Teeth whitening

Dental whitening, also known as teeth 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 teeth, 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: whitening strips, whitening pen, whitening gel, laser whitening, and natural whitening. Traditionally, at-home whitening is done with whitening 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 teeth. 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. Power whitening uses light energy to accelerate the process of whitening in a dental surgery. The effects of whitening 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 dentine can discolor the teeth from inside out. Internal whitening 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 teeth discoloration.

Methods of Teeth Whitening

There are two main methods of gel whitening—one performed with high-concentration gel, and another with low-concentration agents. High-concentration whitening 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 whitening gel, ensuring even and full teeth 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 whitening 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 whitening agent is either carbamide peroxide, which breaks down in the mouth to form hydrogen peroxide, or hydrogen peroxide itself. The whitening gel typically contains between 10% and 44% carbamide peroxide (15% is recommended) which is roughly equivalent to 3-10% hydrogen peroxide concentration.

Low-concentration whitening is far less effective, and is generally only performed at home. Low-concentration whitening involves purchasing a thin mouthguard or strip that holds a relatively low concentration of oxidizing agent next to the teeth for as long as several hours a day for a period of 5 to 14 days. Results can vary, depending on which application is chosen, with some people achieving whiter teeth in a few days, and others seeing very little results or no results at all. Whitening is potentially better at a dentist because the strip or mouth-guard does not completely conform to the shape of the teeth, sometimes leaving the tips of the teeth (near the gumline) unbleached. The whitening agent is typically less than 10% hydrogen peroxide equivalent, so irritation to the soft tissue around teeth is minimized. Dentists as well as some dental laboratories can fabricate custom fitted whitening trays that will greatly improve the results achieved with an over-the-counter whitening method.

A typical course of whitening can produce dramatic improvements in the cosmetic appearance of most stained teeth; however, some stains do not respond to whitening. Tetracycline staining may require prolonged whitening, as it takes longer for the bleach to reach the dentine layer. Case studies have been performed on people with tetracycline stained teeth. They used Custom Bleaching Trays every night for 6 months and saw dramatic results and improvement. White-spot decalcifications may also be highlighted and become more noticeable directly following a whiting process, but usually calm back down with the other parts of the teeth becoming more white. The white spots become less noticeably with the other parts of the teeth becoming more white0. Bleaching is not recommended if teeth have decay or infected gums. It is also least effective when the original teeth color is grayish and may require custom whitening trays. Bleaching is most effective with yellow discolored teeth.

Power or light-accelerated whitening, sometimes colloquially referred to as laser whitening, uses light energy to accelerate the process of whitening in a dental office. Different types of energy can be used in this procedure, with the most common being halogen, LED, or plasma arc. Clinical trials have demonstrated that among these three options, halogen light is the best source for producing optimal treatment results. The ideal source of energy should be high energy to excite the peroxide molecules without overheating the pulp of the teeth. Lights are typically within the blue light spectrum as this has been found to contain the most effective wavelengths for initiating the hydrogen peroxide reaction. A power whitening treatment typically involves isolation of soft tissue with a resin-based, light-curable barrier, application of a professional dental-grade hydrogen peroxide whitening gel (25-38% hydrogen peroxide), and exposure to the light source for 6–15 minutes. Recent technical advances have minimized heat and ultraviolet emissions, allowing a less time-intensive patient preparation procedure. Most power teeth whitening treatments can be done in approximately 30 minutes to one hour, in a single visit to a dental physician. Treatment times and recommendations are dependent on the condition of a person’s teeth at time of treatment.