If you know the functions of tools such as scissors, forks, nutcrackers, and grinders, you will understand how marvellously specialized your teeth are. Although your 20 primary or baby teeth first appeared when you were about six months old, you permanent teeth (32) started to grow out when you were about six or seven years old. The rest will appear when you are between 17 and 21. Your permanent teeth are divided into four different types of sezes and shapes. But each type has a special use, like each tool has in the home or workshop. These four types are incisors; canines or cuspids; biscuspids or premolars; and molars.
The canines or cuspids are the four strong, pointed teeth-one each to the right and left of the incisors. You use your canines much like you use a fork,, to tear larger pieces of food into smaller pieces. The eight biscuspids or premolars are next to the canines-two behind each canine. Bicuspids work like a nutcracker, crushing food into smaller and smaller pieces. The twelve molars are at the rear of your mouth-three next to each set of biscuspids. Because molars have strong, flat surfaces, they work like a grinder, mashing food into thin, pulpy masses.