Teeth whitening strips (Crest Whitestrips®)

- What are they? How are they used? | What kind of whitener (bleaching agent) do they contain? At what concentration? | What additional ingredients are included in their whitener's formulation?

Teeth whitening strips - What are they?

Whitening strips are a type of at-home teeth bleaching product. They were first introduced in 2000 by Proctor & Gamble under the brand name Crest Whitestrips®. Since then, several companies have developed their own similar, essentially equivalent, products.

a) What's the main advantage of using whitening strips?

The primary selling point of this method is that it provides a way for a person to perform comparatively effective whitening treatments, at home and on their own, without having to use bleaching trays.

(Compared to the convenience, ease and simplicity of using whitening strips, the process of performing tray bleaching treatments is generally considered to be a messier, more inconvenient and more noticeable when worn process.)

b) What are the advantages of a "strip" design?

  • The flexible nature of a strip readily conforms to the shape and alignment of your teeth. And that means it won't cause mechanical irritation to soft tissues like bleaching trays can.
  • Because only one side of the strip is coated with the bleaching agent, it acts as a barrier that helps to both prevent the dilution of the whitener and minimize its contact with opposing soft tissues.

    This helps to increase effectiveness and decrease the user's potential for side effects.

 

  • Since the whitener is applied by the manufacturer (and not the end-user), the dosing you receive is very controlled and consistent.

    This helps to ensure predictable whitening results. And aids with product safety and reduces your potential for side effects by way of minimizing the quantity of whitener that's used during each treatment.

  • As compared to all other (reasonably effective) at-home methods, this is probably the simplest, least-messy way to whiten your teeth.

Section references - Gerlach

c) What are whitening strips made out of?

The strips themselves are clear, thin, flexible pieces of plastic (polyethylene) that have been uniformly coated on one side with a thin film that contains hydrogen peroxide (of varying concentration depending on the product, see list below).

The film, whose thickness with some strip designs is as little as 0.2 mm (1/130th of an inch), acts as both the bleaching agent and the adhesive for the strip.

Section references - Gerlach, Crest

Whitestrips are made out of thin clear flexible plastic.

Picture of a Crest Whitestrip.

The whitener is on the side that faces the strip's stiff plastic carrier.

d) What type of whitener is used? / What's its concentration?

  • Most strip products (including Crest Whitestrips®) are coated with a hydrogen peroxide-based whitener.
  • Nowadays, the usual "entry-level" strip product is coated with a 10% hydrogen peroxide (H2O2) agent.
  • Overall, the Whitestrips® brand offers products whose whitener ranges from around 6% up to 14% H2O2 (see table below).

 

Trends in whitener concentration and application times have changed.

In years past, "introductory" products featured strips coated with a 6% hydrogen peroxide whitener (for example Whitestrips® Classic). And their instructions typically called for performing 30-minute treatments twice per day.

Nowadays, entry-level products tend to be coated with a 10% H2O2 concentration whitener (Crest Whitestrips® Vivid and Advanced Vivid). The difference being that these more potent products are only used for 30-minute treatments once a day.

Picture of an individual package of Crest Whitestrips Supreme.

Crest Whitestrips Supreme is formulated with the highest concentration whitener.

Whitestrips® whitener concentrations.

The table below shows what we believe are the hydrogen peroxide concentrations found in the whitener formulations of various members of the Whitestrips® product line.

We've collected this information from research papers, retailer/distributor information and Crest® publications we've seen over the years. We can't be certain that it is (or still is) correct but presume that the values shown are accurate.

 
Comparison of the hydrogen peroxide concentration of Whitestrips®.
Whitestrips® Product Ingredient Concentration
Name Hydrogen Peroxide (H2O2)
Classic 6%
Gentle Routine 6%
Advanced Vivid 9.5%
Luxe Glamorous White 9.5%
Vivid 10%
Professional Effects 10%
1 Hour Express 10%
Supreme 14%

 

Whitener "load."

The peroxide concentration of a strip's whitener really only tells half of the story. That's because the total amount of gel that's placed on each strip (its thickness) will also be a factor in calculating the total amount of peroxide that your teeth are exposed to.

This total is important because teeth bleaching is a direct cause and effect equation.

Greater peroxide exposure = Greater, more rapid whitening effect.

(To the extent of the tooth's ability to be lighten.)

The paradox.

That means it's possible for a strip that has a lower-concentration bleaching agent to deliver a greater dosing of peroxide, if it has a thicker layer of whitener.

The inherent uncertainty.

That conundrum means that it's essentially impossible for anyone who doesn't share in a manufacturer's proprietary product details (which includes pretty much all of us) to be able to estimate with certainty the potential effectiveness of different brands of strips, or even the individual members of a single brand's product line.

