Fluoride: Benefits and Safe Use for All Ages

What fluoride is and why it matters

Fluoride is a mineral found naturally in rocks, soil and water, and in small amounts in foods such as tea, fish and some vegetables. It is not a medication or a modern invention, but decades of research show that people who get the right amount develop fewer cavities, keep their teeth for longer and spend far less time in the dental chair.

The important phrase is right amount. Too little leaves teeth vulnerable; too much over a long period during childhood can cause visible changes in developing enamel. Here is how fluoride works and how to use it sensibly at every age.

How fluoride protects teeth

Enamel is the hardest tissue in the body, but it is not indestructible. Every time you eat or drink, acids from food, drinks and plaque bacteria attack the tooth surface and pull minerals out of it — a process called demineralisation.

Fluoride tips the balance back in your favour in two ways:

• It speeds up remineralisation. Saliva is rich in calcium and phosphate, and fluoride helps these minerals move back into the enamel.
• It builds tougher enamel. When fluoride is present during remineralisation, it forms a mineral called fluorapatite, which resists acid better than the original enamel.

Fluoride also makes it harder for plaque bacteria to produce acid. That is why brushing with fluoride toothpaste twice a day is the single most effective thing most people can do to prevent decay.

Toothpaste: the right amount for each age

Most adult toothpastes in the UK contain between 1,350 and 1,500 parts per million (ppm) fluoride; children's versions vary, so always check the label. As a general guide:

• Under 3 years: a smear of toothpaste containing at least 1,000 ppm fluoride — barely more than a grain of rice.
• 3 to 6 years: a pea-sized amount of 1,350–1,500 ppm fluoride.
• 7 years and older: a pea-sized amount of 1,350–1,500 ppm fluoride.
• Higher decay risk: a dentist may recommend a prescription toothpaste containing 2,800 or 5,000 ppm fluoride.

Two rules matter as much as the amount. Supervise young children and encourage them to spit rather than swallow. Then spit, don't rinse — rinsing with water or mouthwash straight after brushing washes away the fluoride that would otherwise keep working.

Fluoride in water and other sources

Most UK water contains only trace amounts of naturally occurring fluoride. Some areas have been fluoridated deliberately since the 1960s, with levels adjusted to around 1 mg per litre — roughly one part per million. Around six million people in England receive fluoridated water, and decay rates in children there are consistently lower.

Other useful sources include:

• Fluoride varnish, applied by a dentist or hygienist two or more times a year
• Fluoride mouthwash, used at a different time from brushing — never straight afterwards
• Fluoridated salt or milk in some countries, though this is uncommon in the UK

Supplements are not routinely recommended here and should only be used on a dentist's advice, since it is easy to double up with toothpaste and water.

Keeping it safe

Fluoride is safe when used as directed, but regularly swallowing large amounts is not advisable. The main concern is dental fluorosis, which appears as faint white flecks or lines on the teeth. It only develops while teeth are forming under the gums, usually before age eight, and mild cases are purely cosmetic.

• Keep toothpaste out of reach of toddlers and small children.
• Do not give children adult-strength toothpaste unless a dentist advises it.
• Use only a smear for under-threes, and teach children to spit rather than swallow.
• If a child swallows a large quantity of toothpaste, contact NHS 111 or a pharmacist.

A practical routine for every age

Fluoride works best as a habit. Brush last thing at night and at one other time during the day, using the right strength for your age, and avoid eating or drinking for 30 minutes afterwards so the fluoride has time to act.

Adults with receding gums, a dry mouth from medication, or a history of root decay may benefit from higher-strength toothpaste or extra varnish — root surfaces are softer than enamel and decay faster. Older adults in care settings often need help keeping the routine going, particularly where dexterity or memory is affected.

Finally, see a dentist regularly. Fluoride reduces risk; it does not remove it. Check-ups catch early decay while it is still reversible and let your dental team tailor advice to your teeth rather than the average person's.