Donald Trump’s hair causes a lot of controversy: It’s been called a combover and compared to an ear of corn. But is it fake?

A video released on Monday appears to show an incision line down the middle of Trump’s rear scalp as his hair blows in the wind while boarding Air Force One. The clip, which has garnered over four million views, reignited speculation that the president received scalp reduction surgery in 1989.

Trump’s ex-wife Ivana claimed in a 1990 divorce deposition that plastic surgeon Steven Hoefflin, whose past clients included Michael Jackson, Joan Rivers, and Elizabeth Taylor, operated on Trump. He denied the claim, according to a 1993 Newsday report.

The Daily Beast talked with two top plastic surgeons to discuss the procedure and whether or not it appears Trump had it done.

Scalp-reduction surgery pulls sections of the scalp forward to fill in a bald spot.

Dr. Lisa Ishii, a professor of otolaryngology (an ear, nose, and throat specialist) at Johns Hopkins University says the surgery can be tricky.

“Scalp skin is very stiff skin. It’s very hard to pull together the skin edges and get them to close to each other if you cut out anything beyond a half dollar size piece of skin,”she said.

Ishii, a hair transplantation specialist, said that the surgery carries risks.

“If you had a large bald area, you’d have to have several procedures in a row before you actually achieved your goal to cut out the bald spot,” she said. “You can’t do it in one fell swoop.”

Hair transplantation, a procedure take takes hair from one part of the body and moves it to the balding spot, replaced scalp reduction surgery as the standard procedure for hair loss in the 1990s. Dr. Samuel Lam, owner of the Texas-based Lam Institute for Hair Restoration, said hair transplants are less invasive.

“If you continually reduce a crown progressively, it begins to look like a normal slot in the back of the head, and the hairs grow abnormally out,” Lam said.

Ishii does not think has Trump had scalp reduction surgery. “I doubt that’s the route... it’s possible that he had a hair transplant.”

“It’s such an outdated procedure. If you have the money and connection to have a hair transplant” you do it, added Ishii.

But Lam disagrees: “Yes, if you see a vertical incision on the back of the scalp on the crown, that’s very typical of a scalp reduction.”

Given how common scalp reduction surgery was in the 1990s, Lam told The Daily Beast, “most likely, he [Trump] had it.”