Teeth Whitening

Learn about causes of tooth discoloration and how to minimize the change in tooth shade. Learn about different methods of tooth whitening (bleaching), including over the counter products, in office whitening as well as at home whitening with products obtained from your dentist.

What is Teeth Whitening?

Teeth whitening or teeth bleaching as it is commonly known is a process that changes the shade of teeth, to a lighter more natural white, by removal of internal stains, which cause tooth discoloration. Internal stains are usually perceived as yellow or light brown in color. Teeth whitening products are used to eliminate internal stains, or stains that are located inside the tooth. This is in contrast to external stains, which are found on the outer surface of the teeth.


What causes tooth staining?

As mentioned above there are two forms of stains that can affect the shade or color of teeth. Lets examine more closely the internal and external tooth stains and possible causes of staining.

External tooth stains are very common because teeth are affected by substances present in our daily diet. External tooth stains are commonly referred to as extrinsic stains. Pores present in the outer layer of the tooth (enamel) acquire stains, which over time affect the shade or color of the teeth. Some of the more common causes of external tooth stains include chronic tobacco usage, drinking red wine, coffee or black tea. Overuse of prescription mouth rinse known as chlorhexidine or Peridex can lead to stained teeth.

External tooth stains usually don’t require whitening products. The stains can be eliminated with a dental prophylaxis or a tooth cleaning, usage of a whitening toothpaste or other non-whitening products, that claim to whiten your teeth. Most non-whitening products that claim to whiten the teeth are abrasives. The abrasive substances eliminate surface stains sufficiently.



Check out these products that work well for removal of tooth surface stains:

Internal tooth stains, also known as intrinsic stains are usually caused by systemic or more natural changes in the internal structure of a tooth. Usually we have less control over formation of these stains. An example of that is when children begin loosing baby teeth and eruption of permanent teeth begins, parents will comment on the shade difference between the permanent and deciduous or baby teeth. Inherited yellow stains can develop during tooth formation. This is especially true with permanent tooth formation. The shade of adult teeth can be drastically different than the shade of baby teeth due to irregular internal formation and calcification pattern. This is very common and normal. If bothersome I would recommend bleaching the teeth at a later age. Waiting until age of 18-21 is ideal as teeth can become severely sensitive and the overall health of the teeth can be influenced. The teeth respond well to the whitening agents. In certain situations, when a high percentage bleaching agent is used, teeth might end up with irreversible inflammation and require root canal treatments. Always consult a dentist before whitening teeth at an early age.

Aging might be another reason why our teeth become more yellow over time. Apposition of dentin inside the tooth continues throughtout the life of the tooth. The dentin that is produced is irregular in structure. This irregular structure doesn’t allow the light to make it all the way through the tooth, thus giving an appearance of a darker tooth. Teeth discolored due to aging usually respond well to prescription whitening agents.


Here are recommendations for products that are effective and recommended by patients. These products do not require the use of custom whitening tray:

Ingestion of high amounts of fluoride during childhood and teenage years can lead to fluorosis. Fluorosis is identified by brownish stains on teeth and usually an irregular tooth surface. Since most municipal water has added fluoride most of us end up with a much higher ingestion of fluoride than necessary. Affected teeth are usually highly resistant to cavities. However, the appearance of the teeth is usually a major concern for the patients. Fluorosis cannot be reversed later in life and whitening the teeth might not produce the desired results. If the tooth whitening is unsuccessful veneers are recommended to produce the desired effect.

A similar effect can be caused by tetracycline, a commonly used antibiotic. If used during childhood or teenage years, the teeth will end up with brown stains, usually stripes. As with fluoride, the affects are irreversible and whitening products might not produce the desired effect. As with fluorosis, veneers are recommended to cover up any residual stains.


Teeth whitening products are most effective on teeth that are naturally yellow, teeth stained by age, foods, drinks and smoking. These methods usually do not work well with tetracycline and fluorosis stains.


Teeth Whiting Steps for Good Results:

If you are considering whitening your teeth and would like to obtain desired results there are certain steps that you should follow. A cleaning is recommended to eliminate the stains present on the outer part of the teeth and get the oral cavity ready for the bleaching procedure

Cavities need to be treated before teeth are whitened because the whitening solution can penetrate decay and reach inner areas of the tooth, which can cause severe sensitivity and potentially lead to future need for root canal treatment.

