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What causes prognathism? 6 possible conditions

What is Prognathism?

Prognathism refers to a protruding jaw. It is also called an extended chin or Habsburg jaw. The condition is usually a sign of an underlying condition. Talk to your doctor if you suspect your jaw is protruding.

Recognizing Prognathism

You have mandibular prognathism if your bottom jaw extends further out than it should. Maxillary prognathism occurs when your upper jaw protrudes. In bimaxillary prognathism, both jaws stick out further than the rest of your face.

Underlying Causes of Prognathism

Some people are born with a protruding upper or lower jaw without having any underlying conditions. In others, prognathism can be associated with one of the following underlying conditions:


This condition occurs when your body produces too much growth hormone (GH), which causes your tissues to enlarge. Your lower jaw ends up sticking out as it becomes larger. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), it affects about 60 out of every one million people (NIDDK, 2012).

Basal Cell Nevus Syndrome

This is a rare inherited condition that causes abnormal facial characteristics, such as a broad nose, eyes that are too far apart, and a heavy brow. Prognathism occurs in some cases.


This is a very rare condition that people are born with. It can cause shortened arms and legs, hearing problems, a short nose, a protruding jaw, and mental retardation.

When to See the Doctor

Prognathism can cause a condition called malocclusion of the teeth, which means that your teeth are not aligned correctly. This can cause problems with biting, chewing, and talking. Misaligned teeth are also harder to clean, which increases your risk of gum disease and tooth decay. Your dentist can check your jaw alignment and refer you to an orthodontist for treatment.

Acromegaly can raise your risk of having diabetes, high blood pressure, and heart disease when left untreated. It can also cause serious complications such as vision problems and arthritis. Call your doctor if you have a protruding jaw and other symptoms of this condition, such as:

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

Basal cell nevus syndrome is associated with an increased risk of a skin cancer called basal cell carcinoma. If you have any unusual growths or skin abnormalities, see a dermatologist as soon as possible to have them checked out.

This condition can also affect your nervous system and lead to blindness, mental retardation, seizures, and deafness. It is important to see your doctor if you have the physical characteristics of this condition.

Acrodysostosis can lead to arthritis, limited movement in the hands, elbows, and spine, and carpal tunnel syndrome. Call the doctor if your child has physical signs of this problem or developmental problems that could be linked to mental retardation.

Treating Prognathism

Dental Care

An orthodontist can fix a protruding jaw through orthognathic surgery. You can have this done to correct misaligned teeth or for cosmetic reasons. You will have to wear braces to encourage your teeth to move into their new position. Your surgeon will remove and reposition parts of your bones as needed. Your jaw will be held in place with plates, screws, or wires.

Medical Care

Your doctor can diagnose and treat any underlying conditions that are causing your protruded jaw.

Acromegaly can be treated by surgically removing the pituitary tumor that causes the production of too much growth hormone. You might need radiation therapy if the tumor is too big. Your doctor can also prescribe medication to control the amount of growth hormone that is released or block its effects.

If you have basal cell nevus syndrome, treatment depends on what parts of your body are being affected and whether or not you have cancer.

Treatment for acrodysostosis involves special education for mental retardation and orthopedic care for bone problems.

What Happens After Corrective Surgery?

After corrective jaw surgery, you will have to eat a modified diet temporarily. Medications can provide pain relief and you will be able to go back to work about one to three weeks after surgery. Your jaw will need about nine to 12 months to fully heal.

Preventing Prognathism

You cannot prevent prognathism due to genetic conditions, such as basal cell nevus syndrome. You can talk to a genetic counselor if you are planning on having children to find out if there is a the chance of passing the condition on to them.

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See a list of possible causes in order from the most common to the least.



Gigantism is a rare condition that causes abnormal growth in children. It occurs when your child's body produces far too much growth hormone.

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Malocclusion of the Teeth

Malocclusion of the teeth occurs when the teeth are not properly aligned within the mouth. In this condition, teeth may not comfortably fit in the mouth without crowding or spacing, or may be twisted or rotated.

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Acromegaly is a rare condition. It causes excess growth in the bones and soft tissues of the body. Children with the condition can grow to abnormal heights. They may also have an exaggerated bone structure that give...

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Genetic changes that occur while the fetus is growing can cause disorders that are present at birth. These are sometimes referred to as "congenital disorders." Acrodysostosis is one such condition, albeit a rare one...

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Fragile X Syndrome

Fragile X syndrome is an inherited genetic disease that causes intellectual and developmental disabilities. Inherited means that the disease is passed down from parents to children through their genes. Fragile ...

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Basal Cell Nevus Syndrome

Basal cell nevus syndrome is a group of defects caused by a rare genetic condition that can cause tumors in the jaw.

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This feature is for informational purposes only and should not be used to diagnose.
Please consult a healthcare professional if you have health concerns.