Fluoride guide

What fluoride does

Cleveland Clinic says fluoride is a naturally occurring mineral that helps prevent tooth decay: it helps enamel regain minerals lost to acid attacks, reverses early decay, slows demineralization and inhibits cavity-causing bacteria, reducing the risk of cavities by about 25 percent. The ADA says topical fluoride strengthens teeth already in the mouth, making them more resistant to decay, and systemic fluoride becomes part of developing teeth.

Is fluoride safe? Is fluoride in toothpaste harmful?

The ADA recognizes fluoride and community water fluoridation as safe and effective for preventing tooth decay in children and adults when used as directed. Cleveland Clinic says health experts consider fluoride safe and effective at recommended levels, that it can be harmful in large amounts, but toxic levels are hard to reach with over-the-counter products such as toothpaste and mouth rinses. Healthline says overdose from supplements can cause nausea, diarrhea, tiredness and excessive sweating and can be fatal, and advises keeping supplements away from children.

How much toothpaste

The ADA says to brush twice daily with fluoride toothpaste, starting as soon as teeth appear: a smear or grain-of-rice amount under 3 years, and a pea-sized amount at 3 to 6 years with supervision. Cleveland Clinic says children should use only a pea-sized amount, spit it out and be supervised, and that children under 6 should not use fluoride mouth rinses unless a dentist or healthcare provider recommends it.

Water fluoridation

The ADA says the recommended optimal level is 0.7 parts per million, that fluoridation reduces tooth decay by about 20 to 40 percent in children and adults, and that the U.S. Public Health Service confirmed 0.7 ppm as optimal in 2015. Cleveland Clinic gives the same level and says well water can be tested for fluoride content.

Do filters, bottled water or boiling remove fluoride?

The ADA says most bottled water contains less than 0.3 ppm, and that reverse osmosis and distillation systems can remove fluoride but carbon or charcoal filters do not. That answers the question about refrigerator filters in general, which commonly use carbon, but check your filter's documentation. The sources we read do not name specific bottled water brands, such as Poland Spring, and do not say whether boiling removes fluoride, so check the label or the supplier.

Professional fluoride treatment

Cleveland Clinic says a dentist or hygienist paints varnish on the teeth, usually during a routine exam or cleaning, typically in under five minutes, and that many people benefit every six months. The ADA says varnish is professionally applied, needs at least two applications a year for sustained benefit, and the U.S. Preventive Services Task Force recommends it for all infants and children from tooth eruption. See our guide on how long after fluoride treatment you can eat, and when you can brush.

Dental fluorosis

The ADA says fluorosis is a risk from excess fluoride during tooth development, from white streaks to stained pitting of enamel, that it can only develop while teeth are forming, and that it is prevented by using the recommended toothpaste amount and storing toothpaste out of young children's reach. Cleveland Clinic says it is the most common side effect, usually in children under 6, appears as faint white streaks, and most often results from high levels of naturally occurring fluoride such as in well water, and that treatments include bleaching, bonding or veneers because brushing cannot remove it.

Who may benefit most

Cleveland Clinic says adults with dry mouth, gum disease, a history of decay or certain dental devices may also benefit, and Healthline lists people at high risk of cavities. Ask your dentist whether extra fluoride suits you or your child.

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Frequently asked questions