That's so great of you to rescue a Crested! When I was looking for a new puppy, it was a toss up between a Yorkie and a Crested. I obviously went with a Yorkie, but I still have a soft spot for Cresteds.
Regarding his teeth looking rough, that is a common breed characteristic of the hairless variety. They are prone to bad teeth. Goes along with the gene that causes them to be hairless apparently. The powderpuff cresteds have better teeth.
Can't wait to see pictures!