My old girl is 13 1/2 and has only 4=5 teeth in her head, but they are very dirty, I have tried a couple of products that promised the earth but didnt deliver, to clean them. She cant go to the vet because of her age and she is very head shy due to lip fold soreness years ago, can anyone suggest anything that will get rid of the plaque on her teeth...that works, so tired of buying products that just dont deliver.