Your teeth break the food you eat into pieces that can be readily swallowed and digested. Teeth are alive. The pulp at the heart of each tooth contains blood vessels and nerves that sense heat, cold, pressure, and pain. A hard substance called dentin surrounds the pulp. On the crown (the part of the tooth above the gum), the dentin is covered by a layer of enamel. The root of the tooth lies below the gum line and is covered by a protective layer of bone-like material called cementum. In health, the gums fit tightly around the teeth; the roots of the teeth fit into sockets in the jaw. A shock-absorbing material, called the periodontal ligament, lines the socket of each tooth and protects the skull and jawbone from being jarred.
Enamel is the hardest material in you body; however, acids produced through bacterial action can erode enamel and lead to decay, If left unchecked, decay will progress through the dentin and into the pulp resulting in pulpal death and/or abscess formation.
When the pulp dies, the tooth dies. The pulp may die after dental decay has penetrated into it, or sometimes as a result of a traumatic blow to the tooth. Occasionally, a tooth dies for no apparent reason. No symptoms signal the death of a tooth, except that a decayed tooth will no longer be painful. You may not even know that you have a decayed tooth until your dentist tells you. Eventually, most decayed teeth turn slightly gray. Once a dead tooth has been detected, it almost always should be treated. There is a risk, especially following decay, that bacteria from the dead pulp will seep through the end of the root and cause an abscess to form in the surrounding bone.
Dentin contains small canals that lead to the pulp. Bacteria that have progressed through the outer layer of enamel reach these canals and progress directly into the pulp. Your body responds to the invasion by sending white blood cells into the area to combat the bacteria. The blood vessels around the tooth enlarge to accommodate the extra blood and white cells. The enlarged vessels press on nerves entering the tooth, resulting in a toothache. If a significant number of bacteria invade the pulp chamber, the nerve will usually die (even though the white blood cells are fighting off the infection). Once the nerve becomes non vital, the toothache will end; however, the continued presence of bacteria will usually lead to an abscess.
Symptoms of Decay
In the early stages of decay the main symptom is a mild toothache upon eating anything sweet, hot, or cold. If the decay is allowed to continue, you may notice an unpleasant taste (which comes from stagnant food and bacteria trapped inside the cavity). In the final stages of decay, the pulp becomes inflamed. If this is allowed to continue, you may suffer persistent pain. You may also notice sharp or stabbing pains (in the jawbone or below the decayed tooth).
Tooth decay generally doesn't present a risk to one's health as long as it is caught and treated early. However, there is a risk for people suffering from heart disease. If bacteria from an infected tooth enters the bloodstream, the disease may worsen (see Bacterial endocarditis).
Keep dental decay to a minimum by taking good care of your teeth. Brush and floss regularly, reduce your sugar intake, use a fluoride containing toothpaste, and visit your dentist regularly to have your teeth cleaned and examined.