Marie, one thing you might try in order to get Gucci's teeth brushed is using a piece of gauze instead of a toothbrush. Put a little doggie toothpaste on a small piece of gauze on your finger and just rub inside her mouth, especially the ones way back. You might just start by putting your finger in her mouth with nothing on it first and get her used to it. One of my Yorkies fights enough that the gauze is much easier than a toothbrush.
Mycalibabe, I know exactly how you feel. I don't know how small your Yorkie is but as long as your vet is experienced with small dogs it should be fine. I do know the fear though. I was so afraid to do that, that I waited too long on one of ours and the bacteria has spread and she has been in renal failure since last October. That doesn't mean it will happen to yours but I learned the hard way how important it is. Also, personally I always have blood work done just prior to anesthesia.
Always. That will tell your vet if she's healthy enough to tolerate it. My little dogs (Yorkies and others) go to an amazing vet for teeth cleaning. He gives i.v. fluids while they're out and they have a heart monitor, etc. Just like a people hospital!!