Calcium silicate cements endowing bioactivity and sustaining mechanical strength of low-heat-releasing and fast-curing magnesium phosphate cements.

It is known that magnesium phosphate cements (MPCs) show appreciable mechanical strength and biocompatibility, but the hydration reaction processes often lead to intense heat release while the hydration products present weak resistance to mechanical decay and low bioactivity. Herein we developed an MPC-based system, which was low-heat-releasing and fast-curing in this study, by compounding with self-curing calcium silicate cements (CSCs). The MPC composed of magnesium oxide (MgO), potassium dihydrogen phosphate (KH₂PO₄), disodium hydrogen phosphate (Na₂HPO₄), magnesium hydrogen phosphate trihydrate (MgHPO₄·3H₂O) and chitosan were weakly basic, which would be more stable in vivo. The physicochemical properties indicated that the addition of CSCs could increase the final setting time while decrease the heat release. Meanwhile, the CSCs could endow MPC substrate with apatite re-mineralization reactivity, especially, which add 25 wt.% CSCs showed the most significant apatite deposition. What's more, the mechanical evolution in buffer demonstrated CSCs could enhance and sustain the mechanical strength during degradation, and the internal constructs of cement implants could still be reconstructed by μCT analysis in rabbit femoral bone defect model in vivo. Particularly, appropriate CSCs adjusted the biodegradation and promoted new bone tissue regeneration in vivo. Totally, the MPC/CSCs composite system endows bioactivity and sustains mechanical strength of the MPC, which may be promising for expending the clinical applications of MPC-based bone cements.