my older sister had this done as an adult and she was able to stop smoking this way...she will be able to breath thru her teet spaces I am pretty sure of that. she was so pleased with the results and she lsot weight as well which was good. they make liquid vitamins which taste pretty bad but are neccesary since her diet would be great. slim fast make a lower sugar diet drink with more protein that are quite tasty, optima she doesnot need the extra sugars but the fats and proteins.oral gel is good for temporarily numbing her mouth as she has probaably used before sence she already has braces. I am sorry that she is going thru this but earlier than later she she should do fine.
good luck to her and your family.
bizi