Whitening will not work on exposed tooth roots, because roots do not have an enamel layer. Receding gums can cause roots to become exposed.


Whitening can be completed either in a dental office or at home:

In Home Whitening:

  • A gel-like whitening solution, which usually contains hydrogen peroxides, is placed in a tray that resembles a night guard or mouth guard.
  • It is important that the mouthpiece fit well so that the whitening agent remains in contact with your teeth and doesn’t irritate your gums. Over-the-counter mouthpieces will not fit correctly and can cause gum irritation if the whitening agent seeps out.
  • Many people achieve the amount of whitening they want within a week or two, but you may need to wear the mouthpiece for as long as four weeks or longer.
  • The tray is then placed over the teeth for a certain period of time usually from an hour to overnight depending on the percentage of the whitening solution used.
  • This is a safer way of whitening because:
  • Lower percentage whitening agent is used.
  • It is done over a longer period of time.
  • This will minimize the damage done to your teeth
  • Less post-operative sensitivity will be noted.
  • The new shade of the teeth will be more stable and longer lasting.
  • takes a longer time to obtain the results, however results are obtained much safer.
  • Your dentist will want to check to make sure the process is working properly, usually after a week.

In-office Whitening:

  • Usually can take between 30 and 90 minutes and can require up to three appointments with your dentist. The number of visits required will depend on the type of discoloration and how white you want your teeth to be.
  • The desired effects might be seen sooner with in office whitening, however more damage is done to the teeth because of the process involved:
  • Higher percentage hydrogen peroxide solution might be used.
  • The whitening process can be heat or light activated, which can cause unnecessary damage to the teeth.
  • More post-operative sensitivity (to temperature) may be noted.
  • Effects of whitening might not last as long as compared to a slower more stable process.
  • Gray-like appearance of teeth has been noted.
  • Your dentist may want to see you a few days after in-office whitening to check your gums. If your gums were exposed to the whitening agent, they can become irritated.

General Information About Teeth Whitening:

  • Whitening is not a permanent solution. The stains will come back.
  • People who expose their teeth to a lot of staining may see the whiteness start to fade in as little as one month.
  • Those who avoid staining foods and drinks may be able to wait six to 12 months before another whitening treatment is needed.
  • Re-whitening can be done in the dentist’s office or at home.
  • If you have a custom-made mouthpiece and whitening agent at home, you can whiten your teeth as frequently as you wish to.
  • You should discuss your whitening schedule with your dentist, and talk about what whitening products would work best for you.

Risks Associated With Teeth Whitening:

  • Some people may experience a temporary increase in tooth sensitivity.
  • There may be mild gum irritation as well.
  • Whitening procedures should not be done while a woman is pregnant.

Non-Vital Tooth Whitening (completed on root canal treated teeth):

  • Non-Vital whitening is performed only of previously root canal treated tooth.
  • The tooth usually becomes discolored and appears dark gray in appearance.
  • Methods described above most likely will not work on a root canal treated tooth.

The tooth is whiten from the inside (a whitening agent is placed inside the tooth and covered with a temporary filling.

  • The process should be repeated until the desired effect is noted.
  • After the procedure is complete a permanent filling or in most cases a crown should be placed.


Tetracycline Stains On Teeth:

Tetracycline stained teeth are typically very resistant to any form of teeth whitening methods. Therefore, teeth stained with tetracycline require prolonged treatment times before any positive results are visible. Often, however, tetracycline stained teeth are unresponsive to the teeth whitening procedure, especially if the tooth stains are blue/gray in color. Teeth stained by tetracycline may approach but never seem to achieve the appearance of normal teeth.

Due to difficulty with bleaching tetracycline-stained teeth, some dentists advocate intentional root canal therapy, and the use of non-vital bleaching technique to achieve a more acceptable result. While the esthetic result appears much better than that obtained from external bleaching, this approach involves all the inherent risks associated with root canal treatment.

External or conventional bleaching technique offers a safer alternative, even though they may not be as rapid or effective. Full crowns or dental veneers are alternative treatment methods for the difficult tetracycline stained teeth but involve irreversible tooth modifications.