The most likely cause of gum redness is gingivitis or periodontitis. Gingivitis and periodontitis are caused by poor oral hygiene over a long period of time, with a lot of food debris, soft scale, plaque and tartar accumulating on the teeth, between the teeth and in the periodontal pockets. These substances cause direct irritation to the gums on the one hand and provoke an immune response in the gum part on the other hand, making the gums red, swollen, painful, and prone to bleeding when eating and brushing, as well as the phenomenon of bad taste in the mouth. Patients with red and swollen flesh should go for scaling to remove teeth and plaque from the tooth surface and periodontal pockets to create a good oral hygiene environment. For patients with deep periodontal pockets, a deep periodontal scaling treatment is also required. If the periodontal redness is near the apical region, the tooth has chronic periapical infection and requires root canal treatment of the affected tooth. Redness and swelling of the flesh of the tooth may also be due to diseases of the oral mucosa, for example, patients with mouth ulcers may also have red, swollen, painful and eroded gums.