Photocatalytic antibacterial effect of tio₂ film of tiag on streptococcus mutans

Objective: To test through various oxidation procedures the differences in antibacterial activities against Streptococcus mutans (S mutans) of Titanium (Ti) and Titanium silver (TiAg) metals coated with TiO₂. Materials and Methods: This study examined the photocatalytic antibacterial effects on S mutans of Ti and TiAg ubstrates coated with two crystalline forms of TiO ₂ by thermal and anodic oxidation. A bacterial suspension of S mutans was pipetted onto TiO₂-coated metal specimens and uncoated specimens with ultraviolet A (UVA) illumination for 20 to 100 minutes. The same specimen without UVA was used as the control. The level of colony-forming units of S mutans after UVA illumination was compared with that of the control. Results: The level of colony-forming units of S mutans was significantly lower on TiO₂-coated Ti and TiAg metal specimens after UVA illumination than on uncoated Ti and TiAg specimens. The level of colony-forming units of S mutans was significantly lower on the metals coated by anodic oxidation than on those coated by thermal oxidation. The TiO₂ coating on TiAg had a significantly higher and more rapid antibacterial effect than did the TiO ₂ coating on Ti. Conclusions: The antibacterial effect of a TiO ₂ film formed by anodic oxidation was superior to that formed by thermal oxidation. The addition of Ag to the Ti specimen indicated a synergistic effect on the photocatalytic antibacterial property against S mutans.