The amounts of hydroxyl radicals generated by titanium dioxide and 3.5% hydrogen peroxide under 405-nm diode laser irradiation

Sakai, Kohei; Kato, Junji; Kurata, Hiroshi; Nakazawa, Taeko; Akashi, Go; Kameyama, Atsushi; Hirai, Yoshito

doi:10.1134/s1054660x07080075

Cited by 41 publications

(32 citation statements)

References 15 publications

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“…For safety reasons, visible light is preferable to UV light because UV irradiation might not only photolyze H 2 O 2 but also damage normal tissues. Although it has been known that UV irradiation can photolyze H 2 O 2 effectively (4,22), visible light with a wavelength of 405 nm also has an ability to photolyze H 2 O 2 (25). In addition, visible light is much safer than UV light for operators when the disinfection system is applied in a clinical setting.…”

Section: Discussionmentioning

confidence: 99%

Photolysis of Hydrogen Peroxide, an Effective Disinfection System via Hydroxyl Radical Formation

Ikai

Nakamura

Shirato

et al. 2010

Antimicrob Agents Chemother

146

109

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Section: Discussionmentioning

confidence: 99%

Photolysis of Hydrogen Peroxide, an Effective Disinfection System via Hydroxyl Radical Formation

Ikai

Nakamura

Shirato

et al. 2010

Antimicrob Agents Chemother

146

109

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“…In our previous study (8), a laser diode (LD) at 405 nm was used as a light source for safety reasons in terms of clinical application (4,18). In the present study, however, light-emitting diodes (LEDs), which can emit a visible blue light with a high energy density, was used instead of the LD, because LEDs are cheaper and easier to handle compared to LD in terms of clinical application.…”

Section: Methodsmentioning

confidence: 99%

Synergistic Effect of Thermal Energy on Bactericidal Action of Photolysis of H ₂ O ₂ in Relation to Acceleration of Hydroxyl Radical Generation

Shirato

Ikai

Nakamura

et al. 2012

Antimicrob Agents Chemother

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The purpose of the present study is to evaluate the effect of thermal energy on the yield of and the bactericidal action of hydroxyl radical generated by photolysis of H 2 O 2 . Different concentrations of H 2 O 2 (250, 500, 750, and 1,000 mM) were irradiated with light-emitting diodes (LEDs) at a wavelength of 400 ؎ 20 nm at 25°C to generate hydroxyl radical. The 500 mM H 2 O 2 was irradiated with the LEDs at different temperatures (25, 35, 45, and 55°C). Electron spin resonance spin trapping analysis showed that the yield of hydroxyl radicals increased with the temperature, as well as the concentration of H 2 O 2 . Streptococcus mutans and Enterococcus faecalis were used in the bactericidal assay. The LED-light irradiation of the bacterial suspensions in 500 mM H 2 O 2 at 25°C could hardly kill the bacteria within 3 min, while the bactericidal effect was markedly enhanced with the temperature rise. For instance, a temperature increase to 55°C resulted in >99.999% reduction of viable counts of both bacterial species only within 1 min. The photolysis of 500 mM H 2 O 2 at 55°C could reduce the viable counts of bacteria more efficiently than did the photolysis of 1,000 mM H 2 O 2 at 25°C, although the yields of hydroxyl radical were almost the same under the both conditions. These findings suggest that the thermal energy accelerates the generation of hydroxyl radical by photolysis of H 2 O 2 , which in turn results in a synergistic bactericidal effect of hydroxyl radical and thermal energy.A novel disinfection technique where artificially generated hydroxyl radical kills pathogenic fungi and bacteria has been developed in our laboratory (8, 9). The hydroxyl radical disinfection technique is based on the concept that the hydroxyl radical kills microorganisms as a result of oxidation of cellular components, such as cell membrane, nucleic acid, and other cell organelles. In our previous study, the bactericidal effect of photolysis of H 2 O 2 depended on the light irradiation time, indicating that bacteria were killed dependently on the amount of hydroxyl radical (8). Thus, the yield of hydroxyl radical is one of the most important factors which determine the bactericidal effect of the disinfection technique. The yield of hydroxyl radical is affected mainly by two factors when photolysis of H 2 O 2 is used as a hydroxyl radical generator. One is the potency of light to photolyse H 2 O 2 , which is controlled by wavelength and the energy density. The other is the concentration of H 2 O 2 . A high concentration of H 2 O 2 , however, might cause adverse effects when the disinfection technique is applied in the oral cavity (3,16,23). Hence, a low concentration of H 2 O 2 is preferable from a clinical point of view regarding safety issues. Especially, unlike a short-term disinfectant treatment, adverse effects on the normal tissue should be considered in a case of repetitive usage of disinfectant in a long-term treatment. One of the possible strategies to reduce the level of H 2 O 2 is thermal energy. For instance, it was ...

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“…These violet-laser diodes also show promise for medical applications, such as cutting soft tissue [9], laser acupuncture [10], tooth whitening [11][12][13][14], antimicrobial photodynamic therapy [15], and the detection of dental caries [16]. It is also speculated that the wavelength of violet laser diodes is suitable for curing these alternative dental material initiators [4-6, 17, 18].…”

mentioning

confidence: 99%

Light-curing of dental resins with GaN violet laser diode: The effect of photoinitiator on mechanical strength

Kameyama

Hatayama²,

Kato

et al. 2011

Lasers Med Sci

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The purpose of this study was to evaluate whether a Gallium Nitride (GaN) -based violet laser diode (VLM500) could be used as a light source for light-cured dental resins. Three experimental unfilled resins containing different photoinitiators (camphorquinone, CQ; phenyl propanedione, PPD; or mono acylphosphineoxide, MAPO) were evaluated. These resins were lightcured with a VLM500 laser diode, and their ultimate micro-tensile strengths (μTS) were compared to those cured with three different LED light sources (Curenos, G-Light Prima-normal mode and G-Light Prima-PL mode). The VLM500 produced high µTS values in all three resins, and we concluded that this violet laser diode can be used as a light source for light-cured dental resin materials.

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The amounts of hydroxyl radicals generated by titanium dioxide and 3.5% hydrogen peroxide under 405-nm diode laser irradiation

Cited by 41 publications

References 15 publications

Photolysis of Hydrogen Peroxide, an Effective Disinfection System via Hydroxyl Radical Formation

Photolysis of Hydrogen Peroxide, an Effective Disinfection System via Hydroxyl Radical Formation

Synergistic Effect of Thermal Energy on Bactericidal Action of Photolysis of H ₂ O ₂ in Relation to Acceleration of Hydroxyl Radical Generation

Light-curing of dental resins with GaN violet laser diode: The effect of photoinitiator on mechanical strength

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The amounts of hydroxyl radicals generated by titanium dioxide and 3.5% hydrogen peroxide under 405-nm diode laser irradiation

Cited by 41 publications

References 15 publications

Photolysis of Hydrogen Peroxide, an Effective Disinfection System via Hydroxyl Radical Formation

Photolysis of Hydrogen Peroxide, an Effective Disinfection System via Hydroxyl Radical Formation

Synergistic Effect of Thermal Energy on Bactericidal Action of Photolysis of H 2 O 2 in Relation to Acceleration of Hydroxyl Radical Generation

Light-curing of dental resins with GaN violet laser diode: The effect of photoinitiator on mechanical strength

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Synergistic Effect of Thermal Energy on Bactericidal Action of Photolysis of H ₂ O ₂ in Relation to Acceleration of Hydroxyl Radical Generation