Like most other mammals, humans have two successive sets of teeth during life. Primary teeth are different from permanent teeth because they are smaller, have more pointed cusps, are whiter and more prone to wear, and have small, delicate roots. There are 20 primary teeth - four incisors , two canines , and four molars in each jaw. The primary molars are replaced in adults by the premolars, or bicuspid teeth. These are four incisors, two canines, four premolars, and six molars in each jaw.
Incisor teeth are the teeth at the front of the mouth.
They are adapted for plucking, cutting, tearing, and holding. The biting portion of an incisor is wide and thin, making a chisel-shaped cutting edge. Next to the incisors on each side is a canine, or cuspid tooth. It frequently is pointed and rather peglike in shape and, like the incisors, has the function of cutting and tearing food. Premolars and molars have a series of elevations, or cusps, that are used for breaking up particles of food.