Fluoride

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    Last Updated: December 18, 2023

    Fluoride is a mineral found in bones and teeth. Fluoride is often used to strengthen enamel and prevent cavities. Small amounts of fluoride are added to public water supplies in some countries, a process known as water fluoridation.

    Fluoride is most often used for .

    What is fluoride?

    Fluoride is the ionic form of the abundant element fluorine. It occurs in soil, rocks, and water, and is naturally present in food and drink. About 99% of the fluoride in the body is bound to calcified tissues (bones and teeth), and the rest is in the blood. Despite its presence in the body, it’s debated whether fluoride is an “essential” mineral, and there are no set dietary guidelines for fluoride.[1] Fluoride is also found in many toothpastes and in some dietary supplements. While inadequate fluoride intake leads to tooth decay (dental caries), excessive intake can damage tooth enamel and cause other side effects. To prevent tooth decay, fluoridation of community water has been a practice since the 1960s in the United States.[1] Currently, about 30 Western countries have fluoridation policies, but less than half have active community water fluoridation.[3]

    What are fluoride’s main benefits?

    Fluoride’s claim to fame is its ability to stop and reverse tooth decay: when topically applied to the teeth (e.g., in toothpaste or water), it’s integrated into the structure of the enamel. It simultaneously inhibits demineralization and promotes remineralization of the tooth, as well as blocking the activity of plaque-forming bacteria.[4] Toothpaste containing 1000 to 1250 ppm of fluoride prevents caries to a greater degree than non-fluoride toothpaste.[5] Fluoride also plays a role in bone formation and has been used for preventing osteoporosis.[1]

    What are fluoride’s main drawbacks?

    Excessive intake of fluoride (>5-6 mg/daily) can be toxic, and most commonly presents as dental fluorosis (mottled enamel with white/brown spots and pitting). Higher daily doses (10-25 mg/day) of fluoride can lead to skeletal fluorosis, an accumulation of fluoride in bone, which increases bone density, reduces joint mobility, and can lead to fractures and pain; such high doses can sometimes even lead to cardiac complications. Some evidence suggests that the neurological development of children may be stunted by high fluoride exposure, but more research is needed to be sure. Fluoride toxicity most often occurs due to excessive ingestion of fluoridated dental products and in areas with naturally elevated levels of fluoride in the groundwater (e. g., parts of China and India). In cases of fluoride toxicity, calcium is often used to minimize further absorption of fluoride.[1]

    How does fluoride work?

    Fluoride (from drinking water, supplements, tea, or dental products) is absorbed by the small intestine, and about half is excreted via the kidneys. Absorbed fluoride in the blood can bind with apatite in bone and teeth, becoming fluorapatite. Blood and bone concentrations of fluoride are in equilibrium and are impacted by bone remodeling activity and age.[1] Fluoride in toothpaste and mouthwash works locally in the mouth by getting integrated into the structure of the tooth, supporting remineralization of teeth (by speeding up uptake of minerals like calcium and phosphate from the saliva to make stronger crystals on the outer enamel), resisting demineralization by acidic substances in the mouth, and inhibiting the activity of plaque-forming bacteria.[6][7] Fluoride can also be professionally applied as a gel or varnish, allowing fluoride to be released when the mouth becomes acidic, thereby providing longer-term protection to the enamel.[5]

    What are other names for Fluoride

    Note that Fluoride is also known as:
    • Acidulated Phosphate Fluoride
    • Amine Fluoride
    • Silver Diamine Fluoride
    • Sodium Fluoride
    • Sodium Monofluorophosphate
    • Stannous Fluoride

    Dosage information

    Fluoride is consumed from foods, fluoridated water, toothpaste, and some dietary supplements. Apart from some teas, most foods do not contain a substantial amount of fluoride. There is no dietary reference intake (DRI) for fluoride, but adults consume less than about 0.5 mg daily. The maximum safe daily dose of fluoride is 4 mg in adult men and 3 mg in women.[1] In Europe, a number of combination mineral supplements for bone health containing 0.95 mg of fluoride per dose have been on the market for 40 years without reported side effects.[1]

    In community drinking water, the concentration of fluoride to prevent tooth decay ranges between 0.5 and 1.1 mg/L. The US Public Health Service recommends a fluoride concentration of 0.7 mg/L, and the US Environmental Protection Agency set the maximum level as 4 mg/L. The World Health Organization (WHO) guideline recommends 1.5 mg/L fluoride in the drinking water.[2]

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    Frequently asked questions

    What is fluoride?

