The materials for bone and dental implants are tested invitro using simulated body fluid (SBF). The composition of most used SBF differsfrom that of blood plasma by high content of Cl- ions and lower content ofHCO3-ions. Considering the composition of bone-like apatite, which contains carbonateions, the test results could be influenced by this difference. The glass ofsystem Na2O-CaO-SiO2-P2O5 was leached in fluids of composition (in mmol/l): 142Na+, 5 K+, 2.5 Ca2+, 1 Mg2+, 1 SO42-, 1HPO42-, 136 (Cl-+HCO3-). The content ofHCO3- ranged between 5 and 27 mmol/l. The decrease of phosphorus concentrationwas observed after 2 days in all solutions indicating the creation of phosphatelayer on the glass surface. X-ray diffraction (XRD) confirmed the various extentof apatite layer creation in different solutions. The intensity of XRD peaksseems to be more influenced by the initial solution supersaturation than by thesupersaturation values during the interaction. This fact indicates that thenucleation could be the control mechanism of apatite precipitation. Bothexperimental and supersaturation results indicate that the SBF with increasedamount of HCO3- ions is more appropriate and sensible to in vitro testing ofbioactive materials.
