Enhancing Radiopacity and Antibacterial Activity of Osteogenic Calcium Silicate Cement by Incorporating Strontium

Calcium silicate-based cement is commonly used for bone repair and regeneration. Current research focuses on developing innovative antibacterial materials with radiopacity, which is essential for ensuring successful clinical outcomes in procedures like vertebroplasty and endodontic treatments. Strontium (Sr) has emerged as a powerful additive, stimulating bone formation and inhibiting bone resorption. In this study, we evaluated the impact of varying levels of Sr—5, 10, and 20 mol% (designated as CSSr5, CSSr10, and CSSr20) on critical attributes of bone cement, including radiopacity, setting time, in vitro bioactivity, antibacterial efficacy, and osteogenic activity. The findings indicated that as the Sr content increased, the setting time and radiopacity of the cement increased. Remarkably, the cement formulations containing over 10 mol% Sr achieved radiopacity values surpassing the 3 mm aluminum threshold mandated by ISO 6876:2001 standards. Furthermore, incorporating Sr significantly improved MG63 cell attachment, proliferation, differentiation, and mineralization, while also boosting antibacterial properties in a dose-dependent manner. After 48 h of inoculation with E. coli or S. aureus, the CSSr10 and CSSr20 cements showed a bacteriostatic ratio exceeding 1.7 or 2 times that of the control without Sr. In conclusion, the CSSr10 cement could be a promising bone filler, exhibiting favorable setting time, radiopacity, antibacterial ability, and osteogenic activity.