The aim of this study was to investigate how general health, oral conditions, and lifestyle were associated with periodontal disease in adults, as clarifying this relationship may be useful in preventing periodontal disease. Medical checkups were conducted on individuals aged 40, 50, or 60 years. Data were obtained for analysis on a total of 36,110 patients (men, 12,784; women, 22,896). A stepwise logistic regression model was used to calculate the odds ratio (OR) for patients who were ≥code 3 according to the Community Periodontal Index (CPI). Approximately 40, 60, and 70% of men aged 40, 50, and 60 years, respectively, had a CPI score of ≥3. There were 10% fewer women than men at each age. Stepwise logistic regression revealed a BMI score of ≥30 kg/m 2 (OR, 1.44; 95% confidence interval [95%CI], 1.20-1.73); systolic blood pressure of ≥140 mmHg (OR, 1.09; 95%CI, 1.02-1.18); a fasting blood sugar level of ≥110 mg/dl (OR, 1.17; 95%CI, 1.04-1.30); high-density lipoprotein cholesterol level of <40 mg/dl (OR, 1.21; 95%CI, 1.06-1.37); smoker (OR, 1.59; 95%CI, 1.48-1.71); drinking ≥3 cups of Japanese sake per day (OR, 1.09; 95%CI, 1.05-1.14); use of salts for seasoning (OR, 1.17; 95%CI, 1.07-1.28); and fair and poor oral hygiene (OR, 2.27; 95%CI, 2.08-2.47) as significant risk factors for a CPI score of ≥3. These results suggest that smoking, oral hygiene status, and factors associated with metabolic syndrome are associated with periodontitis. This indicates that health guidance on tooth brushing, the importance of quitting smoking, and control of obesity may be effective in preventing the development of periodontal disease in adults.