ABSTRACT Oral cancer kills more than 10,000 adults each year. Earlier detection could improve survival and quality of life, but less than 30% of oral cancers are detected at early stages. While previous research has investigated whether access to health insurance could lead to earlier detection, my preliminary evidence suggests these previous studies miss a critical feature of oral cancer control: access to dental services. Physicians are not recommended to systematically screen for oral cancer, whereas dentists routinely screen for oral cancer as standard of care. My preliminary findings affirm the critical role of dentists in oral cancer control systems. Yet, despite the importance of dental services for detecting oral cancer early, low-income adults face financial barriers to accessing dental services. In fact, the lack of affordable dental coverage leads adults to delay or forgo necessary dental care more than any other healthcare service. Medicaid has filled the dental coverage gap for many adults, but states are not required to provided dental benefits to their adult Medicaid beneficiaries. Consequently, adult Medicaid dental programs have changed over time and vary by state. The volatility of Medicaid dental coverage could be further exacerbating delays in oral cancer detection for low-income adults. To inform policies improving population oral health, this proposal evaluates the impact of access to Medicaid dental services on early-stage oral cancer. Under guided mentorship, I will be among the first to evaluate Medicaid dental policies by analyzing population-based cancer registry data. This novel data includes verified Medicaid enrollment indicators, allowing me to select a valid sample of low-income adults. Aim 1 hypothesizes that Medicaid enrollees exposed to a change in state-level Medicaid dental coverage will change their probability of being diagnosed with oral cancer at an early-stage. Using advances in causal inference methodology, this aim leverages the longitudinal and state-by-state variation of adult Medicaid dental policies to avoid selection bias confounding our estimates. Next, we aim to infer an effect of access to Medicaid dental services on early-stage diagnoses by accounting for county-level dentists per capita. Aim 2 hypothesizes that the effect of changing Medicaid dental coverage on the probability of an early-stage diagnosis is mediated by the number of available dentists. Both research aims will improve the field’s knowledge of oral cancer disparities by identifying heterogenous effects and testing for effect differences across cancer characteristics, sociodemographic factors, and rurality status. By quantifying how access to dental coverage and dental providers affects early-stage oral cancer diagnoses, our evidence will advance policies aiming to control and prevent oral cancer mortality by increasing early detection. Future research can then identify how to alleviate any remaining early-stage oral cancer detec...