Periodontal disease is a multifactorial disease, and its etiology is traditionally divided into local and systemic factors. Among the local factors, dental plaque bacteria and their products are the most important cause of periodontal disease and are the indispensable initiating factor for periodontal disease. Mainly poor oral hygiene, the role of microorganisms, calculus stimulation, especially subgingival tartar is the most harmful. Systemic factors are related to nutritional and metabolic disorders, endocrine disorders, and phytoconstituent disorders. In addition, trauma, the stimulation of bad restorations. It is also one of the etiological factors. The etiology of periodontal disease is complex, and in general, it is divided into local and systemic factors. Local factors have a fairly important role, and systemic factors can affect the response of periodontal tissue to local stimuli, and there is a close relationship between the two. Local factors 1. Plaque is the microbiota that adheres to the tooth surface and cannot be removed by mouth rinsing or water rinsing. It is now recognized that plaque is the initiating factor of periodontal disease and is the main pathogenic factor causing periodontal disease. 2.Tartar is mineralized plaque deposited on the tooth surface. Tartar is also divided into supragingival tartar and subgingival tartar according to its deposition site and nature. Supragingival tartar is located on the tooth surface above the gingival margin and can be seen directly by the naked eye. It is deposited more in the cervical part of the teeth, especially in the areas opposite the openings of the large salivary ducts, such as the buccal side of the maxillary molars and the lingual side of the mandibular anterior teeth. Subgingival tartar is located on the root surface below the gingival margin, in the gingival pocket or in the periodontal pocket, and cannot be seen directly by the naked eye; it must be probed with a probe to know the deposition site and the amount of deposition. Subgingival tartar can be formed on any tooth, but is more frequent on the adjacent and lingual surfaces. The main source of inorganic salts in supragingival tartar is mineral salts such as calcium and phosphorus in saliva. Subgingival tartar is mainly mineral salts provided by gingival sulcus fluid and exudate. Tartar is harmful to periodontal tissues mainly because it constitutes a good environment for plaque attachment and bacterial growth. Tartar itself hinders the maintenance of oral hygiene, which accelerates the formation of plaque and forms irritation to the gum tissue. 3, traumatic occlusion in the bite, if the bite force is too large or abnormal direction, beyond the periodontal tissue can withstand the force, resulting in periodontal tissue damage occlusion, known as traumatic occlusion. Traumatic occlusion includes early contact during occlusion, dental interference, night grinding, etc. 4, other factors including food embedding, bad restorations, mouth breathing, etc. also contribute to the inflammatory process of periodontal tissues. Systemic factors Local factors are the main ones in the occurrence of periodontal disease. Systemic factors are promoting factors in the development of periodontal disease, systemic factors can reduce or change the resistance of periodontal tissue to external stimuli, making it easy to disease, and can promote the development of gingivitis and periodontitis. Systemic factors include endocrine disorders, such as abnormal secretion of sex hormones, adrenocorticotropic hormones, thyroxine, etc. Dietary and nutritional aspects can include vitamin C deficiency, vitamin D and calcium and phosphorus deficiency or imbalance, malnutrition, etc. Hemophilia is extremely closely related to periodontal tissue. Patients with leukemia often have swollen gums, ulcers, and bleeding. Spontaneous bleeding of gums can occur in hemophilia, etc. Long-term use of certain drugs such as phenytoin sodium can cause fibrous hyperplasia of the gums; patients with certain types of periodontal disease such as juvenile periodontitis often have a family history and are thus considered to have a genetic component. In conclusion, the etiology of periodontal disease is complex, and in the treatment, we should not only pay attention to the elimination of local factors, but also take into account the state of the whole body in order to obtain better treatment results.