Enhanced bone repair by silver-doped magnesium calcium phosphate bone cements

The aim was to create magnesium calcium phosphate bone cements (MCPCs) based on struvite and newberyite phases and having antibacterial properties due to the presence of Ag+ ions. An increase of Ag+ concentration from 0.5% to 1.0% substantially enhanced mechanical properties of the cements [compressive strength reached 41 +/- 2 MPa (mean +/- SD)] and increased the inhibition zone up to 8 mm in a disk diffusion test against Escherichia coli and Staphylococcus aureus without toxicity to MG-63 cells in vitro. Analyses of the MCPC samples soaked in Kokubo's simulated body fluid showed the formation of coatings on the cements' surface, corresponding to a merrillite phase and, after 28 days of the soaking, to a bobierrite phase. Histological examination and micro-CT analysis revealed that the newly developed MCPCs are osteoconductive and biodegradable and may be used as a bone substitute.