Toothache from eating and no pain from not eating is commonly caused by problems such as tooth decay, apical periodontitis and cryptic fracture. 1. Dental caries: Since caries is close to the nerve of the tooth, when eating, food enters into the cavity of caries, which will stimulate the nerve of the tooth and cause pain. 2. Periapical inflammation: There is inflammation in the root of the tooth, periapical membrane is congested and edema, and the occlusal pressure increases the burden on the apical tissues, resulting in pain when eating. 3. Cryptic Fracture: tiny cracks on the surface of the crown of the tooth, caused by excessive chewing force, etc. The symptom is that it will cause pain when biting into a specific part, and the degree of pain is related to the depth of the cryptic fissure. All of the above situations can lead to the phenomenon of pain when you eat something, but not when you don’t. If you have the symptom of pain in eating but not in eating, you should go to the hospital in time to clarify the cause of the disease and treat the symptoms.