Blue Cross Blue Shield has a plan called BlueCare that does not have a waiting period for preventative services and many non-surgical procedures. United Healthcare's United Health One is another. Major surgical treatments and restorative work do require some wait time, though that can be curtailed to some extent if you're coming off another dental plan.
No individual applying for health coverage through the individual Marketplace will be discouraged from applying for benefits, turned down for coverage, or charged more premium because of health status, medical condition, mental illness claims experience, medical history, genetic information or health disability. In addition, no individual will be denied coverage based on race, color, religion, national origin, sex, sexual orientation, marital status, personal appearance, political affiliation or source of income.