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Prognathism

Prognathism is an extension or bulging out (protrusion) of the lower jaw (mandible). It occurs when the teeth are not properly aligned due to the shape of the face bones.

Considerations

Prognathism may cause malocclusion (misalignment of the biting surfaces of the upper and lower teeth). It can give a people an angry, or fighter's, appearance. Prognathism may be a symptom of other syndromes or conditions.

Causes

An extended (protruding) jaw can be part of a person's normal face shape that is present at birth.

It can also be caused by inherited conditions, such as Crouzon syndrome or basal cell nevus syndrome.

It may develop over time in children or adults as the result of conditions such as gigantism or acromegaly.

When to Contact a Medical Professional

A dentist or orthodontist may be able to about treat abnormal alignment of the jaw and teeth. Your primary health care provider should also be involved to check for underlying medical disorders that can be associated with prognathism.

Call a health care provider if:

  • You have difficulty talking, biting, or chewing related to the abnormal jaw alignment.
  • You have concerns about jaw alignment.

What to Expect at Your Office Visit

The health care provider will perform a physical examination and ask questions regarding your medical history. Questions may include:

  • Is there any family history of an unusual jaw shape?
  • Is there difficulty talking, biting, or chewing?
  • What other symptoms do you have?

Diagnostic tests may include:

This condition may be treated with surgery. An oral surgeon, plastic facial surgeon, or ENT specialist may perform this surgery.

Alternative Names

Extended chin

References

Taub DI, Jacobs JMS, Jacobs JS. Anthropometry, cephalometry, and orthognathic surgery. In: Neligan PC, ed. Plastic Surgery. 3rd ed. Philadelphia, PA: Saunders Elsevier; 2013:chap 16.

Update Date: 2/25/2014

Updated by: Sameer Patel, MD, Assistant Professor of Pediatrics, Northwestern University, Feinberg School of Medicine, Chicago, IL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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