I have Beau, a Sheltie with such hideous dentition that seasoned veterinarians have drawn back and said 'OMG!' on first looking in his mouth. So my two cents is: I have never seen a difference from anything I have put in the water bowl, be it fragaria vesca or an enzymatic cleaning solution. Save your money, is my comment on that.
I do brush Beau's teeth, using PetzLife gel and a plastic fingertip 'toothbrush'. This helps a bit, it's certainly worth doing. I have not been able to use a scraper with good results on his teeth because he is Not In Favor of that and will not allow it. (The vet, with assistants who can override Beau's vote, can whisk the scale stuff off with a scraper in seconds! I'm so envious!)
Beau still eats things that are helpful in keeping his teeth de-crudded, but they have far less effect on him than they do on my other dogs who have decent and good teeth.
My conclusion is that in dogs, as in people, genes are the overriding factor in dental problems as the dog (or person) ages. But even thought Beau may need to lose his lance canines in the next year, I am still brushing! Onward!