Grinding the teeth that hound helps form the jaw joint. We are born with a square joint but grinding of the teeth helps round that joint out. I worked in the dental field for 18 yrs and this was a common concern for parents. Don't try to stop it, it's good.
She might be getting ready to grow in some back teeth.Just keep giving teethers or a frozen wash cloth. I know both my kids grinded their teeth and there wasn't much I could do about it. Only if they continue it when they get older to go to a dentist and get fitted for a mouth piece. I would call the pediatrician and see what they say. They might have something you can do?