Prognathism

Definition

Prognathism is an extension of the lower jaw (mandible) that occurs when the shape of the face bones cause the teeth to be improperly lined up (misaligned).

Alternative Names

Extended chin

Considerations

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

Common Causes

An extended (protruding) jaw can be part of the normal facial shape a person is born with. It can also be caused by inherited conditions such as Crouzon syndrome or basal cell nevus syndrome. You can develop it as a child or adult from gigantism or acromegaly.

Home Care

It is appropriate to see a dentist or orthodontist to treat abnormal alignment of the jaw and teeth. However, also contact your primary health care provider to rule out medical disorders that can be associated with prognathism.

Call your health care provider if

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

What to expect at your health care provider's office

The health care provider will perform a physical examination and ask questions regarding the patient's 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 also have?

Diagnostic tests may include:

• Skull x-ray
• Dental x-rays
• Imprints of the bite (a plaster mold is made of the teeth)