Periodontitis is a chronic inflammatory disease of the periodontal support tissues, the typical clinical manifestations of which are gingival atrophy, resorption of the alveolar bone, and finally, loosening and even loss of teeth throughout the mouth. In general, during the development of periodontitis, the patient will experience weak bite, poor nutrient absorption, and once the teeth are extensively lost, the lower 1/3 of the face will be shortened, the cheeks will be sunken and deformed, and the bilateral temporomandibular joints will be disturbed. Periodontitis is also a two-way relationship with diabetes, and it has been confirmed that the rate of periodontitis is 2 to 3 times higher in patients with poorly controlled blood sugar than in normal people. It is also more difficult to control blood glucose in patients with periodontitis than in those without periodontitis. Current studies have reported that better treatment of periodontitis can result in a significant reduction in glycated hemoglobin and a reduction in insulin dosage in diabetic patients. Current studies also confirm that patients with periodontitis have a higher chance of developing Alzheimer’s disease, infective endocarditis, and stroke than normal people.