A lump growing on the root of the gum may be caused by periapical abscess, periapical cyst or wisdom tooth pericoronitis. 1. Periapical abscess, also known as alveolar abscess, is a purulent inflammatory disease that occurs in the tissues surrounding the root of the tooth. The main manifestations are severe toothache, increased sense of elongation of the affected tooth, and fear of biting. 2. Periapical cyst, a cyst that occurs in the apical part of the tooth root, is a benign cystic lesion. The most common causes are apical granuloma, chronic inflammation stimulation, trauma or chemical stimulation, etc., which will lead to epithelial remnant hyperplasia in the periodontal membrane, and the continuous exudation of fluids from the surrounding tissues, resulting in the production of cysts. 3. Wisdom tooth pericoronitis, the infection can spread forward along the external oblique line, forming a subperiosteal abscess or breaking into a fistula at the buccal vestibular groove of the first molar, which is easy to be misdiagnosed clinically as apical infection of the first molar or periodontal lesions. Gums root long flesh bumps may be a physiological phenomenon, can also be a symptom of certain diseases, such as periapical abscess, periapical cysts, wisdom teeth pericoronitis, etc., should be timely consultation to find out the cause of the disease.