Silicon-calcium phosphate ceramics and silicon-calcium phosphate cements: Substrates to customize the release of antibiotics according to the idiosyncrasies of the patient.

Bone substitutes based on calcium phosphates can be classified in two major groups: ceramics and cements. Both are biomaterials with excellent biocompatibility that have been studied as local delivery systems for drugs. This study aims to evaluate drug-release kinetics in silicon beta-tricalcium phosphate ceramics (Si-ß-TCP) and in silicon calcium phosphate cements (Si-CPCs). We want to investigate if the differences in composition and in structure of the Si-ß-TCP and the Si-CPC may influence for drug loading and in its release kinetics from the biomaterial. The results obtained indicate that all drug-loaded materials were efficient to tailor drug release kinetics and inhibited the growth of Staphylococcus aureus. The cements prepared with high concentrations of silicon (80% Si-CPC) present zero-order release kinetics, independent of the drug concentration loaded. Si-ß-TCP and Si-CPC offer a simple technology that could serve to personalize the delivery of bioactive molecules according to each patient's needs in the treatment of bone conditions, not only limited to prophylaxis, but also for the treatment of bone infection.

A new iron calcium phosphate material to improve the osteoconductive properties of a biodegradable ceramic: a study in rabbit calvaria.

ß-tricalcium phosphate (ß-TCP) is an osteoconductive and biodegradable material used in bone regeneration procedures, while iron has been suggested as a tool to improve the biological performance of calcium phosphate-based materials. However, the mechanisms of interaction between these materials and human cells are not fully understood. In order to clarify this relationship, we have studied the iron role in ß-TCP ceramics. Iron-containing ß-TCPs were prepared by replacing CaCO3 with C6H5FeO7 at different molar ratios. X-ray diffraction analysis indicated the occurrence of ß-TCP as the sole phase in the pure ß-TCP and iron-containing ceramics. The incorporation of iron ions in the ß-TCP lattice decreased the specific surface area as the pore size was shifted toward meso- and/or macropores. Furthermore, the human osteoblastlike cell line MG-63 was cultured onto the ceramics to determine cell proliferation and viability, and it was observed that the iron-ß-TCP ceramics have better cytocompatibility than pure ß-TCP. Finally, in vivo assays were performed using rabbit calvaria as a bone model. The scaffolds were implanted for 8 and 12 weeks in the defects created in the skullcap with pure ß-TCP as the control. The in vivo behavior, in terms of new bone formed, degradation, and residual graft material were investigated using sequential histological evaluations and histomorphometric analysis. The in vivo implantation of the ceramics showed enhanced bone tissue formation and scaffold degradation for iron-ß-TCPs. Thus, iron appears to be a useful tool to enhance the osteoconductive properties of calcium phosphate ceramics.