Tooth Discoloration

A tooth may become yellow, brown, grey, black, green, blue or orange. The whole tooth can change colour, or the change may be limited to spots, lines or pits.

Coffee, tea, tobacco and some medicines can stain teeth. Ageing can make the enamel thinner and allow the yellow dentin beneath it to show through; injury, infection and some inherited conditions can also change tooth colour.

Surface staining can build up from coloured foods, drinks and tobacco. A colour change can also begin inside a tooth after trauma, tooth decay or infection, so a single dark tooth has a different cause from general yellowing.

Frequent exposure to coffee, tea, tobacco and other strongly coloured products can stain enamel. Some medicines, including tetracycline taken while teeth are forming, can cause deeper colour changes.

The pattern matters: a dentist looks at whether one tooth or several teeth have changed, whether the colour is on the surface or within the tooth, and whether there has been injury, decay, infection or medicine exposure.

Professional whitening uses peroxide products to lighten natural tooth colour. It will not change the colour of crowns, veneers or fillings, and whitening is not appropriate when a tooth is dark because of decay, infection or an injury that needs treatment.

The cause of the colour change shapes the care needed. A surface stain may be approached differently from a dark tooth caused by decay, infection or trauma, and whitening does not alter the colour of existing crowns, veneers or fillings.

Whitening can make teeth sensitive for a short time and can irritate gums if the peroxide contacts them. It should not be used to mask a tooth with decay, infection or injury, because those problems need their own care.

Reducing tobacco use and limiting foods and drinks that stain teeth can reduce surface staining. Regular brushing and cleaning remove plaque and surface deposits, while dental restorations keep their original colour after whitening.