Desde 1950, os benefícios e riscos do uso da água fluoretada têm sido debatidos mundialmente. No passado, foi considerado que o fluoreto ingerido sistemicamente exerceria seu efeito preventivo de cárie pela sua incorporação ao esmalte como fluorapatita, tornando o esmalte mais resistente ao processo de desenvolvimento de lesões de cárie; entretanto, é atualmente reconhecido que o principal efeito da fluoretação da água é local e pós-eruptivo. Por outro lado, independente do declínio de cárie que tem sido observado mundialmente, o benefício anticárie da fluoretação da água continua sendo observado mesmo em países desenvolvidos. Com relação aos riscos, fluoretação da água é considerada uma estratégia aceitável de saúde pública para uso de fluoreto, porque o risco de desenvolvimento de fluorose dental devido à ingestão de fluoreto durante o período de formação do esmalte foi considerado aceitável quando comparado aos benefícios anticárie do flúor. Entretanto, o uso de fluoreto na água para controlar cárie tem gerado controvérsias devido a dados de pesquisa que associam fluoretação da água como causa de algumas doenças sistêmicas. Assim, o objetivo dessa revisão descritiva foi discutir os efeitos sistêmicos (riscos) da fluoretação da água..
Article • Braz. Dent. J. 30
(5)
• Sep-Oct 2019 • https://doi.org/10.1590/0103-6440201903124 linkcopiar
Systemic Effects (Risks) of Water Fluoridation
Autoria
person Jaime A Cury
person Antonio P Ricomini-Filho
person Francine L. Perecin Berti
person Cinthia PM Tabchoury
Correspondence: Prof. Jaime Aparecido Cury, Avenida Limeira, 901, 13414-903 Piracicaba, SP, Brasil. Tel: +55-19-2106-5303. e-mail:
jcury@unicamp.br
jcury@unicamp.br
Figuras | Tabelas
imageFigure 1 Illustration of fluoride metabolism from drinking water. Ingested fluoride is absorbed mainly in the stomach (as HF form) and also in a lower extent in the intestine (a). The blood (b) is the central compartment from which fluoride (F-) will be distributed throughout the body, returning to the oral cavity via salivary glands (c), or being incorporated into hard tissues (d). In a pregnant woman, the fetus can be considered a sub-compartment of the maternal organism, and F- is equally distributed to its tissues (e). The F- absorbed and circulating throughout the body is excreted in the urine (f), while unabsorbed F (chemically insoluble in the form of insoluble salts, such as calcium fluoride - CaF2) is excreted in feces (g). open_in_new

imageFigure 2 Fluoride concentration in saliva (µg F/mL) over time due to mastication of food cooked with fluoridated water (0.70 ppm F - green line) compared with non-fluoridated water (blue line). Fluoride concentration in saliva was determined before meal ingestion (0), during 15 min at meal mastication, and after the mastication period until 60 min. open_in_new

imageFigure 3 Clinical aspect of the different levels of dental fluorosis. A) very mild (small whitish and opaque spots scattered irregularly on the teeth, involving no more than 25% of the surfaces); B) mild (the opacity is more extensive, but does not involve more than 50% of the surfaces); C) moderate (more evident white areas, affecting most of the crown); and D) severe (intense and generalized hypomineralization, with occasional loss of dental structure). Data from children exposed to well water containing 1.4 ppm F, Assistência district, Rio Claro city, SP, Brazil. Pictures kindly donated by Dr Aliete A. Otta-Rui. open_in_new

imageFigure 4 Prevalence of dental fluorosis in Brazil, according to SB 2010 (Brazilian Ministry of Health, 2010 national oral health survey) 16. open_in_new

imageFigure 5 Child presenting severe fluorosis due to exposure to well water containing 1.4 ppm F. open_in_new

