Richard Florida looks at Gallup's data on who goes to the dentists.
This article doesn't mention what seems obvious to me about access to dental care. Because dental medicine's evolution became disassociated from and lower status than other health care activities, it is not routinely thought to be something covered by insurance. Even when people have dental insurance, it routinely covers little more than a yearly check up. Of course people aren't going to the dentist -- they can't afford to!
We go to dentists when we can ... and when we decide we have to.