An Introduction To Dental Whitening
Dental whitening, also known as tooth whitening, is a common procedure in general dentistry but most especially in the field of cosmetic dentistry. A child's deciduous teeth are generally whiter than the adult teeth that follow.
As a person ages the adult teeth often become darker due to changes in the mineral structure of the tooth, as the enamel becomes less porous. Teeth can also become stained by bacterial pigments, foodstuffs and tobacco. Certain antibiotic medications (like tetracycline) can also lead to teeth stains or a reduction in the brilliance of the enamel.
There are many methods to whiten teeth: bleaching strips, bleaching pen, bleaching gel, laser bleaching, and natural bleaching. Traditionally, at-home whitening is done with bleaching gel which is applied to the teeth using thin guard trays. At-home whitening can also be done by applying small strips that go over the front teeth.
Oxidizing agents such as hydrogen peroxide or carbamide peroxide are used to lighten the shade of the tooth. The oxidizing agent penetrates the porosities in the rod-like crystal structure of enamel and oxidizes interprismatic stain deposits; over a period of time, the dentin layer, lying underneath the enamel, is also bleached.
Laser bleaching uses light energy to accelerate the process of bleaching in a dental office. The effects of bleaching can last for several months, but may vary depending on the lifestyle of the patient. Factors which will decrease whitening include smoking and the ingestion of dark colored liquids like coffee, tea and red wine.
Internal staining of dentin can discolor the teeth from inside out. Internal bleaching can remedy this. If heavy staining or tetracycline damage is present on a patient's teeth, and whitening is ineffective, there are other methods of whitening teeth. Bonding, when a thin coating of composite material is applied to the front of a person's teeth and then cured with a blue light can be performed to mask the staining. A veneer can also mask tooth discoloration.
There are two main methods of gel bleaching—one performed with high-concentration gel and another with low-concentration agents. High-concentration bleaching can be accomplished either in the dental office, or at home. Performing the procedure at home is accomplished using high-concentration carbamide peroxide, which is readily available online or in dental stores and is much more cost-effective than the in-office procedure.
Whitening is performed by applying a high concentration of oxidizing agent to the teeth with thin plastic trays for a short period of time, which produces quick results. The application trays ideally should be well-fitted to retain the bleaching gel, ensuring even and full tooth exposure to the gel. Trays will typically stay on the teeth for about 15–20 minutes. Trays are then removed and the procedure is repeated up to two more times.
Most in-office bleaching procedures use a light-cured protective layer that is carefully painted on the gums and papilla (the tips of the gums between the teeth) in order to reduce the risk of chemical burns to the soft tissues.
The bleaching agent is either carbamide peroxide, which breaks down in the mouth to form hydrogen peroxide, or hydrogen peroxide itself. The bleaching gel typically contains between 10-30% carbamide peroxide (15% is recommended) which is roughly equivalent to 3-10% hydrogen peroxide concentration.
Generally, consumer organizations, health sector professionals and people who benefit financially from the dental industry recommend that bleaching products should only be used after consultation with a dentist, while the cosmetic industry, its organizations and people who benefit financially from cosmetic sales argue that, since bleaching products are basically safe, they should be freely available over the counter.
