The facts behind community fluoridation, which can reduce tooth decay by 25%

For decades, fluoride has been at the center of public health debates, hailed by experts as a crucial tool in preventing tooth decay while also facing scrutiny from skeptics who question its safety.

But what does the science say?

Fluoride is a naturally occurring mineral that strengthens tooth enamel, the outermost layer of teeth, making it more resistant to acid-producing bacteria that cause cavities.

There are two other inner layers of teeth — the dentin, which is sensitive to temperature, and the innermost layer, known as the pulp or heart of the tooth.

Teeth are “basically, like an M&M — a hard outside layer with a soft inside,” Dr. Manuel Acosta, a practicing dentist of six years, said.

“Fluoride helps remineralize the outer layer by replacing broken minerals with fluorapatite, which is more resistant to acid breaking teeth down,” Dr. Acosta told NBCUniversal Local. “That is the main benefit of fluoride — it prevents cavities and, in turn, reduces the need for treatments like fillings and crowns.”

Fluoride in water and toothpaste: Is one enough?

Fluoride is commonly added to drinking water in many U.S. cities, a public health measure endorsed by the Centers for Disease Control and Prevention, the American Dental Association and the World Health Organization.

Studies show that community water fluoridation can reduce tooth decay by about 25% in children and adults.

Some wonder whether fluoridated toothpaste alone is sufficient. According to Dr. Acosta, the answer depends on an individual’s oral hygiene and diet.

“People who brush religiously after every meal and avoid carbohydrates can easily get by with just fluoridated toothpaste,” Dr. Acosta said. “But for populations with limited access to dental education and care, fluoridated water is one of the few effective, mass treatments available to prevent tooth decay.”

Despite its proven benefits, some lawmakers and activists continue to push for bans on fluoride in public water. In Utah, for example, legislation has been introduced that would ban community water fluoridation, citing concerns over personal choice and potential health risks.

Public health officials warn such measures could increase cavities and dental health disparities, particularly in marginalized communities.

And, they say, banning community fluoridation would harm people’s health and finances.

“As we have recently seen in other communities, stopping fluoridation leads to more cavities and higher costs for dental care,” Dr. Scott Tomar, associate dean of the University of Illinois Chicago College of Dentistry, said. “On average, every dollar invested in fluoridation saves about $20 in treatment costs. If Utah takes this action, it will not save money, but will put the higher costs of treatment onto the backs of Utah’s citizens.”

Can you get too much fluoride?

While fluoride is beneficial in the right amounts, excessive exposure can lead to conditions such as fluorosis, which causes white patches on teeth, and, in rare cases, skeletal fluorosis, which affects bones and joints, Dr. Acosta said.

Children under two years old, who are more prone to swallowing toothpaste, are often advised to use fluoride-free options until they learn to spit out toothpaste.

Despite concerns, major health organizations maintain that fluoride levels in public water supplies are safe. The CDC sets the optimal fluoride concentration at 0.7 milligrams per liter to balance cavity prevention with minimizing the risk of fluorosis.

Myths and misinformation

Over the years, fluoride has been the subject of conspiracy theories, with claims ranging from government control tactics to severe health risks. Additionally, there are ethical concerns related to the perception of mass medication despite fluoride being naturally occurring.

However, extensive research from institutions like the National Institutes of Health and the CDC has consistently affirmed fluoride’s safety and effectiveness when used within recommended limits.

The debate over fluoride will likely persist, but the scientific consensus remains clear: Fluoride, whether in toothpaste or drinking water, plays a key role in preventing cavities and promoting oral health. Community fluoridation within recommended levels is safe. Less fluoride will likely create more cavities, tooth decay and deteriorated oral health — which may lead to more overall health issues, such as an increased risk of heart disease.

The CDC considers fluoridation of community drinking water as one of the “Ten Great Public Health Achievements” in the U.S. during the 20th century.