Effect of ion substitution on properties of bioactive glasses: A review

Bioactive glasses and glass-ceramics have recently found key applications in biomedicine, mainly for bone repair and replacement. Recent developments in the field of tissue engineering have re-invigorated the quest to enhance the physical and biomedical effectiveness of bioactive glasses and glass-ceramics by incorporation of different elements into the composition of these materials. Although most elements are included in the bioactive glass for the therapeutic benefits (e.g., Ag and Sr), they influence the structure and bioactivity of the glass. This review systematically discusses the influence of the addition of silver (Ag), magnesium (Mg), strontium (Sr), zinc (Zn), aluminum (Al), potassium (P), fluoride (F) and zirconia (ZrO2) elements on the chemical, physical and therapeutic properties of bioactive glasses and glass-ceramics, which are expected to play an important role in the future of bone regenerative medicine. This article describes where these dopant ions fit into the glass structure and how these affect the delivery and properties of the glass as a whole.