I myself was in need of extensive dental care. I sent many emails as well as numerous phone calls. I was told to go to my state website and click on aging and elderly. Sure enough, a few clicks in, I found a website called; Dental Donated Services or http://dentallifeline.org -
You will need to fill out an extensive questionnaire to see if you qualify for this service. You will then receive a postcard saying they have received your application and someone will be in touch asap. Print out your application prior to submitting as they will review this information over the phone with you. They will tell you on the phone if you qualify.
These are real dentists-oral surgeons and labs that donate their time and services. Clinics limit the amount of dental care they provide and dental schools charge approximately half the amount a dentist would charge but take twice as long because you are working with students.
Good luck and the more information you provide on the application the better.