    Fluoride is the ionic form of the abundant element fluorine. It occurs in soil, rocks, and water, and is naturally present in food and drink. About 99% of the fluoride in the body is bound to calcified tissues (bones and teeth), and the rest is in the blood. Despite its presence in the body, it’s debated whether fluoride is an “essential” mineral, and there are no set dietary guidelines for fluoride.[1] Fluoride is also found in many toothpastes and in some dietary supplements. While inadequate fluoride intake leads to tooth decay (dental caries), excessive intake can damage tooth enamel and cause other side effects. To prevent tooth decay, fluoridation of community water has been a practice since the 1960s in the United States.[1] Currently, about 30 Western countries have fluoridation policies, but less than half have active community water fluoridation.[3]

    What are fluoride’s main benefits?

    Fluoride’s claim to fame is its ability to stop and reverse tooth decay: when topically applied to the teeth (e.g., in toothpaste or water), it’s integrated into the structure of the enamel. It simultaneously inhibits demineralization and promotes remineralization of the tooth, as well as blocking the activity of plaque-forming bacteria.[4] Toothpaste containing 1000 to 1250 ppm of fluoride prevents caries to a greater degree than non-fluoride toothpaste.[5] Fluoride also plays a role in bone formation and has been used for preventing osteoporosis.[1]

    Should community water be fluoridated?

    This is a controversial question. Tooth decay is a public health problem affecting many adults and children. But the need for community water to be fluoridated is debated.[1] There is evidence from observational research including 44,268 participants that fluoridation reduces levels of tooth decay and caries in children, compared to no fluoridation, by up to 35%. Fluoridation is linked with 15% more children with no decay in baby teeth and 14% more children with no decay in permanent teeth. However, most of this research is from before widespread use of fluoride toothpaste.[9] There is not enough evidence to know what would occur if fluoridation were removed in the present day.

    What are fluoride’s main drawbacks?

    Excessive intake of fluoride (>5-6 mg/daily) can be toxic, and most commonly presents as dental fluorosis (mottled enamel with white/brown spots and pitting). Higher daily doses (10-25 mg/day) of fluoride can lead to skeletal fluorosis, an accumulation of fluoride in bone, which increases bone density, reduces joint mobility, and can lead to fractures and pain; such high doses can sometimes even lead to cardiac complications. Some evidence suggests that the neurological development of children may be stunted by high fluoride exposure, but more research is needed to be sure. Fluoride toxicity most often occurs due to excessive ingestion of fluoridated dental products and in areas with naturally elevated levels of fluoride in the groundwater (e. g., parts of China and India). In cases of fluoride toxicity, calcium is often used to minimize further absorption of fluoride.[1]

    Does fluoride impact neurological development in children?

    Although more research is needed to know for sure, it appears that excessive fluoride exposure is linked to poorer cognition in children; it’s important to note that community fluoridation in the United States and Canada is far below this level. A meta-analysis of 8 cross-sectional and cohort studies did not find that fluoride exposure via community water fluoridation affects IQ scores in children. However, high fluoride exposure (3.7 mg/L) from natural groundwater in certain geographical areas (e.g., parts of China and India) was associated with lower IQ when compared with lower fluoride exposure (0.7 mg/L). There was no difference in IQ between mean exposure to 0.9 mg/L fluoride when compared to 0.3 mg/L fluoride.[2] Another meta-analysis of 26 observational studies mostly conducted in China found that high fluoride exposure from water is associated with lower intelligence compared to normal fluoride exposure.[8] This data is limited by its observational nature and the presence of various confounding factors. For example, the impact of socio-economic status or exposure to environmental toxins was not able to be controlled.

    Why are certain geographical areas more prone to fluoride toxicity?

    While Western countries like the United States intentionally add a small amount of fluoride to drinking water for dental health, some geographical locations have groundwater that is naturally excessively high in fluoride, and people who live in these areas have a greater risk of developing fluoride toxicity. In some regions of India and China, geothermal and volcanic activity has led to the formation of rocks that have high levels of fluoride. When these rocks are exposed to alkalinity and heat, fluoride is released into the soil and freshwater sources, resulting in high-fluoride food crops and drinking water. Fluoride does not have a taste, odor, or color, and since groundwater is not tested often, high fluoride exposure can go undetected for a long time. It is predicted that some countries in Central Africa are also at high risk for drinking water with excessively high fluoride.[10]

    How does fluoride work?

