Background: While growing evidence suggests a link between periodontal disease (PD) and cardiovascular disease (CVD), the independence of this association and the pathway remain unclear. Herein, we tested the hypotheses that: (1) inflammation of the periodontium (PD inflammation) predicts future CVD independently of disease risk factors shared between CVD and PD, and (2) the mechanism linking the two diseases involves heightened arterial inflammation. Methods: 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (18 F-FDG-PET/CT) imaging was performed in 304 individuals (median age 54 years; 42.4% male) largely for cancer screening; individuals without active cancer were included. PD inflammation and arterial inflammation were quantified using validated 18 F-FDG-PET/CT methods. Additionally, we evaluated the relationship between PD inflammation and subsequent major adverse cardiovascular events (MACE) using Cox models and log-rank tests. Results: Thirteen individuals developed MACE during follow-up (median 4.1 years). PD inflammation associated with arterial inflammation, remaining significant after adjusting for PD and CVD risk factors (standardized β [95% CI]: 0.30 [0.20-0.40], P < 0.001). PD inflammation predicted subsequent MACE (standardized HR [95% CI]: 2.25 [1.47 to 3.44], P <0.001, remaining significant in multivariable models), while periodontal bone loss did not. Furthermore, mediation analysis suggested that arterial inflammation accounts for 80% of the relationship between PD inflammation and MACE (standardized log odds ratio [95% CI]: 0.438 [0.019-0.880], P = 0.022). Conclusion: PD inflammation is independently associated with MACE via a mechanism that may involve increased arterial inflammation. These findings provide important support for an independent relationship between PD inflammation and CVD.