Ideally the upper front teeth should slightly overlap the lower front teeth
and the molars should meet evenly however, perfect teeth are rare and most
people have some teeth that are out of position. Imperfections are not usually a pressing problem unless appearance is adversely affected or biting and chewing are impaired.

A poor bite may occur if teeth are crowded and overlap each other, making them crooked. Another cause is misalignment of the jaws, so that the upper front teeth protrude excessively in front of the lower teeth, or the lower jaw juts out in front of the upper jaw. The back teeth may prevent the front teeth from meeting, a condition known as an open bite.

Causes of Malocclusion

Malocclusion often runs in families and usually develops in childhood when the teeth and jaws are growing. The condition is usually caused by a discrepancy between the number and size of the teeth and the growth of the jaws. Protrusion of the front teeth may also be caused by children who persistently suck their thumbs beyond about age 6. If the primary teeth are lost early (before age 9 or 10) because of decay, the secondary molars that
are already in position may move forward to take up some of the space meant for the new front teeth. The new teeth then become crowded and misaligned.

Symptoms of Malocclusion

The symptoms develop gradually from about age 6 onwards. They may include:

  1. out-of-line, crowded or abnormally spaced teeth
  2. excessive protrusion of the upper teeth in front of the lower teeth
  3. a protruding lower jaw front teeth that do not meet.

Some children have some mild symptoms, but these are often temporary and tend to result from a growth spurt. In severe cases of malocclusion, speech and chewing may be affected. An abnormal bite may be painful or cause discomfort in or around the jaw joint. A severe malocclusion may also affect the facial appearance.

Measures of Malocclusion

  • The dentist will look for malocclusion as part of a dental check-up.
  • If malocclusion is found, a specialist dentist called an orthodontist may take casts of the teeth to study the bite in detail. The orthodontist may also take X-rays of the teeth, especially if some of the teeth have not erupted.
  • Treatment is usually only necessary if malocclusion is severe and causing difficulties when eating and speaking or affecting appearance.
  • If the teeth are overcrowded, some of them may be extracted.
  • Rough or irregular teeth are often reshaped or capped.
  • If required, the teeth may then be aligned using an orthodontic appliance such as a brace.
  • Surgery is very rarely necessary.

It is best to treat malocclusion during childhood, when the teeth and jaw bones are still developing. However, if malocclusion is caused by a severe mismatch in the size of the jaws and teeth, surgery may be needed and treatment may be delayed until adulthood.

Types of Malocclusion

There is a wide range of malocclusions, which can be divided into a small number of groups depending on the position of the first molars. Some common types of malocclusion are shown below.

  1. Misalignment of the molars, causing a slight overbite.
  2. Overbite (also known as overjet), with the molars misaligned.
  3. Incisors retro line (No overlap with lower teeth)
  4. Underbite (also known as Class III malocclusion), with the molars misaligned.

Treatment

Orthodontic treatment

Orthodontics is the correction of crowded or unevenly spaced teeth. Orthodontic treatment is usually performed on older children and adolescents while the teeth are still developing, although adults can also benefit.

Casts of the teeth are taken before an orthodontic appliance, also called a brace,
is applied to move or straighten the teeth gradually. In some cases, it is necessary to extract one or more teeth to make space for others. The treatment is usually long-term and may take several months or years to complete, with regular visits to the orthodontist for check-ups.