What Causes The Discolouration Of A Tooth?

A bright white smile is a sign of health and beauty. Many patients are concerned with discoloured teeth. There are many reasons that a tooth may become discoloured. The most common reason is the food and drink that is being consumed. Luckily, that is also the most treatable and preventable cause.

Let’s take a closer look at the causes of tooth discolouration, how you can help to prevent it and what treatments are available.


Tooth discolouration falls into 3 categories. It can be caused by something that comes into contact with your teeth, something happening inside your teeth (or body) and from aging. While aging is natural and cannot be avoided entirely, there are many causes that you can help to minimize or address once you know what they are.

  • Foods and drinks. Coffee, tea, dark pop, wine and certain fruits and vegetables (such as berries or cherries) can stain your teeth. These usually lead to a purplish undertone being absorbed into the teeth.
  • Tobacco use. Smoking cigarettes or chewing tobacco will stain teeth, typically yellowing them or causing brown stains.
  • Poor dental hygiene. Not brushing, flossing and rinsing enough to remove plaque and stain-producing substances will result in eroding enamel that can yellow the teeth. Any type of decay or cavities will result in brown spots on the teeth.
  • Medications. The antibiotics tetracycline and doxycycline are known to discolour teeth when given to children whose teeth are still developing. Mouth rinses and washes containing chlorhexidine and cetylpyridinium chloride can also extrinsically stain teeth. Antihistamines (like Benadryl), antipsychotic drugs and drugs for high blood pressure also cause teeth discolouration.
  • Dental materials. Some of the materials used in dentistry, such as amalgam restorations, especially silver sulfide-containing materials, can cast a gray-black colour on teeth.
  • Aging. As you age, the outer layer of enamel on your teeth wears away, revealing the natural yellowish colour of the dentin underneath it.
  • Genetics. Some people have naturally brighter or thicker enamel than others.
  • Environment. Excessive fluoride either from environmental sources (naturally high fluoride levels in water) or from excessive use (fluoride applications, rinses, toothpaste, and fluoride supplements taken by mouth) can cause teeth discolouration.
  • Trauma. Damage to your teeth can cause discolouration if the internal tissue is harmed. This can result in dark yellow or gray colouring in the teeth.


In order to prevent staining or premature enamel wear, be sure to brush after you consume food and drinks that can cause staining or damage your teeth. Avoid highly acidic foods that degrade enamel and consider using a straw to consume beverages such as lemon water so they don’t come in contact with your teeth directly. Good oral care habits such as brushing, flossing and regular dental visits keep your teeth healthy and protect your enamel.

If you smoke or chew tobacco, we highly recommend quitting. Though there are numerous other benefits, one important one is that your teeth and mouth will thank you.

Another tip to prevent tooth discolouration is to use fluoride in recommended doses and avoid overusing it, which can cause white spots. You should also try to avoid medications that can cause tooth discolouration when possible (antihistamines and some antibiotics) and discuss alternatives with your health care providers.

Lastly, when you are engaging in contact sports, or if you grind or clench your teeth, be sure to wear the appropriate mouthguards to help you avoid injuries and trauma. Not all accidents can be avoided but you can minimize the chances for damage by properly protecting your mouth when possible.

If you do experience trauma to your mouth, see your dentist as soon as possible to give them a chance to help reduce the long term damage where they can.


If you have a discoloured tooth (or teeth), you’ll likely find that your smile is affected by it. Teeth whitening is the fastest way to brighten your smile and is the most commonly sought after cosmetic procedure. Over the counter whitening rinses generally are not effective at changing tooth colou and whitening toothpastes are very abrasive and not recommended. A custom made bleaching tray with dentist approved whitening gels are the most effective way to safely whiten your teeth. When whitening options won’t do the trick, your dentist may recommend internal bleaching or covering the affected tooth/teeth with a veneer or bonding.

Over the counter whitening – These include strips, rinses, whitening toothpaste, LED lights and anything you purchase from the drug store or over the counter to whiten your teeth. These products are very diverse in their effectiveness and are not generally recommended by your dental team.

Take home treatments – These typically come from your dentist and include a solution that is put inside custom molds and worn daily for a period of time. These products can be effective when used as directed and with the supervision of your dentist.

Zoom Teeth Whitening – The Zoom system will whiten your teeth by up to 8 shades in one 90 minute visit to your dentist’s office, making it one of the most effective options on the market. It works by breaking down the stains on your teeth which happens over time after the initial treatment at your dentist’s office.

Internal bleaching – When discolouration comes from the inside of the tooth, your dentist will need to bleach it from the inside. This is done by placing a bleaching agent inside the tooth for several days and containing it with a small filling.

Veneers or Dental Bonding – In some circumstances, the only way to address a discoloured tooth is to cover it with a veneer or dental bonding. Your cosmetic dentist will mold a tooth coloured porcelain veneer or sculpt bonded resin over the tooth to adjust it to the colour of your other teeth.

Your dentist is best equipped to help you assess the reasons for the discolouration so they can also help you choose the right treatment. While you can buy whitening products at the drug store, it is always best to chat with your dentist before you go that route. If your enamel is already compromised, the abrasiveness of some treatments can actually cause more yellowing. And sometimes external products simply won’t address the issue so you will be wasting your money.

Chat with your dentist about your concerns so they can help you protect your teeth and get a beautiful, white smile!