Pus flowing from the root of a tooth may be a result of chronic periapical periodontitis, which is caused by pulpitis that is not treated promptly. The disease causes a large amount of inflammatory secretions in the apical region to form pus, the root apical alveolar bone is resorbed, and there is redness, swelling, pressure, and long-term drainage of the gingival mucosa in the gingival area corresponding to the root apices, forming fistulas and sinus tracts for drainage of pus. In addition, the abscessed root should be checked for root fracture by taking an x-ray apical radiograph. If the root is fractured due to trauma, it can also cause root abscess. Patients with periodontitis have severe bone resorption in the late stages of periodontitis, which exposes the roots of the teeth and leads to retrograde pulpitis, which can also cause root abscesses.