Manipulation of the degradation behavior of calcium phosphate and calcium sulfate bone cement system by the addition of micro-nano calcium phosphate

The mismatch between the degradation performance of bioactive bone cement (calcium phosphate-CPC and calcium sulfate-CSC) and the growth rate of new bone has always restricted its clinical application. In view of the weak mechanical strength and poor degradation performance of CPC and CSC, this study first prepared micro-nano calcium phosphate (MNC) with different Ca/P ratio and explored the influence of MNC on the hydration and mechanical properties of cement by adding MNC to the CPC and CSC. The results show that MNC can promote the hydration reaction of CPC and CSC and affect the growth of cement crystals. Among all groups, MNC with Ca/P ratio of 1.2 can greatly improve the mechanical properties and setting time of CPC, increase the compressive strength of CPC from 10.18 ± 1.51 to 19.23 ± 0.55 MPa, and shorten the setting time from 38.33 ± 2.89 to 18.33 ± 2.89 min. In addition, the addition of low content of MNC promoted the degradation of CPC, and also promoted the self-reinforcing effect of CPC during the degradation process, and further improved the mechanical properties of cement. MNC not only affects the morphology of CSC crystals but also produces calcium phosphate particles with smaller diameters to fill between the CSC crystals, which reduces porosity, improves mechanical properties, and delays the degradation of CSC. The as-prepared cements were supposed to match the new bone ingrowth in vivo and have the potential application in orthopedic surgery for filling non-load-bearing bone defects.