A Cure for Wellness is one of the most peculiar studio films of recent memory. Director Gore Verbinski (Pirates of the Caribbean, The Ring) uses a decadent 146-minute runtime to thread together Cronenbergian body horror, universal movie monster villainy, a coffee table book’s worth of beautiful photography, and a handful of plot twists that are at once bizarre and predictable. The film is hardly perfect, but it’s memorable — particularly one scene involving poorly done dental work.

Yes, this is your spoiler warning. Dane DeHaan (The Amazing Spider-Man 2, Chronicle) plays the young Wall Street climber named Lockhart who is sent to a mysterious Swiss sanatorium to collect and return one of his company’s senior executives. The spa performs suspicious, anachronistic health practices on wealthy CEO types. These titans of industry want to be absolved of their inner “sickness.”

This is a horror-thriller. Of course the sanatorium’s practices aren’t quite so voluntary. Late in the film, Lockhart, searching for answers behind the declining health of the guests, finds himself on the receiving end of what the film treats as a dental tool, but looks like the sort of drill used in a heist to bust a vault.

The top image is from the moment just before the drill enters the frame. One of Lockhart’s teeth has already fallen out (I won’t spoil why). The drill drives through another of his healthy teeth with a sound that’s both crackly and gushy, like a pail of water thrown on raging fire.

Much of the sequence, surprisingly was shot with practical effects.

“There’s no CG in that sequence,” DeHaan tells The Verge.

“I mean, there’s some compositing,” Verbinksi adds.

“I was actually strapped into that chair,” says DeHaan. “That thing was actually prying my mouth open, and albeit a rubber drill, there was a drill really close to my face. So in a lot of ways that was one of the easier scenes to act. I didn’t know how I was going to react going into it, but it turned out I just kind of squealed like a pig and [Verbinski] kind of loved it. And it was, for me, an incredibly real experience.”

“Yeah,” says Verbinski, “there were really guys in white suits speaking German, holding drills, that were maybe perhaps untrained and getting a little too close to Dane. So yeah, I don’t want to say no acting required, but it wasn’t like ‘look at the green X.’

“I think we’re sort of hardwired in our DNA [...] there’s something about dental work that’s particularly horrifying. In the same way we’re kind of designed to respond to things that slither, I think there’s just something about that sound when you’re in the chair, and they’re actually drilling your teeth. As numbed as you may be, there’s a very specific sound. Or you know, seeing the smoke of dental work start to appear in your eye-line. And your mouth’s wide open and there’s somebody with a mask. Yeah, it’s very specific, you know, and that’s what gives [the moment] its value.”

The film is oddly fixated on Lockhart’s teeth. The film’s final twist is the final freeze frame, a smiling Lockhart with all of his teeth intact. Verbinski has spoken about the film’s dream logic, that certain things are unknowable. But I was curious if DeHaan had a theory about his character’s swift dental recovery?

“That’s the one thing in the movie I didn’t have to think about in terms of what it means, what it represents,” says DeHaan, “because it’s the end of the movie. Gore and I tried a couple different things, and I think it’s cool because it’s one last surprise, and it’s one last question, and it’s why the cure has side effects and will linger. And it will cause conversations, because [...] there is a surprise in this movie around every corner up until the very last second.”