Why Do I Have a Dark Tooth?


Our teeth can become discolored by changes INSIDE the tooth, or by stains to the surface of the tooth – there are three main types of tooth discoloration –

EXTRINSIC –  this occurs when the outer layer of the tooth (the enamel) is stained – often caused through drinking coffee, tea, wine, cola and other drinks and food that cause stains. Smoking also causes extrinsic stains.

INTRINSIC – This occurs when the inner structure of the tooth (the dentin) darkens or has a yellow tint to it – you can get this type of discoloration by –

  • Having too much exposure to fluoride in early childhood
  • You had a trauma that affected the tooth when you were a young child – a fall, for example, may have damaged the developing adult tooth
  • You had a trauma inside an adult tooth and the resulting bleed discolored the tooth
  • You were born with a rare condition called dentinogenesis Imperfecta, which causes amber, purple or grey discolorations.

AGE-RELATED – This is a combination of both Intrinsic and Extrinsic factors. Over time dentin naturally yellows and the enamel that covers the tooth gets thinner as you age allowing the dentin to show through. Smoking and certain foods can also stain teeth as people get older. Also, chips or other injuries can discolour a tooth, especially if the pulp has been damaged.

  • Symptoms – Usually include a stain on the enamel, this can range from yellow tints, white streaks to brown spots or pits. If the enamel has worn down and the dentin is showing through, you may notice a yellow tint.
  • Diagnosis – no special or complicated tests are needed. Your dentist will be able to diagnose tooth discolouration simply by looking at your teeth
  • Expected duration – some tooth discoloration can be removed with professional cleaning. An example of this type of discoloration is coffee. Many stains are permanent, but teeth can be whitened using a bleaching gel, in some cases if the discoloration is very severe or you are just *conscious* of the discoloration a crown or veneer may be required to cover it.
  • Prevention – Brushing your teeth regularly and after every meal will help prevent discolouration. It is also recommended that you rinse your mouth with water after having tea, coffee, wine, cola or any other foods and drinks that can stain your teeth. Regular cleaning by your dentist can also help remove any surface stains.

Intrinsic stains that have been caused by damage to the blood vessels or nerve in the tooth sometimes can be prevented. You may need to have root canal therapy – this is where the inner part of the tooth – the pulp – is removed before it has a chance to decay and darken. Teeth that have been treated by root canal therapy may still darken over time.

To prevent intrinsic stains in children, limit their early exposure to fluorides. Once the enamel has been formed fluoride won’t discolour their teeth.

Treatment – Many extrinsic stains that have been caused by food and drink can be removed via regular professional cleaning and home care. Good home care includes flossing, brushing and rinsing after meals.

Discoloration can also be removed by applying a bleaching agent to the tooth enamel, the dentist applies a whitening gel to your teeth that is activated by the use of light – it can make teeth whiter in just 30 to 45 minutes. Follow up treatments may be required. Alternatively, you can use a home/over the counter whitening kit, these aren’t as strong as the whitening service provided by your dentist and can take up to 4 weeks to show signs of improvement. These treatments may be via a whitening strip you stick to your teeth or a type of mouthpiece that you fill with a whitening agent, mouthpieces are NOT as secure – more a one size fits all approach and results can vary.

Whitening toothpastes may remove some minor stains from the tooth enamel, they do NOT change the overall colour of your teeth.

If the darkening to your tooth has been caused by root canal therapy then a whitening gel; will NOT help. Your dentist may, however, consider suggesting a crown or veneer is used instead.

Bleaching won’t lighten all stains so your dentist may consider covering the discolored area instead, this is useful if you have a damaged or chipped tooth.

Teeth can be covered with a colour-matched composite bonding material, or you can opt for veneers – these are thin ceramic shells that cover the outer surfaces of the tooth.

Tooth discoloration is considered a cosmetic problem. If you are unhappy with how your teeth look visit your dentist to discuss your options. Any change in the colour of a child’s normal teeth should be evaluated by your dentist.



About the Author: Martin French

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