Fluoride: Why Your Dentist Recommends It (and the Myths to Ignore)

If you have spent any time on the internet, you have run into strong opinions about fluoride. Some of them are informed. A lot of them are not. This post walks through what fluoride actually does, why every major dental and medical body recommends it, and where the concerns are — and are not — well-founded.

What fluoride actually does

Enamel is built from a mineral called hydroxyapatite. When you eat, bacteria in your mouth produce acids that pull minerals out of enamel — a process called demineralisation. Saliva and fluoride push those minerals back in — remineralisation. Cavities form when demineralisation outpaces remineralisation for long enough.

Fluoride does two things: it accelerates remineralisation, and it makes the resulting enamel stronger than what was there before. Teeth that grow in with adequate fluoride exposure are meaningfully more resistant to decay for life.

The evidence

Community water fluoridation has been called one of the ten great public health achievements of the 20th century by the CDC. Studies consistently show it reduces cavities by 20 to 40 percent in children and adults compared to unfluoridated water. Every major dental and medical organisation in the world — including Health Canada, the Canadian Dental Association, the American Dental Association, and the World Health Organization — supports its use.

Calgary voted to remove fluoride from the water supply in 2011 and reintroduce it in 2021 after seeing measurable increases in childhood cavities during the intervening decade. That real-world data is one of the clearest illustrations of what fluoride does at a population level.

The myths worth addressing

"Fluoride is toxic"

The dose makes the poison. Water is toxic in large enough quantities. So is oxygen. Fluoride at the concentrations used in water (about 0.7 parts per million) and toothpaste (1,000 to 1,500 ppm) has been studied for decades with no evidence of harm at those levels.

"Fluoride lowers IQ"

This claim comes from a handful of studies conducted in regions with naturally occurring fluoride levels many times higher than what is used in North American water — sometimes 5 to 10 times higher. Those studies do not translate to the concentrations used here. Studies at typical Canadian levels have not found any cognitive effect.

"Fluoride causes cancer"

This has been studied repeatedly and thoroughly. No credible evidence has established a link between fluoride at recommended levels and any type of cancer.

"My kid does not need fluoride"

Children benefit most from fluoride, because their permanent teeth are still forming. Adequate fluoride exposure in childhood produces stronger enamel that lasts a lifetime. Skipping it does not just affect them today — it affects the teeth they will have at 40.

Where legitimate caution applies

Fluorosis in kids

Very young children who swallow too much toothpaste can develop mild fluorosis — faint white streaks on the permanent teeth. This is cosmetic, not harmful, and easily avoided: for kids under three, use a rice-grain-sized amount. For kids three to six, a pea-sized amount. Supervise brushing until they can reliably spit.

Well water

If your household uses well water, get it tested. Some wells have naturally high fluoride and some have almost none — both are worth knowing about.

What we actually recommend at Cloud Dental

A fluoride toothpaste twice a day, drinking tap water (Calgary's water is now fluoridated at the recommended level), and a professional fluoride varnish at hygiene visits — especially for children and for adults with a history of cavities or sensitivity. That is it. It is one of the cheapest, most effective interventions in medicine, and the evidence for it is overwhelming.

If you have specific concerns about fluoride for yourself or your children, bring them up at your next visit. We would rather talk them through than have you make the call based on what the algorithm served up last Tuesday.