...she can't close her mouth, chew, or sleep with it in. It's for pulling her lower jaw forward: it has these plastic bits that stick up to stop her jaw from moving back. Apparently they're fairly common.
She's been told to wear it all day and all night or she'll need it for longer (but she can take it out for cleaning). She hasn't been able to sleep with it in (but it has been only two nights), or eat anything that needs mouth movement. She was supposed to be able to eat properly again eventually, but I have no experience with this so I don't know how long its likely to be...
Any advice please because she's already thinking of giving up on it and I'd rather be able to persuade her not to!