Bleaching Discoloured Teeth

Teeth develop naturally in a variety of shades and foundational colours. They will naturally darken with age and their appearance can be affected by the accumulation of surface stains acquired from the use of tobacco products and the consumption of certain foods or drinks. Although teeth are not naturally meant to be completely white, today’s society looks for a brighter smile. With this in mind, dental professionals are able to provide two methods of improving the colour appearance of their patient’s teeth. These procedures fall into two main categories: surface whiteners, which have very limited abilities, and bleaches.

Surface Whiteners

These products use special abrasives to improve the product's ability to remove surface stains. Most products in this category are either toothpastes or chewing gums. The effectiveness, however, of these products is limited to very minimal surface stains and is unable to address any discolouration that is within the tooth itself.


Most bleaching products are peroxide-based and are actually capable of altering the colours of the tooth itself. However, not all tooth discolourations respond to tooth-bleaching treatments. Individuals contemplating tooth-bleaching should consult with a dentist to determine the cause of the tooth discolouration and to determine whether a bleaching treatment will have the desired result. This step is especially important for patients with fillings, root canal treatments, crowns and/or with extremely dark stains on the anterior teeth.

A number of different bleaching techniques and products are available to patients. Your dentist will use one of these two methods to whiten your teeth: Vital bleaching is done on "living" teeth and can be used to whiten your teeth if they have become stained by food or tobacco, or if they have become dark with age.

Non-vital bleaching is bleaching done on teeth that are no longer "alive." If your tooth has changed colour because of a root canal, non-vital bleaching can lighten your tooth from the inside out.

There are three methods for bleaching teeth. The method that will work best for you depends on the number of teeth that need to be bleached, and on how badly they are stained (or discoloured). Your dentist may suggest:

  1. Putting a special bleach on your stained teeth and using a light to start the bleaching action; this must be done in a controlled environment such as a dental office by a professional; or
  2. Wearing a custom-made mouth guard filled with a special bleach for part of each day; or
  3. In the case of a single discoloured tooth that has been root canal treated, an internal placement of a special bleach mixture that would be sealed to the tooth for a number of days or weeks until the process is completed.

Whitening a Discoloured Tooth after Root Canal

If you've had a root canal some time ago and notice the tooth is now darkening, the tooth can be restored by a technique known as internal or non-vital bleaching without the use of veneers or crowns. For darkened root canal treated teeth, often a simple walking bleach method is used. Here a bleaching agent is sealed inside the tooth and refreshed over a series of week;. this method is safe and effective. For very dark teeth often a crown or veneer is needed to mask the discolouration also after whitening. The reason why a root canal treated tooth darkens is that the treatment requires removal of the pulp tissue from the canals inside the roots. As a result, the dentin which comprises most of the tooth is no longer living and often tends to darken over time. Bleaching a root canal treated tooth involves placement of a bleaching agent into the empty pulp chamber of the non-vital, discoloured tooth. Internal bleaching is a more conservative option compared to restoration with veneers or crowns, but is sometimes used to lighten teeth before the application of these techniques to prevent the discolouration of the natural tooth from showing through. In addition, porcelain veneers or crowns may be required not only to improve colour, but also strengthen a root canal treated tooth.