Prognathism is a condition in which part of the jaw protrudes, causing the chin or upper jaw to jut forward. It can be genetic, as in the case of the famous Hapsburg jaw, or it can be the result of a medical condition. Depending on the severity of the condition, various treatments can be used to reduce the protrusion. Medical treatment is usually used when the jutting jaw interferes with eating, breathing, or speaking, or if someone feels profoundly uncomfortable about his or her facial structure.
There are three types: mandibular, maxillary, and alveolar. In mandibular prognathism, the lower jaw protrudes, causing the chin to jut out from the face. Maxillary prognathism involves the upper jaw, and typically creates an elongated facial appearance. Patients with alveolar prognathism experience abnormalities around the part of the jaw where the teeth are located, with the teeth jutting out from the face at an angle.
In some cases, prognathism is simply genetic. People from certain family lines and people in some regions of the world naturally have this condition, and it is a fairly common family trait. In other instances, it may be caused by a genetic mutation, or a genetic disorder such as Crouzon syndrome. It can also develop in response to conditions which emerge later in life, like acromegaly, a disorder in which too much growth hormone is produced. If the problem develops suddenly, it can be a sign that someone is experiencing a medical condition which needs to be addressed.
Sometimes, prognathism can be caused by physical trauma or by some activity on the part of the patient. Alveolar prognathism, for example, is linked with thumb-sucking in children. Routine sucking of the thumb or fingers night after night can cause the teeth to move in the jaw, just as wearing orthodontics can correct the positions of drifting teeth. The jaw may also move after a break or serious injury, especially if it is not set properly.
Often, medical professionals recommend leaving prognathism alone. However, it can become a problem, and in these instances, there are some corrective measures which can be taken. Corrective orthodontics which slowly pull the jaw into a less extreme alignment can be useful, especially in children, since they are still growing. Surgery can also be used to correct the condition, although the surgery can be expensive and the recovery time tends to be lengthy.