Skip to main content

Fluorides

Sodium fluoride

Also listed as NaF, fluoride

The most common fluoride in toothpaste and mouthwash. Among the best-proven ingredients in any personal-care product: it cuts tooth decay by about a quarter.

Strong evidenceTypical strength: Toothpaste 1,000-1,450 ppm fluoride (0.22-0.32% NaF; EU cosmetic maximum 1,500 ppm); daily rinse 0.05% NaF (about 225 ppm)

What it is

Fluoride makes enamel harder for acid to dissolve and helps early decay re-harden. Sodium fluoride is the simplest way to deliver it: most toothpastes carry about 1,000-1,450 ppm fluoride (0.22-0.32% sodium fluoride), and daily mouthwashes about 225 ppm (0.05%).

The benefit comes from fluoride sitting on the teeth, not from swallowing it. That is why the advice is to spit out the excess and not rinse straight after brushing.

How strong is the evidence?

Strong evidence

Decades of randomised trials, pooled in Cochrane reviews, show fluoride toothpaste prevents about 24% of decayed, missing and filled tooth surfaces in children, with a dose-response: 1,450-1,500 ppm does slightly better than 1,000-1,250 ppm. Adults benefit too. Fluoride rinses add protection in children. The main downside, dental fluorosis (white flecks in enamel), comes from young children swallowing toothpaste while their teeth are forming.

What it's used for, checked

Prevents tooth decay

Holds up

High-certainty evidence from dozens of trials in children and adults.

Higher strength protects more

Holds up

1,450 ppm beats 1,000 ppm slightly; 5,000 ppm pastes are prescription products, mainly for high-risk adults.

Fluoride mouthwash adds protection

Holds up

Supervised rinsing cut decay about 27% in children; useful for people at high risk. Use it at a different time from brushing so you don't rinse the toothpaste fluoride away.

Fluoride in toothpaste lowers children's IQ

Unproven

The IQ debate concerns drinking water above 1.5 mg/L (about twice the US target level), not toothpaste used as directed and spat out.

Works well with

  • hydrated-silica
  • potassium-nitrate

Don't combine with

  • calcium carbonate as the abrasive (the calcium binds the fluoride in the tube, which is why chalk-based pastes use sodium monofluorophosphate instead)

Who should be careful

  • Children under 3: a smear the size of a grain of rice; ages 3-6: a pea-sized amount, with an adult supervising so they spit rather than swallow.
  • Dental fluorosis risk is from swallowing during tooth formation (under about age 6); the evidence linking toothpaste before 12 months to fluorosis is weak.
  • Swallowing a large amount (for example a child eating from the tube) can cause stomach upset or worse: call a poison control centre.
  • Prescription-strength pastes (up to 5,000 ppm) are for people a dentist has assessed as high-risk, mostly adults; do not use them for young children.

The studies

Every citation is checked against its PubMed record.

  1. Fluoride toothpastes of different concentrations for preventing dental caries.
    Walsh T, Worthington HV, Glenny AM, Marinho VC, Jeroncic A · Cochrane Database Syst Rev · 2019 · Systematic review / network meta-analysis

    96 trials. High-to-moderate certainty that 1,000-1,250 ppm and 1,450-1,500 ppm fluoride toothpastes reduce caries in children and adolescents versus non-fluoride paste, with 1,450-1,500 ppm slightly better; 1,000-1,100 ppm also reduced decay in adults. Side effects were minimal where reported.

  2. Fluoride toothpastes for preventing dental caries in children and adolescents.
    Marinho VC, Higgins JP, Sheiham A, Logan S · Cochrane Database Syst Rev · 2003 · Systematic review / meta-analysis

    Across 70 trials in 42,300 children, fluoride toothpaste prevented about 24% of decayed, missing and filled surfaces compared with non-fluoride paste; the effect was bigger with higher concentration, more frequent and supervised brushing.

  3. Topical fluoride as a cause of dental fluorosis in children.
    Wong MC, Glenny AM, Tsang BW, et al. · Cochrane Database Syst Rev · 2010 · Systematic review

    Mostly observational and at risk of bias: starting fluoride toothpaste before 12 months of age was weakly associated with more (mostly mild) fluorosis, and higher-fluoride pastes raised fluorosis risk in trials. Where fluorosis is a concern, under-6s may use pastes below 1,000 ppm.

  4. Fluoride mouthrinses for preventing dental caries in children and adolescents.
    Marinho VC, Chong LY, Worthington HV, Walsh T · Cochrane Database Syst Rev · 2016 · Systematic review / meta-analysis

    37 trials (15,813 children), mostly supervised school rinsing with sodium fluoride at 230 ppm daily or 900 ppm weekly: about 27% fewer decayed, missing and filled surfaces in permanent teeth (moderate-quality evidence).