A child holding their head in their hands

Fluoride. The evidence is clear that it is an extremely important tool for preventing painful and costly tooth decay in children. But, as with most minerals, it is possible to have too much of a good thing.

Think for a moment about iron. Consuming too little iron can result in anemia, but consuming too much can lead to serious complications like liver disease. To achieve optimal health, you must find an appropriate balance.

Fluoride presents a similar case. An optimal amount of fluoride can do wonders for a child’s oral health and greatly improve the child’s quality of life. Too much fluoride, on the other hand, can potentially lead to adverse effects, such as fluorosis. The key is to find the right balance.

In this article, we will discuss the following topics:

What Is Fluorosis?

Fluorosis refers to developmental enamel defects that result from children ingesting excessive amounts of fluoride while their dental enamel is still developing. The severity of fluorosis depends on the amount of fluoride ingested, as well as when and for how long during the enamel formation process the fluoride was ingested.

In its milder forms, fluorosis appears as barely noticeable white marks on the teeth. Very mild to mild cases do not affect the functionality of a child’s teeth. Occasionally, they may present aesthetic concerns, especially if the fluorosis-related discoloration appears on a child’s front teeth, but often the white marks are difficult to see and do not negatively affect a person’s quality of life.

A severe case of fluorosis, in contrast, can result in pitted, stained teeth that present serious aesthetic concerns and are more susceptible to breakage.

In the United States, nearly all cases of fluorosis are very mild to mild. Severe cases are rare here; they are typically seen in parts of the world where the water supply naturally contains fluoride concentrations many times higher than the optimal water fluoridation level of 0.7 mg/L recommended by the U.S. Public Health Service. (The idea of an optimal water fluoridation level is similar to the idea of a daily recommended amount of a vitamin or mineral – you can read more about it below.)

Fluorosis can occur in both primary (“baby”) teeth and permanent teeth, though it is believed to be much less common in baby teeth.

Fluorosis in Baby Teeth

Formation of the enamel on a child’s baby teeth begins in utero and continues into early childhood. Research suggests that, in areas with optimal or suboptimal water fluoride levels, most fluorosis in baby teeth results from postnatal fluoride exposure, rather than prenatal exposure. Given that the development of primary molar enamel begins later than the development of the enamel on primary incisors (front teeth), it is therefore not surprising that a child’s primary molars are typically the only baby teeth affected by fluorosis. 

Fluorosis may be harder to detect in baby teeth than in permanent teeth. In addition to fluorosis in baby teeth often being limited to less visible teeth, baby teeth are naturally whiter than permanent teeth, which may make it more difficult to see fluorosis-related white specks.

Fluorosis in Permanent Teeth

The formation of enamel in a child’s permanent teeth begins during infancy and continues until the child is around 8 years old (with the exception of the enamel on the child’s wisdom teeth, which develops later). Once a child’s dental enamel is fully formed, fluoride ingestion will no longer lead to fluorosis.

What Causes Fluorosis in Children’s Teeth?

Fluorosis results from ingesting excessive amounts of fluoride, but how does this usually happen?

A child’s risk of fluorosis depends on the total amount of fluoride ingested, so it is important to consider all sources of fluoride consumption in determining risk. That said, researchers commonly point to several main issues that can increase the chances of developing fluorosis.

First, consumption of water with overly high concentrations of fluoride is known to increase the risk of fluorosis. Water naturally contains fluoride, but the amount of fluoride varies greatly between different bodies of water. In the United States, community water fluoridation involves increasing the fluoride concentration of community drinking water that naturally has lower fluoride concentrations up to the U.S. Public Health Service’s recommended water fluoridation level of 0.7 mg/L. This recommended level was selected to achieve an ideal balance between decreasing the American public’s risk of tooth decay while minimizing the risk that Americans will develop fluorosis. However, some water sources in the United States naturally contain fluoride levels that are higher than the optimal level of 0.7 mg/L. Children under the age of 9 who drink water from sources that naturally contain high levels of fluoride are at increased risk of fluorosis. The CDC provides information on how to determine the fluoride concentration in your community’s water.

