Carbamide peroxide whiteners - What are the safety concerns? / Why are some whitening gels formulated using hydrogen peroxide?

What are the safety concerns associated with using a carbamide peroxide tooth whitening gel?

While it is important to know that a teeth whitening system can be effective, it is clearly much more important to know that it is safe to use.

Research studies (stemming back to the introduction of tray-based teeth bleaching technique in 1989) have collectively documented that although tray whitening systems can create side effects, those utilizing a 10% carbamide peroxide whitener (such as those typically dispensed by dentists in their offices) can be considered to be safe to use.

And, in fact, tray-based teeth whitening has gained widespread acceptance by the dental community as a whole. The overwhelming majority of dentists in this country do offer tray teeth whitening systems to their patients because they know it has been time-tested to be both safe and effective.

Carbamide Peroxide vs Hydrogen Peroxide: Why aren't all whitening gels formulated with the same compound? / Are the safety concerns the same?

Throughout our pages we make reference to the use of carbamide peroxide whiteners with tray-based teeth whitening technique. You might ask yourself, what is carbamide peroxide and why is it used in tooth whitener formulations?

A bleaching gel's peroxide component is the ingredient that produces its tooth whitening effect.

In the case of tooth whiteners, it is their peroxide component that serves as the active ingredient for the tooth whitening process.

Peroxide compounds are capable of breaking down (oxidizing) those pigmented compounds that have become entrapped in a tooth's enamel layer. Because the byproducts that result from this reaction are colorless, the tooth receives a lightening effect.

Technically speaking, it's hydrogen peroxide that creates tooth whitening.

The compound that is the immediate precursor of the actual molecules that produce a tooth whitener's lightening effect is hydrogen peroxide. When hydrogen peroxide decomposes it releases "free radicals." It is these highly reactive molecules that then break down the colored compounds that have cause a tooth's staining.

If hydrogen peroxide does the bleaching work, then why is carbamide peroxide used in tooth whitener formulations?

Carbamide peroxide is used in tooth whitener formulations because when it initially starts to break down it produces hydrogen peroxide (and urea). It is this created hydrogen peroxide that then produces free radicals and subsequently a tooth whitening effect.

There can be a number of reasons why a manufacturer or dentist might prefer to make or use a product that contains one or the other of these two of peroxides. For more information about this subject, please use the following links.

What ingredients do tooth whitening gels contain?
Reasons why some bleaching gels are formulated with carbamide peroxide and others with hydrogen peroxide.

The safety concerns regarding hydrogen peroxide and carbamide peroxide whiteners are very similar.

A bleaching gel's formulation can have a profound effect on the manner in which it should be utilized. A product's directions should always be read and complied with. From a standpoint of whitening science and the chemistry involved, however, those bleaching gels formulated with either carbamide or hydrogen peroxide work in a similar fashion and have similar safety concerns.

Please note that we have chosen, primarily for the sake of being able to be specific and accurate in our statements, to limit the comments on our pages to whitening gels (intended for use with tray whitening technique) having a 10% carbamide peroxide formulation.

What are the safety concerns associated with the use of 10% carbamide peroxide tooth whitening gels?

A) Can carbamide peroxide teeth whiteners cause cancer?

Concerns have been postulated that whitening gels might possibly cause cancer of the soft tissues of the mouth. These concerns are related to the fact that the peroxide contained in tooth whiteners breaks down to form molecules called "free radicals." Free radicals are capable of causing cellular damage.

The appropriate use of dentist-monitored at-home teeth whiteners containing 10% carbamide peroxide have not been shown to produce a carcinogenic risk. In regards to this matter, the following facts might help to put your concerns at ease.

• The concentration of hydrogen peroxide produced by these whiteners is low, on the order of 3.5%. Studies involving hydrogen peroxide at about this same concentration (actually 3.0%) have not shown a carcinogenic risk.
  
  
• When used with custom bleaching trays, the contact between the tooth whitener and a person's oral soft tissues is minimal.
  
  
• One of the human body's primary defenses against the adverse effects of peroxide is a compound found in saliva. This compound has been calculated to be able to effectively neutralize about 30 mg of peroxide in one minute. The typical single application of carbamide peroxide tooth whitener is only about 3.52 mg.
  
  
• Calculations have estimated that, on average, the total amount of peroxide that a person is exposed to each day when bleaching their teeth is less than .1% of the daily production of peroxide created by their liver.

B) Can carbamide peroxide teeth whiteners damage tooth enamel?

Studies evaluating 10% carbamide peroxide whitening gels have found minimal or no effect on the microhardness or mineral content of tooth enamel surfaces. Additionally, scanning electron microscope studies evaluating the enamel surface of teeth that have been bleached have typically not shown damage either. As a point of comparison, studies have shown that exposure to soft drinks and fruit juices can cause comparable or greater alteration of tooth enamel than tooth whiteners.

Two clinical cases have been documented in dental literature where the use of an over-the-counter tooth whitener did adversely affect tooth enamel. These cases involved whiteners that had either: a high peroxide content, an acidic pre-rinse, or the whitener itself was acidic.

These whiteners were used without the oversight of a dentist. The tooth damage caused by these whiteners was irreversible and the dental treatment needed to repair the damage involved significant effort and cost.

C) Will carbamide peroxide tooth whiteners damage a tooth's nerve?

Research studies evaluating the use of dentist-dispensed at-home tray-based teeth whitening systems utilizing a 10% carbamide peroxide whitener have not identified a problem associated with the health of tooth nerve tissue. The clinical observations of the dental community as a whole seem to confirm these conclusions as well. One study's specific findings were that no one in their 4.5 and 7-year follow-up groups reported requiring root canal treatment for any tooth that had received whitening treatments.

D) Will peroxide-based teeth whiteners damage existing dental restorations?

Teeth can be whitened using an at-home bleaching system employing a 10% carbamide peroxide whitener with little concern about significant damage to a person's existing fillings. More than 15 years of clinical use of these products has not revealed any significant problems or concerns.

Some studies have suggested that some degree of interaction or change might occur with white dental fillings, amalgam dental fillings, and some types of dental cements. However, the clinical significance of these effects is still considered to be inconclusive.

Our "Effects of peroxide whiteners on existing dental work." page discusses this topic in greater detail.

The main difficulty encountered in conjunction with existing dental work is that it will not lighten during the whitening process (with the exception that the color of porcelain veneers may be affected, as discussed on the page referenced above). This means that pre-existing dental work will usually have to be replaced so to match a person's new, post bleaching tooth shade.