"There's no evidence to support the advertising claims.”
Browsing the toothpaste category on Amazon or Google has become something of a disorienting experience. Next to the tried-and-true Crest and Colgate, you’ll find products with ingredients that make healthy teeth sound less like a hygiene habit and more like an art project (charcoal and clay) or a scone recipe (baking soda, salt, spices, and lemon juice).
Many of these oral-health alternatives are sold based on the idea that they’re more natural, eco-friendly, or free from genetically modified organisms, soy, or gluten. And some promise more than a sparkling smile—for instance, strengthening your teeth, detoxifying your mouth, reducing inflammation, or killing bacteria, viruses, and fungi all in one fell swoop.
Those bold proclamations caught the eye of dental researcher John Brooks and his colleagues, Nasir Bashirelahi and Mark Reynolds, at the University of Maryland School of Dentistry. Last year, the trio published a research review of charcoal and charcoal-based tooth-cleaning products—many of which also contained bentonite clay—in the Journal of the American Dental Association.
In their search of the literature—an effort which, Brooks points out, was not funded by the ADA or any toothpaste companies—the scientists found zero high-quality evidence charcoal or clay were safe or effective. What they did unearth were a few poorly designed studies, and even those had mixed results. For instance, two papers from India came to opposite conclusions about whether charcoal was more or less effective at reducing cavities than chewing on a stick.
“We’re not necessarily saying that these products are bad,” Brooks says. “We’re just saying that there’s no evidence to support the advertising claims.”
This dearth of science makes swishing with soot a risk not worth taking, says dentist Matt Messina, an ADA spokesperson and professor at The Ohio State University College of Dentistry. It also stands in contrast to the reams of data supporting fluoride’s benefits. For instance, a 2010 meta-analysis included 79 trials on 73,000 children and teens, and found formulas containing at least 1,000 parts per million (ppm) of fluoride cut cavities by about one-fourth compared to placebo. Similar benefits have been shown in adults.
Public battles have been waged over fluoride in drinking water, with opponents raising concerns about long-term health effects like bone disease, arthritis, and thyroid dysfunction. It’s true that too much of the mineral can cause staining and white spots called “mottling” of the teeth. That’s actually how fluoride’s effects were discovered in the first place. Coloradoans who drank from naturally fluoridated mountain streams turned up with strong but severely discolored molars and incisors.
Very high doses of fluoride can be toxic—symptoms of overdose include stomach pain or intestinal blockage, and you should call poison control if someone, especially a small child, swallows a whole tube. However, there’s little evidence the strictly regulated amounts in toothpaste or fluoridated water have risks that outweigh the benefits, Messina says.
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To understand those perks, it helps to know how tooth decay works in the first place. On the outside, your teeth are covered with hard enamel; beneath that, there’s a softer, yellower layer called dentin. And then there’s the squishy inner pulp, where blood vessels and nerves reside. When we eat, bacteria in our mouths feast too, and sugar’s their meal of choice. As they dine, they release acids that eat away enamel, creating decay. Once your enamel’s gone, you’re out of luck—your body doesn’t make any more after your grown-up teeth grow in, Messina says.
“If we want to prevent cavities, the bacteria thing is a numbers game,” Messina says. You can physically displace bad bugs (and the sugars they feed on) by brushing and flossing or kill them off with antibacterial ingredients in toothpaste or mouthwash.
Or, you can work the other angle, neutralizing the acids they produce with a base-like buffer. Saliva does this naturally, and so does baking soda—in fact, it was one of the earliest toothpastes, and while its mild grit turns some people off, others prefer the taste and feel, Messina says.
But what fluoride has that baking soda lacks is the ability to seep into the enamel and strengthen it, a process called remineralization. Ironically, that was a claim made by many of the charcoal and clay products Brooks studied, which have never been shown to have this benefit. That’s why Messina advises using baking soda in combination with a fluoride rinse.
Charcoal, meanwhile, absorbs chemicals; in fact, it’s used to treat people who’ve been poisoned. So even if you were to use a product with both charcoal and fluoride, and there are a few, you’d risk neutralizing fluoride’s benefits, Messina says. Plus, charcoal is more abrasive than baking soda, potentially wearing away enamel.
As for other “natural” ingredients—whitening agents like lemon are acidic, adding to the potential for enamel damage. And salt is also abrasive, not to mention contraindicated for people with high blood pressure or otherwise on a low-sodium diet, Messina says.
Toothpaste isn’t regulated by the FDA or any other federal agency. The ADA tests formulas for safety, efficacy, and fluoride content. Any brand with the organization’s Seal of Acceptance contains enough fluoride to protect the average individual’s teeth, Messina says, though some people with extremely dry mouths due to illness or medications may be prescribed pastes with higher doses.
Besides fluoride, what else should you look for in a paste? There’s an array of other ingredients that can add to the cost of a standard tube—but might be worth it, depending on your needs, Messina says.
Receding gums or damage to the enamel can cause teeth to be more sensitive to hot, cold, and other sensations, Brooks says. Sensitive-teeth toothpastes contain ingredients like stannous fluoride or potassium salts that numb nerves or clog tiny holes in teeth’s surface, easing the ache after a few weeks of regular use.
If you’re prone to tartar—that hard, crusty buildup that further boosts your risk of decay—tartar-control formulas with ingredients called pyrophosphates reduce its stickiness. But you’ll need to start using it after a professional cleaning to get the benefits, Messina says. Finally, if you already have gum disease or gingivitis, an added antibacterial compound like a chlorhexidine might help battle cavity-causing bugs.
Meanwhile, there are other ingredients certain people might want to avoid. Essential oils such as spearmint, peppermint, or cinnamon can trigger allergic reactions, and a foaming agent called sodium lauryl sulfate often irritates the mouths of people prone to ulcers there (and isn’t essential to toothpastes’ effectiveness, a 2016 study found).
Your best bet, Messina says, is to rely not on marketing claims, be they about the wonders of charcoal or whether nine of ten dentists agree on a particular brand of premium paste. Instead, get a personalized recommendation from the only dentist who matters—the one you see, and who knows your own oral health risks and needs.
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