Effect of strontium-containing compounds on bone grafts

Biomaterials are biocompatible materials that are used to repair bone defects caused by trauma and bone infections, or bones injured in wars and accidents. Calcium phosphates (CaPs), which have a bioinert structure due to high corrosion resistance and being stable in the body, are the most used biomaterial and considered to be bioactive materials because they are perceived by the body as its tissue and have an accelerating healing effect. CaPs are used extensively for hard- and soft-tissue applications in medicine because of their elemental composition, high level of similarity to the minerals in bone and teeth, and high biocompatibility within the body. However, due to low fracture toughness values or poor mechanical properties of CaPs, different additives like strontium (Sr) and its compounds are added into them to improve their properties. Especially in recent years, it has become an important purpose and field of study to produce more economical alternative CaPs-based, as well as Sr- and its compounds-added biocompatible bone grafts and implant materials having enhanced microstructure and mechanical properties. Sr and its compounds that improve the mechanical properties of CaP compounds have been indicated as an impressive stimulant for bone repair and new bone formation. Sr2+ ion (Sr ranelate), which is used as a drug, especially in osteoporosis disorders, reveals biocompatibility and also increases bone fracture repair. This review explains the literature on the morphological and mechanical properties of CaP-based Sr compounds, which have been added into various CaP-based bone grafts or used as implant coating on bone grafts. Also, biocompatibility studies on bone grafts containing Sr are explained, and it is aimed to contribute to the studies done in this area.