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Preventive

Fluoride treatments and fissure sealants

Available on the NHS

Professional fluoride varnish, prescription-strength toothpaste and protective sealants for back teeth - simple ways to prevent and even reverse early decay.

Also called: fluoride varnish, high-fluoride toothpaste, pit and fissure sealants, fissure sealing

A close-up of a clean back tooth showing the grooves on its biting surface
The grooves on a back tooth, where fissure sealant is applied Photo: Dr. Henning Storbeck, Public domain

About fluoride treatments and fissure sealants

Fluoride strengthens tooth enamel, helps repair early damage and makes teeth more resistant to acid. As well as fluoride toothpaste, your dental team can paint fluoride varnish onto the teeth, and dentists can prescribe higher-strength toothpaste for people at higher risk of decay: 2,800ppm (for ages 10 and over) or 5,000ppm (for ages 16 and over), used for example with frequent decay, gum recession or a dry mouth.

Cochrane reviews support these measures. Fluoride varnish was linked to an average 43% reduction in decayed, missing and filled permanent tooth surfaces in children and adolescents (moderate-quality evidence), and resin sealants reduced decay in children's back teeth compared with no sealant.

Fissure sealants are thin plastic coatings painted onto the grooves of the back adult teeth, usually soon after they come through - around age 6 for the first permanent molars and between 11 and 14 for the second. Placing them is quick and painless, with no drilling or injections.

How it works

  1. Fluoride varnish: the teeth are dried and the varnish is painted on
  2. Sealants: the tooth is cleaned, prepared with a special solution and dried
  3. The liquid sealant is painted into the grooves and hardened with a light
  4. High-fluoride toothpaste: prescribed by your dentist and used in place of your normal toothpaste

Time, lifespan and cost

Time needed
A few minutes per tooth for sealants; fluoride varnish takes a few minutes at a routine visit.
How long it lasts
Your dentist will check sealants at routine visits. Fluoride varnish is reapplied at intervals your dental team recommends.
On the NHS?
Available on the NHS. Applying fluoride is part of Band 1 NHS treatment in England (£27.90 from 1 April 2026) and sealants are listed under Band 2, unless you are exempt. NHS dental care is free for under-18s. NHS charges

Private cost

Private fees vary widely between practices and depend on the complexity of your case and the materials used, so we do not quote a typical price. Always ask for a written treatment plan with costs before you agree to treatment. (Source: NHS: How much NHS dental treatment costs)

Pros and cons

Pros

  • Quick and painless
  • Can help reverse very early decay
  • Good evidence for preventing decay, especially in children
  • Fluoride varnish and sealants are available on the NHS

Cons

  • Sealants only protect the biting surfaces - the rest of the tooth can still decay
  • Too much fluoride while teeth are forming can cause faint white marks (fluorosis), although this is rare and usually mild
  • High-fluoride toothpaste is prescription only

Aftercare

  • Keep brushing twice a day with fluoride toothpaste - sealants are an extra layer of protection, not a replacement
  • After fluoride mouthwash, the NHS advises not eating or drinking for 30 minutes
  • Use prescription toothpaste exactly as directed

Risks and side effects

  • Dental fluorosis from excess fluoride in young children - use only a smear or pea-sized amount of toothpaste and encourage spitting out

Your dentist should explain the risks that apply to you before you agree to treatment.

Problems it can help with

Gums shrinking back to expose the roots can cause sensitivity and 'long' looking teeth. The causes and how to stop it getting worse.

RoutineOptions

Sharp twinges with cold, hot, sweet or acidic food are common. Why teeth become sensitive, what helps at home and when to see a dentist.

RoutineOptions

Decay often starts silently and ends in holes, pain or infection. How it develops, the early warning signs and the treatments at each stage.

See a dentist soonOptions

Common questions

Are fissure sealants painful?

No. There is no drilling or injection; the sealant is painted on and hardened with a light.

Can adults have fluoride varnish?

Your dentist may recommend fluoride varnish or high-fluoride toothpaste for adults at higher risk of decay, such as those with gum recession or a dry mouth.

Is fluoride safe?

The Oral Health Foundation says fluoride is safe and very effective when used in the right amount. Children should use a smear (under 3) or a pea-sized amount (3 and over) of toothpaste.

Useful at home

Products that can help with day-to-day care alongside this treatment. Ask your dental team what suits you. Some links may be affiliate links.

Sources we used

Checked September 2026. Guidance changes, so always follow the advice of your own dental team. About our sources.