My daughter would initially let me brush her teeth but since hitting 18 months or so won't let me anymore!
I have to say my solution has been to let her do it herself? Generally she will have a good old chew on the brush but more recently has been watching my husband and I and gives them a bit of a scrub?
They are just trying to assert their independence so maybe let her do it herself? Let's face it i'm sure none of us are feeding our children anything that's going to rot their teeth to the extent that we need to panic? They are still so small and I find that sometimes it's ok to just let them have a go themselves, the more you push the less likely they are to let you do it? My daughters teeth are absolutely fine