Oral problems

Colour of teeth

Since the enamel of permanent teeth is slightly transparent, the yellowish colour of the underlying dentine is shown through it. Therefore, permanent teeth will appear slightly yellowish. As we get older, the dentine increasingly grows thicker, and it is normal that our teeth become more yellowish.

Photograph of a set of yellowish permanent teeth.Slightly yellowish permanent teeth

The enamel of deciduous teeth is not as transparent as our permanent teeth. That is why deciduous teeth look milky white.

Photograph of a set of milky white deciduous teeth.Milky white deciduous teeth

Factors causing tooth discoloration

There are two factors causing tooth discoloration — internal factor and external factor.

  1. External factors causing tooth discoloration

    • Brown and black stains on the surface of teeth

      Photograph of black stains on the inner surfaces of lower front teeth.Teeth with black stains


      Drinking of dark-coloured beverages, such as tea, result in the food colours being adsorbed onto the tooth surfaces.


      The dentist will use:

      • Dental pumice to remove the stain, and then prophylaxis paste to smoothen the tooth surfaces; or
      • Prophyjet — utilizing air to spray a mixture of fine baking soda powder and water onto the surfaces of teeth to remove stains.

        Animation showing the use of prophyjet to remove the stains on the lower teeth.Prophyjet cleaning
        Photograph of lower teeth after removal of black stains.Teeth after black stain removal


        Avoid drinking dark-coloured beverages to minimize food colours being adsorbed.

      • Green and orange stains at the surface of teeth

        Photograph of front teeth with orange stains.Teeth with orange stain


        Teeth has not been cleaned thoroughly, and the accumulated dental plaque contained bacteria or fungi that can produce colour and formed green and orange stains.


        Dentist will perform scaling to remove accumulated dental plaque and stains.

        Photograph of front teeth after removal of orange stains.Teeth after orange stain removal


        Brush the teeth every morning and before bed at night, and use dental floss to remove dental plaque to keep the teeth white.

  2. Internal factors causing tooth discoloration

    Photograph of front teeth having greyish-blue to brownish-yellow stains.Teeth appear to be greyish-blue to brownish-yellow


    If there was certain sickness or, if tetracycline (a kind of antibiotics) is taken during the development of teeth, the teeth formed will be greyish-blue to brownish-yellow.


    • Bleaching
    • Laminate Veneer
  • Teeth appear to be greyish-black

    Cause 1

    • Tooth decay

      Photograph of a set of deciduous front teeth some of them show black tooth decay.
    • Treatment

      The dentist removes the tooth decay, and then puts on a filling.

      Photograph of a set of deciduous front teeth having the black tooth decay removed and then restored by a tooth-coloured filling.

    Cause 2

    • Pulp necrosis

      Photograph of an upper incisor turning greyish-black.

      The pulp becomes necrotic because of tooth trauma or tooth decay, and the tooth will appear greyish-black.

    • Treatment

      Endodontic treatment must be done to treat the discoloured tooth which has pulp necrosis.

      Photograph of that greyish-black upper incisor turning ivory white after root canal therapy.Tooth after root canal therapy

      If teeth still appear greyish-black, dentist can treat the discoloured teeth by bleaching, laminate veneer or crown.

  • Brownish-yellow or white patches at the surface of a tooth

    Photograph of a set of permanent teeth with brownish-yellow patches.
    • Early tooth decay
    • Disturbance during the development of tooth
      If a deciduous tooth is so decayed that the pulp is exposed, the bacteria, via the apex of the tooth, will cause an infection in the vicinity of the developing permanent successor. This will disturb the development of the enamel of the permanent tooth, resulting in the formation of brownish-yellow patches.

      Animation of the process of how a severely decayed deciduous tooth disturb the development of the enamel of its permanent successor resulting in the formation of brownish-yellow patches on the tooth.
    • Fluorosis
      Long term excessive fluoride ingestion will alter the development of the enamel of teeth. This disturbance will show as white patches on the teeth.


    • Early tooth decay
      Dentist can apply topical fluoride onto the surfaces of teeth so that the early tooth decay lesion can be remineralised.

      Photograph of one of the lower back teeth  having its chewing surface applied with topical fluoride.
    • Disturbance during the development of a tooth or Fluorosis
      Treatments such as Filling, Laminate veneer or Crown.

      Photograph of a set of front teeth after filling with composite resin.Tooth after filling