A broken tooth should almost certainly be extracted as it can allow bacteria to get into the blood stream. The cost is going to vary widely depending on where you live and what kind of anesthetics are used. When Odo had 2 teeth extracted (both canines) and the rest of them cleaned, using the more expensive anesthetics for the procedure, it was about $400. Since Odo's a senior at 13 years old, we took extra precautions with him. When you see the vet, you can ask for an estimate of charges. Canines tend to be a bit harder to extract because of their deep roots. My vet also does dental xrays to ensure that all of the tooth material was removed--cats have slender roots that tend to splinter, so it's important to get all of the tooth.