Bagsy is correct, this needs to be taken care of now. There is no 'cheaper' fix.
The tartar build-up has caused major gum disease as well as bone involvement that needs to be taken care of by a veterinarian. Getting a blood panel done to assess all organ functions needs to be done first, then the anesthetic and medical protocol can be specifically tailored to your pet.
Dogs (and cats too) often hide dental problems until they have progressed past simpler preventative treatments and will require more extensive care that must be addressed by a veterinarian.