Toothache is one of the most common symptoms of dental diseases in dentistry. There is a common saying about toothache, which is “toothache is not a disease, but pain is fatal”. However, before treating toothache, it is necessary to clarify the cause of toothache, so what can cause toothache? Pulpitis is mostly caused by the development of tooth decay. Since the pulp is surrounded by hard tissues, after the inflammation, the pulp is filled with blood and exuded, and the pressure is obviously increased, and there is nowhere to spread, so the affected tooth has a burst of intense pain, and the pain is even worse at night when lying down, which often leads to sleepless nights. Pulpitis pain often spreads to other parts of the tooth, and the patient sometimes cannot specify which tooth is in pain, requiring the doctor to use various means to pinpoint it. Dentin hypersensitivity Due to excessive tooth wear or decay, the outermost layer of hard enamel is destroyed and the inner layer of sensitive dentin is exposed, which causes unpleasant soreness and pain when rinsing with cold water or eating irritating food because the pulp nerve is stimulated. Over time, the pulp will become congested, and then develop into pulpitis, pulp necrosis, periapical inflammation and other conditions, causing great pain to the patient. Periapical inflammation Pulpitis is not treated in time and continues to develop, spreading to the tissue around the root tip where more serious inflammation can occur. The tooth starts with a painful, elongated sensation, and gradually develops to a point where it is too painful to touch, and continues to throb, sometimes with swelling and pus in the gums and face near the tooth. Inflammation of the soft tissues around the wisdom tooth when it is blocked in the process of eruption. When it first occurs, only the posterior teeth of the lower jaw feel localized swelling and pain, and cannot chew. In severe cases, the pain may be severe and may spread to the auriculotemporal region, and there may even be difficulty in opening the mouth and swallowing, accompanied by systemic symptoms such as fever, weakness and loss of appetite. Periodontitis is an inflammation of periodontal tissues characterized by frequent bleeding of gums, repeated swelling and pain, pus flow, fishy taste, and retention of dirt and calculus on the tooth surface. In the advanced stage of periodontitis, extensive resorption of the alveolar bone leads to loose teeth and weakness in chewing, making it impossible for patients to eat normally. Periodontitis is the main cause of tooth loss. The toothache is not a minor problem, when the tooth pain is best to go to the hospital as soon as possible to check, so that small diseases do not become big diseases.