The primary teeth are pushed out and replaced during childhood and adolescence by the larger and stronger permanent teeth. Each of the matching pairs of upper and lower teeth has a specialized task in chopping up and grinding food. The tooth seen in detail is a molar, used for grinding. The main function of the teeth is to break up food into fragments small enough to swallow and digest. Human beings are omnivores - they eat both animal and vegetable food.
Human teeth have two basic shapes to chew both kinds of food.
A tooth has two main parts, the crown and the root. The root is the part normally located below the gum. It rests in a socket in the jawbone. The crown has an outer layer of enamel, which protects it from wear and decay. Enamel is made up almost entirely of calcium and phosphorus, and is the hardest substance in the body.