Dental care for low income?

I have really bad bottom teeth. I need to get them fixed as soon as possible, as I am having toothaches at least twice a month. Really bad ones. I'm on disability, so going to a dentist is out of the question. I looked up the dentistry school in Oklahoma and it isn't free like other states are. Does anyone know of any dentist that does pro bono work? Plus, does anyone know who I can write to about getting dental care for the low income. They have medical for the low income, but you never hear of anyone trying to get dental care for the low income.
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I've never heard of free in dental schools, usually it's at a great discount that you get the treatment and get worked on by students. I don't really know about any pro-bono works
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