DIY beauty hacks like hair dyeing, nail art, and even homemade bathroom products aren’t uncommon on TikTok, but a new and disturbing body modification trend has dentists flustered. 

People are grinding their uneven teeth down with nail files and uploading the videos to the app. 

Dr. Chad Evans, co-founder of Texas-based Smile Magic Family Dental, told Insider he became aware of the trend after colleagues showed him the videos on TikTok. As the father to two tween girls, Evans said he’s concerned. “It’s not the same as filing your fingernails. If you file your fingernails today, they’ll grow back tomorrow,” Evans said. “Our teeth are permanent.”

Teeth are made up of layers. The outer layer, or enamel, is the strongest and most important layer according to Evans as it protects our teeth from decay. 

“The moment that you remove tooth structure, if you don’t know what you’re doing, you’re doing irreparable damage and destruction to your teeth,” Evans told Insider.