D.M.
Okie dokie! I totally know where you are at, and to be honest I had a pediatric dentist tell me to relax and not freak out because these teeth were going to fall out anyway. She told me what I needed to focus on was the act of teaching and guiding my son how to maintain his own teeth, but not depend on him to do it himself.
Your daughter is doing exactly what every other toddler at her age would do!! LOL. My son would chew on it forever if I let him, especially when he was teething...it's a bit too early for her to have mastered the technique completely.
My son's dentist's instructions were super simple, and eased my mind...so, she said to get a tootbrush that my son could associate with a show, doll, cartoon or whatever that I could use to show him how to do it. Explain, Diego (or whoever you choose) is going to help you clean your teeth today, and then to demonstrate, and then show him how to do it while letting him try. As, he has gotten older (now 2) he has gotten the hang of it and actually its a huge part of our morning and bedtime routines. But, as per the dentist, I still follow that up with a wet washcloth to get the spots he missed. My son's dentist said, kids don't really fully get the hang of how to get the job done until about 4 years old and that's just in time, for most kids, for the permenant teeth!
Really it's great what she said, 'think of these as practice teeth'...they still need to be cleaned and taken very good care of but, it's a learning time for your toddler. Every day is about learning something, and mastering something. Just make brushing the teeth a fun experience, and give her some ownership over the process...make it about becoming a big girl.
Good luck.