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Humans (unlike apes and primates in general) have orthognathic faces. In other words, human faces lie beneath the anterior cranial fossa (which is the area just behind the forehead, holding the front lobes of the brain). Apes, for example, have prognathic faces that project outward from the anterior cranial fossa. Therefore, prognathism refers to an extension of the lower jaw (the mandible). The jaw protrudes out from the face, so it appears to bulge.
Prognathism is also sometimes referred to as an extended chin or Habsburg jaw. It happens when the teeth are not correctly aligned. The face bones and general facial structure can cause the misalignment of teeth and, as such, prognathism. That said, prognathism can also be genetic or caused by an underlying condition.
There are three types of prognathism. Mandibular prognathism happens when the bottom jaw extends out from the face further than it should. Maxillary prognathism, on the other hand, occurs when the upper jaw protrudes out from the face. Bimaxillary prognathism happens when both the top and bottom jaw stick out further than the rest of the face.
These conditions may be caused by the misalignment of teeth, a genetic disorder, or an underlying medical condition. Likewise, all of these conditions may be perfectly fine to live with, or they may cause some issues with talking, eating, and breathing.
Misaligned teeth are often the cause of prognathism. The teeth can actually change the shape of the jaw as they grow in. Many people are also born this way. Simply, their faces are structured with a jaw bone that sticks out from the time they are born.
However, in some cases, an underlying condition may be at the root of prognathism. Here are some of the underlying medical conditions that can cause prognathism:
While prognathism is not always passed down, it can be genetic. A family medical history of an unusual jaw shape or an abnormal alignment of the jaw can be behind prognathism in some cases.
Talk to your health care provider about your chances of passing down prognathism.
The symptoms of prognathism vary from person to person. These symptoms may include the following:
Unfortunately, you cannot prevent a case of prognathism that is due to genetic conditions. A protruding jaw may just be part of a person. And it may not be an issue.
You can help prevent the jaw from changing shape by properly aligning your teeth. For example, a dentist or orthodontist may give you braces, a retainer, or a mouthguard to help correct an underbite.
You can also treat prognathism with medical care and/or orthodontic treatment if you already have it. For some people, treatment may be necessary to talk, eat, and breathe properly.
Prognathism is not always a problem. Sometimes, the symptoms associated with prognathism do not significantly impact someone’s life. Beyond changing the shape of their face, they can still talk, eat, and breathe properly. Prognathism may only pose cosmetic insecurities for them if there are any concerns at all.
In some cases, prognathism does affect a person’s day-to-day living. Fortunately, prognathism can be treated in a variety of ways. Here are some options to treat prognathism if you choose to seek care:
If you have prognathism, talk to your health and/or dental care provider about your treatment options.
Center Turó Park Medical. “Prognathism: What Is It and How to Recognize It?” Turó Park Dental & Medical Center, 2 Jan. 2020, turoparkmedical.com/blog/prognathism/.
“Crouzon Syndrome: MedlinePlus Genetics.” MedlinePlus, U.S. National Library of Medicine, 18 Aug. 2020, medlineplus.gov/genetics/condition/crouzon-syndrome/.
“Facts about Down Syndrome.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 5 Dec. 2019, www.cdc.gov/ncbddd/birthdefects/downsyndrome.html.
“Multimedia Encyclopedia - Penn State Hershey Medical Center - Penn State Hershey Medical Center.” Penn State Hershey Health Information Library, pennstatehershey.adam.com/content.aspx?productid=117.
“Prognathism: MedlinePlus Medical Encyclopedia.” MedlinePlus, U.S. National Library of Medicine, medlineplus.gov/ency/article/003026.htm.
“What Is Prognathism and How Is It Treated?” Oral Surgeon, www.faceandjawsurgery.com/what-is-prognathism-and-how-is-it-treated/.