A hole in the innermost part of the gums may be caused by apical periodontitis. Apical periodontitis may be caused by bacterial infection, physical factors and chemical stimulation, mainly on the periapical tissues, resulting in tissue damage, inflammation, resulting in a hole in the gums, apical periodontitis can be due to caries, endodontics and other pathologies leading to infection of the dental pulp, and the spread of infection to the periapical. Apical periodontitis is mainly divided into acute periapical periodontitis and chronic periapical periodontitis, different types of periapical periodontitis performance there are some differences, but the main manifestation of the local abnormal sensation and dysfunction, which will lead to pain in the patient, discomfort in chewing, and some patients may also have the appearance of pus. It is recommended that patients go to a regular hospital in time, under the diagnosis of the doctor, according to the patient’s specific condition, to take targeted treatment, pay attention to oral hygiene in life, to protect the teeth, and try to avoid eating cold, irritating food.