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Tooth Whitening

Tooth whitening (or bleaching) is a simple, non-invasive dental treatment used to change the color of natural tooth enamel and is an ideal way to enhance the beauty of your smile.

Because having whiter teeth has now become the number one aesthetic concern of most patients, there are a number of ways to whiten teeth.  The most popular method is using a home tooth whitening system that will whiten teeth dramatically.  Since tooth whitening only works on natural tooth enamel, it is important to evaluate replacement of any old fillings, crowns, etc.  Replacement of any restorations will be done after bleaching so they will match the newly bleached teeth.

Tooth whitening is not permanent.  A touch-up maybe needed every several years, and more often if you smoke, drink coffee, tea, or wine.

Reasons for tooth whitening:

  • Fluorosis (excessive fluoridation during tooth development).
  • Normal wear of outer tooth layer.
  • Stained teeth due to medications (tetracycline, etc.).
  • Yellow, brown stained teeth.

What does tooth whitening involve?

This type of tooth whitening usually requires two visits.  At the first appointment, impressions (molds) will be made of your teeth to fabricate custom, clear plastic, trays.

At your second appointment, you will try on the trays for proper fit, and adjustments will be made if necessary.  The trays are worn with special whitening solution either twice a day for 30 minutes or overnight for a couple of weeks depending on the degree of staining and desired level of whitening.  It is normal to experience tooth sensitivity during the time you are whitening your teeth, but it will subside shortly after you have stopped bleaching.

You will receive care instructions for your teeth and trays, and be encouraged to visit your dentist regularly to help maintain a beautiful, healthy, white smile.

 Safety Concerns of H2O2 Bleaching Products 

The safety concerns regarding potential systemic effects are no longer a primary issue given the H2O2 is limited to the oral cavity and does not reach levels which would induce systemic toxicity. However, patients should be advised not to smoke or drink alcohol while undergoing bleaching treatment as H2O2 can promote tumour growth in the presence of DMBA (tobacco carcinogen) in vitro. 

There are documented local adverse effects of bleaching products.

Tissue Burns

  • Occurs when high concentrations of peroxide are used, mainly in-office bleaching.
  • Improper use of at-home bleaching can lead to mucosal irritation or burns due to prolonged exposure to the active ingredients
  • Usually transient.

Tooth Sensitivity

  • Sensitivity to temperature changes is a common clinical side-effect.
  • Sensitivity is transient and generally does not persist after the cessation of bleaching.
  • Increased risk when bleaching agent is higher concentration or changed more than once a day.
  • Long-term studies regarding effect of H2O2 exposure on pulp lacking.
  • Exercise caution and avoid bleaching in patients with carious teeth, exposed dentin and defective restorations.

Gingival Irritation

  • Irritation linked to the concentration of H2O2 and gingival contact.
  • Mild to moderate occurring 2-3 days after beginning treatment at-home.
  • Usually result of an ill-fitting bleaching tray (at-home) or leak in the gingival barrier protection (in-office).

Effects on Enamel

  • Mineral loss occurs during bleaching but, is not significant as there are remineralization capabilities within the oral cavity.
  • Few changes noted in SEMs of bleached enamel surfaces on a micron scale.
  • Alterations in enamel surfaces attributed to products which use and acidic pre-rinse and low pH gels.
  • Presently, no clinical evidence of enamel effects with the use of at-home bleaching agents monitored by dentists (2 significant cases of enamel damage using OTC products).

Effects on Dentin

  • While bleaching agents are not intended for dentin surfaces, dentin is exposed to bleach in cases of occlusal attrition and root recession.
  • In vitro evidence of decreased dentin mechanical properties following direct and prolonged exposure to at-home bleach.

Effects on Restorations

  • Bleaching may affect the chemical/physical properties of restorative material.
  • Residual bleach within enamel and dentin immediately after the cessation of bleaching significantly impairs subsequent bonding attempts. Therefore, dentists should delay all bonding procedures until at least 1 week has passed after the end of bleach treatment.

Chlorine dioxide bleaching agents are also available and are used mainly in beauty spas and cruise ships. These agents make teeth more susceptible to re-staining, strip enamel from tooth surfaces irreversibly while reducing the enamel’s natural lustre and cause sensitivity.