Bactericidal effect on S. mutans using N-TiO2 with combined treatment of low concentration H2O2 and visible light.

Purpose: To test the feasibility of nitrogen-doped TiO₂ nanoparticles in the killing of Streptococcus mutans (S. mutans) for short term treatment.

Methods: For the study, S. mutans were treated with the combinations of N-TiO₂, visible light, and without/with 0.5% H₂O₂ inclusion. Visible light was irradiated for 3 minutes one time.

Results: Methylene blue solution was degraded (bleached) 5-30% by one of N-TiO₂ (or TiO₂) + visible laser (405 or 660 nm) +0.5% H₂O₂ conditions owing to almost linearly producing free radicals through photocatalysis. Antibacterial outcomes treated with N-TiO₂ were slightly better than those by TiO₂ regardless of test condition. Also, killing of S. mutans treated with 405 nm laser was slightly better than those by 660 nm laser.

Clinical Significance: S. mutans can be eliminated using N-TiO₂ with clinically acceptable light (wavelength, intensity) and low concentration H₂O₂ condition under short term treatment.