A large and growing number of adults are covered by public insurance, and the Affordable Care Act is predicted to dramatically increase public coverage over the next several years. This study evaluates how such large increases in public coverage affect provider behavior and patient wait times by analyzing a common type of primary care: dental services. We find that when states add dental benefits to adult Medicaid coverage, dentists' participation in Medicaid increases and dentists see more publicly insured patients without decreasing the number of visits provided to privately insured patients. Dentists increase the total number of visits they supply each week while only modestly increasing the amount of time they spend working. They achieve this primarily by making greater use of dental hygienists. As a result, dentists' income increases. Wait times increase modestly, with the largest increases in wait times observed in states with restrictive scope of practice laws governing dental hygienists. These changes are most pronounced among dentists who practice in poor areas where Medicaid coverage is greatest.