Professional whitening treatments

- Is using a bleaching light really necessary? - What does research show? / What ingredients do in-office whiteners contain?

Teeth bleaching lights - Are they really needed?

Some, but certainly not all, professional teeth whitening systems recommend that a bleaching light should be used when treatments are performed.

Here are some of the brand names (and associated light types) of systems that do:


Picture of light activation of tooth whitening gel.

Some systems recommend "light activation" of the whitener.

Is using a light unit really necessary?

Spoiler Alert: It's not.
Over the years there has been a large amount of controversy in the dental community about whether or not "light activation" really benefits (speeds up, enhances) the tooth-whitening process.

What's the light supposed to do?

Here's a general idea of how the use of a bleaching light is typically stated to work:

  • Light "activation" triggers a photocatalyst within the whitener that assists in breaking its hydrogen peroxide content down into its reactive components (termed "free radicals").
  • This, in turn, speeds up the rate at which the tooth whitening process takes place (shorter appointments) and enhances the treatment's results (whiter teeth).

Note: Modern bleaching lights are not used for "thermal" activation of the whitener (heating it so to increase its reactivity). Doing so can be harmful to teeth. - See below.

What does dental research say about this topic?


Historically, dentists had noticed that:
  • Some people's teeth lighten at a faster rate than others. (Some patients require more treatment sessions.)
  • A person's teeth only have so much potential to lighten. (Not all patients can get the same results.)


These variables make creating a whitening research study difficult. After all, how would you know if the subjects in the test group that didn't get great results didn't just have naturally stubborn teeth?

Split-arch design.

Picture of a case in a split-arch tooth whitening study.

In a split-arch study, each side receives a different version of the treatment.

The answer to this problem came in what is called "split arch" design.
Using this method, each subject's teeth are divided into halves (left and right). One side gets one treatment, the other another. (The term "arch" in dentistry means either the upper or lower teeth.)

Using this method, the variability between subjects is eliminated. Only a comparison between a person's left and right sides is made, not the results obtained by different people. This method is the gold standard for evaluating whitening techniques.

Graphic showing an in-office tooth-bleaching light.

An in-office tooth-bleaching light.

Research studies:

a) Hein 2003 - A "no" vote.

This study used a split-arch design (the first to do so in published research) to evaluate the effectiveness of 3 professional-grade whiteners (LumaArch®, Optilux 500® and Zoom!®) with and without the use of a bleaching light.

Findings: The conclusions were that the use of the lights did not lighten teeth more than the use of the whiteners by themselves.

b) Tavares 2003 - A "yes" vote.

This study evaluated the BriteSmile® system.

Findings: It reported that the use of a bleaching light did make a substantial difference in the whitening outcome.

Criticisms of this study:

  • It did not use a split-arch design.
  • The improvement in tooth shade was measured immediately after the treatment session was completed. (See below for an explanation about why this is a problem.)


Picture of whitening gel applied that does not require light activation.

Treatment without light activation.

c) CRA 2003 - A "no" vote.

Coincidentally, during about the same time frame when the Tavares study came out, Clinical Research Associates (CRA) published the findings of their review of professional whitening systems (and the use of bleaching lights) in their March 2003 newsletter.
This review used split-arch design to study 7 in-office products (LaserSmile®, LumaArch®, Niveous®, Opalescence Xtra Boost®, PolaOffice®, Rembrandt® 1 Hour Smile-Whitening Program, and Zoom®).

Findings: Its conclusions were that the use of a bleaching light did not enhance the bleaching process over the use of the whitener alone.

Notes: At a later date, CRA tested the version of the BriteSmile® system they had available to them (they were limited by restrictions imposed by BrightSmile® in regard to what type of testing could be performed on their current product) and found the use of a light (a laser) did not affect bleaching efficacy. (Christensen 2003, CRA 2003, Haywood 2009)

d) Kugel 2006 - A "no" vote and explanation.

This 2006 publication seems to provide an explanation that helps to resolve the conflicting results found by Tavares and the Hein and CRA studies.

Findings: Using a split-arch design, it was determined that results using a light-activated system did appear lighter but only initially.

When the subjects' teeth were re-evaluated at a point 2 weeks after the treatment, no difference was found between the light and non-light sides.

Explanation: This paper attributed the initial lightness seen with the teeth treated with a bleaching light to a dehydration effect that occurs as they dry out during their treatment process, not to increased whitening efficacy due to light activation.

