Prognathism

Prognathism is when your upper jaw, lower jaw or both jaws protrude (jut out). It can look different ways, depending on the type:

• Mandibular prognathism (most common): Your lower jaw sticks out farther than your upper jaw. Another name for it is Habsburg jaw. This name comes from the Habsburg royal dynasty in Spain. Many family members from the 1500s through the 1700s had a pronounced lower 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.

Sometimes, prognathism is barely noticeable and doesn’t cause health issues. If this is your situation, you likely won’t need treatment.

If it’s more severe, though, it can cause a misaligned bite (malocclusion). Malocclusion can cause a number of health issues. It can lead to dental wear and tear, chewing difficulties and speech problems. A healthcare provider can recommend treatments that can help.

Symptoms of prognathism

A prognathic jaw may or may not cause symptoms, depending on its severity. In addition to having a protruding jaw, symptoms may include:

• Breathing difficulties
• Difficulty chewing
• Speech problems
• Trouble brushing your teeth and flossing

Prognathism causes

Prognathism is a congenital condition. This means you’re born with it. Often, parents pass down genes to their biological children that cause one jaw to be larger than another. Sometimes, it’s a sign of a condition or syndrome, like:

• Acrodysostosis: A person with acrodysostosis usually has a small upper jaw. This makes their lower jaw appear larger in comparison. Other symptoms include a short nose, short arms and short legs.
• Acromegaly: This pituitary gland condition occurs when your body makes too much growth hormone. It can lead to enlarged tissues, like 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.
• Down syndrome: People with Down syndrome have an extra chromosome that affects development. It can lead to excessive jaw growth in some cases.
• Gorlin syndrome: This inherited condition causes abnormal facial development. In some cases, this includes prognathism.

While prognathism usually presents at birth, it can happen later in life due to dental injuries (like blunt force trauma to your mouth). Rarely, it can happen because of childhood habits, like thumb sucking or pacifier use. In excess, these habits can impact how the bones in your child’s face develop.

Complications of this condition

Prognathism can lead to:

• An overbite or underbite
• Cavities and gum disease
• Dental misalignment
• Dislocated jaw
• Temporomandibular joint (TMJ) disorders
• Tooth erosion
• Tooth grinding

How doctors diagnose this condition

​Your healthcare provider will examine you 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 how your teeth fit together
• Dental impressions, which your provider can use to create a model of your teeth and see how pronounced a misaligned bite is

How is prognathism treated?

Treatment depends on the severity of your condition. Usually, skeletal issues like prognathism require surgery. Orthodontic treatments, like braces, may be all you need when prognathism is mild. But usually, treatment involves both.

Corrective jaw surgery

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

Orthodontic treatment

If you’re like most people, you’ll begin treatment with braces or clear aligners. Once your teeth are in better alignment, you’ll get jaw surgery. But treatment is different for everyone. Your healthcare provider will explain what to expect.

When should I see my healthcare provider?

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

What can I expect if I have prognathism?

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

If you’re planning on having children and want to know if there’s a chance of passing a condition to them, see a genetics counselor. They can help you understand how likely it is that your child will inherit a prognathic jaw.

Can you fix prognathism without surgery?

In very mild cases, orthodontics alone may be enough to correct this condition, 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.