An injectable porous bioactive magnesium phosphate bone cement foamed with calcium carbonate and citric acid for periodontal bone regeneration

Magnesium phosphate cement (MPC) has been evaluated as a novel bone substitute owing to its favorable biocompatibility, plasticity, and osteogenic potential. However, the low porosity of MPC prevents growth factors and osteoblasts from fully growing into the material, thereby limiting its clinical use. In this study, different concentrations (0-5%) of calcium carbonate and citric acid (CA) were used as foaming agents to prepare porous MPC. The MPC containing 3% CaCO3/CA exhibited the best physicochemical properties, including greater porosity, improved injectability, extended setting time, and decreased hydration temperature. The proliferation and adhesion of cells on 3%CaCO3/CA-MPC were higher than those on MPC alone. To explore its osteogenesis in vivo, 3% CaCO3/CA-MPC and Bio-Oss (R) bone powder were implanted into periodontal bone defects in rats for 4 weeks and 12 weeks, respectively. Micro-CT and histological analysis demonstrated the improved bone regen-eration of 3%CaCO3/CA-MPC compared to the blank group (P < 0.05); it had slightly lower bone regeneration than the Bio-Oss (R) group but no statistical difference. The results indicated that porous MPC foamed with calcium carbonate and CA improved its physicochemical properties and enhanced its biocompatibility, making it a promising material for bone regeneration.