Whitening strips make your teeth whiter by utilizing a flexible adhesive plastic strip which applies and holds the bleaching gel against the enamel.
The teeth whitening is solely due to the hydrogen peroxide in the gel. The purpose of the strip is to act as a delivery/applicable mechanism for the gel to reach and stay on the teeth. That is how whitening strips work.
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Whitening strips contain bleaching gel
Whitening strips contain hydrogen peroxide which is the main bleaching agent in ALL teeth whitening products. Yes, the take home trays, whitening pens, toothpastes, mouthwashes, and even at the dentist treatments all use peroxide or at least some derivative of it.
That means it has legitimate whitening material in the product so there is no reason as to why it wouldn't work. The only difference is that the strips contain a lower concentration of peroxide when compared to an in-office whitening session at the dentist. Although it does contain a higher concentration than say whitening mouthwash or toothpaste.
How does hydrogen peroxide whiten teeth?
The actual strips don't whiten your teeth because they're simply there to deliver or help apply the hydrogen peroxide to your teeth. It is the peroxide that does the bulk of the heavy lifting that makes your teeth whiter. Without the hydrogen peroxide, your teeth would not lighten in color at all.
Hydrogen peroxide whitens your teeth by diffusing through each layer of the tooth while chemically oxidizing all of the embedded stains. When we say each layer of the tooth, we mean it because this bleaching agent is capable of even reaching the pulp.
Since the peroxide is able to travel through the tooth to bleach it, that means the strips can whiten extrinsic and intrinsic stains. That makes it more effective than whitening toothpaste which utilize abrasives to remove extrinsic stains only. The reason why brushing can only remove exterior stains is because the bristles cannot come into contact with the deeply embedded intrinsic stains.
Therefore teeth whitening strips can work because they do contain bleaching material in it. It is the hydrogen peroxide within the strips that permit them to remove extrinsic along with intrinsic teeth stains. That is how teeth whitening works with the strips.
Purpose of the flexible plastic strip
The flexible plastic strips don't whiten your teeth because that effect is solely due to the hydrogen peroxide. The entire purpose of the strips is meant as a medium to apply or deliver the whitening material onto the surfaces of your teeth.
The strips have an adhesive on it that allows it to stick to the surfaces of your teeth so that the peroxide can be in constant contact with your enamel. Without the strips, the whitening gel may slide off your teeth or get washed away by saliva. Therefore you should think of them as a delivery mechanism that holds it against your teeth.
It is similar to skin patches that hold numbing medication to alleviate muscle aches. The patches themselves do not relieve your pain but it is the anesthetic in the patches that do. Thus, they work in a very similar manner to whitening strips.
Different types of whitening strips
Not all teeth whitening strips are the same because there are different types of them. Some of the strips dissolve while others do not.
The vast majority of the strips do not dissolve:
Crest 3D whitestrips
That means after you finish the treatment time you will need to manually remove the strips from your teeth. They won't disintegrate all on their own.
There is one product from Moon oral care which utilizes self dissolving whitening strips. Their strips do not need to be removed because they will naturally dissolve on their own by the end of the treatment. According to them, it is a "no mess" option.
Are whitening strips effective?
Whitening strips are effective in making your teeth whiter because they do contain hydrogen peroxide. That is the only ingredient which is able to oxidize intrinsic and extrinsic stains.
However they are not as effective as a professional option such as take home trays from your dentist and the in-office sessions. The main differentiating factor is that the options from your dentist typically contain a higher concentration of hydrogen peroxide.
Nonetheless, the strips should be more effective than other options such as whitening mouthwash and toothpastes. The reason being it tends to have a higher concentration of peroxide than those two.
Therefore the effectiveness of the strips is somewhere along the middle of the spectrum for teeth whitening products. They're a good option since they're inexpensive and they work better than toothpaste.
Effectiveness of dissolving vs non-dissolving strips
We do want to make a quick comment about the dissolvability of whitening strips. The non-dissolving ones probably work better than the ones which do dissolve.
Teeth whitening works based on contact time so the longer that the gel stays in contact with your teeth the more effective it will be. If the strips dissolve quickly, your saliva can wash it off your teeth fairly easily. We don't want that to happen, we actually want the strips to not dissolve so that it can hold the gel against the teeth.
The non-dissolving flexible strips also hold an advantage in that they double up as a saliva barrier. It protects the bleaching gel from the saliva, which is a very important point because saliva contains salivary peroxidases. These are enzymes which deactivate peroxide, which means they inactivate the whitening gel.
Therefore saliva is the arch-nemesis of whitening gels. It is also why you want to figure out ways on how to stop saliva when you're whitening.
Do whitening strips damage teeth?
The strips will typically cause mild and transient teeth sensitivity but it won't permanently damage them. According to the American Dental Association, you can expect the sensitivity to show up after the second-third day of treatment. However it should resolve after about 4 days after stopping the treatment.
According to research studies, most concentrations of hydrogen peroxide can produce adverse effects but they usually all recover after stopping usage. Their recommendation was that if you were to use a higher concentration product, you need to use it for a shorter amount of time.
All concentrations below the in-office products did not produce any lasting toxic effects on the pulp. The only one which was capable of doing so was a high concentration for a long period of time.
For that reason alone, it is important to only whiten for the specified amount of times that the instructions say to use it for. Therefore they are safe to use since they are an OTC product. Their concentration is not potent enough to cause any damage anyway.
Whitening strips work by utilizing hydrogen peroxide, which is the primary bleaching agent in the product. The entire purpose of the strips is simply to hold the whitening gel against the teeth so that it can whiten them. Without them, the gel may not stay on the teeth.
This is an inexpensive option that everyone can try. If it works then that is great because it is easy and you can save a lot of money. If it doesn't work then you'll need to give one of the more professional options a try!