Unsatisfactory contact between the upper and lower teeth

  • Most common between the ages of 6 and 14
  • Often runs in families
  • Poor oral hygiene and thumb sucking beyond the age of 6 are risk factors
  • Gender is not a significant factor

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.

Malocclusion may occur when the teeth are crooked because they are crowded and overlap each other or when the upper front teeth protrude too far in front of the lower front teeth. Less commonly, the lower teeth protrude in front of the upper front teeth. Sometimes, the back teeth prevent the front teeth from meeting properly, a condition known as an open bite.

What are the causes?

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. In children, protrusion of the front teeth may also be caused by thumb sucking beyond about the age of 6.

If the primary teeth are lost early (before the ages of 9 or 10) because of decay (see Dental caries), the secondary molars that are already in position may move forwards to take up some of the space meant for the new front teeth. The new teeth then become crowded and misaligned.

What are the symptoms?

From about the age of 6, the symptoms develop gradually and may include:

  • Out-of-line, crowded, or abnormally spaced teeth.

  • Excessive protrusion of the upper teeth in front of the lower, or a protruding lower jaw.

  • Front teeth that do not meet.

Some children have mild symptoms, but these are often temporary and tend to result from a growth spurt.

Speech and chewing are affected in severe cases of malocclusion. An abnormal bite may be painful and may also affect the appearance, particularly the lower-jaw profile. Arthritis may develop in the temporomandibular joint (see Temporomandibular joint disorder) in rare cases.

What might be done?

The dentist will look for malocclusion as part of a dental checkup. If 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, especially if some of the teeth have not erupted.

Treatment is usually necessary only if malocclusion is severe and is causing difficulties when eating and speaking or affecting appearance. If the teeth are overcrowded, some of them may be extracted. If required, the teeth may then be aligned using an orthodontic appliance (see Orthodontic treatment). Surgery is necessary only in rare cases.

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.

Treatment: Orthodontic Treatment

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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