Is sodium tripolyphosphate used in place of salt in dog food?

It is used in dog food as a cleaning agent for the teeth, as it helps keep tartar from forming around the gum line. It is controversial as it only helps if the teeth are clean already, and it is not the best thing for dogs to ingest (or Humans). Petcurean puts in in some of there dog food formulas Now Grain Free Small Breed, does it help, I've used it for a year and a bit, dog still has tartar problems, has had her teeth cleaned by vet twice. I've gone back to Champion Pet Foods as I feel their products have better ingredients and give better results, no tripolyphosphate, and no sodium selenite. Hope this helps.