Access to oral health care is a critical need for the adult Medicaid population. Following the 2014 expansion of Medicaid eligibility in Kentucky, millions of adults became eligible to receive dental benefits. We examined the impact of the expansion on adult Medicaid enrollees’ use of hospital emergency departments (EDs) for conditions related to dental or oral health in the period 2010–14. Based on our analysis of data for Kentucky from the State Emergency Department Databases, we found that the rate of discharges for these conditions from the ED increased significantly, from 1,833 per 100,000 population in 2013 to 5,635 in 2014. Adults covered by Medicaid who used the ED for treatment of oral health conditions in 2014 had high levels of chronic comorbidities and were more likely to be male and nonwhite than those in earlier years. To avoid costly and inappropriate use of the ED, states considering adding an adult Medicaid dental benefit should consider also making changes to assist beneficiaries in obtaining access to the dental health care delivery system.