The association between periodontitis and lung function: Results from the National Health and Nutrition Examination Survey 2009 to 2012

Background We aimed to explore the association between periodontitis and lung function in the United States. Methods The data was based on the National Health and Nutrition Examination Survey (NHANES) 2009 to 2012. Periodontitis was defined following the CDC/AAP (Centers for Disease Control and Prevention/American Academy of periodontology) classification. Lung function measurements included forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio. Linear regression and binary logistic regression were used to explore the association between periodontitis and lung function measurements. Restricted cubic spline was used to assess the dose–response relationships between the mean attachment loss (AL), the mean probing depth (PD) and spirometry‐defined airflow obstruction (FEV1/FVC