17.7: Fluoride
- Page ID
- 58203
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Fluoride is often thought to be merely an additive which can help prevent tooth decay. It’s very effective at doing so. The savings in the cost of dental care is much more than the cost of adding fluoride to the water supply.
Fluoride prevents decay by becoming incorporated into tooth enamel, making it more resistant to the acid produced by mouth bacteria. This process occurs during the formation and calcification of the enamel. The formation and calcification of the crowns of all of the permanent teeth, except for the 3rd molars (wisdom teeth), are completed by 8 to 9 years of age. Although some teeth mineralize before birth, there is no proof that maternal fluoride ingestion during pregnancy is protective.
Fluoride in drinking water, toothpaste, mouth rinse, etc., also helps protect adults’ teeth, mainly by promoting the remineralization of the surface enamel (see Chap. 5). Fluoride may also be helpful in strengthening bone.
Fluoride is present in various concentrations in all natural water supplies, and the related variation in levels of tooth decay provided early evidence of fluoride’s protective effect. For example, the fluoride content of the water in Quincy, Illinois was no more than 0.2 parts per million (ppm), and they had more than three times as many dental cavities as nearby Galesburg, where the fluoride in the water was 1.9 ppm.
Fluoride at 0.7 ppm in the drinking water is the recommended level. This level provides protection against decay without the mottling (fluorosis) of the enamel of developing teeth that can be caused by excessive fluoride.
The discovery that mottled teeth in high fluoride areas were highly resistant to tooth decay led to the discovery of fluoride’s protective effect. At fluoride levels of 2 ppm or more during tooth development, the enamel can develop small areas that are “extra white.” At 4 ppm or more, there may be brown stains.
Other causes of brown stains on the enamel include exposure to the antibiotic tetracycline during tooth development from before birth to about 8 years old.
For water supplies with less than 0.7 ppm fluoride, the addition of fluoride is recommended. Fluoridation substantially reduces the number of decayed teeth. Also, there’s substantial evidence that fluoridation of water lowers risk of osteoporosis, by strengthening bone.
For infants who are exclusively breast fed, and for children who don’t have access to fluoridated water, daily fluoride drops or tablets are advised, as prescribed by a physician or dentist.
Only about three-fourths of the U.S. population has access to an adequately fluoridated municipal water supply. Unlike most public health measures, fluoridation is voted on by communities. Many people are frightened by being told, for example, that fluoride is a rat poison. In large enough doses, it is, in fact, a rat poison—even a human poison for that matter. The size of the dose determines the hazard. (When water supplies have been naturally excessive in fluoride, communities have, on occasion, voted down proposals to lower the fluoride level, wanting to leave their water “natural.”)
The benefits and safety of water fluoridation have been studied for 70+ years. Its effectiveness in dramatically reducing the prevalence and severity of tooth decay in the U.S. is said to be 1 of our 10 greatest public health achievements in 20th century.7