Periodontal disease is a chronic inflammatory disease that occurs in the supporting tissues of the periodontium. There are four main symptoms: gingivitis, periodontal pocket formation, alveolar bone resorption, and tooth loosening. The relationship between periodontal disease and systemic diseases Cardiovascular diseases: The incidence of coronary heart disease is 20% higher in patients with periodontitis than in the normal population, and 70% higher in men under 50 years of age with periodontitis or without teeth. The incidence of fatal coronary heart disease and cardiac arrest in patients with severe alveolar bone resorption is 2-3 times higher than the normal population, respectively. Patients with periodontitis and gingivitis are 3 times more likely to have a stroke. Diabetes: Patients with periodontitis and gingivitis are seven times more likely to develop diabetes than normal people, and diabetic patients have three times the rate of periodontitis than normal people. Periodontal disease and diabetes have a two-way relationship. It is scientifically proven that diabetes is one of the risk factors for periodontal disease and periodontal disease can have an impact on diabetes. Respiratory system: The incidence of chronic respiratory disease is 1.77 times higher in people with poor oral hygiene than in those with good oral hygiene. Elderly people, patients with Alzheimer’s disease, cerebrovascular disorders and post-operative patients are prone to aspiration because of reduced swallowing and coughing reflexes, and are at increased risk of pneumonia and aspiration pneumonia from periodontal pathogenic bacteria or other intraoral bacteria. Periodontal disease and preterm birth and low birth weight newborns: The rate of preterm birth and low birth weight newborns born to pregnant women is 7.5 times higher than that of the normal population. Preterm low birth weight infants are associated with maternal periodontitis. Researchers have detected oral microorganisms in amniotic fluid and amniotic membranes, and one of the most isolated bacteria was Clostridium nucleatum, a common bacterium of the oral cavity. Transient bacteremia from the oral cavity infects the amniotic fluid through blood transmission and the placenta. Other associations: in addition there is a strong association with smoking, osteoporosis, obesity and metabolic syndrome! Periodontal disease has become the leading cause of tooth loss in adults!