Teeth are hollow inside. 1. The structure of a tooth is made up of enamel, dentin, osteoid, and pulp. The first three are hard tissues that surround the crown and root of the tooth that form the tooth. In the central area of the crown and root is a cavity, which is in the part of the crown called the pulp cavity. Inside is a soft pulp tissue made up of nerves and blood vessels called the dental pulp. 2. The tooth can be divided into enamel, dentin and pulp cavity from outside to inside. The pulp cavity is hollow and rich in blood vessels, nerves, lymph and connective tissue. The pulp tissue has the function of nutritional repair and acute sensation. When a tooth is broken due to trauma or has deep caries, resulting in extensive tooth loss, the pulp cavity within the tooth can often be seen. When a patient experiences tooth pain, he or she should go to the hospital immediately to clarify the cause and choose a targeted treatment.