Dentistry

A tooth consists mainly of hard dentin, which is covered on the tooth’s crown and neck by even harder enamel. At the center of a tooth is the pulp cavity, which contains the tooth’s blood, nerve, and lymph supply. The root of a tooth, covered by cementum, is embedded in a socket in the jaw. The peridontal membrane, an extension of the gum, lies between the cementum and the bone.

Dental caries (decay) and gum disease are among the most common disorders of developed societies, and research shows that poor dental hygiene is the prime factor in tooth decay.
Techniques of dentistry are becoming more and more sophisticated, but prevention is both better and cheaper than cure. Habits that encourage good dental hygiene, from attention to diet to regular brushing and flossing of the teeth, and appropriate use of fluorides, improve the likelihood of retaining healthy teeth particularly if these habits are taught to children as the first permanent teeth emerge at about the age of seven.

The teeth

The growth of the 20 first teeth begins when a baby is in the womb. Calcium for the formation of the baby’s bones and teeth is taken from the mother’s own supply, so if her diet contains insufficient calcium, the baby’s requirements may cause the mother’s teeth to deteriorate.
Generally, teeth begin to emerge from the gums at about six months after birth, first the front teeth, then those at the sides and the back. Gradually through childhood, these teeth are replaced by a set of 32 permanent teeth. The back molars, known as the wisdom teeth, are the last to emerge.

Each tooth consists of a crown (the visible part) and the root, which anchors it in sockets in the jaw. A tooth consists mainly of hard dentin. The crown is coated with even harder enamel, while the root is covered with cementum to help anchor it in the jaw. Inside each tooth is a cavity full of pulp, carrying nerves and the tooth’s blood and lymph supply. Decay usually begins at the enamel and eats through the dentin to the pulp. When decay reaches the pulp, pain and inflammation follow, and the tooth may die.

Tooth decay usually starts (A) at the chewing surface. Abscess and inflammation of pulp (B) occur if initial decay is not prevented and the pulp is penetrated. The tooth must then be treated with root canal therapy (C) in which the pulp is removed and the pulp chamber is cleaned and smoothed. Insertion of anchoring material and a post into the treated tooth ID) may then be necessary to hold the artificial crown in place.

Treating decay

Decay is caused by the corrosive action of the acid in plaque, a sticky substance that forms from minute food particles and adheres to the enamel surface of the teeth. The first step in treating early decay is to drill out the decayed matter and to replace it with a hard substance (filling) so that decay does not recur.

The usual technique is to create a clean cavity with a high-speed drill, then to fill this cavity with amalgam (a mixture of silver, tin, copper, zinc, and mercury) in the back teeth, or a white resin for the front teeth. Each cavity is first lined with an insulating material to protect the sensitive pulp from temperature changes that are easily transmitted by the metallic amalgam. If the decay has reached the pulp, the pulp cavity can be cleaned out and then filled with a sterile substance to save the tooth. This is called root canal therapy. Badly decayed teeth, once they have been repaired, can be capped (rebuilt) with gold or porcelain crowns to restore the tooth’s function and aesthetics. Cosmetic dentistry can also be done to change teeth that are damaged or discolored. This is done using bonding, plastic or porcelain facings, or crowns.

Dental care from an early age helps to ensure that the teeth remain healthy throughout a person’s lifetime.

Extraction

Badly decayed teeth can cause extremely painful abscesses in the gums; if root canal therapy is not indicated, the tooth may need to be removed to cure the abscess. But extraction may be necessary even when the teeth are healthy. The usual reason for this is overcrowding in the mouth. Wisdom teeth that do not emerge normally should also be removed to allow the other teeth to grow properly. Extractions can be done under local anesthesia, which blocks the nerves of the teeth and jaw, or under general anesthesia, which causes temporary unconsciousness.

Replacement teeth

False teeth can be made to fill the gaps left by an extraction. A single tooth can be screwed into the jaw (implant) or attached to adjacent teeth (fixed bridge). Two or more teeth can be attached to a plastic or metal or plastic plate which fits in the mouth (partial removable denture). A full set of false teeth (full denture) is fabricated to fit the interior of the mouth.

An adult’s mouth contains 32 teeth, 16 in the upper jaw and 16 in the lower jaw. The rear molars are also known as wisdom teeth.

Orthodontics

Orthodontics is the branch of dentistry that is involved in correcting faults in the positioning of the teeth. Many people’s permanent teeth emerge crooked or too crowded, often looking unsightly and also making good dental hygiene difficult.

Some teeth may need to be removed in order to reduce overcrowding in a growing jaw. If this is done, the remaining teeth can then be repositioned gradually with the aid of an adjustable brace, which is either clipped over the teeth or cemented temporarily to their surfaces. A child’s teeth can also be pushed out of alignment by habits such as constant thumbsucking orchewing on pencils. In such cases, the habit needs to be stopped before the orthodontic treatment can be effective.

Preventive measures

The importance of the prevention of decay is constantly emphasized by dentists. Plaque is formed most readily by sticky, sugary food particles, so it can be minimized by avoiding excess sugar in the diet, and also by avoiding snacks between meals. Cleaning the teeth thoroughly after every meal, using a goodquality brush and proper brushing technique, is also advised by dentists. Dental floss should be used for cleaning between the teeth. Also, some public health authorities add fluoride to the water supplies because it helps reduce the occurrence of tooth decay.

Regular visits to the dentist are essential, so that the teeth can be cleaned and polished, any decay can be detected at the earliest opportunity, and specific advice can be given if necessary. Some dentists also use fissure sealants to smooth out the cracks where plaque can lodge.

AIDS

In the 1980’s the AIDS virus became a great medical concern. To eliminate the transmission of the HIV virus, dentists and other health professionals adopted the use of barrier techniques. The use of masks, gloves, and glasses has become common. Also sterilization procedures have become more rigorous. There will certainly be more changes in the future as better methods for infection control are developed.