The effect of hydrofluoric acid treatment of titanium and titanium dioxide surface on primary human osteoblasts

The aim of the study was to investigate solely the effect of fluoride on the surface chemistry of polycrystalline ceramic titanium dioxide (TiO2 ) and metallic titanium (Ti) and its effect on proliferation and differentiation of primary human osteoblasts (NHO).

The NHO cells were exposed to fluoride-modified and unmodified samples for 1, 3, 7, 14 and 21 days. The fluoride effect on the mRNA expression was quantified and measured. The secretion of cytokines and interleukins in the cell culture medium was measured by Luminex, gene expression by RT-PCR, and compared with untreated controls. The effect on cell growth after 1 and 3 days in culture was measured using [(3) H]-thymidine incorporation. Fluoride release was measured using an ion-selective electrode. The surfaces were examined by X-ray photoelectron spectroscopy and profilometry.

The fluoride release study detected that fluoride content easily washed off in TiO2 coins when compared with Ti coins. No increase in cell proliferation was found among fluoride-modified TiO2 surfaces compared with controls, except for washed Ti coins with fluoride modification. The cell differentiation with regard to gene expression showed no significant differences in both fluoride-modified and unmodified samples and less effect on protein release for all groups.

The fluoride from hydrofluoric acid treatment on Ti and TiO2 surfaces gave no specific effect on primary human osteoblast cells. The study indicates that the released fluoride is not the unique factor for the bioactivity of Ti and TiO2 surfaces.