The effect of ultraviolet treatment on surface characteristics, bacterial adhesion, and cellular response of TiO₂ nanotubes

Objectives: Titanium dioxide (TiO₂) nanotube is emerging as a provocative target for oral implant research. The aim of this study was to evaluate the effect of UV on the wettability behavior, bacterial colonization and fibroblast proliferation rate on TiO₂ nanotube surfaces prepared using different anodization voltages, aimed to be used an implant abutment material.
Methods: Four different experimental materials were prepared: (1) TiO₂ nanotube 10 V; (2) TiO₂ nanotube 15 V; (3) TiO₂ nanotube 20 V; (4) Commercial pure titanium as a control. TiO₂ nanotube arrays were prepared in an aqueous electrolyte solution of hydrofluoric acid (HF, 0.5 vol.%). Different anodization voltages were used to modify the morphology of the TiO₂ nanotubes. Equilibrium contact angles were measured using the sessile drop method with a contact angle meter. The investigated surfaces (n=3) were incubated at +37°C in a suspension of Streptococcus mutans for 30 min for bacterial adhesion and 3 days for biofilm formation. Human gingival fibroblast proliferation rate up to 7 days was assessed using AlamarBlue assay^TM. The data were analyzed using one-way ANOVA followed by Tukey’s post-hoc test.
Results: Water contact angle measurements on TiO₂ after UV treatment showed a total hydrophilic behavior regardless of the anodization voltage. Ranking of the UV-treated surfaces of experimental groups from lowest to highest for bacterial adhesion was: TiO₂ nanotube 20 V < Ti and TiO₂ nanotube 15 V < TiO₂ nanotube 10 V (P<0.05) and for bacterial biofilm formation was: TiO₂ nanotube 20 V - TiO₂ nanotube 10 V < Ti - TiO₂ nanotube 15 V (P<0.05). Fibroblast cell proliferation was lower on TiO₂ nanotube surfaces throughout the incubation period and UV light treatment showed no enhancement in cellular response.
Conclusions: UV treatment enhances the wettability behavior of TiO₂ nanotube surfaces and could result in lower bacterial adhesion and biofilm formation.