Antibacterial titanium plate anodized by discharging in NaCl solution exhibits cell compatibility

Implant surfaces should be modified to acquire excellent cell compatibility as well as antibacterial activity. Our previous study demonstrated large decreases in the amounts of oral bacteria on antibacterial titanium plates with increasing contact time with the plates. In particular, titanium plates discharging in 1 M NaCl (Ti-Cl) demonstrated high antibacterial activity. Since Ti-Cl was prepared using a NaCl solution, we hypothesized that Ti-Cl would exhibit low toxicity toward cells. In this study, the surface topography of Ti-Cl was observed by scanning electron microscopy. In addition, the initial adhesion and proliferation of osteoblastic MC3T3-E1 and fibroblastic L929 cells on Ti-Cl were investigated to elucidate the cell compatibility of Ti-Cl. Cell binding protein adsorption onto Ti-Cl was observed by fluorescein isothiocyanate labeling. The results demonstrated that since the TiCl3 formed on the Ti-Cl surface was hydrolyzed into HCl, HClO, and TiOH after immersion in pure distilled water, TiCl3 contributed to the antibacterial activity of Ti-Cl. On the other hand, TiO formed on the Ti-Cl surface enhanced cell extension and cell growth through a larger adsorption of fibronectin compared with the pure titanium control. These findings suggest that antibacterial titanium is a promising material for use in dental implant systems.