I have my cats teeth cleaned every few years or when the vet says, "Time for cleaning" - and I make it a point to ask at their annual exam.
I have tried using products you put into the water, but they didn't drink a lot of water (they got enough from their food), so I ended up chucking the "seasoned" water daily to keep it from getting yucky. Literally money down the drain.
I tried the spray, but cats don't like the SOUND of anything spraying, let alone your spraying anything anywhere in their presence. Unless you get your cat as a kitten and get them used to your fingers in their mouth (rubbing gums, gently checking), it's just not going to happen. I am hoping to try emptying the loquid into a pill bottle that I can dip my finger in (no spritz noise or spray action) and try to rub their gums. We'll see.