Effects of light sources and visible light-activated titanium dioxide photocatalyst on bleaching

Abstract

The objective of this study was to evaluate, using methylene blue (MB), the effects of various light sources on the bleaching action of hydrogen peroxide (H2O2) with two titanium dioxide (TiO2) photocatalysts -an ultraviolet light-activated TiO2 photocatalyst (UV TiO2) versus a visible light-activated TiO2 photocatalyst (VL-TiO2). Five experimental solutions (VL-TiO2+H2O2, UV-TiO2+H2O2, H2O2, VL-TiO2, UV-TiO2) were prepared by mixing varying concentrations of H2O2 and/or TiO2 photocatalyst with MB solution. For H2O2-containing solutions (VL-TiO2+H2O2, UV-TiO2+H2O2, and H2O2), the concentration of H2O2 was adjusted to 3.5%. For the four different light sources, low-and high-intensity halogen lamps and blue LED LCUs were used. All the experimental solutions were irradiated by each of the light sources for 7 minutes, and the absorbance at 660 nm was measured every 30 seconds to determine the concentration of MB as an indicator of the bleaching effect. On the interaction between the effects of light source and bleaching treatment, the high-intensity halogen with VL-TiO2+H2O2 caused the most significant reduction in MB concentration. On the effect of light sources, the halogen lamps resulted in a greater bleaching effect than the blue LED LCUs.

Effects of 405 nm Diode Laser on Titanium Oxide Bleaching Activation

“…4,[7][8][9][10]31,32 Those studies used various substrates, such as extracted human teeth, 4,31,32 bovine teeth, 8,10 hematoporphyrin-stained paper 9 and dye solution. 7 Teeth were used after staining with tea, 4,10 blood, 31 or dye. 32 It should be noted that using extracted teeth, results of a study would be more clinically relevant compared with other in vitro studies in which teeth were not involved.…”

“…The laser irradiation, stirring, and measurement cycle was repeated 14 times for each sample to reach a total irradiation time of 7 min. The experiment was conducted on three samples under each condition, which was determined based on a previous study 7 and a pilot study. The concentration of the remaining MB in the solution after laser irradiation was determined using a standard curve previously drawn in the pilot study by plotting the known concentrations and the determined absorbance of the sample solution of MB at various concentrations.…”

“…The VLTiO 2 was the same catalyst used for the Pyrenees but its concentration was 10% of that in the commercial product, as determined from a previous study. 7 Laser irradiation and bleaching A 405 nm diode laser (experimental HH-02, Sumitomo Electric Industries, Osaka, Japan) was used in this study. The spectrum of the radiation was in the interval of 400-410 nm, with the peak on the 405 nm wavelength, and the range of output power was 100-1000 mW.…”

“…The concentration of the remaining MB in the solution after laser irradiation was determined using a standard curve previously drawn in the pilot study by plotting the known concentrations and the determined absorbance of the sample solution of MB at various concentrations. 7 The concentration was calculated according to the following equation: Non, non-irradiation; CW, continuous wave; PW, pulse wave; D, duty; W, pulse duration (width of pulse).…”

“…As a result, simpler molecules that diffuse out of the tooth or reflect less light are formed, creating a successful bleaching action. 2 The bleaching reaction depends upon the type of discoloration involved and the chemical and physical environment present at the time of action, that is, concentrations, 2,3 heating, 4 lightening, 5 pH, 6 co-catalysts, [7][8][9][10] times of application, 3 and other conditions. Most current office bleaching products employ high concentration H 2 O 2 to produce higher amounts of free radicals.…”