A large and growing number of adults are covered by public insurance, and the Affordable Care Act is expected to dramatically increase public coverage over the next several years. This study evaluates how such large changes 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 expand coverage of dental services to adult Medicaid beneficiaries, dentists’ participation in Medicaid increases and dentists see more publicly insured patients without decreasing the number of visits provided to privately insured patients. Dentists supply a greater number of visits each week while only modestly increasing the amount of time they spend working. They achieve this in part by making greater use of dental hygienists. As a result, dentists’ income increases. We find no significant changes in the amount charged for services. Wait times increase modestly, with the largest increases in wait times observed in states with restrictive scope of practice laws governing dental hygienists.