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Carbamide Peroxide For Teeth Whitening: Things To Know

Updated: Dec 19, 2023

It is well established that hydrogen peroxide (HP) can whiten your teeth since ZOOM uses a 25% product for in-office sessions. However you've probably also seen some teeth whitening products which contain carbamide peroxide (CP) instead.

carbamide peroxide whitening gel by kor in icebox
carbamide peroxide whitening gel by kor in icebox

Examples of CP based products:

  • Auraglow teeth whitening

  • Opalescence PF

  • Smile Titan

Does it also whiten your teeth and how does it do so? We will explain everything there is to know about carbamide peroxide for teeth whitening.

Does it whiten your teeth?

Similar to hydrogen peroxide, carbamide peroxide does possess the ability to make your teeth whiter. Both of them will remove both types of stains on your teeth, extrinsic and intrinsic ones. There have been studies which compared HP vs CP and also varying concentrations of CP with itself.

According to a study in JADA, which compared a 10% vs 15% carbamide peroxide product, the latter showed a more significant color change. Both concentrations whitened the teeth but the more concentrated one made the teeth whiter.

16 percent carbamide peroxide whitening gel

There was also another study in JADA, which compared 20% carbamide peroxide with 7.5% hydrogen peroxide. Initially, the CP whitened the teeth more but by the end of the study both products whitened teeth to the same degree.

It is also important to note that despite the differing concentrations, they were actually relatively similar. The reason being CP:HP is in a 3:1 ratio. That means 30% CP will produce about 10% HP. Therefore the concentrations in that study were relatively similar.

In conclusion without a shred of doubt, carbamide peroxide can and will whiten your teeth if you put it in your mouth.

How does carbamide peroxide whiten teeth?

Carbamide peroxide whitens your teeth by decomposing into perhydroxyl, a very potent free radical that can oxidize stains.

The first step is decomposing carbamide peroxide into hydrogen peroxide. After all, another name for CP is urea-hydrogen peroxide and is essentially a source for HP. It is simply a mixture of urea and hydrogen peroxide. This is why it's really not that different from HP.

Credit: Aina N. Gadanha, Charline R. Rossini, João P. S. Fernandes & Márcio Ferrarini

After it breaks down into hydrogen peroxide, it will further decompose into water and oxygen. However there are many intermediary steps where free radicals are formed such as perhydroxyl.

hydrogen peroxide decomposition to radicals - reaction equations

It is these intermediate byproducts which bleach your teeth. They literally diffuse through the tooth and oxidize all of the stains. Well to be more precise, the radicals oxidize double conjugated bonds of stain molecules. It transforms the double bonds to single bonds.

Hydrogen peroxide oxidation of double bonds
Credit: Clifton Carey

The more double bonds the stain molecules have the more light it will absorb and the less of it it will reflect. When they are converted to single bonds, it will absorb less light and reflect more of it.

That makes the stains appear whiter or to be more precise, it just makes them invisible to the naked eye. The stain molecules were technically never removed since they're still in the tooth but they just appear white to us. That is basically how hydrogen whitens teeth and since carbamide peroxide is the precursor, it just requires an extra step in the process.

How long does it take to whiten?

Depending on the concentration of carbamide peroxide used, the speed of whitening will differ. A more concentrated product will show results faster than a less concentrated one.

This was demonstrated in a study by Dental Materials, which compared 0%, 10%, and 17% carbamide peroxide.

  • Color change was observed after 3 days with the 17% product.

  • For the 10% it took about 7 days for a noticeable color change.

  • However at the 1 week mark, there were no significant differences in whitening between the 10% and 17% groups.

Based on the study above, it seems like the more concentrated CP product will get your teeth white faster. Although the end result will be the same regardless of what concentration you used. That is consistent with most research studies showing that all whitening concentrations can whiten your teeth to the same level. It's just that lower concentration products require more time to get to the same end result.

How does it compare to hydrogen peroxide?

Hydrogen peroxide will whiten your teeth faster than carbamide peroxide because there are less steps involved. It will also decompose faster and due to its naturally unstable structure.

crest whitening strips use hydrogen peroxide
crest whitening strips use hydrogen peroxide

According to Opalescence, hydrogen peroxide exerts most of its whitening effect within 30-60 minutes. That is in contrast to carbamide peroxide which exerts 50% of its whitening effect in the first 2 hours and slowly releases the rest over the next 6 hours.

Carbamide peroxide will whiten your teeth at a slower rate but will eventually get you to the same result nonetheless. You can think of it as an extended release form of hydrogen peroxide. What contributes to the extended release is the addition of carbopol in CP.

Are there any side effects?

As with all teeth whitening products, the two most prominent side effects are sensitivity and gum irritation. However these symptoms should be mild and transient in nature. They usually subside on their own about 4 days after stopping treatment.

The amount of sensitivity from carbamide peroxide whitening is highly dependent on treatment time and the concentration.

A study in the Journal of the American Dental Association tested various treatment times with 10% CP. What they found was that the longer they used the product, the more sensitivity that was felt.

  • The group that whitened 8 hours a day experienced a lot more sensitivity than the 1 hour a day group.

  • The groups that whitened only for 15 and 30 minutes all experienced the same level of sensitivity.

The conclusion was that the longer you placed the peroxide on your teeth, the more sensitivity you will have!

Last but not least, typically a higher concentration of CP will result in more tooth sensitivity. This was verified in a study which compared 10% carbamide peroxide with 16%. The higher concentration group experienced more sensitivity during the 1st and 3rd weeks of treatment.


Carbamide peroxide is an effective tooth whitener since it is a precursor to hydrogen peroxide. It actually whitens your teeth via the same exact mechanism since it literally decomposes into HP. Basically it produces powerful free radicals during its decomposition which can oxidize stains.

The only downside is that it can make your teeth sensitive but that is the same with all whitening products. All of these whitening gels are very acidic and as you can imagine, putting acidic materials on your teeth is not pleasant. The good news is that these adverse effects are only transient in nature which means they'll heal itself after enough time has passed.


David Chen 200 x 200.jpg

About the author: Dr David Chen, DDS

Hello, I'm Dr Chen and I'm an actively practicing dentist in Long Island City, NY. I graduated from Columbia University College of Dental Medicine in 2016 but prior to going to dental school I was already working in the dental field. It's been more than a decade since I first got to know dentistry and let me tell you, time flies by quickly. Since then I've developed a fondness for writing, which is how this all got started!

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Medical Disclaimer:

This blog is purely meant for information purposes and should not be used as medical advice. Each situation in your mouth is unique and complex. It is not possible to give advice nor diagnose any oral conditions based on text nor virtual consultations. The best thing to do is to go in person to see your dentist for an examination and consultation so that you can receive the best care possible.

The purpose of all of this oral health information is to encourage you to see your dentist and to inform you of what you may expect during your visit. Due to the unfortunate nature of dentistry, there isn't really any true home remedies that will get rid of dental problems. Roughly 99.99% of them require in-person intervention by a healthcare professional.

Hint: That is the reason why you can't eliminate seeing dentists in your life!

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