    Fluoride (from drinking water, supplements, tea, or dental products) is absorbed by the small intestine, and about half is excreted via the kidneys. Absorbed fluoride in the blood can bind with apatite in bone and teeth, becoming fluorapatite. Blood and bone concentrations of fluoride are in equilibrium and are impacted by bone remodeling activity and age.[1] Fluoride in toothpaste and mouthwash works locally in the mouth by getting integrated into the structure of the tooth, supporting remineralization of teeth (by speeding up uptake of minerals like calcium and phosphate from the saliva to make stronger crystals on the outer enamel), resisting demineralization by acidic substances in the mouth, and inhibiting the activity of plaque-forming bacteria.[6][7] Fluoride can also be professionally applied as a gel or varnish, allowing fluoride to be released when the mouth becomes acidic, thereby providing longer-term protection to the enamel.[5]

    Update History

    References

    1. ^Berger MM, Shenkin A, Schweinlin A, Amrein K, Augsburger M, Biesalski HK, Bischoff SC, Casaer MP, Gundogan K, Lepp HL, de Man AME, Muscogiuri G, Pietka M, Pironi L, Rezzi S, Cuerda CESPEN micronutrient guideline.Clin Nutr.(2022-Jun)
    2. ^Kumar JV, Moss ME, Liu H, Fisher-Owens SAssociation between low fluoride exposure and children's intelligence: a meta-analysis relevant to community water fluoridation.Public Health.(2023-Jun)
    3. ^Peckham S, Awofeso NWater fluoridation: a critical review of the physiological effects of ingested fluoride as a public health intervention.ScientificWorldJournal.(2014)
    4. ^Featherstone JDPrevention and reversal of dental caries: role of low level fluoride.Community Dent Oral Epidemiol.(1999-Feb)
    5. ^Walsh T, Worthington HV, Glenny AM, Marinho VC, Jeroncic AFluoride toothpastes of different concentrations for preventing dental caries.Cochrane Database Syst Rev.(2019-Mar-04)
    6. ^ten Cate JMContemporary perspective on the use of fluoride products in caries prevention.Br Dent J.(2013-Feb)
    7. ^Marquis REAntimicrobial actions of fluoride for oral bacteria.Can J Microbiol.(1995-Nov)
    8. ^Duan Q, Jiao J, Chen X, Wang XAssociation between water fluoride and the level of children's intelligence: a dose-response meta-analysis.Public Health.(2018-Jan)
    9. ^Iheozor-Ejiofor Z, Worthington HV, Walsh T, O'Malley L, Clarkson JE, Macey R, Alam R, Tugwell P, Welch V, Glenny AMWater fluoridation for the prevention of dental caries.Cochrane Database Syst Rev.(2015-Jun-18)
    10. ^Podgorski J, Berg MGlobal analysis and prediction of fluoride in groundwater.Nat Commun.(2022-Aug-01)

    Examine Database References

    1. Dental Health Metrics - Walsh T, Worthington HV, Glenny AM, Marinho VC, Jeroncic AFluoride toothpastes of different concentrations for preventing dental caries.Cochrane Database Syst Rev.(2019-Mar-04)
    2. Dental Health Metrics - Valkenburg C, Van der Weijden F, Slot DEIs plaque regrowth inhibited by dentifrice?: A systematic review and meta-analysis with trial sequential analysis.Int J Dent Hyg.(2019-Feb)
    3. Dental Health Metrics - Chou R, Pappas M, Dana T, Selph S, Hart E, Fu RF, Schwarz EScreening and Interventions to Prevent Dental Caries in Children Younger Than 5 Years: Updated Evidence Report and Systematic Review for the US Preventive Services Task Force.JAMA.(2021-Dec-07)
    4. Dental Health Metrics - Benson PE, Parkin N, Dyer F, Millett DT, Germain PFluorides for preventing early tooth decay (demineralised lesions) during fixed brace treatment.Cochrane Database Syst Rev.(2019-Nov-17)
    5. Dental Health Metrics - He S, Choong EKM, Duangthip D, Chu CH, Lo ECMClinical interventions with various agents to prevent early childhood caries: A systematic review with network meta-analysis.Int J Paediatr Dent.(2023-Sep)
    6. Bone Mineral Density - Melek J, Sakuraba AEfficacy and safety of medical therapy for low bone mineral density in patients with inflammatory bowel disease: a meta-analysis and systematic review.Clin Gastroenterol Hepatol.(2014-Jan)