Most of us cut the first of our primary or baby teeth at six months of age and the rest of the set during the next two or three years. Those twenty teeth are replaced gradually from about the age of six by our permanent teeth.
These, thirty-two in number, are divide into eight incisors, the chisel-shaped teeth at the front of the mouth, which are designed for cutting; four canines, the longest teeth, made for tearing food apart; eight premolars, or bicuspids, which have a grinding action; and twelve molars, the back teeth, which are also grinders. The molars include the wisdom teeth the last to appear – if they do so. Some people never get them.
All teeth have the same basic structure. At the heart of each tooth is pulplike matter containing blood vessels and nerves. This is enclosed in a hard substance known as dentine. The tooth is locked into the gum by its rots, which fit into sockets in the jawbone and are covered by cementum, a bony an sensitive material. Tying the cementum to the gums and the jaw is the periodontal ligament, which has an important additional function or absorbing shock as our teeth bang and grind together when we chew.
Enamel, the hardest substance in the body, covers the exposed areas of our teeth. But, for all its durability, it isn’t designed for sugar-rich diets. Residues of these foods ferment as they break down, producing an acid that slowly erodes the enamel. Healthy teeth are an invaluable asset, affecting not only our enjoyment of food but our appearance and self-confidence.