Prognathism is a protrusion of your upper jaw, lower jaw or both. This condition may be inherited, or it could be caused by an underlying health condition. Treatment involves a combination of corrective jaw surgery and orthodontics.


Prognathism, or protrusion of the lower jaw.
Prognathism is a protrusion of the lower jaw.

What is prognathism?

Prognathism is when your jaw protrudes, or juts out. This typically involves your lower jaw. Prognathism is a congenital condition. This means that people are born with it. But while symptoms may be present at birth, they can also emerge later in life due to dental injuries (such as blunt force trauma to your mouth) or childhood habits (like thumb sucking).

What does prognathism look like?

There are different types of prognathism, including:

  • Mandibular prognathism. Your lower jaw sticks out farther than your upper jaw.
  • Maxillary prognathism. Your upper jaw sticks out farther than it should. Maxillary prognathism is sometimes called alveolar prognathism.
  • Bimaxillary prognathism. Both your upper and lower jaws protrude, or stick out.

Prognathism can range from mild to severe. Some cases are more noticeable than others and can significantly impact your quality of life.

Who does prognathism affect?

Prognathism affects both men and women, though it’s slightly more common in men.

How common is prognathism?

Prognathism affects about 0.5% to 2.0% of children and 2.0% to 4.0% of adults.

How does prognathism affect my health?

A protruding jaw can cause malocclusion (where your teeth don’t fit together properly). Malocclusion can cause a number of health issues, including dental wear and tear, chewing difficulties and speech problems.

Misaligned teeth are also more difficult to brush and floss. As a result, many people with prognathism have an increased risk for tooth decay (cavities) and gum disease.


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Symptoms and Causes

What are the symptoms of prognathism?

People with prognathic jaw can develop a wide range of symptoms, depending on the type and severity of their condition. Common prognathism symptoms include:

What causes prognathism?

Simply stated, prognathism happens when your facial bones grow abnormally. There can be several reasons why this happens. In many cases, people simply inherit a larger jaw. In other words, the condition is passed down to children by parents and isn’t linked to any underlying medical conditions. However, in some instances, prognathism may be a symptom of certain conditions or syndromes, such as:

  • Acromegaly. This pituitary gland condition occurs when your body makes too much growth hormone. It can lead to enlarged tissues, such as an oversized jaw.
  • Crouzon syndrome. This is a genetic syndrome that causes the seams of your skull to fuse abnormally. This can result in prognathism or other head and facial irregularities.
  • Basal cell nevus syndrome. This inherited condition causes abnormal facial development. In some cases, this includes prognathism.
  • Acrodysostosis. This condition affects bone growth. People with acrodysostosis usually have a small upper jaw, which makes their lower jaw appear larger in comparison. Other symptoms of acrodysostosis include a short nose and short arms and legs.
  • Down syndrome. Because people with Down syndrome have an extra chromosome that affects development, it can result in excessive jaw growth in some cases.


Diagnosis and Tests

How is prognathism diagnosed?

Your healthcare provider will perform a comprehensive physical examination and ask questions about your symptoms and family history. They may also take:

  • Dental X-rays, which show your teeth and supporting jawbone.
  • A skull X-ray (cephalometric radiograph), which shows a side view of your face, including your jaw joints and occlusion (how your teeth fit together).
  • Dental impressions, which are used to create a model of your teeth.

Management and Treatment

How is prognathism treated?

Prognathism treatment depends on the severity of your condition. Generally speaking, skeletal issues like prognathism require surgery. Some mild cases may be addressed with orthodontics, such as braces. A combination of both surgery and orthodontics is recommended in most instances.

Orthognathic surgery

Also called corrective jaw surgery, orthognathic surgery involves repositioning your jaw bones to improve health, function and appearance. Once your orofacial bones are positioned properly, your teeth will fit together better as well.

Orthodontic treatment

Orthognathic surgery is usually performed in conjunction with braces or clear aligners. In many cases, you’ll begin treatment with braces and undergo jaw surgery later on, once your teeth are in better alignment. But treatment is different for everyone. Your healthcare provider can tell you what to expect in your unique situation.

Can you fix prognathism without surgery?

In very mild cases, prognathism may be corrected with orthodontics alone, but this isn’t the norm. Braces can move teeth, but they can’t move your facial bones. So, if skeletal abnormalities are moderate or severe, then you’ll likely need surgery as part of your treatment.


How long does it take to recover from orthognathic surgery?

All in all, it takes about nine to 12 months to recover from orthognathic surgery. Your healthcare provider will give you detailed instructions to follow during this time, including dietary guidelines. Though full recovery takes up to one year, you’ll be able to return to work, school and normal routines in about two to three weeks.

What are the risks of orthognathic surgery?

As with any surgical procedure, there are risks associated with orthognathic surgery. Possible complications include:

  • Postoperative infection.
  • Nerve damage.
  • Jaw pain.
  • Jaw fracture.
  • Bite problems.
  • Slight relapse of jaw position.


Can I prevent prognathism?

Because prognathism is a congenital condition (present at birth), there’s nothing you can do to prevent it from happening. If you’re planning on having children and you want to know if there’s a chance of passing a genetic condition to them, you can schedule an appointment with a genetic counselor.

Outlook / Prognosis

What can I expect if I have prognathism?

If you have prognathic jaw, your healthcare provider will discuss your treatment options with you in detail. Chances are, you’ll need surgery to correct the issue.

Living With

When should I see my healthcare provider?

If you have a protruding jaw, talk to your healthcare provider. They can help determine if prognathism is simply a cosmetic issue or if it’s interfering with your health and function. If your condition causes serious issues — such as difficulty chewing, speaking or breathing — call your healthcare provider right away.

A note from Cleveland Clinic

Prognathism can have a significant impact on your dental function and overall health. People with prognathic jaws may also feel embarrassed or self-conscious about their appearance. Orthognathic surgery can reduce dental wear and tear, improve your chewing function and enhance your facial features. If you think you might have prognathism, talk to your healthcare provider. They can find a solution to meet your needs.

Medically Reviewed

Last reviewed on 04/28/2022.

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