What Can I Do About My Cats Rotting Teeth?

i seriously don't know if there rotting yet but do know there draining a lot. The vet said years ago that its because he don't hunt or anything so he never uses his fangs to tear anything. I called all my vets local and they say they don't do tooth extractions on cats so now what do i do? I live in a small town and can't afford too much money to go to a big city. he's 8yrs old and other wise very healthy. I have always gave him teeth cleaning treats but guess that didn't help much either. Is there anything i can do at home and sometimes he foams at mouth due to this drainage that stinks.