Georgetown clinic is a good source. Their # is 206-461-6943. It used to be a “sliding scale” fee schedule, probably still is. The dental quality is very good at the community clinics. Not 2nd rate dentists or dentistry, but very caring people that work there. Also the SeaMar Clinic which relocated to 15th Ave SW, I believe. Their # is 206-762-3263. You can also call the Seattle King Co Dental Society as they have a list of all of the community clnics, the # 206-443-7607.
Hope that helps.