Hi,
I've never heard of anyone having this sort of problem after Oral Surgery. I'll try and find some information for you.
In my opinion, whether or not the screws have to be removed the bone will heal across the surgical cut similar to a broken leg. It may take longer for this to occur without rigid fixation but, the process will still happen. She should be able to have teeth placed in the area either implants or dentures.
Cheers,
Mike