Bio-active glass coatings manufactured by thermal spray: a status report

Superficial modification of implants via the incorporation of biocompatible coatings is an attractive option in biomedicine because of the positive attributes associated with bioactive materials. Bioactive glasses are an important subset of biomaterials that are known to stimulate bone regeneration; they are interesting materials that can be employed as bioactive coatings due to their unique response in physiological environments. Numerous clinical case histories and scientific studies have focused on successful examples of bioactive glasses being used in-vitro and in-vivo. However, unlike other biomaterials such as hydroxyapatite, bioactive glasses have not yet reached full potential as thermally sprayed coatings. The lack of fundamental research focused on establishing correlations between the available bioactive glass chemical compositions, the processing parameters selected for specific thermal spray processes, and the obtained coating performance has limited the use of bioactive glass compositions as reliable coatings. This paper reviews the current state of the art of thermally sprayed bioactive glass coatings; it looks at different studies dealing with thermally sprayed bioactive glass coatings in order to identify their strengths and weaknesses and provides key scientific points that could be explored in future investigations. This manuscript includes a brief introduction to bioactive glasses, an overview of thermal spraying techniques and current products, and a discussion of recent developments in this field.