What’s fluoride varnish? And why do children need it?

18th February 2021 | Posted by: Vanessa Giraud

Featuring expert advice from dental surgeon Lucy Smith, to help protect your children’s teeth.

Lucy Smith

Lucy Smith BDS, SpaDental Chard

We all want our children to have the best – and that includes wanting them to have the healthiest teeth possible. Taking good care of children’s teeth from when they’re very small helps them to have stronger teeth as adults. Which is why fluoride therapy is an important inclusion in children’s preventive dental care.

To help prevent dental caries, your dentist is very likely to prescribe appropriate applications of fluoride varnish for your children’s teeth. SpaDental dentist Lucy Smith shares her expert advice in answer to parent’s questions.

What can I expect during my child’s dental check?

All children need ongoing systematic reviews of their oral health.  As no two children have the same dentition, a dentist prepares an individual plan for effective and safe fluoride treatment.

Lucy says: “We risk assess all children at every appointment and determine low, medium or high risk for developing caries.  There are many factors to consider, such as diet, oral hygiene, existing signs of caries, enamel defects, history of decay, sibling history of decay, attendance record, medical history, fluoride use and saliva flow.”

At each dental appointment, the dentist will explain the next steps needed to care for your child’s teeth.

Lucy advises parents to consider three areas. “To tackle tooth decay we try to:

  • reduce the presence of bacteria, through brushing and oral hygiene advice,
  • reduce sugars so that bacteria have nothing to metabolise, through diet advice, and
  • strengthen the enamel, through the use of fluoride toothpaste, mouthwashes, and varnishes.”

This means that the dentist will offer advice about oral hygiene and diet that parents need to take responsibility for at home. The dentist will usually schedule six-monthly reviews, including topical fluoride applications as appropriate, adding an extra layer of protection.

Why is fluoride important?

Fluoride is important for tooth care because it changes the structure of teeth, making them even stronger and more resistant to acid erosion that weakens tooth enamel.

Lucy explains: “Dental decay forms when oral bacteria metabolise sugar and produce acid. This acid demineralises the tooth structure. The structure of the tooth is made up of hydroxyapatite crystals which are soluble in acid. When we add fluoride, the crystals become fluorapatite (F- ions replace the H+ ions). These fluorapatite crystals are stronger and much more resistant to acid attack. Fluoride also bolsters the natural antibacterial action of saliva and promotes remineralisation of the tooth structure.”

During the last century observation and then evidence based research linked fluoride with a reduction in dental decay. Now recognised as a major health benefit, fluoride redirected the focus of modern dentistry towards preventive care.

These days, the vast majority of toothpastes and mouthwashes we use contain varying amounts of fluoride to prevent tooth decay. About 10% of the population of the UK has mains water with either natural or added fluoride. A dentist will take exposure to fluoride into consideration when prescribing fluoride therapy.

What is fluoride varnish?

Fluoride varnish is a coating applied directly to all or some teeth. Its use is an effective way to deliver fluoride directly to the tooth surfaces where it can make a difference. It adheres to the surface, and interacts with the enamel, to strengthen it. Although research shows that people who have grown up with fluoridated water have stronger teeth, topical application to the teeth themselves is the most effective treatment.

How is fluoride varnish applied?

A dentist or clinician will carefully paint the varnish onto the tooth surfaces. It sticks to the enamel, and gradually hardens. The process only takes a few minutes, and is painless.

Lucy says: “We have a certain amount of fluoride varnish which is safe to use for different age groups. We only apply fluoride to children who are over the age of 3: no more than 0.25ml varnish for a full mouth in children aged 3-6; no more than 0.4ml varnish for a full mouth in children over 6. These amounts are determined because fluoride varnish contains an extremely high concentration of fluoride – 22600ppm!

Children have to avoid eating and drinking for around 45 minutes after we have applied varnish for it to work properly, but it has been shown to reduce caries incidence by 30%.”

In some cases, the dentist places fluoride varnish on a particular area if a child has one tooth affected by an enamel formation problem. At each dental appointment, the dentist will review the need for fluoride varnish.

Keep in mind:

Consuming too much fluoride while the teeth form can cause discolouration (dental fluorosis). Therefore:

Moreover, some children may have fluoride applied to their teeth by a health professional in school. If this happens, the school will inform parents and offer advice for after care too. It is important that you inform the child’s own dentist of this intervention.

Lucy explains: “A lot of children are now coming in and parents are reporting that they are having fluoride varnish placed six monthly in school – presumably by a school nurse, visiting dentist, or dental therapist. This is a really good initiative, but we do now have to be bit careful that we don’t apply it as well and therefore give them more than they should be getting! Emphasis also needs to be on the importance of still attending regular dentist appointments as disease is not diagnosed or treated in schools. Fluoride varnish is a preventive measure and can slow progression of disease, but doesn’t cure it!

Which fluoride toothpaste should I buy?

fluoride varnish in connection with toothpast use. ppm shown on tube.

It’s important to read the small print on your tube of toothpaste. Notice this tube has 1450ppm of fluoride, and is not suitable for small children.

It is important that children use toothpaste with the correct age-appropriate concentration of fluoride. On the tube, notice the stated concentration measured in ppm, which means parts per million, and indicates a very diluted active ingredient.

For children with a low risk of developing caries:

Young people at a higher risk of developing caries:

For the prevention of caries in children’s teeth, fluoride varnish application helps to strengthen tooth enamel. However, tooth brushing and a good oral hygiene routine are vital too!


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