EVALUATING THE PHASE-COMPOSITION OF THE SURFACE OF BIOACTIVE GLASSES FOLLOWING THEIR INTERACTION WITH SIMULATED BODY-FLUID, WITH THE USE OFX-RAY-DIFFRACTION ANALYSIS

Following interaction with simulated body fluid, apatite and calcite w ere identified on the surface of bioactive glasses. The phase composit ion of the glass surface layer after elution is affected by the experi mental conditions. At a high ratio of sample surface area (S) to the v olume of the leaching solution (V), calcite was identified in the surf ace layer, whereas a low ratio (a large volume of the solution) had le d to the formation of apatite. From the point of view of crystallograp hy, the apatite was not well developed, and its detection limit by the X-ray diffraction method was less than 5%. The calcite was well devel oped Phosphorus-free glasses exhibited a higher tendency to calcite fo rmation than the phosphorus containing ones. Suitable experimental con ditions with respect to the SN ratio have to be chosen in the ''in vit ro'' testing to ensure availability of phosphorus in the solution thro ughout the exposure, as otherwise calcite would eventually precipitate on a thin layer of apatite.