  • As teeth become dehydrated their color tends to lighten.
  • Then, as they regain moisture (over the following hours and days), their color begins to fade.


This explains why the evaluation made 2 weeks after the treatments showed no difference in whiteness whether a light had been used or not.

  • Both methods created the same level of color improvement.
  • The extra lightening effect that was seen initially with cases where a bleaching light was used faded over time. (It was due to the temporary dehydration effect.)


So is the use of a bleaching light really necessary?

No, based on the above findings, one would have to conclude that it's not.

Picture of an in-office bleaching light unit.

Bleaching light units look impressive.

Why do some dentists use bleaching lights?

In 2005, CRA (the group whose research was mentioned above) polled dentists about why they use a light. Some of the responses were: (Haywood 2009)
  • Because it came with my system.
  • Because patients ask for it.
  • Because it's good for marketing.

These are probably aren't the reasons you might have expected, or hoped for.

Why do manufacturers emphasize the use of lights?

Companies that make in-office systems are eager to claim that their product's bleaching light is an important part of the bleaching process. That's because doing so helps to ensure sales of their light units, a piece of equipment that can cost your dentist many thousands of dollars.

Additionally, the use of a bleaching light during the process adds fanfare and makes the whitening process seem more impressive. And that impression of something special tends to appeal to consumers and helps to drive demand for their product.


Are there any professional systems that don't require the use of a bleaching light?

Many systems do not incorporate the use of a bleaching light into their protocol (or else consider it an optional step). At our last check, some of the brands that take this approach are:


Are there any reasons why a light shouldn't be used?

1) The more equipment your dentist must buy, the more they must charge.

Your dentist is a business person just like anyone else. And if the whitening protocol they use includes the use of a light unit, it will simply add to their expenses and yours too.


2) Exposing the patient's teeth to heat must be avoided.

No whitening protocol should allow the teeth being treated to be exposed to elevated temperatures. The use of some types of bleaching lights may allow this to occur.

The problem.

Overheating teeth increases their potential for experiencing post-operative sensitivity, pain, and/or nerve tissue damage. An increase on the order of 10 degrees F within a tooth's nerve space is thought to be able to cause irreversible nerve damage. (Sulieman 2008)


Historically, the whole idea of using a light specifically was to create a heating effect. That's because a warmer whitening solution produces a faster breakdown of the hydrogen peroxide into its reactive components.

Dentists know better nowadays. Today's lights are designed so they have minimal potential for creating a heating effect or else are used in a manner (constantly moved around) so no substantial heating takes place.

In-office tooth whiteners - Ingredients, Characteristics.

Every professional whitening system comes with its own unique whitener. And while the exact formulation of each brand varies, collectively they all share a number of similarities.

What active ingredient is used?

Professional-level whiteners are usually hydrogen-peroxide based products. Their concentration typically ranges between 17 and 50%. (For specific values, see our review of professional whitening systems.)

(At-home products usually use a whitener that contains the equivalent of 3 to 10% hydrogen peroxide. This difference in concentration explains why professional treatments can produce results so much more quickly. Use this link for other comparisons between at-home and in-office systems.)

How do tooth whiteners work?

The hydrogen peroxide component of a whitener breaks down to form "free radicals." It's these very reactive molecules that then create the tooth-whitening effect (by way of interacting with and breaking down the molecules that have caused the tooth's staining).

A neutral pH is best.

Manufacturers try to formulate their whiteners so they have a neutral (non-acidic) pH. That's because tooth enamel is a mineralized tissue and exposing it to an acidic whitener, especially for an extended period of time, could damage it.

Ensuring product freshness.

Many professional whiteners come prepackaged as two individual components. They are then mixed by the dentist, at the time of use. This approach helps to ensure product freshness because the active ingredients are not combined and allowed to react until right before the time of their application.

Other products come pre-mixed. The advantage here is there is no question about the precise strength of the whitener, it was mixed at the factory. As a way of helping to extend shelf life, pre-mixed products often need to be stored at a cool temperature (like in a refrigerator).

Desensitizing agents.

As a way of helping to minimize the risk for post-treatment tooth sensitivity, some systems incorporate desensitizers into the formulation of their whitener. The two most frequently used compounds are fluoride and potassium nitrate.


During the bleaching process it's possible for the patient's teeth to become dehydrated (discussed above). Creating a product whose water content is 10 to 20% can help to avoid this problem. (Sulieman 2008)



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