Toronto, Canada - Zac Efron first became known for his role as basketball player Troy Bolton in High School Musical, as his career as a Hollywood heartthrob took off. Yet, within the last few years, Efron was seen less, with speculation ramping up about the actor's looks.

Efron appeared on the red carpet this week for the first time in almost three years - and looked significantly different.

Appearing at the Toronto International Film Festival for his upcoming film The Greatest Beer Run Ever, his jawbones looked more prominent. It upped even more speculation over whether the 34-year-old might have undergone plastic surgery – an internet rumor that surged last year.

Yet, the star addressed the rumors in a new cover interview for the October issue of Men's Health, citing that an accident in 2013 is responsible for his changed facial features.

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The Greatest Showman actor said he'd been running through his house with socks on and slipped, hitting his chin on the edge of a granite fountain and shattering his jaw.

He said he lost consciousness after the impact, and that his chin bone was "hanging off his face" when he woke up.

"It sucked. I almost died," he said in another interview this week.

As a result, Efron said his jaw muscles started to grow, and "just got really, really big"

Despite therapy, his face changed as a result. Meanwhile, he said didn't hear about the widespread rumors that he had gone under the knife until his mother called him one day and confronted him about "jaw-gate."

The star regularly uses social media to announce new projects, but otherwise, noted he tries to avoid it.

"If I valued what other people thought of me to the extent that they may think I do, I definitely wouldn’t be able to do this work," he said.