EFFECT OF THE SUBSTITUTION OF LA2O3 FOR CAO ON THE BIOACTIVITY OF 2.5CAO-CENTER-DOT-2SIO(2) GLASS

Glasses of the following composition were prepared: (2.5-x)CaO . x/3La (2)O(3) . 2SiO(2) (0 less than or equal to x less than or equal to 1). Their behavior when soaked in a simulated body fluid (SBF) was studie d by means of electron microscopy (EM) equipped with an energy-dispers ive system (EDS) for elemental analysis, IR spectroscopy, and x-ray di ffraction. All the studied glasses react with SBF by forming a calcium phosphate layer. This layer appears to be increasingly thinner with i ncreasing amounts of La2O3 substituted. The experimental results are i n good agreement with mechanisms reported in the literature. Moreover they suggest that lanthanum oxide is retained in the layer below the p hosphate. After 6 days of soaking, crystalline hydroxyapatite is forme d in the case of La2O3 free glass. (C) 1996 John Wiley & Sons, Inc.