The teenager from Minnesota, US, had previously held the Guinness World Record for having the “widest gape” until Phillip Angus managed to open his mouth 9.52cm in 2019.
But Isaac refused to be beaten, so went about “training” to reclaim his title.
And he has now done just that after managing to gape his mouth to a whopping 10.175 cm.
Footage shared to the Guinness World Records’ TikTok page in May has catapulted Isaac to a new level of fame, having been seen more than 90 million times.
It shows the youngster comfortably fitting a Coca-Cola can in his mouth, followed by a large apple, a water bottle and even a baseball.
Another clip shows how Isaac can fit a gigantic burger in his mouth all at once.
The astonishing videos have more than 160,000 comments from fans who were understandably gobsmacked (pardon the pun) at the feat.
“Watching this made my jaw hurt,” one wrote.
“This is what the dentist expects when they tell me to open wide.”
A third was worried about what would happen if Isaac happens to get “lock jaw”.
Isaac has said the new record has made him a small-time celebrity and that he even gets spotted when he’s out in public.
“One time at the movie theatre the employee who was giving us our tickets said to me, ‘You look familiar! Are you a child celebrity?’
“We laughed and said she must have seen the Guinness World Records video!”
The teenager is often asked whether opening his mouth so wide hurts.
“It doesn’t hurt but it can get tired if I open for a long period of time,” he explained.
It comes after a couple set a new world record for their difference in height – with the wife towering over her husband.
James Lusted has a rare type of Dwarfism known as Diastrophic Dysplasia.
His wife Chloe is nearly 2ft taller than him which has seen them secure the record.