States frequently expand or limit dental benefits for adults covered by Medicaid. As part of statewide health reform in 2006, Massachusetts expanded dental benefits to all adults ages 19–64 whose annual income was at or below 100 percent of the federal poverty level. We examined the impact of this reform and found that it led to an increase in dental care use among the Massachusetts adult population, driven by gains among poor adults. Compared to the prereform period, dental care use increased by 2.9 percentage points among all nonelderly adults in Massachusetts, relative to all nonelderly adults in eight control states. For poor Massachusetts adults, the effect was larger—an eleven-percentage-point increase in dental care use above the increase among the state’s nonpoor residents. The Massachusetts experience provides evidence that providing dental benefits to poor adults through Medicaid can improve dental care access and use. Our results imply that the lack of expanded dental coverage for low-income adults under the Affordable Care Act is a missed opportunity to improve access to oral care.