Robert De Niro once paid dentist £4,000 to have his teeth ground down to look more menacing for movie role

It goes without saying that Robert De Niro is one of the greatest actors of his generation, but his commitment to one particular role helps set him apart even further.

The 79-year-old actor is well-known for putting in the extra effort to ensure his performances are spot-on; the star worked as a cabbie for several months to prepare for his role in Taxi Driver and gained 60lbs (27kg) to play heavyweight champ Jake LaMotta in Raging Bull.

But when he was cast as Max Cady in 1991’s Cape Fear, De Niro went further again.

For those unfamiliar with the film, it centres on convicted rapist Cady (played by De Niro), who is released from prison and hatches a plot to track down and exact revenge from public defender Sam Bowden (played by Nick Nolte) whom he blamed for sending him to prison.

To get into character, De Niro opted to undergo costly - and painful sounding - unnecessary dental work to look the part. Ouch.

De Niro forked out $5,000 (around £4,080 at today's conversion rate) to have his teeth filed down so he’d look more sinister in the flick and it worked.

Photo 12 / Alamy Stock Photo

De Niro went through a complete transformation for the role, alongside his teeth being filed, he worked out to give Cady a prison-gym-honed physique and covered his body in fake tattoos.

Of course, De Niro didn’t want to be stuck with the teeth he’d had designed for Cady, so once the movie wrapped, he had to splash out another $20,000 to have them fixed. Rather you than me, pal.

For what it’s worth, the movie went on to become a box office smash and De Niro earned himself a best actor nomination at the Oscars - so arguably the effort and expense was all worth it.

​​Moviestore Collection Ltd / Alamy Stock Photo

De Niro’s commitment to a character doesn’t end with what he’s willing to put his body through, either.

When filming The Deer Hunter, released in 1978, De Niro insisted on using a real bullet during the tense Russian roulette scene.

According to Michael Cimino - director of the Oscar winning film - De Niro requested a live cartridge and, somewhat surprisingly, co-star John Cazale agreed ‘without protest’.

However Cazale is said to have ‘obsessively’ checked and rechecked the gun before each and every take to make sure that the live round was not next in the chamber. I mean, I can’t say I blame him there.