The composition of a bleaching gel's formulation will typically adhere to a fairly standardized set of ingredients.
Those whiteners intended for use in bleaching trays need to possess certain basic characteristics. In order to meet these requirements, the following types of compounds are typically included in a bleaching gel's ingredient lists.
1) A bleaching agent.
Historically, the active ingredient contained in tooth whitening gels has been carbamide peroxide.
When exposed to water (which of course is abundant in the oral environment), carbamide peroxide breaks down into hydrogen peroxide (and urea). It is this hydrogen peroxide component that subsequently breaks down and produces the actual molecules (free radicals) that produce a tooth whitening effect.
Different whitening products will likely contain different concentrations of bleaching agent.
It is common that a company will manufacture more than one whitening gel product, each of which has its own specific carbamide peroxide concentration (typically ranging somewhere between 10 and 38%).
The advantage of a higher concentration whitener is that the tooth whitening effect will be produced more rapidly. The disadvantage of a higher concentration gel is that it will be more likely to create bleaching side effects (such as tooth sensitivity and gum irritation).
An important fact to know is that either form (meaning either a relatively higher or lower concentration whitening gel) can be used to produce an essentially identical end level of tooth lightening effect.
Side Bar : Why don't we discuss the use of hydrogen peroxide whitening gels on our pages?
Our pages typically shy away from discussing the use of whitening gels that have been formulated with hydrogen peroxide (as opposed to carbamide peroxide). At least a part of our reason for doing so is founded upon the history of tray-based at-home whitening technique.
Carbamide peroxide-based whitener was the first type of bleaching gel to be used with tray whitening methodology. And over the years it has been the one most studied. Because of this we think that it makes an excellent choice. However, we will readily concede that several quality manufacturers do make hydrogen peroxide-based gels.
( Related: Why are some whitening gels formulated with carbamide peroxide while others contain hydrogen peroxide? )
Not all tooth whiteners have the same instructions set.
One concern that we have is that not all whiteners are intended to be used in the same fashion. The type of peroxide used in the formulation, the concentration of this peroxide and the pH of the whitener all play profound roles in determining what application time frame is suitable for a product.
Since we don't want to create any confusion for our readers, on our pages we only discuss the use of a neutral pH 10% carbamide peroxide whitening gel with tray-based at-home teeth whitening technique. This way we can be specific and accurate when discussing details on our pages.
2) Gelling agents.
So to be suitable for use in a bleaching tray, a whitening gel must be viscous enough (thick enough) that it doesn't easily escape.
At the same time, however, a gel does need to be runny enough that it readily spreads out and covers over the teeth being treated. In order to meet these requirements, most whiteners contain an emulsifying (thickening) agent so their flow characteristics are ideal.
3) Desensitizing Agents.
Some manufacturers include a desensitizing agent in the formulation of their bleaching gels. They feel that by doing so they can help to minimize the degree of bleaching-induced tooth sensitivity that the users of their products experience.
Many brands of whiteners contain desensitizing agents.
As a point of interest, here's a listing of some of the brands of whiteners (typically sold directly to dentists for use with their patients) that do contain a desensitizing agent. In most cases the desensitizing compound that has been added is fluoride.
Nupro White Take Home, Discus Dental NightWhite, Discus Dental DayWhite, GC TiON Take Home, Natural Elegance Plus, Venus White, Pola Day, Pola Night, Opalescence PF
[ Source: Dentistry Today. Guide to At-Home Whitening Systems. December 2008. ]
4) Flavoring Agents.
So to help to insure that the use of their product is as pleasant as possible, many manufacturers include a flavoring agent in the formulation of their whitening gels. This is especially common with tooth whiteners that contain a relatively higher concentration of bleaching agent.
Many brands of tooth whiteners contain flavoring agents.
As a point of interest, here's a list of some of the brands of whiteners (typically sold directly to dentists for use with their patients) that do contain flavoring.
Beyond StayWhite, Sapphire Take Home, Nupro White Take Home, Discus Dental NightWhite, Discus Dental DayWhite, Zoom! Weekender, Natural Elegance Plus, Venus White, Life-Like Cosmetic Solutions, Omni White & Brite, Pola Day, Pola Night, Star White, Opalescence PF
[ Source: Dentistry Today. Guide to At-Home Whitening Systems. December 2008. ]
5) Stabilizers.
Peroxides are by nature relatively reactive. And because of this tooth whiteners tend to degrade over time, which in turn compromises their effectiveness.
As a way of increasing the shelf life of their products and insuring customer satisfaction, the formulation of most whiteners includes a stabilizer. Unless otherwise stated, you can anticipate that most carbamide peroxide-based whitening products are intended to have a shelf life of at least one year.
6) Buffering Agents.
The pH (measured acidity) of a whitening product should be as close to neutral as possible (pH 7.0). Whiteners that have a comparatively high level of acidity are more likely to create bleaching-induced tooth sensitivity and, in extreme cases, even tooth damage.
It is generally considered that an acceptable pH range for a whitening gel is between 5.5 and 8.0. As a way of achieving this measure, most whitening gel formulations include buffering agents.
