Tooth whitening

Tooth whitening can be one of the safest and cost effective ways of improving your smile. There are a number of causes of tooth discolouration and it is important to ensure a proper diagnosis is made of the cause. It is worth noting that some of the causes of tooth discolouration, if untreated, may have serious consequences for both your teeth and your general health.

Extrinsic (surface) discolouration:

Life in general can lead to the build-up of surface stains that discolour the teeth, especially if you are a smoker or tea/coffee/red wine/spice consumer. Regular dental hygiene visits and good oral home care will reduce the severity of stain build up. It is wise to have dental hygiene visit prior to undertaking tooth whitening.

Some toothpastes (for example “smokers toothpastes”) contain abrasive particles specifically to assist in the removal of surface stains. Care needs to be taken using these products as they can damage tooth enamel and thus are not recommended for regular use.

Intrinsic (internal) discolouration:

Over time, small molecules permeate through microscopic defects in the enamel and cause a change in the optical properties of the tooth which make it look more yellow – this is known as intrinsic staining. The tooth whitening process oxidizes these molecules which improves the optical properties of the tooth, making it look whiter.

3 types of tooth whitening

Over the counter

Over the counter products such as whitening strips and gels will whiten the teeth, but have some safety and effectiveness issues. Whitening works most effectively when the whitening product is in contact with the whole enamel surface for a period of time. Whitening products break down in saliva, so saliva needs to be excluded for the products to work. Thus, over the counter whitening products take a very long time to work and the results are blotchy – because saliva is not excluded and the active product breaks down quickly, in addition the active agent is not held against all the tooth surfaces. Products such as HiSmile fall into this category. Safety issues can arise with some products where the acid level is high – causing erosive damage to tooth enamel.

Custom made tray-based

A custom-made tray is fabricated to fit your teeth. A pH neutral carbamide peroxide gel is worn in the trays either overnight or for 2 hours a day – your choice. This method allows the gel maximum contact time with the teeth before it breaks down in saliva and thus is an effective and permanent colour change with very little short term regression. This method is the most cost-effective form of whitening relative to results. Occasionally some people may experience temporary tooth sensitivity using this method.

In the chair

The teeth are isolated using a rubber dam and a very concentrated whitening solution is placed on the teeth – it is important that there is no contact with the gums as the material will cause a chemical burn. The material may be heat activated to speed the process. The use of a light to activate the material (if it doesn’t provide heat) is merely a marketing tool as light itself makes no difference to the bleaching process.

There is a significant level of regression with this form of whitening and it often requires either top-up with a custom tray (see above) or several sessions in the chair. This method of whitening can cause extreme tooth sensitivity, often requiring pain-relieving medication because the strong concentration of the whitening material is irritating to the dental pulp. As this method requires time in the dental chair, it is more expensive than other methods. This is a good method to use if you have a major event coming up and don’t have sufficient time to use tray based whitening.

Whitening endodontically treated teeth

Often teeth that have had endodontic (root canal) treatment, will appear considerably darker than the adjacent teeth. This may be a result of the original trauma to the tooth causing bleeding from the dental pulp resulting in a darker colour, or it may be due to the materials used in the endodontic treatment remaining in the crown of the tooth with resultant discolouration. The process to whiten endodontically treated teeth involves the tooth crown being opened via the original endodontic access site and a “walking bleach” placed inside the cavity.  This is sealed over with temporary filling. The process may need to be repeated several times. When the whitening is complete a filling is placed back inside the access cavity.

General information

Depending on your staining history, whitening may require a ‘top-up’ every 2-10 years as you will accumulate new intrinsic stains which will change your tooth colour. If you use the tray based method, you keep your trays and get a new supply of whitening gel to top-up.

Whitening will not change the colour of existing restorations such as fillings or crowns and veneers. These restorations may need to be replaced after whitening if they no longer blend in.

Call us today to find out whether whitening will make a difference for you.