Fluoride For Kids & Cavities: The Myths & The Science [Parent’s Guide]

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Hi, I’m Dr. B, practicing functional dentist for 35 years. I graduated from the Dugoni School of Dentistry in San Francisco, CA in 1987 and am a member of the American Academy of Dental Sleep Medicine (AADSM), Academy of General Dentistry (Chicago, IL), American Academy for Oral Systemic Health (AAOSH), and Dental Board of California. I'm on a mission to empower people everywhere with the same evidence-based, easy-to-understand dental health advice that my patients get. Learn more about Dr. B

You don’t need fluoride in your toothpaste, or in your water, or in your mouthwash. Yes, fluoride helps fight cavities (sometimes called “tooth decay” or “dental caries”). But it definitely isn’t the right choice for everyone.

No judgment if your family uses fluoride — but there are alternatives. My 3 daughters grew up without any fluoride in their toothpaste or water, and none have ever developed a single cavity!

This guide is for parents who want to weigh the risks and benefits of fluoride toothpaste (as well as fluoride varnish and fluoridated tap water).

What is in this guide?

  • Scientific evidence
  • Fluoride’s benefits
  • Fluoride’s risks
  • List of 4 different fluoride products
  • Frequently asked questions about fluoride
  • Myths about fluoride

Consider this your go-to guide whenever you want to know when to let your young children use fluoride. You might be surprised about this dentist’s feelings on the use of fluoride for kids!


The tide is changing.

Contrary to what the Centers for Disease Control and Prevention, the American Dental Association, and American Academy of Pediatrics claim, I fully believe that fluoride is not the miracle of modern medicine many say it is.

Fortunately, more people than ever before in the past hundred years are catching on to the potential dangers of fluoride.

In November 2019, a federal judge actually ordered that a case regarding potential dangers of water fluoridation against the Environmental Protection Agency (EPA) be permitted to go to trial. 

The case was heard in June 2020 and the judge delayed ruling. According to the director of the Fluoride Action Network, Paul Fan, Ph.D.:

“He has not yet made a ruling, but he said it was undeniable that fluoride posed a neurotoxic hazard and that EPA was basing their defense on an overly restrictive standard with respect to what constituted an “unreasonable risk”.”

Progress is being made against the government’s automatic response that water fluoridation is the best thing to happen in modern dental medicine.

Fluoride Sources

Fluoride is generally found in one of 4 sources:

  1. Fluoride toothpaste — toothpaste products that contain fluoride. The ADA only gives its seal of approval to fluoride toothpastes. So most mainstream toothpastes contain fluoride.
  2. Fluoride varnish — the gel-like substance your dentist or dental hygienist gives you right after a teeth cleaning. Fluoride varnishes contain very high levels of fluoride.
  3. Fluoridated water supply — public drinking water with added fluoride. Since the mid-1900s, America has been fluoridating much of its public tap water. More than two-thirds of America’s water supply contains enough fluoride that the CDC says will prevent tooth decay.
  4. Fluoride supplements — prescribed fluoride, usually for young children. Fluoride supplements may come in several forms: tablets, drops, lozenges, and high-fluoride mouthwash or toothpaste.

Does fluoride prevent cavities?

Yes, topical fluoride prevents cavities — but at a cost. Not only may fluoride be toxic to children, but it can also cause dental fluorosis, especially in children 8-years-old and younger. (Dental fluorosis occurs when spots of white discoloration permanently stain teeth.)

Fluoride toothpaste and varnish may prevent cavities, but the evidence is limited to non-existent that fluoridated water prevents tooth decay. 

Why would fluoride you swallow help your teeth, even if it doesn’t touch your teeth on the way down? The theory was that it would strengthen teeth “from the inside”, but this has never been sufficiently proven.

If fluoride is ingested via toothpaste, the risk of the many neurological and other problems associated with fluoride consumption rise dramatically.

A CDC study showed that more than a third of children put way too much toothpaste on their toothbrush, leading to an increased likelihood of swallowing and ingesting fluoride. They’re “supposed” to use an amount of fluoride toothpaste the size of a grain of rice, but end up loading their brush full of toothpaste.

Most kids overuse toothpaste and are probably swallowing at least some of it. Your swallowing reflex doesn’t sufficiently develop until you’re at least 6 years old.

Fluoride can prevent cavities, but at a cost. There is limited evidence that fluoride prevents cavities by creating a protective layer of fluorapatite on the teeth. Also, fluoride may be antibacterial, although this could ultimately kill beneficial bacteria in your oral microbiome — not just harmful cavity-causing bacteria.