table_chartTable 1
Fluoride concentration (µg F/g = ppm F) in dental biofilm of schoolchildren according to conditions of water fluoridation and fluoride concentration in public water supply of Piracicaba, SP, Brazil, 1986-87.
| Condition of water fluoridation (fluoride concentration) | µg F/g (mean ± SD) |
|---|---|
| Fluoridated (0.8 ppm F) | 3.2±1.8 (n=91) |
| Interrupted (0.06 ppm F) | 0.2±0.1 (n=41) |
| Re-fluoridated (0.7 ppm F) | 2.6±1.9 (n=55) |
-
On the other hand, fluoride ingested from water and absorbed in the gastrointestinal tract enters the bloodstream (Fig. 1), and is distributed throughout the body, being able to cause systemic effects, acute or chronic.
table_chartTable 2
Fluoride concentration in fluoridated products, amount of fluoride in 1 mL or 1 g of product and amount of product required to expose a 20 kg child (5-6 years old) to the probably toxic dose (PTD) of 5.0 mg F/kg
| Product | Fluoride (F) concentration (ppm F) | Amount of F in 1 mL or 1 g | Amount of product required for a 5-6 years old child (20 kg) to be exposed to the PTD |
|---|---|---|---|
| Fluoride Varnish (5% NaF) | 22,000 | 22 mg/g | 4.5 g |
| Acidulated phosphate fluoride gel (1.23% F) | 12,300 | 12.3 mg/g | 8.1 g |
| Mouthrinse for weekly use (0.2% NaF) | 900 | 0.9 mg/mL | 111 mL |
| Dentifrice (0.11% F) | 1,100 | 1.1 mg/g | 90 g (1 tube) |
| Mouthrinse for daily use (0.05% NaF) | 225 | 0.225 mg/mL | 444 mL |
| Fluoride supplement (2.21 mg of NaF) | 1.0 mg F/tablet | 100 tablets | |
| Optimally fluoridated water | 0.7 | 0.0007 mg/mL | 143 liters |
table_chartTable 3
Prevalence of dental fluorosis in schoolchildren from Três Lagoas, MS, Brazil, exposed to non-fluoridated water (Schools A and B) and exposed to well water containing 1.4 ppm F (School C).
| Schools and Fluoride concentration in water (ppm F) | Prevalence of normal teeth and with different levels of fluorosis (%) | |||||
|---|---|---|---|---|---|---|
| Levels of Fluorosis | ||||||
| Normal | Questionable | Very mild | Mild | Moderate | Severe | |
| A (0.0) | 87.9 | 9.4 | 2.7 | 0.0 | 0.0 | 0.0 |
| B (0.0) | 91.0 | 5.8 | 2.6 | 0.6 | 0.0 | 0.0 |
| C (1.4 ppm) | 33.8 | 23.6 | 24.0 | 11.8 | 4.2 | 2.5 |
table_chartTable 4
Dose of fluoride ingestion (mg F/kg/day) by children (20-30 months old) from Piracicaba, SP, Brazil (n = 39) and Ibiá, MG, Brazil (n = 32) due to the ingestion of fluoridated water (diet of liquids and solids) and fluoride dentifrice.
| City location | mg F/kg body weight/day | ||
|---|---|---|---|
| Diet | Dentifrice | Diet + Dentifrice | |
| Piracicaba, SP, (kindergarten) | 0.04 | 0.052 | 0.092 |
| Ibiá, MG, (home) | 0.027 | 0.061 | 0.088 |
table_chartTable 5
Chronology of campaigns against water fluoridation and allegations used (modified from Newbrun, 1996).
| Year | Allegations |
|---|---|
| 1950 | Communist plan |
| 1960 | Toxic waste, polluting |
| 1970 | Government conspiracy |
| 1980 | Industrial interests, cancer in humans, |
| Aging, Alzheimer’s disease | |
| 1990 | AIDS, bone fracture, birth rate |
| 2000-present | Decreased IQ, hypothyroidism |
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