Toothpaste is OK. Unless you're eating it, which most people don't.
I'm LESS hungry after brushing my teeth. And much of the nasty taste is eliminated which reduces my desire to cover it up with something tasty.
There's nothing wrong with practicing good hygiene during a fast.
Remember that when you fast, you are an ambassador of fasting. If you smell like a septic tank and look like a train wreck to your friends, family, and coworkers they will be put off of fasting and you will get a reputation of a slob and a weirdo.