Severe periodontitis has a developmental process, if the maintenance is better, can also appear 20 years without losing teeth. Chronic periodontitis has a complex etiology, mostly related to genetics, systemic diseases, plaque is the initiating factor of periodontal disease, severe periodontitis has a developmental process, generally need to pay attention to oral hygiene, regular scaling, periodontal scaling when necessary, as long as the periodontal maintenance is proper, patients suffering from periodontitis may not lose their teeth in 20 years. Another is invasive periodontitis, the main causative organism is associated with Actinobacillus actinomycetemcomitans, most common in adolescents, periodontal destruction is serious, the course of the disease develops rapidly, if the treatment is not appropriate, there will be six months to a year within the case of tooth loss . Severe periodontitis, we should consult a doctor in time, under the guidance of the doctor for standardized treatment, to avoid adverse consequences.