Dental care is expensive. That's not a big problem for the affluent, most of whom have dental benefits anyway. But, it's a very big deal for the less well off. As a consequence, many if not most people without dental benefits forego preventive and routine care. And a lot of them wind up in hospital emergency rooms when pain caused by diseased teeth and gums becomes unbearable.
In his landmark 2000 report, "Oral Health in America: A Report of the Surgeon General," Surgeon General David Satcher wrote that "there are profound and consequential disparities in the oral health of our citizens." Those disparities persist, and not only that, but lack of access to affordable dental care has spread to the middle class.