Bleaching refers to the process of lightening the stains or colours inside enamel or dentine by using chemical agents.


To whiten teeth and regain the normal colour of the teeth.



Bleaching agents are used to oxidize the colour pigments in the discoloured teeth in order to whiten these teeth.


Bleaching agents contain chemicals such as Carbamide Peroxide, Hydrogen Peroxide , etc.

Procedures for bleaching

Bleaching vital tooth
Dentist will use different bleaching methods according to various oral conditions:

  • Take impressions of teeth to make a set of models. Construct a custom whitening tray from the dental laboratory. The patient should fill the tray with the bleaching solution and wear it over the teeth overnight. In addition, the patient should wear the tray every night according to the dentist's instructions and return to the dentist for follow-up appointments according to schedule.
  • Photograph showing a custom made whitening tray ready to be worn by a patient for bleaching the teeth.

  • In the dental clinic, the dentist can use a strong light to catalyse the more concentrated bleaching agents to whiten teeth in a shorter time.
  • Photograph showing front teeth before bleaching. They look light brown.
    Before bleaching

    Photograph showing front teeth after bleaching.  They look milky while.
    After bleaching

Treatment duration: 3 to 6 months

Bleaching of non-vital tooth treated by root canal therapy

  • Endodontic treatment (Root canal therapy) of the tooth must be completed first.
  • Place a cotton pellet soaked with whitening agent inside the pulp chamber and then fill up tooth opening.
  • Visit dentist periodically to check the progress of bleaching, and change the cotton pellet with whitening agent accordingly. When whitening effect is achieved, remove the cotton pellet, clean the pulp chamber and filled up the tooth cavity.
  • Photograph of a longitudinal section of a pulp-treated tooth after bleaching.

Duration: The treatment ends when the stains or colours are lightened, which takes approximately 1 - 3 months.

Points to note before using bleaching agents

Points to note after bleaching

Last revision date: 18 January 2012