Periodontitis is a chronic inflammatory and destructive disease that invades the gums and periodontal supporting tissues. Its main features are: periodontal pocket formation, gingival inflammation, alveolar bone resorption and varying degrees of tooth loosening. Numerous studies have concluded that periodontitis is the main cause of tooth loss in humans, with the highest incidence especially in adolescents and the elderly. Since the 1980s, it has been generally accepted abroad that periodontitis is a group of diseases that includes mainly the types of prepubertal periodontitis, juvenile periodontitis, aggressive periodontitis, adult periodontitis and periodontitis with systemic diseases. Although the pathogenesis of periodontitis is not well cleared, a large number of studies have shown that a certain type of bacteria may be associated with a certain type of periodontitis. These bacteria accumulate in large numbers under the gingiva and secrete toxins that spread inflammation, leading to periodontal pocket formation and alveolar bone resorption, resulting in periodontitis.