Hans has perfect teeth, even though he's 14 years old! And the kitten's teeth are healthy as well. I don't even bother brushing them since they're doing fine.
Mer has had gingivitis problems since I brought him home in June, and I had his teeth and gums cleaned by the vet in August. (I was so nervous since he had to be anethesitized. It was a good thing it was done, though, because when they removed a wax buildup while he was under, they discovered his eardrum was torn.) Brushing doesn't seem to make much difference since it's not a build-up, but an infection. I use an oral rinse on him every other day, and he HATES it. I feel so guilty. Not only does it taste like rancid oranges, but it burns. (I put a little on my tongue before I used it on him so I knew what kind of reaction to expect.) The oral rinse clears up the inflammation and his gums start to look like a normal pink instead of dark red. I don't know how long it will be before he needs another dental work-up. I'm hoping I can stretch it for a few years.