Improvement of mechanical strength of calcium sulfate bone cement using carboxymethyl cellulose and silicon dioxide

Calcium sulfate (CS) is a commonly used filling material for bone defects; however, its mechanical strength requires further enhancement. The hydration process of CS significantly influences its mechanical properties. This study aims to improve these properties by incorporating carboxymethyl cellulose (CMC) and silicon dioxide (SiO 2 ) to optimize the hydration process of calcium sulfate hemihydrate (CSH). After adding CMC, the content of CSH in the hydrated material significantly increased, while the amount of calcium sulfate dihydrate (CSD) decreased. In the XPS analysis, the Ca 2p peaks exhibited notable shifts following the addition of CMC and SiO 2 . The mechanisms by which the hydration process influences mechanical strength were further analyzed. It was found that Ca 2+ ions from CSH chelated with CMC, while SiO 2 formed Si-O-Ca bonds with Ca 2+ , both affecting the hydration process of CSH in different ways. The optimal addition amounts of CMC and SiO 2 were both determined to be 1.5 %. Compared to pure CS, the mechanical properties of the experimental group increased by 520 %, rising from 4.28 MPa to 22.25 MPa. Additionally, the injectivity and erosion resistance were improved. All materials showed no cytotoxicity in hemolysis and cell experiments. In summary, this study demonstrates how the mechanical strength of CS can be enhanced by incorporating CMC and SiO 2 to influence its hydration process.