What is Carbamide Peroxide Teeth Whitening?

What is Carbamide Peroxide Teeth Whitening?

Most people are familiar with hydrogen peroxide and might even have that familiar brown bottle in their medicine cabinet. Hydrogen peroxide has many uses including as a disinfectant, for bleaching hair, and even for removing ear wax. It is also an active ingredient in many teeth-whitening products. People may be less familiar with carbamide peroxide. It has many of the same applications and is also used to whiten teeth. 

Whether going to the dentist for teeth whitening or doing it at home, there might be confusion about choosing a product with hydrogen vs. carbamide peroxide. Does one work better or last longer? Are both carbamide and hydrogen peroxide safe? Although not exactly interchangeable, the differences between the two may not be as significant as one might think.

How Peroxide Solutions Brighten Teeth

A peroxide is any chemical compound containing two oxygen atoms. Adding hydrogen makes hydrogen peroxide, which is an oxidizing agent. This means that it causes a chemical reaction where the oxygen atoms lose electrons, altering the substance it is applied to. In the case of teeth whitening, hydrogen peroxide brings about a chemical reaction that works to dissolve most stains on teeth.

Carbamide peroxide is a combination of hydrogen peroxide and urea, another chemical compound that is also called carbamide. While it has a slightly different chemical makeup, carbamide peroxide is also an oxidizing agent and works on stains in the same way that hydrogen peroxide does.

Both compounds are applied to the teeth by the dentist in the form of a gel, or worn at home in trays that fit over the teeth.

Carbamide or Hydrogen Peroxide Tooth Whiteners—What’s the Difference?

Since hydrogen peroxide and carbamide peroxide remove stains with a chemical reaction, they are technically bleaching agents rather than whitening agents . Most people think that tooth whitening and bleaching are the same thing, but there is a slight difference. Bleaching usually refers to the use of chemicals that change the shade of the tooth’s enamel, whereas whitening is simply removing surface stains caused by things like coffee or wine. 


The real differences between carbamide and hydrogen peroxide are their strength and speed. Carbamide peroxide contains hydrogen peroxide in a 1:3 ratio. This means that a carbamide solution has only 10% hydrogen peroxide. In other words, carbamide peroxide is only a third as strong as hydrogen peroxide used by itself.

Bleaching Speed

In addition to hydrogen peroxide’s higher concentrations, the two work at different rates. Carbamide peroxide’s oxidizing power releases in the first 2 hours, and then continues to work for up to 6 more hours. Because it spends more time in contact with the teeth, it is often used in products that are worn overnight.

Hydrogen peroxide breaks down faster and does most of its work in the first 30 to 60 minutes. This is more likely to be used at the dentist’s office where a dental professional brushes it on and cleans it off while the patient is in the office.

Both types of peroxide solutions break down, becoming water when exposed to light. This is why hydrogen peroxide is sold in brown rather than clear bottles at the store. 

How Higher Concentrations of Whiteners Affect Tooth Sensitivity

The concentration of hydrogen peroxide and carbamide peroxide in teeth whitening products is safe when used properly. But any type of whitening treatment can cause short-term sensitivity. Using whitening products too often or leaving them on too long can make the situation worse.

The fact that carbamide peroxide takes longer to break down and is usually left on teeth longer means that the sensitivity can be a bit more intense. It may also cause more irritation to the gums, especially if precautions are not taken to protect them from contact with the chemicals. 

Most patients, however, do not see much difference in carbamide vs. hydrogen peroxide when it comes to sensitivity. Going to a dental professional for treatment is the best way to avoid any issues. And as long as over-the-counter products are used correctly , at-home whitening with either product should not cause teeth to be unusually sensitive.

Seeing the dentist for whitening also has the advantage of their expertise about what will work best on the particular stains in a patient’s mouth.

Success Rate of Carbamide Peroxide Teeth Whitening

As bleaching agents, both hydrogen and carbamide peroxide are equally effective. A study conducted by the American Dental Association found that initially, patients using carbamide peroxide had a more significant change. But after 12 weeks, the results were the same for teeth treated with hydrogen peroxide and carbamide peroxide.

Dentists also see little difference in “rebound.” Rebound is when a patient sees an initial dramatic change in shade that disappears within a few days. Both carbamide and hydrogen peroxide produce effects that last for a comparable period of time.

No whitening is permanent, however. Depending on the type of treatment and degree of staining, whitening or bleaching can last months or even years. But eventually, it will need to be refreshed to maintain the desired shade of white.

Tooth Whiteners and Different Types of Stains

Tooth discoloration can come from external sources (extrinsic) that cause surface stains. Common causes are:

  • Tobacco use
  • Red wine
  • Coffee or tea

Many over-the-counter products can help with this type of discoloration by giving the teeth a deep cleaning. These products may include a peroxide solution as their active ingredient or just abrasive ingredients to scrub away stains. 

Intrinsic stains are harder to remove as they penetrate beyond the tooth’s surface. The causes of these types of stains are:

  • Heredity
  • Aging
  • Tooth decay
  • Antibiotics and other medications

Unfortunately, in some cases, even the most powerful whitening agents will have no effect on intrinsic stains. 

If stains are removable, both carbamide and hydrogen peroxide will do an equally good job. The higher concentrations of these bleaching agents do more than just clean. They break down the chemical makeup of the stain so it disappears little by little with each treatment.

Teeth Whitening Choices

Before patients attempt any teeth whitening, they should check with their dentist to make sure their teeth are healthy. If tooth decay is present, the harsh chemicals can cause pain beyond the normal, mild sensitivity that is expected with teeth whitening. 

The drugstore and online marketplace are filled with a variety of whitening toothpaste, rinses, gel strips, and trays. Some of these contain either hydrogen peroxide or carbamide peroxide. At-home products may be fine for some stains, but they are less powerful than what a dentist will use. They typically contain peroxide in a concentration of 3% to 10%.

Dentists have access to much higher concentrations of chemicals because they offer them in a controlled, professional environment. They may use peroxide solutions up to about 40%. Their supervision during treatment will also ensure that the teeth and gums are protected and that the desired effect is achieved without over-bleaching.

Seeing the dentist for whitening also has the advantage of their expertise about what will work best on the particular stains in a patient’s mouth. They may suggest a special product or procedure such as Zoom! or laser teeth whitening for the best results.

If there is no hope of changing certain stains with typical bleaching techniques, the dentist can discuss other options. Veneers or dental bonding can completely cover teeth that have permanent intrinsic stains or that are beyond repair.

Consider Teeth Whitening With a Dentist

Teeth whitening is a popular and effective way to refresh the appearance of your smile. Carbamide peroxide, like hydrogen peroxide, can help you achieve that goal. If you’d like to find a dentist who offers teeth whitening, use our online search tool and make an appointment for a consultation.