Human tooth. For other uses of tooth or teeth, see Tooth (disambiguation). The human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digestion. Humans have four types of teeth: incisors, canines, premolars, and molars, each with a specific function. 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.