Videos on the social media platform feature young influencers and amateurs showing off the dangerous tooth-smoothing technique, which involves grinding the enamel with an ordinary emery board or metal nail file. “I’m gonna file my teeth down with a nail file because they’re not perfect,” says one young woman, says one young woman, @miadio. “I have some ridges and we’re ballin’ on a budget,” she says.

Enamel is the hardest structure in the body—harder than bone—and protects your teeth in the harsh, acidic environment of the mouth. So when you remove that outer protective layer, you’re more prone to cavities, your teeth can become sensitive, and you could even cause damage to the nerve, which is painful, Dr. Hoss explains.

In dentistry, “enameloplasty” involves removing small amounts of enamel to alter a tooth’s shape or appearance. But it’s only used in rare circumstances, says Dr. Hoss, who practices orthodontia. “We don’t do enameloplasty to straighten your teeth,” he says. If one tooth looks longer than another, it’s because one tooth is erupted longer or it’s tipped, crooked, or crowded.

So, all in all, the current TikTok trend is not only cringe-worthy, it’s completely unnecessary, he says. But, he adds, “After 24 years of practicing, I’ve literally seen everything.”