How you brush your teeth — and what you use to do it — matters.
Recently, dentist Dr. Jin-Ho Phark says he's noticed patients asking about fluoride-free toothpaste options. Phark is an associate professor of clinical dentistry at the Herman Ostrow School of Dentistry of University of Southern California.
"There's a lot of interest from the patients," Phark says. "I hear that also regularly from students."
One product that patients are asking about in particular is a calcium phosphate mineral called hydroxyapatite. Many patients, Phark says, may have seen the products on social media, "being pushed by influencers and other people quite intensively."
The traditional fluoride toothpaste became common in the late 1950s, according to the Centers for Disease Control and Prevention, when Procter & Gamble Co. released Crest nationally. Over the next few decades, oral care products with fluoride as their active ingredient became widely available around the world. These products help protect the outer layer of teeth from cavity-causing bacteria.
And dental health is important because it's related to so many systems in your body, from your heart to digestion.
Want the latest stories on the science of healthy living? Subscribe to NPR's Health newsletter.
"There are these connections made between your oral health, and the bugs that you have in your mouth, and systemic health and even the composition of your gut microbiome," says Dr. Livia Tenuta, a dentist who specializes in preventing tooth decay and associate professor at the University of Michigan School of Dentistry.
The claim
The promise of hydroxyapatite? Many of the things you care about when it comes to toothpaste: cavity protection, whitening, enamel-strengthening. But without fluoride.
Health experts widely agree that fluoride — a naturally occurring mineral — is beneficial to health. But curiosity is growing about fluoride-free options.
"There is an increasing number of people who are refusing fluoride totally, or hesitant to take it, especially for their children," says Bennett Amaechi, a professor of dentistry at the University of Texas at San Antonio.
That hesitancy stems from a history of skepticism about fluoride. Health Secretary Robert F. Kennedy Jr. has blamed the fluoridation of water for a number of health problems, including arthritis, bone fractures, bone cancer, IQ loss, neurodevelopmental disorders and thyroid disease.
Low levels of fluoride are generally considered safe and key to preventing cavities. Amaechi says there's no concrete evidence about potential harms of fluoride when it comes to children's IQ. And research that has found associations between fluoride and IQ has looked at very high levels of fluoride — over twice what's recommended in the U.S. water supply. The CDC previously named the addition of fluoride to public drinking water one of the top 10 great public health achievements of the 20th century, alongside vaccinations and family planning. They also say fluoride in water reduces cavities by 25%.
Still, Kennedy's criticism of fluoride seems to have made its way to toothpaste — and opened up space for products that use hydroxyapatite instead.
So what is hydroxyapatite?
The hype around hydroxyapatite is, in part, due to its similarity to tooth enamel. There's also some research that suggests hydroxyapatite can help with tooth sensitivity.
Tooth enamel is mostly made of calcium and phosphate. Those minerals form the outer layer of your teeth, which protects the internal layers of tissues, nerves and blood vessels, from damage.
Your enamel is stronger than your bones, but still susceptible to damage over time from things like sugary foods and dental plaque. Bacteria in your mouth feed on sugars, and produce acids that eat away at the outer layer of your teeth. Tenuta says over time, that process sets the stage for tooth decay, often referred to as caries, or eventually cavities (a hole in a tooth that comes from this decay).
She says fluoride toothpaste helps protect teeth by "remineralizing" them with calcium and phosphate.
"When [fluoride is] available in our saliva, in the dental plaque that we were not very perfect in brushing, that fluoride that is left over after brushing with the fluoride toothpaste will actually bring minerals back to the tooth," Tenuta says.
Fluoride works with those minerals to form a new compound that protects teeth. It acts like a shield for your enamel. But you need to brush with fluoride toothpaste consistently. Dentists recommend twice daily to keep those minerals around in our mouths.
Hydroxyapatite is thought to work in a slightly different way. These products seem to get into tiny crevices in the tooth enamel.
Many hydroxyapatite products use a form called nano-hydroxyapatite, which has smaller particles that, in theory, can more easily penetrate pores in enamel, though research data is limited.
The evidence
Amaechi, who studies hydroxyapatite use, says fluoride is extensively researched, especially in long-term studies. But he says early research on hydroxyapatite is positive.
"When it comes to remineralization and preventing caries manifestation, it is as effective as fluoride," Amaechi says.
Amaechi was an author on a 2021 study in the journal Scientific Reports, that followed 177 children for almost one year, and compared hydroxyapatite toothpaste to fluoride toothpaste. The researchers tracked tooth decay in each group, and found that both groups had similar outcomes. That study included funding from Dr. Wolff Group, a German company that owns two brands that make hydroxyapatite toothpastes.
That company contributed funding to another study, published two years later in the journal Frontiers in Public Health. Researchers found similar results after tracking 171 adults, comparing tooth decay in participants using a hydroxyapatite toothpaste to those using a fluoride toothpaste for 18 months. Both groups showed similar outcomes, suggesting that hydroxyapatite worked as well as fluoride in the study. However, the participants in the study were mostly healthy young adults without any severe oral health problems.
Tenuta says she'd want to see more long-term studies, especially in people with high risk of tooth decay.
"There are very few studies and they recruited participants of low caries risk," she says.
One shorter-term study in 2019, published in the Journal of Investigative and Clinical Dentistry, did compare a hydroxyapatite toothpaste to fluoride toothpaste in 133 people who were at higher risk of caries. After a little over five months, the researchers found both toothpastes performed similarly.
The bottom line
Hydroxyapatite toothpastes tend to be more expensive than fluoride ones — some over a dollar more expensive per ounce.
For patients who are open to both options, "I will advise them to use fluoride because fluoride has more evidence supporting its efficacy," Amaechi says.
Tenuta agrees.
"I would recommend as a best option to stick to a fluoride toothpaste because that's what we have a lot of evidence behind," she says.
The American Dental Association, a professional group for dentists, said in an email to NPR they acknowledge more people are using products with forms of hydroxyapatite and that some evidence suggests those products can contribute to remineralization.
However, research on the ingredient is new, "and evidence regarding its clinical effectiveness remains limited and ambiguous, especially regarding clinical indications," wrote ADA Consumer Advisor spokesperson Dr. Ada Cooper.
Instead, the ADA recommends you brush your teeth twice a day for two minutes with a fluoride toothpaste, floss daily and regularly visit a dentist.
Copyright 2026 NPR