Every tooth is a living part of body containing nerves and blood vessels. The part that is visible in the mouth is the crown and the longer portion anchored inside the gum and the bone is the root.
In the internal parts of the tooth, the outermost hardest white cover is known as the enamel. The inner relatively less hard is the dentin. It surrounds the pulp containing blood vessels and nerves of the tooth. The pulp tissue is connected to the circulatory and nervous system via a foramen at the apex of the tooth. Surrounding the roots, which are also made up of dentin, there is a thin bone like layer called cementum. The jawbone is connected with cementum through a shock-absorbing membrane, the periodical ligament.