Medicaid Accountable Care Organizations and Children's Oral Health and Access to Care - Project Summary Poor oral health and access to dental care is a major public health issue for children, and particularly for children insured by Medicaid. Accountable care organizations (ACOs) are a financing and delivery system reform that incentivize care integration and population health and have shown promise for improving health outcomes. Medicaid ACOs aim to promote care coordination and linkages to community-based services. ACOs have been used by Medicaid programs in 21 states and show promise for improving health outcomes. In 2018, Massachusetts launched 17 Medicaid ACOs to facilitate care coordination and promote patient-centered and high-quality care. In 2023, Massachusetts added requirements for twice yearly fluoride varnish applications, annual structured screening for a usual source of dental care, and maintaining and sharing, as needed, a list of dentists accepting Medicaid patients—launching what we call the Medicaid ACO-Oral Health (ACO-OH) model. This proposed study will construct a unique statewide dataset containing patient, insurance, clinician, and organizational factors and provide additional preliminary data for a future mixed-methods study. In Aim 1 we will identify and describe children and primary care clinicians (PCP) in Massachusetts enrolled in Medicaid ACOs. These analyses will enable us to characterize ACO participants and inform development of analyses related to the effect of Medicaid ACOs on child and PCP outcomes. In Aim 2, we will compare rates of fluoride varnish applications during the first year of the ACO-OH model among PCPs in ACOs. These analyses will enable us to show the feasibility of our approach and identify any early changes in rates of fluoride varnish applications in the first year partially exposed to the ACO-OH model. Completion of these aims will enable us to develop a rich dataset of children and PCPs in Massachusetts, which will be critical for producing preliminary analyses and results that will lay the groundwork to generate hypotheses to be tested in the larger study. This proposed study is significant due to longstanding differences observed for children’s oral health outcomes and timely due to the increasing recognition of the importance of medical-dental integration in promoting children’s oral health.