Background & Significance: Chronic pain is a high prevalence problem for which full agonist opioids are commonly prescribed. Harm of full agonist opioids may outweigh benefit in which case switch to buprenorphine is often recommended. To make decisions about switching from full agonists to buprenorphine, patients and providers need valid information about benefits and harms. The FDA recently issued a warning about the use of transmucosal buprenorphine and dental problems based on an accumulated case series of approximately 315 cases without control patients. Therefore, there is a significant gap in understanding of the relative risk of dental problems between full agonist opioids and buprenorphine Innovation & Impact: Our study will harness the “Full VA” sample of the Veterans Aging Cohort Study (VACS) containing ~8 million individuals to assess the relative risk of transmucosal buprenorphine vs. full opioid agonists vs. no opioid therapy for dental problems using a rigorous cohort design, adjusting for hypothesized confounders. This innovative work will examine various patterns of opioid exposure (full agonist vs. switch to partial agonist) that reflect real-world clinical comparisons to inform risk discussions with patients. Specific Aims: 1. To determine the association between incident long-term opioid agonist (full and partial) receipt and tooth decay, cavities, oral infections, and loss of teeth (here forward referred to as composite adverse dental outcome: CADO) compared to no long-term opioid agonist receipt, adjusting for relevant sociodemographic and clinical factors. 2. Among individuals with incident long-term full agonist opioid receipt, to examine the association between patterns (stay on full opioid agonists vs. switch to buprenorphine vs. stop) of opioid receipt and CADO. 3. Among individuals with incident long term opioid receipt who do not switch, to examine the association between greater opioid exposure (mg MEDD x time = total mg MEDD) and CADO, stratified by immunosuppressive properties of individual opioids. Methodology: Based on our previous methods using VA's Corporate Data Warehouse (CDW), we will identify a large retrospective cohort of all Veterans with incident long-term opioid therapy (LTOT) over the period of 2010-2019, matched 1:2 with Veterans who lack LTOT receipt and observe the cohort over time for patterns of opioid receipt—both full and partial agonist--and adverse dental outcomes. For the primary outcome (CADO), a Cox proportional hazards model will be our primary approach to assessing pattern of opioid receipt, demographic and treatment characteristics in relation to time to outcome. In the subset of patients who receive full agonist opioids exclusively (i.e. lack partial agonist receipt), we will examine the association between total quantity of opioid exposure, immunosuppressive properties of the opioids and adverse dental outcomes. Next Steps/Implementation: Results of this study will help inform risk dis...