May 2, 2021

Understanding problems with jaw anatomy

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How bones and joints work together to create strong jaw anatomy, and what happens when they don’t.

A jaw that’s too small, too large or crooked can cause problems with chewing, speaking, breathing and even sleeping. The shape of your jaw and your jaw anatomy also affect the way your face looks. 

Bones are the framework for the face. The size and position of facial bones determine how well the teeth fit together. Together, the positions of the jaws and teeth affect chewing, speaking and how well the jaw joint works. 

The jaws also hold and support soft tissues, like facial muscles, lips and your tongue. 

The temporomandibular joints (TMJs) – the jaw joints — allow the lower jaw to move smoothly.

The lower jaw (mandible) supports the bottom row of teeth and gives shape to the lower face and chin. This is the bone that moves as the mouth opens and closes.

The upper jaw (maxilla) holds the upper teeth, shapes the middle of the face and supports the nose.

A good bite (occlusion) means that the upper and lower teeth are straight and fit together properly.

Common alignment problems

The lower jaw holds the tongue, which moves as you talk and eat. The upper jaw shapes the floor of the nasal cavity, allowing normal airflow. Normally, muscles are evenly developed on both sides of the face.

Some common problems with jaw alignment:

  • The lower jaw is too far back (retrognathia). Biting can be difficult. The chin appears receding.
  • The lower jaw is too far forward (prognathia). This causes the chin to protrude. Lower teeth may jut outward to overlap the upper teeth.
  • Teeth don’t meet (open bite). An open bite is often due to a long upper jaw. This can cause a “gummy smile.” Or the problem may be that the rear of the lower jaw is too short. In this case the open bite is often associated with abnormalities of the jaw joint. An open bite can also be caused by prolonged thumb sucking or improper tongue position at rest and when swallowing. An open bite can make it impossible to close the lips.
  • Jaws are uneven (asymmetry). Uneven jaws are larger or smaller on one side than on the other. Or one side may be too far forward or back. The face may look off-center or crooked.

What happens when jaws are not aligned

When the jaws are not lined up properly, it can create challenges such as:

  • Chewing problems. You may find it difficult to bite into a sandwich or an apple, or to keep food in your mouth as you chew. The jaw joints may be stiff or painful.
  • Speech problems. It may be difficult to make certain sounds or to speak clearly.
  • Breathing problems. If the airway is narrow or blocked, breathing may be noisy or difficult. You may have sleep apnea (breathing that stops during sleep).
  • Problems with appearance. You may be unhappy with the way you look. This can make you self-conscious and may affect your confidence.
Young woman laughs with a friend.

Vanderbilt’s oral and maxillofacial surgeons care for people with complex injuries, diseases or deformities of the jaws and face. The team has the expertise to manage or repair a wide variety of problems, with a goal of reducing pain and providing better quality of life. For an appointment, call 615-322-2377.

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