There are alternatives, such as hydroxyapatite, that fight cavities but don’t come with the same high risks as fluoride.

Fluoride in Toothpaste vs. Fluoridated Water

How much fluoride is in toothpaste vs. fluoridated water vs. fluoride varnish? All answers are listed in ppm (parts per million).

  • Kids toothpaste: 500-1000 ppm
  • Adult toothpaste: 1500 ppm
  • Prescription fluoride toothpaste: 5000 ppm
  • Fluoridated drinking water: 0.7 ppm
  • Fluoride varnish: 12,300 ppm

While there is far less fluoride in water, we swallow water in quantities many hundreds of times over the fluoride toothpaste we may accidentally ingest.

Plus, 90% of the fluoride in tap water isn’t even sodium fluoride, like what’s in toothpaste. It’s hydrofluorosilicic acid (a phosphate fertilizer byproduct), which leaches lead in pipes. Hydrofluorosilicic acid, also called HFS or FSA) has never been researched for its impact on the human body.

Fluoride toothpaste literally has a Poison Control notice on it because you or your child will get sick if you eat it. Fluoride toothpaste may disrupt your oral microbiome and work against the cavity-fighting benefits by killing good bacteria.

Simply put, risks exist when you use fluoride toothpaste, and risks exist when you drink water. At the end of the day, I never drink fluoridated water. 

But I may recommend fluoride toothpaste for young ones in special cases — namely, special needs individuals, children undergoing chemotherapy, and very low-income families.

Fluoride Varnish: Pros & Cons

Pros FOR fluoride varnish:

  • Can help prevent cavities
  • Beneficial for young children who mouth breathe, particularly special needs children
  • May be necessary for kids from low-income families who cannot afford more expensive, healthy food or hydroxyapatite toothpaste

Cons AGAINST fluoride varnish:

  • Kids can easily swallow fluoride varnish, which has up to 20x more fluoride in it than toothpaste

What is the max amount of fluoride for kids to ingest? The max amount of fluoride for kids is under 100 mg of fluoride, according to the toxicity standard for fluoride intake. 

Ultimately, you want to stay well below the threshold of fluoride toxicity: 5 mg/kg of body weight. (I would add that there is no right amount of fluoride; it is not a nutrient.)

I would suggest you ask your dentist to skip the fluoride varnish. It’s not worth the risk in most cases.

Fluoride Questions to Discuss with Your Dentist

Q: Should my child use fluoride toothpaste?

A: Your child can use fluoride toothpaste if they know how not to swallow. Topical fluoride does prevent cavities. (Although I would argue that the amount of fluoride in toothpaste is not enough to actually help.)

However, fluoride toxicity is not well understood, meaning scientists do not know for sure whether fluoride toothpaste contributes to long-term fluoride toxicity.

Since children’s swallow reflexes are not well developed, and kids toothpaste products are usually flavored, it is highly likely children will swallow fluoride toothpaste on occasion.

Q: Should my child get fluoride varnish?

A: Your child should not get fluoride varnish at the dentist unless you believe it’s truly necessary. Children are likely to swallow some of this highly concentrated fluoride, for one. 

I would only recommend going this route if your child has an extraordinarily high risk for cavities. Even then, varnish is only an adjunct to other ways you can work to naturally prevent and reverse your children’s cavities.

Q: Should my child drink fluoridated water?

A: Your child should not drink fluoridated water. There is no reliable evidence that ingesting fluoride can prevent cavities, but there are dozens of well-designed studies that suggest it’s dangerous when ingested.

In particular, fluoride exposure during gestation and early life is associated with neurological issues from IQ deficits to ADHD risk.

There are plenty of affordable water filters available that filter out fluoride from tap water. Also, a lot of bottled water comes with no fluoride.

Q: Should I switch to hydroxyapatite toothpaste?

A: You should switch to hydroxyapatite toothpaste if you’re using fluoride toothpaste or an alternative. Hydroxyapatite (HAp) can heal cavities while remineralizing teeth — just like fluoride, but without the toxicity risk factor.

I’m shocked how many dentists are totally unaware of what hydroxyapatite toothpaste even is. HAp is a recent development in oral health, but a lot of evidence already supports the safety and efficacy of HAp toothpaste.

