You may want to consult with your dentist or oral surgeon to see the risks and benefits of your particular situation. If she's young and the teeth are somewhat straight, they may be able to provide antibiotics and see if the roots will move up more and get further away from the nerves. If not, permanent numbness may occur, going from the back of the jaw area to the lip.
It sounds like the nerves are tangled up with the teeth. If the nerves are severed, that would cause complete permanent numbness. If they are not completely severed, they could get damaged. I'd be careful because along with numbness, she could also have permanent pain. Go to an oral surgeon to have the teeth removed or re-evaluated for a second opinion. Do not let a general dentist do this.