Chitosan Bioceramic Composites for Bone Regeneration: Insights from <i>In Vitro</i> and <i>In Vivo</i> Studies

Bone-related pathologies due to injuries, trauma, and disease are a burden on the current health system that will only continue to grow as the population's life expectancy increases. The field of biomaterials aims to address these concerns by exploring, investigating, and optimizing bioregenerative grafts. In the context of bone regeneration, many biomaterials aim to achieve autograft-level regenerative properties, such as osteoconduction, osteoinduction, and low immunogenicity but also aim to address the disadvantages, such as the need for a secondary operation, donor site burden, and limited donor availability. Chitosan (CS) is a natural polymer well-studied in the field of biomaterials; it is known for its ease of fabrication, biocompatibility, antibacterial nature, and being a nonproteinaceous polysaccharide, which offers the advantage of low immunogenicity. However, CS lacks any osteogenic potential and is often combined with a bioceramic, creating a biocomposite scaffold. Bioceramics are ceramics specifically designed to aid bone regeneration due to their potential osteogenic properties. Although CS-bioceramic composites have been extensively studied, most research emphasizes their physicochemical properties, with limited attention to biological performance and <i>in vivo</i> outcomes. This review presents current findings on the regenerative potential of various CS-bioceramic composites, with a particular focus on <i>in vitro</i> and <i>in vivo</i> studies.