I forgot one thing remember the BONES MUST BE RAW I don't want you to make a mistake as I would not want to be the cause of a cooked bone hurting your dog. What type of food do you feed your hound is important as the cost may be more but get a high qualitiy food and not the vet's food is not always the best even though they may say so. Just my take
You should go and get a knuckle bone from the grocery store and give it to the dog raw. Do this everyday for a week. Freeze the bone and reuse for the week. I am not sure where you live but where we live we can get raw turkey necks and this is like a toothbrush for our dogs and should help. Did the vet show you the problem ???? Are there exrays of any possible damage to the teeth ?? Can she chew her food and does she appear to have trouble chewing ?? These are signs of tooth problems and how long have you been seeing this vet ?/ I suggest if not long then get a second opinion after a few weeks of raw bone chewing and you will know right away if the dog has a toothache if she doesn't seem to have trouble chewing a bone then don't get convinced to spend money. I hate vets who look at this option as the only one as it is too risky to sedate an older dog and why as she is 12 and like us teeth aren't as good as when we were kids and in her case a puppy
Personally - I don't like having to put an older dog under sedation. I used to work for a vet - and there is no way a dogs teeth can be cleaned in 15 min. A normal procedure takes about an hour.