Great as a preventative
I used to use this all the time for my cats & I really did notice one ex stray who had really yellow teeth & bad breath that after 6 months to a year his teeth were much whiter & his breath much better. I ran out of it & kept forgetting to re-buy & his teeth went back to being yellow & his bad breath returned, so it definitely works. It's important to point out that where tartar is concerned, it is unlikely to get rid of it once it has formed, but it is a good at preventing it or from worsening