Fluoride varnish is a professional dental treatment that applies a high concentration of fluoride directly to the teeth. It sets quickly on contact with saliva, releasing fluoride slowly over several hours.
Fluoride strengthens tooth enamel, making teeth more resistant to the acids produced by bacteria after eating sugar. It can also help reverse very early signs of decay before they become cavities. NICE recommends fluoride varnish as a core preventive treatment for both children and adults at risk of decay.
Who should have fluoride varnish?
NICE guidelines and SDCEP guidance recommend fluoride varnish for:
Children aged 3 and over — at least twice a year as part of routine dental care
Children at higher risk of decay — up to four times per year
Adults with moderate or high risk of decay — at least twice a year
People with dry mouth (xerostomia)
People with exposed root surfaces that may be sensitive or at risk of root decay
People undergoing orthodontic treatment with fixed braces
What does the procedure involve?
Fluoride varnish application is quick and completely painless:
The teeth are cleaned and dried
The varnish (a pale yellow, sticky gel with a pleasant smell) is painted onto all tooth surfaces with a small brush
The varnish sets on contact with saliva within seconds
After application, you should:
Avoid eating or drinking for at least 30 minutes
Avoid rinsing, spitting, or brushing your teeth until that evening
Eat only soft foods on the day of application
Is fluoride varnish safe?
Professional fluoride varnish has a well-established safety record when applied by a dental professional. Although the varnish contains a high concentration of fluoride, only a very small amount is used and it is not swallowed in significant quantities.
Swallowing small amounts of fluoride varnish during application is not harmful. For very young children, a pea-sized amount of varnish is used to minimise any swallowing.
Fluoride varnish is not suitable for people with a known allergy to colophony (a tree resin used in the varnish). Please tell your dentist if you have any known allergies before treatment.
Fluoride and overall decay prevention
Fluoride varnish works best as part of a complete prevention programme:
Brush twice daily — last thing at night and at one other time — with fluoride toothpaste containing at least 1,000 ppm fluoride. For children aged 0–3, use a smear of toothpaste with at least 1,000 ppm fluoride. For children aged 3–6, use a pea-sized amount. For children over 6 and adults, use toothpaste with 1,350–1,500 ppm fluoride.
Spit after brushing, do not rinse with water — this keeps a protective layer of fluoride on the teeth
Reduce sugar intake and frequency — what you eat matters, but how often you eat sugar is just as important
Attend regular dental check-ups
Questions to ask your dentist
How often do you recommend fluoride varnish for me or my child?
Is my child's decay risk low, moderate, or high?
Are there any other preventive treatments I should consider alongside fluoride varnish?
This leaflet is for general information only and does not replace professional dental advice. It is intended to support — not replace — the discussion with your dentist about your individual options, risks, and treatment plan. Treatment outcomes vary between patients depending on individual circumstances. Your dentist will confirm exact fees and what is suitable for your specific circumstances before you agree to any treatment.
References
Aligned with guidance from: SDCEP, NICE, Public Health England, FGDP(UK).