Overton, 23, suffered the hairline fracture during the third Test in Perth after falling awkwardly trying to take a caught-and-bowled chance at the WACA.
After England’s series-sealing defeat, Overton revealed he had been told he could suffer a punctured lung if he dived and hurt himself again in the same place.
Curran, 22, was called up to replace the injured Steven Finn in November, and is the brother of fellow Surrey star Sam and son of the late ex-Zimbabwe, Northamptonshire and Gloucestershire all-rounder Kevin.
Root confirmed England’s only change in his pre-match press conference at the MCG, as the tourists seek to bounce back after going 3-0 down and therefore losing the Ashes in Perth last week.
“There’s one change. Tom Curran comes in and makes his debut - for Craig Overton,” he said.
Explaining why seam-bowling all-rounder Curran has got the nod, as a like-for-like replacement, Root added: “I think Tom offers a lot. He’s a real competitor. He’s got that very similar work ethic, and way he goes about things, to Craig.
“He’s always wanting to get in the contest, and you know you’re always going to get absolutely everything out of him. He’s also very skilful.”