In Vitro and In Vivo Biological Properties of Calcium Silicophosphate-Based Bone Grafts: Silicocarnotite and Nagelschmidtite

Accidents, trauma, bone defects, and oncological processes significantly impact patients' health and quality of life. While calcium phosphates and bioactive glasses are commonly used as bone fillers to facilitate bone regeneration in orthopedics and traumatology, they exhibit certain disadvantages compared to calcium silicophosphate phases. This study evaluates the in vitro cytocompatibility and in vivo osteogenic properties of two-third-generation ceramic phases: silicocarnotite (SC) and nagelschmidtite (Nagel). These phases were synthesized via a solid–state reaction and characterized using X-ray diffraction and scanning electron microscopy. In vitro behavior was assessed through bioactivity tests, cell viability, proliferation, and inflammatory profiles by detecting cytokines and reactive oxygen species. Osteogenic properties were evaluated by detecting bone-associated proteins in MG-G3, hFOB1.19, and MC3T3-E1 cell lines after 3, 7, and 14 days. 45S5 Bioactive glass (BG), hydroxyapatite (HAp), and osteogenic medium were employed as control standards for bone formation. SC and Nagel phases exhibited higher viability percentages as well as osteoconductive and osteoinductive behavior. Finally, SC and Nagel bone grafts were implanted in a Wistar rat model to assess their in vivo ability to induce bone formation, demonstrating complete osseointegration after 12 weeks. Histological evaluation revealed osteocytes forming osteons and the presence of blood vessels, particularly in rats implanted with Nagel. Given their favorable biological performance, SC and Nagel emerge as promising candidates for bone grafts in orthopedics, traumatology, and maxillofacial surgery.