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The dark side of light radiation in teeth bleaching
By Katie Bird, 30-Jan-2009

Light radiation used in teeth bleaching treatments may be both useless and dangerous, according to recent research.

Many tooth whitening treatments suggest the use of a light source as it is believed to help improve the oxidising effect of the bleaching compound hydrogen peroxide.

However, a recent study in the journal Photochemical and Photobiological Sciences, argues that using lamps makes no difference to the end result and may be dangerous for the client and the operator.

Researchers form the Nordic Institution of Dental Materials investigated 7 different bleaching systems that were commercially available on the Scandinavian and US markets in 2005.

Using human molars donated after extraction, the team bleached one half of the tooth following the manufacturers’ recommendation and the other was left as a control.

Half of the bleached teeth received both the bleaching gel and the radiation and the other half just the bleaching gel.

The team then went on to investigate the light sources to see whether the treatment time exceeded the recommended exposure times to such radiation.

Light didn’t make teeth whiter

According to the study, there was no statistical difference in the colour change of the teeth with bleaching gel and radiation and those treated simply with the product.

Although the study acknowledges that the exposure to clients and operators of the machinery will vary greatly between clinics and treatments, it concludes that the use of optical radiation in teeth bleaching poses a health risk.

Clients may be exposed to up to 60 minutes of radiation to the teeth and mouth area, and the scientists note that little is known about the effects of visible light and UV radiation on mucous membranes such as the inside of the mouth.

In addition, depending on the placing of the lamps and the protection worn, clients may experience a dangerous level of radiation to the eye, the scientists claim.

These two factors, coupled with the fact that there were no discernable benefits from the radiation, led the researchers to advise against using light-assisted tooth bleaching.

Source: Photochemical and Photobiological Sciences
DOI: 10.1039/b813132e
In vitro efficacy and risk for adverse effects of light-assisted tooth bleaching
Ellen M. Bruzell, Bjørn Johnsen, Tommy Nakken Aalerud, Jon E. Dahl and Terje Christensen

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High-tech dentistry
What is necessary and what is not

Gordon J. Christensen, DDS, MSD, PhD

There has been an enormous amount of hype about using lights to enhance tooth bleaching when using different concentrations of hydrogen peroxide. Continued clinical observation of this bleaching concept has shown that at the initial bleaching appointment, the teeth bleached with hydrogen peroxide and a light appear to be somewhat lighter than teeth on which only hydrogen peroxide was used. The slight difference in tooth color observed as a result of bleaching with lights and hydrogen peroxide versus bleaching with hydrogen peroxide alone appears to be temporary and caused by the light’s dehydration and heating of the teeth.3,4 After a few days to weeks, there appears to be no significant shade difference between teeth bleached with lights and those bleached without lights.
Although research varies as to the effectiveness of bleaching using lights, many of the lights used for in-office bleaching appear to be primarily a psychological factor for the patient.
All of us await a truly effective, fast and nonsensitizing method of whitening teeth. Until that appears, at-home bleaching still is the most popular and predictable method used by most dentists.


Ask Dr. Christensen
Gordon Christensen
July 1, 2003
by Gordon J. Christensen, DDS, MSD, PhD
In this monthly feature, Dr. Gordon Christensen addresses the most frequently asked questions from Dental Economics readers. If you would like to submit a question to Dr. Christensen, please send an email to
Question ... "Recently, I've read: "Light augments tooth whitening with peroxide" (Tavares M, Slultz J. et al, JADA 134 (2) 167-175). This seems to be supportive of using lights with in-office bleaching. I've assumed that light application used with in-office bleaching was only a marketing tool, with little clinical value. Unfortunately, I'm not certain as to what mechanism for whitening is truly happening with the lights ..." (This question has been shortened and rearranged from the original form).
Answer from Dr. Christensen ... Over many years Clinical Research Associates (CRA) has studied the effect of light and heat on bleaching. The latest of their studies was published in the most recent CRA Newsletter (March 2003), in which we reported on the characteristics of several in-office bleaching systems using light. The following quote includes part of the CRA conclusions from that newsletter: "Use of lights according to the manufacturer's directions did not improve lightening for any system tested." Systems tested in the CRA study were: LaserSmile, LumaArch, Niveous, Opalescence Xtra Boost, PolaOffice, Rembrandt 1 Hour Smile-Whitening Program, and Zoom. Tests on BriteSmile have not yet been completed. Further scientific information on the lack of the effect of lights will be published in a bleaching supplement to Compendium next month. As with any concept, what actually happens and what the patient thinks is happening may be two different things. In these studies, light use did not speed or increase the bleaching over the use of bleaching chemicals alone. Therefore, as you stated in your question, there is little reason to use lights with bleaching except for marketing and "special effects." Unfortunately, it appears that in the eyes of some manufacturers and dentists, the marketing influence of lights is more important than their actual influence on the bleaching procedure.