Bactericidal effect of the photocatalystic reaction of titanium dioxide using visible wavelengths on Streptococcus mutans biofilm

Background: The aim of this study was to determine the effect of titanium dioxide (TiO2) photocatalysis induced by the application of clinically acceptable visible light at 405 nm on the growth of Streptococcus mutans biofilms. Methods: S. mutans biofilms were grown on a hydroxyapatite (HA) disk and deposited in a rutile-type TiO2 solution at a concentration of 0.1 mg/mL. TiO2 photocatalysis was measured for exposure to visible light (405 nm) and ultraviolet (UV) light (254 nm) produced by light-emitting diodes for 10, 20, 30, and 40 min. After two treatments, the number of colonies formed in the final S. mutans biofilm on the HA disk were measured to confirm their viability, and the morphological changes of S. mutans were evaluated using scanning electronic microscopy. Results: The bactericidal effects of 254- and 405-nm light resulted in > 5-log and 4-log reductions, respectively (p < 0.05), after 20 min of treatment and a > 7-log reduction after 40 min of treatment in both treatment groups relative to the control group. Conclusion: It was confirmed that the antibacterial effect could be shown by causing the photocatalytic reaction of TiO2 in S. mutans biofilm even at the wavelength of visible light (405 nm) as at the wavelength of ultraviolet light (254 nm). (C) 2017 Elsevier B.V. All rights reserved.