[HPFGU-Movie] Emma has braces?

[Valerie Flowe]

Anyone else notice that Emma has braces in some scenes in OotP?
I particularly noticed in the Room of Requirement when she stuns Ron. 
Now I can't recall but I know I've seen video of her, Rupert and Dan, 
and she has braces. Was that in the GOF interviews?? Anyway, I wonder 
why they didn't just have her wearing braces the whole time, instead of 
trying to hide them? Hermione's parents are, after all, dentists, and 
in the book anyway, she is supposed to have big teeth. So it would be 
right in character!
Valerie