An adult has 32 permanent teeth. The incisors and canine teeth tear and cut food, and premolars and molars are used to grind and crush. The 4 back teeth are called the wisdom teeth (or third molars).
Internal Structure of Teeth
The 3 main parts of a tooth are the crown, neck, and root. The crown (the part of the tooth you see--above the gums) is covered by a protective, bony layer of enamel, and the root of the tooth is covered by a sensitive, bonelike substance called cementum.
A hard substance known as dentin surrounds the pulp, which contains nerves (sensing heat, cold, pain, and pressure) and blood vessels (nourishing the tooth). The gums (or gingiva) fit around the teeth, and the roots of the teeth fit into sockets in the jawbone. Lining the sockets is a tissue called periodontium.