Role of acid attack in the in vitro bioactivity of a glass-ceramic of the 3CaO.P2O5-CaO.SiO2-CaO.MgO.2SiO2 system.

Abstract A non-bioactive glass-ceramic (GC13) that contains hydroxyapatite (Ca 5 (PO 4 ) 3 OH), diopside (CaMg(SiO 3 ) 2 ) and althausite (Mg 2 PO 4 OH) as crystalline phases has been obtained by thermal treatment of a parent bioactive glass (G13) of nominal composition (wt%) 40.0 CaO–34.5 SiO 2 –16.5 P 2 O 5 –8.5 MgO–0.5 CaF 2 . To induce bioactivity, GC13 was chemically treated with 1  m HCl for different periods of time. After chemical etching the in vitro studies showed formation of an apatite-like surface layer. In this article the influence of etching time both on the surface composition of the glass-ceramic and on the growth rate of the apatite layer is studied. It is concluded that the presence of hydroxyapatite in the glass-ceramic, associated to microstructural fluctuations, can favour apatite deposition in vitro.