Pneumonia is related to oral health of the elderly and intensive care unit patients. However, studies on the relationship between overall oral health and pneumonia in the general population have been limited. The purpose of this study was to investigate the association between oral health and pneumonia using a nationwide population-based Korean cohort database. Data from 122,251 participants who underwent health screening and oral examinations in 2004 or 2005 were analyzed. Cox proportional hazard regression analysis was performed to evaluate the association between oral health and pneumonia. The risk of pneumonia increased significantly in groups with a higher number of dental caries and missing teeth, with respective adjusted hazard ratios (HRs) and 95% confidence interval (CI) of 1.265 (1.086-1.473; p = 0.0025) and 1.218 (1.113-1.332; p < 0.0001), and decreased significantly in frequent tooth brushing and regular professional dental cleaning groups, with respective adjusted HRs and 95% CI of 0.853 (0.786-0.926; p = 0.0001) and 0.920 (0.855-0.990; p = 0.0255). In addition, regardless of age and comorbidities, oral health status and oral hygiene behaviors were associated with pneumonia. The results indicate that improved oral health may reduce the risk of pneumonia in the general population.