If your jaw protrudes, it’s known as prognathism. This trait is sometimes called extended chin or Habsburg jaw. Typically, prognathism refers to the lower jaw sticking out more than usual. However, there are several different types of prognathism:

  • mandibular prognathism: your lower jaw protrudes
  • maxillary prognathism: your upper jaw protrudes
  • bimaxillary prognathism: both your lower and upper jaws stick out

Prognathism can cause an overbite or underbite depending on which jaw is affected. Prognathism may be a sign of an underlying medical condition, which could require treatment.

Talk to your healthcare provider if you suspect that your jaw is protruding and you have difficulty talking, biting, or chewing.

Some people are born with a larger jaw that’s genetically inherited and not caused by an underlying medical condition.

In other cases, prognathism may be a sign of one of the following conditions which are extremely rare:

  • Acromegaly occurs when your body produces too much growth hormone. This causes your tissues to enlarge, including your lower jaw.
  • Basal cell nevus syndrome is a rare inherited condition that causes abnormal facial characteristics, including prognathism in some cases.
  • Acrodysostosis is a very rare congenital condition that affects bone growth. People with this condition tend to have short arms and legs, a short nose, and small upper jaw, which makes the lower jaw appear larger than normal.

Many people may have a prognathic face from birth, and it may not be a problem. Prognathism can cause complications that may require treatment, such as misaligned teeth.

If you have prognathism that’s caused by an underlying medical condition, such as gigantism or acromegaly, you may also need additional treatment for that condition.

Gigantism is an increase in growth hormone before the growth plates in the bones have closed, and the condition presents in kids. Acromegaly is also an increase in growth hormone, but the increase occurs after the growth plates have closed, and the condition presents in adults.

Misaligned teeth

Prognathism can cause a condition called malocclusion of the teeth, which happens when your teeth aren’t aligned correctly.

Misaligned teeth can cause problems with:

  • biting
  • chewing
  • talking

They’re also harder to clean than properly aligned teeth, which increases your risk of gum disease and tooth decay.

If you suspect that your teeth are misaligned, make an appointment with a dentist.

They can:

  • check your jaw alignment
  • take X-rays
  • refer you to an orthodontist for treatment if needed


Acromegaly is rare and affects 60 people per million. The most common cause of acromegaly is a tumor on your pituitary gland or in other parts of your body.

If left untreated, acromegaly can raise your risk for developing:

It can also cause complications such as vision problems and arthritis.

Contact your healthcare provider if you have a protruding jaw and other symptoms of acromegaly, such as:

  • protruding brow
  • widened nose
  • increased space between your teeth
  • swollen hands and feet
  • swelling in your joints
  • muscle weakness
  • joint pain

Basal cell nevus syndrome

Basal cell nevus syndrome, or Gorlin syndrome, affects an estimated 1 in 31,000 people. Basal cell nevus syndrome raises your risk for a type of skin cancer called basal cell carcinoma.

If you develop unusual spots or growths on your skin, let your healthcare provider know. If they suspect that the spot or growth might be cancerous, they may refer you to a dermatologist for testing.

In severe cases, basal cell nevus syndrome can affect your nervous system. This can cause complications such as:

Let your healthcare provider know if you or your child has a protruding jaw and other symptoms of basal cell nevus syndrome, such as:


Acrodysostosis is extremely rare. Only 80 cases have been reported, according to the International Osteoporosis Foundation.

Children are born with acrodysostosis. If your child has this condition, it raises their risk for arthritis and carpal tunnel syndrome.

It may also limit their ability to move their:

  • hands
  • elbows
  • spine

It can also affect their intellectual development, which may lead to challenges at school or in other areas of life.

Make an appointment with your healthcare provider if your child has a protruding jaw and other signs of acrodysostosis, such as:

  • short height
  • short arms or legs
  • malformed hands or feet
  • unusually curved spine
  • small, upturned nose
  • widely spaced eyes
  • low-set ears
  • hearing problems
  • intellectual disability

An orthodontist can adjust a protruding jaw and misaligned teeth by using braces. They work closely with oral surgeons who can fix protruding jaws with orthognathic surgery. You might choose to have this done to correct misaligned teeth or for cosmetic reasons.

During this surgery, the surgeon will remove and reposition parts of your jaw bones.

Usually prognathism occurs with a smaller jaw, so the smaller jaw may be made slightly longer, while the larger jaw is set back. They will use plates, screws, or wires to hold your jaw in place as it heals.

You may need to wear braces before and after surgery to encourage your teeth to move into new positions.

If you have prognathism that’s caused by an underlying medical condition, your healthcare provider might recommend other treatments to manage that condition.


If you have acromegaly that’s caused by a tumor, your healthcare provider may surgically remove the tumor. In some cases, you might need radiation therapy to shrink the tumor.

Your healthcare provider may also prescribe medication to control the amount of growth hormone that your body releases or block the effects of growth hormone.

Basal cell nevus syndrome

If you have basal cell nevus syndrome, your healthcare provider’s recommended treatment plan will depend on what parts of your body have been affected.

If you develop basal cell carcinoma, your healthcare provider can use surgery to remove it.


If you or your child has acrodysostosis, your healthcare provider’s recommended treatment plan will depend on how the condition has affected you or your child.

For example, they may recommend surgery to help correct bone abnormalities. They may prescribe nutritional supplements to help promote growth. They may also refer you or your child to educational, vocational, or social support services to help manage an intellectual disability.

After corrective jaw surgery, you’ll need to eat a modified diet while your jaw heals. When you’ve recovered, usually after 6 weeks, you can return to eating a regular diet.

Your surgeon may prescribe medications to provide pain relief while your jaw heals.

If you don’t develop any complications from surgery, you’ll likely be able to return to school or work in about 1 to 3 weeks after surgery.

Your jaw will need about 9 to 12 months to fully heal. Talk to your surgeon about your post-surgery recovery and when you can return to work or school.

There’s no way to prevent prognathism that’s caused by inherited or genetic conditions, such as basal cell nevus syndrome.

If you’re planning to have children and you want to learn if there’s a chance of you transmitting a genetic condition to them, your healthcare provider may refer you to a genetic counselor. They can help you understand and manage the potential risk.

Prognathism happens when your lower jaw, upper jaw, or both halves of your jaw protrude beyond the normal range. It can be caused by a genetic or inherited condition or an underlying medical condition. It can also develop for unknown reasons.

To realign your jaw, your healthcare provider may refer you to an oral surgeon or plastic facial surgeon for corrective jaw surgery.

If your teeth don’t fit well together because of prognathism, you can see an orthodontist or dentist who can adjust the position of your teeth.

If the prognathism is caused by another condition, your healthcare provider may recommend additional treatments for that condition.