Hi Kate,
I don't have a dog. Once, when I was at a dentist, I wondered what people did to maintain their dog's dental health. I think I asked someone (I don't recall if it was a dentist or another professional), about how dogs' teeth are brushed.
I mean...they have to open their mouths, and you have to put a foreign object in there.
I suppose if the dog trusted you and knows what you're going to do, it's fine.
What you said about dry over wet food was interesting. I would'ved guessed that wet would be better.