Whitening works by applying carbamide or hydrogen peroxide solution to the tooth surface. Peroxide whitener reacts with water to form hydrogen, which produces the whitening. The degree of tooth whitening obtained is directly proportional to the strength of the whitening solution and the amount of time the solution is in contact with the tooth. Concentrations used for tooth whitening can be as low as 2-5% or as high as 22-35%. Some patients experience no side effects in whitening, while others experience tooth sensitivity and/or burns to the soft tissue.
Results depend on a number of factors:
- The strength or percentage of the bleaching solution
- The amount of time the bleaching agent remains active
- The amount of time the active solution is in contact with your teeth
- The number of repeated applications
Disadvantages of whitening include, but may not be limited to:
- The possibility of extreme tooth sensitivity to cold and air
- The burning of gum tissue (excess solution can spread to gum tissue and cause burns)
- There is a limit to how white your teeth may become; many patients have unrealistic expectations and continue to seek whiter and whiter teeth, even after their teeth have been whitened as far as they will go.
- Fillings and crowns will not whiten with your teeth; if you have a crown or fillings in the area you plan to bleach, you may need to have them replaced after you have reached your bleaching goals.
Whitening strips are impregnated with various percentages of bleaching agent and can be purchased over the counter. They are placed on your teeth like a band-aid, wrapping around the edges of your teeth. Depending on the strength of the strips, these strips whiten your teeth over time. With repeated use, your teeth will whiten, and at some point, you will reach an end point where no further whitening will occur.
- Whitening trays are a take-home system that involves filling custom trays with various percentages of whitener and placing them over your teeth for a period of time. There are custom trays manufactured by your dentist that fit only you. There are over-the-counter trays, which do not hold bleaching solution as close to your teeth as the custom trays will. It is the close proximity of the bleaching agent to the tooth surface that whitens your teeth.
- In-office whitening systems are used under the supervision of your dentist. This system uses a powerfully high percentage of bleaching agent, and heat from a UV light activate and heighten the bleaching reaction. Gum tissue around your teeth is blocked with a protective “dam” because the solution can burn the soft tissue.
- Internal bleaching is whitening your tooth from the inside. If you have a tooth that has changed color following a root canal treatment that does not need a crown, this procedure may help. Once a tooth has had a root canal treatment and the color of the tooth has changed, your dentist can bleach the tooth from the inside. Once the root canal treatment has been completed and the opening to the canal has been sealed, a mixture of superoxyl and peroxide is placed on a cotton pellet and sealed inside the crown of your tooth. This method of whitening is called a “walking bleach,” and it will lose its power to whiten and have to be replaced with a fresh solution in a few days. This type of whitening can take between one and as many as six or more visits to reach the desired results. The length of time required to reach the desired results is usually dependent on how long your tooth has been dead.