Young men are chewing extra-hard gum for a more chiseled look. Docs warn against trend.

TikTok has fueled the explosion of innocuous fitness trends like “hot girl walks” and “biohacking.”

But health experts worry a new facial fitness craze could become more harmful than beneficial: Videos of young men chewing rock-hard gum to achieve the perfect jawline.

“Do-it-yourself or direct-to-consumer products that claim to ‘change’ facial structure without the active supervision of a doctor have the potential for unintended, irreversible consequences,” Dr. John Callahan, president of the American Association of Orthodontists, said in a statement to USA TODAY.

Like many grassroots trends, the promised outcome is not based on scientific findings.

Chewing extra-hard gum likely won't result in the chiseled jawline that young men may seek, experts say, and it could damage jaw joints and teeth.

The most recognized among the few brands of chewing gum for jawline workouts is Jawliner. On its website, the company recommends chewing the gum for no longer than 10 to 15 minutes every other day.

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However, this recommendation isn’t mentioned in the dozens of TikTok videos featuring young men who create sponsored content for the brand.

“I chewed and chewed and chewed,” said @carsonteagarden in a video tagged to indicate he's earning a commission . “I chewed at the gym; I chewed when working. I chewed anywhere I was at. I was always chewing my gum.”

The TikTok user, who has over 121,000 followers, did not respond to USA TODAY’s request for comment.

Companies that sell rock-hard chewing gum claim the extra force will work out the masseter muscles that run from the cheekbone to the lower jawbone.

Social media users promoting the product say working out this muscle has helped them define their jawline, but that’s not how it works, says Dr. James Q. Swift, professor at the University of Minnesota School of Dentistry. Constant chewing can make the masseter muscle bigger, giving a “robot” or squared look, but it won’t reduce the fat around the face to create more definition in the jawline.

Dr. Edmond R. Hewlett, a professor at the UCLA School of Dentistry and spokesperson for the American Dental Association, says the bones you're born with define the jawline.

“It’s your lower jaw that’s going to define the shape of your jaw,” he said. “Working that muscle will not change the actual jawbone.”

Swift also noted that working out the masseter muscle calls for repetition, it doesn't matter how hard someone bites, which means people can still work out this muscle with regular chewing gum.

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What concerns health experts most about chewing rock-hard gum is the risk of injury. Constant chewing can slowly wear at the teeth and a forceful bite can cause them to break.

“If (the companies) say don’t chew more than 15 minutes, that limits the frequency but it doesn’t minimize the force,” Swift said. “If a device was that hard, you could generate enough force with your jaws to break teeth.”

Chewing something forcefully and consistently can also cause issues with the temporomandibular joint, also known as TMJ, which connects the lower jaw to the skull.

People with TMJ disorders typically suffer jaw pain and headaches, have difficulty chewing and sometimes report a clicking or popping sound or locking in their jaw joint.

“That’s not the easiest thing in the world to treat,” Swift said. “They sometimes need surgery to resolve their pain and noise.”

On the company’s website, Jawliner says its products do not cause TMJ dysfunction. Officials did not respond to USA TODAY’s request for clarification.

There’s no functional benefit to strengthening the masseter muscle, Swift said, unless you're a competitive eater. Health experts urge patients to practice caution and consult a medical professional before embarking on a new fitness or wellness trend.

“It’s ‘buyer beware,’” Hewlett said. “When folks have a question about their oral health, it’s best to see a dentist and get trained and knowledgeable answers.”

Adrianna Rodriguez can be reached at adrodriguez@usatoday.com.

This article originally appeared on USA TODAY: Young men are chewing extra-hard gum for a more chiseled look. Docs warn against trend.