Promising review: "My dog's molars were turning black and he had a ton of buildup on his canines. In the photo (above), just imagine everywhere you see slight yellow, instead covered in black and brown gunk and hard plaque. His gums were beginning to look inflamed. And, of course, his breath could kill a horse. After one week of constant use (a cap full for every bowl of water) you could see an obvious difference in tooth color. I was blown away. (Why can’t human mouthwash do such a good job on our teeth?) After three weeks, his molars were almost completely clean. After a couple months of use, the plaque on his canines was soft enough to brush some of it off, which was totally impossible before. Plaque covered the canine approximately 70%. Obviously that's no longer the case. Idk what insane solvent this is made of, but it keeps his gross mouth clean as a whistle. Now I don’t have to worry about my picky princess mutt losing his teeth because he can’t be bothered to chew anything." —BaconPancakes
Get it from Amazon for $6.87.