ObjectiveTs:he aim of the study was to investigate changes in osteoblast number and viability in contact with biomaterials and to compare both tests. Methods: Human primary culture osteoblasts were seeded on the polished surfaces of hydroxyapatite, alumina, titanium and surgical steel. After 4, 9, 14,24 and 48h cultures were subjected to XTT viability assay. Subsequently Hoechst staining of nuclei was performed. Number of cells on each sample was counted. Results: There were no differences in cell viability measured by means of XTT assay between osteoblasts cultured on hydroxyapatite and alumina during 48 hours of experiment. However on titanium as well as on surgical steel cell viability was significantly lower than on bioceramics. The lowest viability was noticed on surgical steel. Cell number on titanium was significantly higher than on steel. There were no differences between cell numbers on hydroxyapatite and alumina as well as between investigated bioceramics and metals. Nucleus number and the results of viability assay were compared. There was no correlation found between number and viability of cells. Conclusion: the results of a single test may not provide sufficient information on the interaction between cells and implant. Application of a battery of tests is necessary in material biocompatibility investigation in vitro.

Keywords: Cell Viability, Osteoblasts, biomaterials, in vitro methods