Malocclusion is an abnormal alignment of the teeth or upper and lower jaws that prevents the teeth from meeting properly.

• If teeth are out of alignment, abnormal pressure is put on them, making them more likely to loosen or fracture.
• Malocclusion may make biting, chewing, or speaking difficult.
• Braces or retainers can usually realign teeth, but sometimes surgery is needed.

Occlusion refers to the alignment of the teeth and the way in which the upper and lower teeth fit together. Ideally, the upper teeth fit slightly over the lower teeth. Proper alignment of teeth prevents undue force from being placed on just a few teeth and keeps the lips, cheeks, and tongue away from the biting surfaces. If the teeth are maloccluded (out of alignment), undue strain is placed on some of the teeth, which may fracture portions of the crown or loosen the teeth.

Causes

A common cause of malocclusion is disproportion between jaw size and tooth size or between the size of the upper and lower jaws. These differences can result in the overcrowding of teeth and in an abnormal bite. Another cause is loss of one or more teeth. When a tooth is lost, nearby teeth tend to drift into the newly available space, moving them out of alignment. Less common causes of malocclusion include misalignment of a jaw fracture, thumb sucking beyond the age of 4, tumors of the mouth or jaw, and improper fitting of crowns, fillings, retainers, or braces. Malocclusion may have a hereditary component.

Symptoms and Diagnosis

Malocclusion usually causes no symptoms at first. Eventually, though, it may result in a loosening or fracture of misaligned teeth because of the strain placed on them. Severe malocclusions may also cause difficulty or discomfort when biting or chewing, as well as speech difficulties. Malocclusions that prevent full access for proper oral hygiene may increase the risk of gum disease and cavities.

Malocclusion can be diagnosed by the dentist during a dental examination.

Prevention and Treatment

After loss or removal of a tooth or teeth (for example, to make way for other permanent teeth), movement of remaining teeth can be prevented with braces or other orthodontic appliances. Once the teeth are properly aligned and the braces are removed, the person is usually required to continue wearing a retainer at night for 2 to 3 years to maintain the position of the teeth.

Malocclusion can be corrected in a number of ways. Teeth can be realigned by applying a continuous mild force through the use of an orthodontic appliance, such as braces (wires and springs carried by brackets that are fixed to the teeth with dental adhesive) or a retainer (a removable brace combining wires and a plastic plate that snaps into the roof of the mouth). For some minor malocclusions, orthodontic therapy can be done with appliances that are barely visible. Occasionally, when an orthodontic appliance alone is not sufficient, jaw surgery may be necessary. Other methods of treating malocclusion include selective grinding of some teeth or building them up with the use of crowns or other dental restorations.

Last full review/revision October 2008 by James T. Ubertalli, DMD