I was going to ask about dental issues too. There may be something that needs to be looked at even if you no longer are trying to bit her, especially if she's older and not been recently floated. My 24 year old gets floated just about every year, though this last time, he was still good so we just did the mares.
We have her teeth checked every year when she agets her shots and coggins done. She has not had to be floated the last couple times. She seems to be able to go every other year.