Benefits of hydroxyapatite toothpaste:

  • HAp is good for your oral microbiome. It prevents harmful bacteria from attaching to your tooth enamel, without killing bacteria. Fluoride seems to have an antibacterial effect, including potentially killing beneficial bacteria.
  • HAp increases the microhardness of human enamel.
  • 10% HAp is as effective as an amine fluoride toothpaste at preventing and reversing tooth decay in children.
  • HAp prevents and reverses enamel erosion, better than over-the-counter fluoridated toothpaste.
  • The protective coating HAp provides for your teeth is sturdier than the coating fluoride provides.
  • HAp is biocompatible, and not a neurotoxin like fluoride is.
  • When used as an alternative to fluoride, HAp prevents fluoride toxicity and enamel fluorosis.
  • HAp toothpastes seem to whiten and brighten teeth more than standard toothpaste — without any whitening agents or abrasives. It’s the only toothpaste that offers some intrinsic (internal) whitening benefit.

Q: Should I use fluoride while pregnant or breastfeeding?

A: While you’re pregnant or breastfeeding, do not ingest fluoride if you can help it.

In 2020, a study conducted in California found that mothers living in fluoridated communities had significantly higher levels of fluoride present in amniotic fluid and their blood and urine than pregnant people in non-fluoridated communities. 

A 2017 study linked prenatal fluoride exposure in Mexico with lower IQ scores when a child’s age is 4 to 12. 

A 2011 systematic review concludes that “children in high-fluoride areas had significantly lower IQ scores than those who lived in low-fluoride areas.”

Q: Without fluoride, how can we prevent cavities?

A: There are many ways to prevent cavities without fluoride:

  • Healthy diet (low on carbohydrates, sugars)
  • Organic foods
  • No more processed foods (basically anything that is packaged or pre-made)
  • Nasal breathing, if mouth breathing is a problem
  • Brushing your teeth and flossing — without fluoride, they still fight cavities
  • Hydroxyapatite toothpaste
  • Oral probiotics

What is fluoride toxicity?

Sometimes called “fluoride poisoning”, fluoride toxicity is not well understood. It is defined by excess consumption of fluoride. The minimum dose likely to cause fluoride toxicity is 5 mg/kg of body weight. That’s 129 mg for a 57-pound person, the average weight of an 8-year-old.

Fluoride toxicity may be caused by:

  • Fluoride turning to hydrofluoric acid, which burns tissue
  • Fluoride reacting with calcium, which inhibits nerve function
  • Fluoride reacting with calcium, triggering electrolyte imbalance
  • Fluoride inhibiting enzymes, poisoning cells
  • Fluoride increasing free radical production, which increases oxidative stress, all because fluoride is a very reactive element

8 acute (short-term) fluoride toxicity symptoms (these are typically seen only in industrial exposures):

  1. Nausea
  2. Vomiting
  3. Hypocalcemia
  4. Tetany
  5. Low blood pressure
  6. Excess saliva
  7. Coma
  8. Convulsions, leading to death in rare cases

11 chronic (long-term) fluoride toxicity symptoms:

  1. Dental fluorosis
  2. Skeletal fluorosis
  3. Allergies
  4. IQ deficits
  5. ADHD
  6. Indigestion
  7. Kidney problems
  8. Numbness
  9. Muscular spasms
  10. Birth defects
  11. Cancer

Myths About Fluoride

Government health agencies and non-profit associations have propagated myths about fluoride for many decades.

The CDC named the fluoridation of public drinking water one of the “top 10 greatest health achievements of the 20th century”.

However, countries that don’t fluoridate their water have seen similar reductions in cavities to countries that regularly add fluoride, according to data from the World Health Organization.

The ADA says, “Community fluoridation has proven benefits…that benefits the entire community.”

Yet, no reliable studies have been conducted to measure the reduction of cavities in adults who drink fluoridated water.

The WHO admits that excess fluoride consumption leads to dental fluorosis or skeletal fluorosis. But they stop short of admitting there are any other potential health risks associated with fluoride consumption.

The Cochrane Library, one of the most trusted organizations for scientific reviews, concluded the following in a 2015 systematic review:

  • Water fluoridation is not proven to reduce cavities across different socioeconomic status levels.
  • Stopping water fluoridation may not have any effect on community cavities.
  • There were no studies showing that water fluoridation prevented cavities in adults that included both a control group and a later check-up.

It is important to remember that cavities are not due to a fluoride deficiency. Fluoride doesn’t treat the root cause of tooth decay. You don’t need fluoride to prevent cavities.

I will admit that fluoride treatments may be helpful for special needs children, who cannot properly brush, as well as children from low-income families, who cannot afford healthy foods or premium toothpaste. But fluoride is not the riskless miracle that many organizations tout.

The Bottom Line

Whether your child uses fluoride products is up to each individual parent. Every child’s dental health needs are different, and you know your child better than anyone.

As a parent, choosing whether to give your kids fluoride can be overwhelming. I hope this pros and cons guide has made things easier!

14 References

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