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What is Fluoride and how does it help teeth?

Fluoride is a mineral that occurs naturally in many foods and water. Every day, minerals are added to and lost from a tooth's enamel layer through two processes, demineralization and remineralization. Minerals are lost (demineralization) from a tooth's enamel layer when acids -- formed from plaque bacteria and sugars in the mouth -- attack the enamel.


How does fluoride help to prevent decay?


In What Forms Is Fluoride Available?

As mentioned, fluoride is found in foods and in water. It can also be directly applied to the teeth through fluoridated toothpastes and mouth rinses. Mouth rinses containing fluoride in lower strengths are available over-the-counter; stronger concentrations require a doctor's prescription.

Fluoride is found naturally in many foods and water supplies, and is also added to some drinking water. Having 0.7 to 1.2 parts of fluoride for every million parts of water (0.7ppm to 1.2ppm) has been shown to have the best effect. All water contains some fluoride. Your local water supplier can tell you how much fluoride is in your drinking water.

Fluoride is also naturally present in some foods and drinks, for example fish and tea. Some countries add fluoride to their table salt and milk instead of to the water supplies. One cup of tea can contain between 0.3 milligrams and O.5 milligrams of fluoride, and if you drink it with milk your teeth will also benefit from the calcium. It is best to drink tea without sugar to reduce the risk of tooth decay even more.

Your dentist can also apply fluoride to the teeth as a gel, foam, or varnish. These treatments contain a much higher level of fluoride than the amount found in toothpastes and mouth rinses. Varnishes are painted on the teeth; foams are put into a mouth guard, which is applied to the teeth for 1 to 4 minutes; gels can be painted on or applied via a mouth guard. Fluoride supplements are also available as liquids and tablets and must be prescribed by your dentist or doctor.

When Is Fluoride Intake Most Critical?

It is certainly important for infants and children between the ages of 6 months and 16 years to be exposed to fluoride. This is the timeframe during which the primary and permanent teeth come in. However, adults benefit from fluoride too. New research indicates that topical fluoride, such as that contained in toothpastes and mouthwashes, are as important in fighting tooth decay as in strengthening developing teeth.

All children up to three years old should use a toothpaste with a fluoride level of at least 1000ppm (parts per million). After three years old they should generally use a toothpaste that contains 1350ppm to 1500ppm (most adult toothpastes contain this). This will depend on the individual child so please discuss this with your dentist.

Parents should supervise their children's tooth brushing, and use only a pea-sized smear of fluoride toothpaste until they are about 7 years old.


  • Dry mouth conditions
  • Dry mouth caused by diseases such as Sjögren's syndrome, certain medications (such as allergy medications, antihistamines, anti- anxiety drugs, and high blood pressure drugs), and head and neck radiation treatment makes an individual more prone to tooth decay. The lack of saliva makes it harder for food particles to be washed away and acids to be neutralized
  • Gum disease : Also called gingivitis, gum disease can expose more of your tooth and tooth roots to bacteria increasing the chance of tooth decay
  • History of frequent cavities : If you have one cavity every year or every other year, you might benefit from additional fluoride

Ask your dentist if you could benefit from additional fluoride.

What are the side effects?



Severe fluorosis may lead to the enamel being pitted and discoloured (severe fluorosis is rare in the UK).

Is Fluoride Safe?

Many reports have been published throughout the world about the pros and cons of fluoride. After many years the scientific conclusion is that fluoride toothpaste and correctly fluoridated water, salt and milk are of great benefit to dental health, help to reduce decay, and cause no harmful side effects to general health. Studies carried out for the government by York University and the Medical Research Council have failed to find any evidence that fluoride added to water causes harmful side effects.


Worldwide, over 300 million people drink fluoridated water supplies. Many millions more regularly use fluoridated toothpaste. In America for example, well over half of the population have fluoridated water supplies. This has led to improved levels of dental health which in turn benefits general health.

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