Safety concerns associated with carbamide peroxide tooth whiteners.

In the case of tooth whiteners, it is their peroxide component that is their active ingredient. Peroxide molecules break down (oxidize) pigmented compounds trapped in a tooth's enamel into colorless byproducts, thus producing a lightening effect. As it happens, the peroxide that is counted upon to perform this oxidation process is hydrogen peroxide. So, right now you may be wondering why, since it is hydrogen peroxide that does the work, do our pages stress the use of carbamide peroxide tooth whiteners?

Carbamide peroxide is a compound composed of hydrogen peroxide and urea. In the presence of water carbamide peroxide breaks down into its component parts, thus providing the hydrogen peroxide needed to perform the tooth whitening process (the urea plays no role). The reason carbamide peroxide is used in whiteners is because it is a relatively more stabile molecule than hydrogen peroxide. By using carbamide peroxide in their whitener formulations manufacturers can deliver the hydrogen peroxide needed to produce the lightening effect yet create a product that has a more predictable and longer shelf life.

Another factor to be considered is this. When the compound hydrogen peroxide is used in a whitener it typically decomposes fairly rapidly, at least in comparison to a carbamide peroxide formulated gel. The net result can be that the whitener will become depleted of those molecules that create its whitening effect, possibly as quickly as within the first hour of it being placed into the user’s mouth.

In comparison, carbamide peroxide degrades more slowly. Studies have shown that a carbamide peroxide tooth whitener will release about 50% of its whitening potential during the first two to four hours of being in the user’s mouth and then the remainder over the next two to six hours. This slower release of peroxide, and associated more gradual whitening process, is thought to help to minimize whitening side effects.

---

What are the safety concerns associated with the use of 10% carbamide peroxide teeth whiteners?

As we state in our section titled "About at home teeth whitening products: Know what you are buying.", all references to teeth whiteners, bleaches, bleaching agents, bleaching gels, etc... found on the pages of this topic refer to 10% carbamide peroxide whitening products. With the continued accumulation of data by dental researchers over the last 15 years, it has become generally accepted by the dental community that 10% carbamide peroxide whiteners (when utilized in conjunction with tray-based whitening technique) are safe to use (when these products are used as directed by both the product's manufacturer and the person's dentist).

Will 10% carbamide peroxide teeth whiteners cause cancer?

Concerns have been postulated that teeth whiteners can possibly cause cancer of the soft tissues of the mouth. These concerns are related to the fact that the peroxide contained in teeth 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.

• 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 using custom bleaching trays fabricated by a dentist the contact between the tooth whitener and a person's soft tissues ("gums") is minimal.
  
  
• One of the human body's main 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 30mg of peroxide in one minute. The typical single application of carbamide peroxide tooth whitener is only 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.

Will 10% carbamide peroxide teeth whiteners damage tooth enamel?

Studies evaluating 10% carbamide peroxide whiteners have found minimal or no effect on the microhardness or mineral content of tooth enamel surfaces. Scanning electron microscope studies of the enamel 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 teeth whitener has adversely affected the enamel of a person's teeth. These cases involved whiteners that had either: a high peroxide content, an acidic pre-rinse, or the whitener itself was acidic. These whiteners were purchased and 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.

Will 10% carbamide peroxide teeth whiteners damage the nerve in my tooth?

Research studies and the clinical observation of the dental community as a whole have not identified a problem associated with the use of dentist-dispensed at-home tray-based teeth whitening systems utilizing a 10% carbamide peroxide whitener and the health of the nerve tissue found in the user's teeth. 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.

Will peroxide-based teeth whiteners damage my 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 some of the findings related to the effect peroxides can have on various types of dental materials and restorations.) Your dentist can address any specific concerns you may have during your pre-whitening dental examination.

The main difficulty encountered in conjunction with existing dental work is that it does not lighten during the whitening process (with the exception that the color of porcelain veneers may be affected, as mentioned in the link 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.