Effects of titanium oxide photocatalyst on oral bacteria

Abstract

Photocatalysis of titanium oxide is known to have an antibacterial effect on Pseudomonas aeruginosa and Escherichia coli, and is widely-applied to medical science. Also in dentistry, the use of titanium oxide in dental materials is thought to prevent dental caries and periodontal disease.
The aim of this study was to examine the antibacterial activity of a titanium oxide coat on the surface of gold-silver-palladium alloy and a commonly used dental metal. Antimicrobial activity was evaluated by the size of each inhibition ring formed on agar and the number of persistent Porphyromonas gingivalis and Streptococcus mutans, after the floating bacteria were directly inoculated on the alloy.
As a result, inhibitory zones were found in the experimental group coated with titanium oxide, but the inhibitory zones were not found in the shading group covered with aluminum foil or in the non-coated group. Further, in the experiments where bacteria were dropped directly on the discs, exposed to light and inoculated on agar, the number of persistent bacteria decreased with exposure time. On the other hand, the number of bacteria did not change in the shading or non-coating groups, regardless of exposure time. These results suggested that the titanium oxide coated on the gold-silver-palladium alloy surface has an antibacterial effect on Porphyromonas gingivalis and Streptococcus mutans.