Mine have cruddy teeth too… and it could be the hard, hard water... or in the case of OJ it is genetic as all the dogs from his Dam have terrible teeth... and he would always have extractions and so to the point that they just fell out by themselves....
By the way, I tried the oxyfresh... no real help.... And OJ too, after a teeth cleaning, he was like a baby pup again, which told me that his teeth were bothering him....