Fluoride varnish: what it does and who can benefit
Originally published
Fluoride varnish is a concentrated fluoride preparation painted onto teeth by a dental professional. It can help reduce the risk of tooth decay in children and adults who need additional protection.
It works alongside daily brushing and other preventive care. It does not make teeth immune to decay, and it cannot replace treatment for a cavity that needs a filling or other dental care.
How does fluoride varnish work?
Fluoride helps enamel resist acid attack and supports repair of early mineral loss at the tooth surface. The varnish holds fluoride against the teeth for a period after application. It is not a permanent coating that blocks all bacteria.
The teeth may feel coated or look slightly different temporarily, depending on the product. Varnish is different from a fissure sealant, which fills grooves in the biting surface of a tooth. A dentist may recommend either or both according to the risk of decay.
Who should have it?
Fluoride varnish is part of preventive care for children. The NHS advises that children aged three and over should be offered it at least twice a year. Younger children may also need it if their risk of decay is increased. Tell your dental team about applications at school, nursery or another practice so they can coordinate care.
Adults may benefit when there is a higher risk of decay, for example because of dry mouth or exposed root surfaces. Braces or difficulty cleaning can also affect the prevention plan, but wearing an appliance does not mean that everyone needs the same schedule.
Some fluoride products can help with sensitivity. Persistent sensitivity still needs an assessment to check its cause; varnish is not a cure for every painful tooth.
What happens at the appointment?
The dental team checks that the product is suitable, dries the teeth and applies a small amount with a brush. Application usually takes only a few minutes and does not involve drilling. Let the team know if you are anxious or uncomfortable so they can adapt the appointment.
Before treatment, mention allergies, asthma, previous reactions to dental products and any current mouth ulcers or soreness. Some varnishes contain colophony, a resin that can cause an allergic reaction. A different product or preventive approach may be needed for some patients.
After the varnish is applied
Follow the instructions for the product used. The team will tell you when to eat, drink and brush again and whether to avoid particular foods for a short time. These instructions are not identical for every varnish, so ask if anything is unclear.
If you develop a reaction, seek advice promptly. Swelling of the tongue or throat or difficulty breathing needs emergency help through 999.
Keep up everyday prevention
Brush twice daily with fluoride toothpaste, including last thing at night, and spit out rather than rinse after brushing. Children need the right amount and fluoride concentration for their age, with help from an adult until at least age seven. See our guide to children’s toothpaste.
Limit how often teeth are exposed to sugary foods and drinks. Fluoride varnish does not cancel out frequent sugar intake, and acidic drinks can cause tooth wear as well as creating other concerns for your teeth.
Your dentist will recommend the application frequency and review interval for you or your child. Read about other preventive treatments for children or contact us to discuss a prevention plan.