I just wanted to add that while some water additives have questionable ingredients like xylitol, healthy mouth does not. I use it by syringing some in their mouths after brushing because one dog (Teddy!) is unwilling to drink it from the bowl.
ETA: you really need to brush EVERYDAY for maximum benefit. I skipped one day last week on winston and OMG the next night I needed a jackhammer. No matter what I feed him, he easily forms LOTS of plaque. I think his mouth is dryer than some dogs and the vet dentist encouraged me to give him crunchy treats and let him chew to get saliva flowing. I'm trying but it seems futile. He is the worst one I have and he's only 3. Very sad
