[5] Relatively high ingestion of fluoride by babies and children may result in white marks on the teeth known as fluorosis.

[10] Fluoride toothpaste, with concentrations of 1000 ppm and above, reduces the risk of dental caries in school-aged children and adolescents.

[10] The use of fluoride supplements during the last six months of pregnancy has no significant impact on the incidence of fluorosis in children.

The lethal dose for most adult humans is estimated at 5 to 10 grams, equivalent to 32 to 64 mg elemental fluoride per kg of body weight.

[21] In 1974, a three-year-old child swallowed 45 milliliters of 2% fluoride solution, triple the fatal amount, and died.

The fluoride was administered during his first visit to the dentist, and the dental office was later found liable for the death.

The main mineral found in natural tooth enamel is hydroxyapatite rather than the fluorapatite created in the presence of fluoride.

[23] The remineralization cycle, critical to decay prevention, occurs when fluoride is present in the oral cavity.

[10][24][25] Fluoride ions are involved in three principal reactions of remineralization:[24] Iso-ionic exchange by the replacement of F− for OH¯ in apatite and crystal growth of fluorapatite from supersaturated solutions are able to occur during exposure to low levels of fluoride (0.01–10 ppm F) over long periods of time.

Reaction of apatite dissolution with CaF2 formation occurs in higher levels of fluoride (100–10,000 ppm F) and the addition of CaF2 or a CaF2 containing compound.

The antimicrobial effects require concentrations of fluoride at least 10 ppm F, which only occurs briefly in the mouth with oral fluoride-containing products.

[27] Fluoride does not prevent cavities but rather controls the rate at which they develop, and so repeated exposure throughout the day is essential for its effective function.

[34] Most toothpastes with fluoride contain mild abrasives in order to remove heavier debris and light surface staining.

First, it is available as a free ionic fluoride which can react with the tooth structure, interfere with the metabolism of bacteria in plaque, or absorb to the oral mucosa.

When combined with the stannous ion (Sn2+), fluoride in toothpaste appears to have a wide range of benefits to oral health.

Some anti-sensitivity toothpastes with fluoride on the market contain the ingredients called strontium chloride or potassium nitrate which help to alleviate tooth sensitivity.

[53] Acidulated phosphate fluoride (APF) gel or foam comprises a sodium fluoride solution, paste, or powder that has been acidulated with hydrofluoric acid to pH 3 to 4, buffered with a phosphate, and mixed with a gel or foam vehicle such as carboxymethyl cellulose.

[58] A specific benefit when using foam is that less product is required during application, which results in a lower fluoride dose and lessens the risk of accidental ingestion.

[53] Head and neck radiation treatment may destroy the cells of the salivary gland which can result in dry mouth.

[59] More research is required regarding the efficacy of fluoride gels in treating initial dental decay lesions.

[36] Fluoride varnish is a resin-based application that is designed to stay on the surface of the teeth for several hours.

[36] Currently, there is also no published evidence that indicates that professionally applied fluoride varnish is a risk factor for enamel fluorosis.

Fluoride varnish has shown to be effective in reducing initial dental decay lesions in both primary and permanent dentition.

[60] Application of fluoride varnish every six months is effective in preventing dental decay in primary and permanent teeth of children and adolescents.

[58] Devices that slowly release fluoride can be implanted on the surface of a tooth, typically on the side of a molar where it is not visible and does not interfere with eating.

[10] A Cochrane review also found no evidence that daily fluoride supplementation in pregnant women was effective in preventing tooth decay or causing fluorosis in their children.