Cavities are tooth decay. The itchy inside of caries is mainly due to the caries itself, but may also be caused by pulpitis, periapical inflammation and so on. You should consult a doctor to find out the cause of the problem. 1. The cause of caries itself: caries is mainly caused by bacterial attack on dentin, which has no nerves, but if the patient’s symptoms are serious and the cavity is deeper, it will affect the nerve and cause the patient’s teeth to itch. 2. Pulpitis: When the caries cavity is large, it is easy to expose the pulp, which causes pulp infection. At this time, patients often feel tooth pain or itching, but can not specify the exact location of the discomfort. 3. Periapical inflammation: when the caries cavity area is large, it will also cause periapical inflammation, periapical inflammation will cause alveolar bone resorption and gum recession, resulting in the exposure of the root of the tooth, the root tip of the inflammation leads to periapical lesions, and even an itchy feeling of the tooth. There may be other reasons for the itchiness inside the caries, so it is recommended that the patient consult the doctor in a timely manner to clarify the specific cause and follow the doctor’s instructions for treatment.