I have pretty good results with giving Ginger plain ol’ amoxicillin for her mouth. It’s free at most human pharmacies, but you obviously need a prescription for it first. I get it in a chewable pill for Ginger and she eats it rigt from my hand. I bet you could crush one up for your kitty and hide it in her canned food.
They do make several water additives to clean teeth. Not sure if they’re just for dogs, or if they have some for cats too. May be worth a try. I’ve seen something like this at the vet I interned for.
