in its composition was prepared and their characteristics evaluated. A solution of phosphoric acid (3.0 M) as liquid phase was mixed with the β-tricalcium phosphate, at a powder/liquid of 1:1 (wt%) ratio. An amount of 20 wt% collagen was added to the CPC and pH, temperature and setting times were monitored. Cements were characterized by XRD, FTIR, apparent porosity and SEM, in addition to mechanical behavior by elastic modulus analyses. The 20 wt% collagen amount showed suitable setting time. Monetite was the major phase in cement, as result of the methodology used. The presence of collagen covered the calcium phosphate particles, influencing in the setting time, dissolution reaction and formation of other phases in the cement, in addition to preserving a residual amount of the precursor ceramic phase. The collagen also decreased the apparent porosity, due to the coverage of the dicalcium phosphate crystals, allowing the filled of the microporosity. The elastic modulus values obtained were similar to those reported in the literature. The addition of collagen altered its mechanical performance to elastic modulus values between the cortical and trabecular bone range.