That depends on how bad the tartar is already. Beyond the cost, I am concerned with anesthesia for something like a dental cleaning. I am hoping to avoid that because I have a hard enough time getting through the worry filled day when my babies are spayed.I can't imagine sedating them for their teeth. You can buy a Dental Care Kit at Petsmart for around $10. It has a small soft toothbrush, a fingertip toothbrush and a tube of special toothpaste. If she will let you do it, regular brushing will help. There are also dental wipes you can buy from Dr Foster & Smith but I am not sure how well those work. It might be easier than convincing her to let you use a toothbrush depending on how easy she is to work with. I have Persians so they are used to combing, nail trims, face washed and ear cleanings. This is just one more thing for them.
"One cat just leads to another" - Ernest Hemingway