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

Extended chin

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.

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.

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

It is appropriate to see a dentist or orthodontist to treat abnormal alignment of the jaw and teeth. However, your primary health care provider should also be involved to check for any underlying medical disorders that can be associated with prognathism.

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

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 have?

Diagnostic tests may include:

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