It is important for you to discipline your daughter when she acts aggressively. I understand your hesitation, but it is not helping her to refrain from discipline. Otherwise, you are unwittingly condoning, or at least reinforcing, what she is doing. Now, limit-setting may not be all you can do. It would be prudent to arrange an evaluation with a child psychiatrist, who can then collaborate with your daughter's other health care providers in order to reach some conclusion about possible pharmacological treatment to diminish her impulsivity and aggression.
But the other thing I found really helpful with the mouthing (not the agression part)is to provide lots of really challenging snacks to give their mouths heavy work. Hard beer pretzels, Stella Doro breakfast treats, fruit roll ups, swedish fish, Laffy Taffy. Heavy duty chew food. Just make sure she's mature enough not to choke.
I even bought a vibrator, on the advice of our OT, for them to put in their mouths. Embarassing when guests visit? Sure. But they really enjoy it.