Second, and relatedly, some research suggests that consumption of infant formula that is reconstituted with fluoridated water – even optimally or suboptimally fluoridated water – may increase a child’s risk of fluorosis. More research is needed in this area, but parents who feed their babies reconstituted infant formula should be aware of this potential risk and may wish to consider consulting with their child’s pediatrician or pediatric dentist about the best type of formula to use for their baby.

Third, while dietary fluoride supplements are a valuable tool for cavity prevention in certain children, inappropriate use of these supplements has been associated with the development of fluorosis. The American Dental Association has established guidelines regarding proper use of fluoride supplements.

Fourth, ingestion of large amounts of fluoride toothpaste and/or fluoride mouth rinses by young children has been associated with fluorosis. Young children often swallow toothpaste and mouth rinse, and they may be tempted to use more toothpaste than necessary, especially when the toothpaste comes in a fun flavor.

How to Prevent Fluorosis in Children’s Teeth

The American Dental Association suggests taking the following steps to help minimize your child’s risk of fluorosis:

  • Breastfeed your infant or, if you primarily feed your baby formula, consult your doctor about the best type of formula to use.
  • Make sure your child uses an appropriate amount of fluoride toothpaste when brushing (no more than a grain-of-rice-sized amount for children under three and no more than a pea-sized amount for children ages 3-6).
  • Do not give fluoride mouth rinses to children under the age of six unless advised to do so by a dentist or other healthcare professional, as young children may accidentally swallow mouth rinse. If you think your child may need more fluoride, talk to a pediatric dentist about the best ways to increase your child’s fluoride exposure – for young children, other methods of topical fluoride application, like fluoride varnish treatments, carry a much lower risk of ingestion and may be recommended.
  • Never give your child fluoride supplements except as prescribed by your child’s pediatrician or dentist. The prescription should follow the ADA’s recommendations with respect to dietary fluoride supplements.
  • The U.S. Environmental Protection Agency requires public water systems to notify customers if the naturally occurring fluoride level in their water exceeds 2 mg/L. If the fluoride level in your water exceeds this threshold, consider using an alternative water source. If you source your drinking water from a private well, have the fluoride level in your well tested annually.

Remember that fluoride is an extraordinarily valuable tool for protecting children’s teeth against cavities. While too much fluoride can be harmful, the solution is not to abandon use of this highly beneficial tool altogether. Rather, the ideal solution is to find a happy medium – enough fluoride to help protect your child’s teeth, but not so much fluoride that it harms them. When in doubt, consult with your child’s pediatrician or pediatric dentist about the proper amount of fluoride for your child.

Board-Certified Pediatric Dentists in Dallas/Fort Worth

If you have questions about whether your child is getting an appropriate amount of fluoride, a pediatric dentist can help. Schedule an appointment with Hurst Pediatric Dentistry’s Dr. Lin by calling (817) 510-6400 or requesting an appointment online.

Hurst Pediatric Dentistry is located in Hurst, Texas, and provides pediatric dental treatments to children from Hurst, Euless, Bedford, Colleyville, North Richland Hills, Keller, Southlake, Westlake, Trophy Club, Grapevine and the surrounding area.

This article is intended to provide general information about oral health topics. It should not be used to diagnose or treat any disease or as a substitute for the advice of a healthcare professional who is fully aware of and familiar with the specifics of your case. Always seek the advice of your dentist or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.


Dr. Jin Lin

Doctor Jin Lin, Board Certified Pediatric Dentist

Dr. Jin Lin is a board-certified pediatric dentist with a passion for helping children achieve healthier, more beautiful smiles. He earned his Bachelor of Science degree from Cornell University and his Doctor of Dental Medicine (D.M.D.) degree from the Harvard School of Dental Medicine. After graduating cum laude from dental school, he completed his post-doctoral pediatric dentistry training at Boston Children’s Hospital and the Harvard School of Dental Medicine, where he served as chief resident and worked with children with a wide variety of special medical and dental needs, including children with rare syndromes.