The human teeth function is mechanically breaking down items of food by cutting and crushing them in preparation for swallowing and digestion. There are four different types of teeth, namely incisors, canines, molars and premolars. Each type of tooth has a different job. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla (upper jaw) or the mandible (lower jaw) and are covered by gums. Teeth are made of multiple tissues of varying density and hardness.