When is excessive teeth whitening harmful to oral health?

Excessive teeth whitening can cause damage. Here’s what you need to know

By Sarah Novak

Flashing a sparkling set of pearly whites may feel glamorous, but people who get overzealous with popular teeth whitening treatments can put their oral health at serious risk. TikTok and Instagram influencers are buying a lot of new over-the-counter whitening products, and celebrities’ typically snowy teeth can make the rest of us feel self-conscious about our smile. And in a 2022 survey, almost half of dentists said they use social media to advertise cosmetic treatments.

“Patients want it so white that it looks unnatural,” says Ronald Perry, professor of comprehensive care at Tufts University School of Dentistry. He first noticed an increased interest “with social media and beyond [it] flourished during the pandemic. People started seeing their teeth over Zoom and thinking they looked yellow.”

For 37 million Americans tried some form of teeth whitening product or procedure in 2020. The wide range of over-the-counter treatments include gel-filled trays, strips, and pens—while dentists can use a powerful whitening gel and laser. Experts say using over-the-counter products as directed by manufacturers is generally safe, but warn that overuse can be costly to your teeth: over-whitening can damage enamel, burn gums, cause long-term tooth sensitivity or even bleaching so much natural tooth color that it becomes translucent.

Regarding the support of scientific journalism

If you enjoy this article, please consider supporting our award-winning journalism subscription. By purchasing a subscription you help ensure the future of compelling stories about the discoveries and ideas that shape our world today.

Most over-the-counter treatments use the same active ingredient: hydrogen peroxide. It starts an oxidation reaction that removes the discoloration above and below the tooth surface – and in doing so makes the enamel more permeable or even porousaccording to a 2015 study in European Journal of Dentistry. In addition, a 2018 Dental journal study found that direct exposure of teeth to whitening agents, including hydrogen peroxide and carbamide peroxide, can lead to unpleasant sensitivity in dentin which is full of nerves (the stiff yellow tissue that makes up much of the internal structure of a tooth and covers the nerves). And as the enamel layer degrades, the dentin itself can eventually become visible—defeating the purpose of treatment entirely. “What we end up seeing is the underlying, more yellowish dentin,” he says Steven Stirlinghead of the department of restorative dentistry at the University of Kentucky. “And at the tips of the teeth, where there is no dentin, it looks like glass.”

Damage from occasional whitening applications is usually not permanent because saliva contains a small amount of electrolytes, including phosphates and calcium, which can help remineralize teeth. Foods such as dairy products, dark leafy vegetables and fish also contain certain minerals that strengthen teeth, and toothpastes with fluoride and hydroxyapatite can strengthen enamel. However, people who continually abuse whitening products can develop long-term tooth sensitivity or even significant tooth decay, he says. Nadia Rodrigueza cosmetic dentist in New York. Hydrogen peroxide in bleaching treatments can chemically burn the gumsespecially if the products are not applied properly.

So how white can your teeth safely get? This depends on how much enamel you start with. “A younger person tends to have more enamel, which means their teeth may turn whiter than an older person’s,” says Rodriguez. Bleaching your teeth to a shade slightly whiter than the whites of your eyes is usually considered best practice, he says.

Moderate teeth whitening is safe and effective, Perry says. Overall, the data show that professional whitening is done in a dental office it is generally harmlessas long as people wait at least six months to a year between sessions. Tooth sensitivity is a common side effect, but it usually subsides a few weeks after treatment. Most at-home whitening kits are also considered safe if users follow the manufacturer’s instructions. Many such treatments should only be applied for up to two weeks, and Rodriguez advises waiting three to four months before whitening again (at-home treatments contain a lower percentage of hydrogen peroxide than in-office treatments).

White teeth can make people feel more presentable and confident. But Rodriguez warns that those flashy smiles advertised on social media often sell a false narrative. “When people have absurdly white teeth on social media, they are [likely] not their real teeth,” he says. The look can be enhanced with social media filters or achieved through porcelain overlays, called veneers, which can cover any imperfections or stains.

For most of us who want brighter teeth, Perry argues that the basics of routine dental health are a good place to start and may be enough. “Before you do anything else, get a professional cleaning to remove hardened plaque, tartar and a large amount of stains from your teeth,” he says. And only then decide if additional whitening still makes sense for you.