Dental care can be a matter of life and death. Yet millions of Americans can't afford a visit to the dentist. An investigation by FRONTLINE and the Center for Public Integrity reveals the shocking consequences of a broken safety net. Poor children, entitled by law to dental care, often cannot find a dentist willing to see them. Other kids receive excessive care billed to Medicaid or major surgery for preventable tooth infections. For adults with dental disease, the situation can be as dire -- and bankrupting. While millions of Americans use emergency rooms for dental care, at a cost of more than half a billion dollars, corporate dental chains are filling the gaps in care, in some cases allegedly overcharging patients or loading them with high priced credit card debt. Correspondent Miles O'Brien investigates the flaws in our dental system and nascent proposals to fix them.