A toothache after eating hard food may be caused by periodontitis, periapical disease of the pulp, cryptocleidosis and so on, which should be consulted in time. 1. Periodontitis: the main symptoms are gum recession, root exposure, loose teeth, when the teeth are loose, there will be chewing weakness and eating pain. 2. Pulp periapical disease: when the inflammation in the pulp cavity spreads to the periapical tissues along the apical foramen, making the apical area appear inflammatory exudates, and even granulomas, abscesses and cysts have appeared. The excessive biting force stimulates the inflammatory substances around the apical area, which can cause pain when biting hard objects. 3. Cryptic fissure: If you suddenly bite into something too hard such as gravel when chewing, it may increase the occlusal force on the tooth, thus forming a cryptic fissure; shallow cryptic fissures often have no obvious symptoms, but deeper cryptic fissures are sensitive to cold and hot stimuli, and pain may occur when eating hard food. This symptom alone is not enough to determine the disease, do not rule out other factors caused by the patient is recommended to consult a doctor in a timely manner, by the doctor to clarify the cause of the disease, to give targeted treatment.