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The Informed Parent

Facts About Fluoride

by Louis P. Theriot, M.D., F.A.A.P.
Published on Mar. 17, 2014

I was seeing Kacie for her 9-month well check, accompanied by her mom and grandmother who was visiting from back east. The exam went fine as Kacie was doing remarkably well in terms of growth and development. When we were about to finish, Grandmother said, “…Well, go ahead. Ask him!”

Kacie’s mom shrugged her shoulders and said, “My mother wants me to ask why Kacie isn’t getting any fluoride drops. She distinctly remembers giving me and my brothers drops that were by prescription only.” Grandmother seemed pleasantly vindicated when I said that she was right, that we did in fact use fluoride drops until the late 1990’s. This generated a whole discussion about dental cavities, which I think might be informative for parents.

Dental caries (cavities) are caused by bacteria that produces acids as a byproduct of carbohydrate metabolism. These acids dissolve the calcium-phosphate mineral of the enamel which leads to it’s demineralization and results in a cavity. The more common such bacterium are streptococcus mutans and lactobacillus. Frequent consumption of sugar sweetened drinks and juices, or putting a child to bed with a bottle or sippy-cup of milk or juice bathes the teeth with carbohydrates. These serve as a substrate for the bacteria to produce the damaging acids and cause the cavities.

The benefits of fluoride in preventing cavities has been know since the early 20th century. It was observed that people who consumed naturally fluoridated water were more resistant to dental caries. Fluoride has been shown to be of benefdit AFTER the tooth has erupted. It aids in the incorporation of calcium and phosphate into the enamel, and this strengthens the teeth. Fluoride itself is also incorporated into the enamel as fluoroapetite. This is harder than the normal enamel and less resistant to the effect of the aids produced by the bacteria.

Community fluoridation of public water started in the mid-1900’s. Grand Rapids, Michigan was the first city to do this in 1945. Currently, the decision to fluoridate the water is made at the city and local level. The amount of fluoride in the public water varies greatly from city-to-city. Health organizations are calling for a universal fluoride level of 0.7 parts per million (ppm), but this has not yet happened. This is to provide enough fluoride to protect the public as a whole but not run the risk of too much fluoride. This can lead to a condition called fluorosis. Fluorosis can cause staining and mottling of the teeth, and can actually cause a weakening of the enamel leading to caries.

Fluoride drops and tablets were used as a supplement beginning in the 1950’s. However, recent studies question the effectiveness of fluoride taken orally. The drawbacks of oral fluoride are that it requires a prescription and is absorbed systemically. It has a greater risk of causing fluorosis because of the amount of fluoride one is exposed to already with fluoridated toothpaste and water. In 2000 the American Academy of Pediatrics did not renew its policy of dosing with fluoride drops and tablets. Many foreign countries have actually come out against their use.

Since the literature has shown that fluoride benefits are optimal when used topically, fluoridated toothpaste has become one of the mainstays of cavity prevention. It has been shown that after brushing (and not rinsing) the fluoride remains present for 2-6 hours and enhances re-mineralization of the enamel. The FDA has allowed over-the-counter sale of toothpaste that contains either 1,000 ppm or 1,100 ppm of fluoride for use in children.

The concern for children was the amount of fluoride they might swallow in the act of brushing. And, could this lead to fluorosis? It was shown that a two-year-old typically ingests about 2/3 of the toothpaste when brushing. If one uses an amount of toothpaste about the size of a grain of rice and brushes twice a day as recommended, they would at most ingest 0.08 mg of fluoride. This is less than they would receive if they were given routine fluoride drops or tablets. It is recommended that children who are at risk for cavities should brush twice a day with a grain of rice size dab of toothpaste when the first tooth erupts. For those not at risk, this should be started at around one year of age. It is also recommended that they do not rinse after brushing as this actually causes them to swallow more toothpaste and decreases the protective benefit of the fluoride.

Other ways of delivering fluoride directly to the teeth are with gels and varnishes. Of the two, the fluoride varnishes are optimal because they adhere to the enamel better that the gel. They allow for longer levels of fluoride in the enamel and are less likely to be swallowed that the gels. It is recommended that at risk children should receive fluoride varnishes twice a year, starting at one year of age.

After our little discussion, Kacie’s Grandmother looked at her daughter and very proudly said, “You see, nobody ever listens to me. But the doctor said I was right!:” She beamed when her daughter conceded, “Yes Mom, you were right.” 

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