Why do teeth get discoloured?
There are many reasons why teeth can become discoloured. Simple things like drinking tea, coffee, red wine or other food and drink with strong colourings can cause it. Smoking is another major cause, which can result in a yellowed appearance to the teeth.
As people grow older their teeth can become darker naturally. Tooth decay, fillings and tartar build-up can also all contribute to discolouration.
Teeth have nerves and blood vessels inside them. If these nerves and blood vessels are damaged (this can happen because of decay, or if the teeth are knocked) the tooth may get darker.
Some types of staining can be caused by diseases or medicines. For example, if a type of antibiotic called tetracycline is given to children whose teeth are still developing, their adult teeth may form with a yellow or greenish tinge.
There are many simple ways to improve the appearance of discoloured teeth. Visit your dentist or hygienist to have your teeth scaled and polished on a regular basis. This involves removing any tartar that has built up. Your dentist or hygienist will also give you advice about preventing tooth decay.
Regular toothbrushing, stopping smoking and cutting down on strongly coloured food and drink will help stop stains returning.
Whitening toothpastes are slightly abrasive, which may help to remove surface staining. However, they do not alter the natural shade of your teeth.1
Your dentist can also give you advice about replacing your metal fillings and crowns with tooth-coloured ones.
There are a number of different products available to bleach teeth. Some you can buy and use yourself, while others require a visit to the dentist.
Over-the-counter kits
Over-the-counter (OTC) kits are sold in most major chemists throughout the UK. In general, they contain rubber mouthguards (moulds that are approximately the same shape as your teeth) and tubes of bleaching gel.
After squeezing some of the gel into the mouthguards, you place them over your teeth, usually for about 30 minutes at a time.
The bleaching ingredient in the gel is called hydrogen peroxide. OTC kits only contain weak hydrogen peroxide, and tend not to be as effective as stronger products that may be used by your dentist.
Using bleaching gels in this way may not work for certain types of discolouration, such as that caused by metal fillings or damaged blood vessels inside a tooth. Ask your dentist for advice before using one of these kits, as there may be a more effective way to achieve the result you're looking for.
Professional tooth bleaching
There are several different ways that dentists can bleach your teeth. These are separated into external techniques (where the bleach is placed outside of the tooth) and internal techniques (where the bleach is placed inside the tooth). They are described in more detail below.
External bleaching
This means that the colour of the teeth is lightened by placing a bleaching gel on the outer (external) surfaces of the teeth. Once again, using bleaching gels in this way may not work for certain types of discolouration, such as that caused by metal fillings or damaged blood vessels inside a tooth. There are two ways to do external bleaching.
* "Home" bleaching - this is similar to the OTC kit method, but with two main differences. Firstly, your dentist makes the rubber mouthguards so that they fit your teeth precisely, and secondly, the bleaching gel is stronger so it tends to be more effective. Your dentist will give you tubes of bleaching gel and instructions on how to put the gel in the mouthguards. You will need to wear the mouthguards for a few hours each day. It may take a few weeks to achieve the colour that you want. Your dentist will give you detailed instructions.
* In the surgery - this is also known as "laser" or "power" bleaching. Your dentist will put a rubber seal around your teeth to protect your gums. Then, the bleaching gel is painted onto your teeth and a special, bright light is pointed at them. This light speeds up the whitening process. The procedure takes one to two hours.
Internal bleaching
This means that the colour of a tooth is lightened by placing a bleaching product inside the tooth. Internal bleaching can only be done on teeth that have been successfully root treated. This means that the blood vessels and nerves inside the tooth have been replaced with a rubber filling.
To bleach a tooth in this way, the dentist will drill a hole (if it is a front tooth, the hole will be on the back so that you can't see it) and put the bleaching product into the hole. The hole will be sealed with a temporary filling, leaving the bleach inside the tooth. The procedure won't hurt because the tooth has no nerve inside it.
You'll have to go back to your dentist about a week later to have the temporary filling and bleach taken out. If you are satisfied with the new shade, your dentist will fill the hole with a tooth-coloured filling. Sometimes, the colour hasn't lightened enough, and the process needs to be repeated. Occasionally, internal bleaching needs to be combined with other whitening techniques to achieve the desired effect.
How long will it last?
The whitening effects of different bleaching methods can last for a few years, but this varies from person to person. An analysis of professional "home" bleaching found that for people who achieved a lighter shade, only half of them still had whiter teeth six months later.2 Your eating, drinking, smoking and toothbrushing habits may have an effect on how long the treatment lasts.
It's important to bear in mind that bleaching doesn't always result in the whiteness that you expected. The results vary from person to person and depend on the shade of your teeth before bleaching. For this reason, it is important to discuss all the possible options for improving the appearance of your teeth with your dentist before you make a decision.
Will bleaching damage my teeth?
There is no evidence to suggest that tooth bleaching is harmful to the gums, but it isn't clear what the long-term effect on the nerves and blood vessels inside the teeth are.2
All dental treatment carries a risk of side-effects, which are the unwanted, but mostly temporary effects of a successful treatment. Potential side-effects include sensitivity of the teeth to hot and cold, a sore throat, tender gums and white patches on the gums.
These side-effects are more likely to occur during or immediately after "laser" bleaching and should disappear after a few days. Contact your dentist if the symptoms persist.
Who shouldn't have bleaching?
There are some instances when a dentist may recommend that you do not have bleaching. For example if you have decay, this should be treated before starting any whitening treatments. Similarly, your gums should be healthy, so if you have any gum disease this should be treated.
If your teeth are extremely sensitive to hot and cold food or drinks, or if there are lots of fracture lines on your teeth, bleaching may not be recommended.
Some types of staining (eg tetracycline antibiotic staining) do not respond to bleaching as well as others. Bleaching, if successful, can take longer on tetracycline stained teeth.
Bleaching won't work on false teeth, crowns, veneers or fillings (including tooth-coloured fillings). Instead, your dentist may be able to replace these with lighter ones.
Bleaching is not recommended for children whose teeth are still developing or for pregnant or breastfeeding women.
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