I give mine a bone + dry food (as the canned stuff can give them plaque) as he had a bit or plaque buildup when we got him.
We we brushing his teeth when we initially got him but the vet said the buildup isn't too bad - it's within average tolerance - and giving him a bone or something to chew on should suffice.
We gave him a piece of elk antler and the thing lasts, our dog likes it, and it works as far as well can tell.