Just got back from the vet with Toto and can't believe I saw this thread ... Dr. Coons and I just had a very long discussion about this! [Just had to peek in before going to the office!]
When he checked Toto's teeth he said that they are in remarkable condition for her age and size ... he was
really nice and didn't add "and as pampered as she is!"
Anyway, I asked him about the stuff that you put in their water ... he said that he doesn't find that it does any good. I asked him about the PetzLife ... he said that the gel might make a little difference, but it's due to the brushing.
I said, you know I'm looking for a "magic bullet" here?
He said that chewing items like the little rope dental toys or the C.E.T. chews and giving a litte hard kibble do as much good as anything else. He wouldn't recommend the C.E.T. chews if they gobble them up but since Toto is a little "nibbler" to give her a half daily. They are slower to digest is the reason he wouldn't recommend them to those who gobble them up. He also said that Toto will be fine for at least another year!
Haven't had time to read all your posts but will later.