Yu Xia, Jukun Song
AIM: To characterise global co-occurrence patterns of periodontal disease and oral cancer using Global Burden of Disease (GBD) 2021 data (1990-2021) and identify shared and condition-specific risk factors. METHODS: We analysed adult incidence (≥25 years) across 204 countries and 68 risk factors. Countries were classified by incidence quartiles as concordant, periodontal-dominant, or oral-cancer-dominant. Shapley Additive Explanations (SHAP) modelling, negative binomial regression, network analysis, and Granger causality testing were applied. RESULTS: In 2021, global Periodontitis incidence: 1740.92 per 100,000 population (males: 1746.63; females: 1735.63) far exceeded oral cancer (8.97 per 100,000 population (males: 11.81; females: 6.21). Of 204 countries, 72 countries (35.29%) were periodontal-dominant, 62 countries (30.39%) oral-cancer-dominant, and 70 countries (34.31%) concordant. High-burden clusters appeared in South/Southeast Asia, while Northern Europe and North America showed the lowest rates. Key oral cancer risks included tobacco chewing (risk ratio [RR] = 1.075, 95% CI: 1.053-1.096), iron deficiency (RR = 1.067, 95% CI: 1.002-1.136), and high alcohol use (RR = 1.019, 95% CI: 1.000-1.038). Primary periodontal risks were high systolic blood pressure (RR = 1.007), lead exposure (RR = 1.006), and processed meat consumption (RR = 1.006). Granger causality testing suggested potential temporal precedence of periodontal disease (F = 3.323, P = .020), though causal inference is limited by the ecological study design and potential unmeasured confounding. CONCLUSIONS: Periodontal disease and oral cancer exhibit overlapping yet distinct global distributions. Shared exposures (tobacco, pollutants) drive comorbidity, while condition-specific risks necessitate tailored prevention. Integrated primary care approaches targeting modifiable risks could substantially reduce disease burden.