That's because without this basic information (whitener thickness and peroxide concentration) it's not possible to actually calculate the total "load" of the active ingredient the strip contains and therefore your teeth are exposed to.

e) How does the whitener work?

While not entirely the whole story, it can be said that whitening-strip science generally involves a process where the hydrogen peroxide component of the whitener permeates into the tooth's hard tissues (enamel and dentin).

Once inside these tissues, the peroxide ultimately breaks down into very reactive molecules referred to as "free radicals." These agents in turn breakdown the molecules found within the tooth's tissues that have caused its discoloration (they are referred to as "chromophore molecules").

The appearance of the tooth lightens up because the breakdown products formed are comparatively colorless.

Section references - Kwon

Picture of one set of Crest Whitestrips still mounted on their carrier.

One pair of Crest Whitestrips (upper/lower, the lower strip is the shorter one) as they come on their carrier.

Thin-film chemistry.
The thing that's unique about whitening strips is that this method utilizes the normal process of peroxide teeth whitening but applies this science in the form of "thin-film" chemistry.
This simply means that the process of tooth bleaching doesn't require that the teeth are immersed in a large quantity of the active ingredient (hydrogen peroxide in the case of strips). But instead just enough to cover over their surface.
An advantage of using strips.

Whitening-strip technique takes this concept of thin-film chemistry to an extreme.

The coating of whitener applied may be as little as 0.2 millimeters in thickness (the thickness of a piece of paper is usually around 0.1 millimeter). (The exact thickness placed varies from product to product.)

But due to the use of this thin-film approach, the total amount of peroxide that the user is exposed to per application (whitening session) can be up to 1/2 to 1/5th as much as with tray-based technique.

Section references - Gerlach


What additional ingredients are found in Whitestrips®?

As you might guess, beyond just hydrogen peroxide (the whitener's active ingredient), a whitening strip's gel coating contains a number of additional ingredients that are used to enhance its characteristics. Some of them serve multiple functions.

Thickeners and agents that aid in strip adhesion.

This category seems to include most of a strip's added ingredients: Glycerin, Carbomer, Polyvinylpyrrolidone (PVP), PEG, Acrylates Copolymer.

Moisturizing agents.

Water, PEG and Glycerin are included in the gel's formulation to help keep the user's teeth properly hydrated during the bleaching process.

Taste modifiers.

Sodium Saccharin, which is an artificial sweetener.

pH balancer.

Sodium Hydroxide.


Additional things to know about whitening strips.

How are they used?

In a nutshell, a strip is positioned over your teeth and then gently pressed into place. At the end of your session, the strip is simply peeled off and discarded.

(Instructions for using Crest Whitestrips® products.)

Picture of the directions printed on the packaging of Crest Whitestrips (the strips are worn for 30 minutes duration).

Many Whitestrips products are worn for 30 minutes. Check the instructions that come with your product to be sure.

How long are the strips worn?
As mentioned above, historically strips (like Crest Whitestrips® Classic) were worn 30 minutes a day, twice a day. The trend with newer products is once-a-day use, typically for 30 minutes.

Directions about application times, how many days strips should be worn and how many kits may be used all vary with different products (primarily based on its whitener's peroxide concentration). These manufacturer recommendations should be adhered to for best results and avoiding side effects or complications.

(We discuss application times for Crest Whitestrips® products on this page.)

It's OK to quit early.

Of course, if a person has already achieved the whitening results they desire before they've used the entire contents of their box of strips, or if the side effects they experience become significant, treatments may (and should) be terminated at any time.

(Here are details about how to manage side effects by adjusting your treatment sessions.)

How effective is using whitening strips?

There's no question that this technique can make a good initial choice. And for most users, it will produce the whitening results they seek.

  • Studies suggest that choosing strips is more effective than using a brush-on whitener (whitening pen) or whitening toothpaste.
  • And under certain conditions, strips can give results equal to those obtained via the use of an at-home tray-based system (10% carbamide peroxide). But when both are used with a protocol that maximizes their effectiveness, using a tray system seems to hold the advantage.

 

We have an entire page dedicated to the issue of whitening strip effectiveness. And another that discusses how long your results will tend to last before touch-up treatments are needed.

 
 
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 Page references sources: 

Crest website. What are the Ingredients in Crest 3D White Whitestrips?

Gerlach RW, et al. Professional vital bleaching using a thin and concentrated peroxide gel on whitening strips: an integrated clinical summary.

Kwon SR, et al. Review of the Mechanism of Tooth Whitening.

All reference sources for topic Teeth Whitening Strips.

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