Dissolution kinetics, selective leaching, and interfacial reactions of a bioglass coating enriched in alumina

Bioglass coatings are interesting for developing a direct bond between pros theses and bone. But the high solubility of these materials limits their ap plication. The addition of alumina can be used to control their solubility, but may inhibit the bonding mechanisms. In this paper, we study a bioglass in the SiO2-Na2O-CaO-P2O5-K2O-Al2O3-MgO system. After delays of implantati on from 2 to 12 months, the bioglass/bone interface is characterized by ene rgy-dispersive X-ray spectroscopy coupled with scanning transmission electr on microscopy. Bioglass dissolution can be decomposed into three steps with selective leaching. Results show that, at 2 months after implantation, the bioglass is composed of Al, Si, Ca, and P. Alumina addition increases the coating stability without inhibiting the bonding process. Complex physicoch emical reactions take place at the bioglass periphery. The coating bonds to bone through a Ca-P layer on top of a pure Si-rich layer. These phenomena are associated with bioactivity properties, which occur for up to 6 months. After 12 months, the bioglass is composed of silicon, (C) 2001 Academic Pr ess.