Orthodontics deals with the correction of teeth that are wrongly positioned. Ideally, teeth and jaws should match each other. As the face grows and the deciduous teeth are lost, the permanent teeth that replace them should slot neatly into place with no gaps and no crossing, forming a symmetrical elliptical arch like a string of pearls. The upper teeth should lock into the lower arch so that, when moved, the jaw joint moves smoothly in its socket.
It is of course possible to be less than ideal and still be quite acceptable.
Treatment is needed when the appearance or the function of teeth is less than satisfactory. Things go wrong for a variety of reasons. Some faults are inherited. A small jaw may be characteristic of one side of the family, and large teeth a feature of the other side. A particular face shape and skeletal pattern may go back for generations. Other faults are acquired. A disease suffered while the teeth are growing in the jaws can affect their formation. Teeth may be lost prematurely from decay or an accident. At times some teeth do not appear at all. Some undesirable habits, such as mouth-breathing due to a permanently blocked nose, thumb-sucking, tongue-thrusting or lip-sucking, can easily displace some of the teeth temporarily or permanently.
The orthodontist is trained to predict the growth pattern of the jaws and how to re-direct it. Special X-rays of the head show how the teeth are lying in the skull and what influence they exert on the profile of the face. The jaw may be jutting aggressively forward, or lie too far back and give the appearance of a weak-looking chin. The orthodontist sets out to correct both the appearance and function of the misplaced teeth. If there is a shortage of room for all the teeth, either the arch is expanded to make more room, or some teeth are extracted. To expand the arch, small steel bands are cemented around the upper molar teeth. A detachable metal frame fits into the bands and, with the aid of an elastic strap passing behind the neck, the frame pulls those teeth backward and outwards to make a bigger arch and allow room for all the other teeth.
The optimum time for orthodontics is at puberty. There is a sudden spurt of body growth at this age, when the last of the permanent teeth appear and the face and jaws expand to their final adult shape. The growing bone can be re-directed to a desirable pattern. This is done by attaching wire springs to the teeth to guide them gently to their new positions. Under the small but constant pressure of the spring, the bone in front of the tooth is resorbed and the tooth moves into the space created. New bone is then formed behind the tooth to fill the space created by the movement. After several months when the teeth are in their new position, the bands are removed and often a temporary appliance is inserted to prevent the whole process from reversing to its original position. Orthodontics may be done at any age at all, but the best results are achieved at the optimum age.
Orthodontists sometimes move single teeth, particularly in adults, for reasons such as improving its position to take a crown or a bridge. At times an eye tooth may be held up in the palate, and in these cases a hook and spring are attached to its crown to pull it down into position.
With the substantial current reduction in decay rates at puberty, orthodontics has become an attractive option for many people. Teeth that are correctly aligned are much easier to keep properly clean. They are more efficient for chewing, and their superior appearance contributes markedly to an enhanced self-image.
Orthodontics may sometimes seem expensive in the short term, but when amortised over a lifetime of perceived benefit, it is very cost effective.