title: Effects of 405 nm diode laser on titanium oxide bleaching activation.
abstract: OBJECTIVE
  The objective of this study was to evaluate the effects of a 405 nm diode laser on bleaching reaction of H(2)O(2) and VL-TiO(2) on methylene blue (MB) dye.
  
  
  BACKGROUND
  Visible light activating titanium dioxide photocatalyst (VL-TiO(2)) may improve efficacy of hydrogen peroxide (H(2)O(2)) bleaching agents used in dentistry while contributing to their safety by lowering the required concentration of peroxide.
  
  
  METHODS
  The experimental solution was prepared with H(2)O(2), VL-TiO(2), MB, and pure water. The final concentration of H(2)O(2) was 3.5% and that of MB was 10 ppm. The experimental solution of 3 mL in a quartz cell was irradiated by a 405 nm diode laser with various powers, duty cycles, and pulse durations for 7 min.
  
  
  RESULTS
  In all irradiation conditions, the increase in laser irradiation time gradually decreased the MB concentration. Irradiation by higher output power showed more reduction of MB concentration. Pulse durations as short as 5 ms with duty cycle reduced to 25% did not affect the degree of the reduction in MB concentration compared with continuous wave irradiation at the same average output power.
  
  
  CONCLUSIONS
  It was concluded that using 405 nm diode laser, the bleaching effects of VL-TiO(2) depended upon the irradiation time and the average output power, regardless of pulse duration or duty cycle.
authors.affiliation: Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Eri
authors.initials: E
authors.lastname: Tano
authors.forename: Masayuki
authors.initials: M
authors.lastname: Otsuki
authors.forename: Junji
authors.initials: J
authors.lastname: Kato
authors.forename: Alireza
authors.initials: A
authors.lastname: Sadr
authors.forename: Masaomi
authors.initials: M
authors.lastname: Ikeda
authors.forename: Junji
authors.initials: J
authors.lastname: Tagami
mesh_terms: D006801:Humans; D054023:Lasers, Semiconductor; D008751:Methylene Blue; D017319:Photosensitizing Agents / Q000627:therapeutic use; D014025:Titanium / Q000627:therapeutic use; D014073:Tooth Bleaching / Q000379:methods
chemical_list: D017319:Photosensitizing Agents; C009495:titanium dioxide; D014025:Titanium; D008751:Methylene Blue