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Retrognathia is a condition in which one jaw is set behind the other at a longer distance than typical. It is classified as a type of malocclusion, which is the misalignment of the teeth that is caused by the abnormal positioning of the jaws. Retrognathia is also called retrognathism, and it can be categorized according to which jaw is affected.
The human jaw consists of the maxilla and the mandible. The maxilla is formed by two bones fusing at the roof of the mouth, thus constituting the upper jaw. This structure holds the row of upper teeth in place. The mandible, which has the shape of a horseshoe, constitutes the lower jaw and secures the lower row of teeth.
The mandible is more frequently affected by retrognathia than the maxilla. In such an instance, the condition is called mandibular retrognathia. This means that the lower jar recedes to the point when it is too far back in relation to the upper jaw. Conversely, maxillary retrognathia involves the recession of the upper jaw, pushing it behind the lower jaw.
Mandibular retrognathia is commonly but erroneously classified as an overbite. The term overbite refers specifically to the front teeth of the maxilla overlapping that of the mandible. It does not refer to the mandible being set too far behind the maxilla.
Retrognathia is primarily caused by genetics. Another common cause is injury or trauma, especially in situations when the jaw does not heal properly. Infants are particularly prone to the latter, as they are in an age range in which the bones are still forming. Other factors include bone-related infections and surgery for oral cancer.
Although retrognathia is generally not a dangerous condition, it can cause difficulty in eating, pose problems to overall dental health, and alter facial appearance. People with this sort of affliction can choose to correct the jaw deformity and achieve a normal occlusion, which is the relationship between the upper and lower teeth, by opting for braces to align the teeth and surgery for grafting or removing portions of the jaw. Orthodontists, who are responsible for the braces, and dental surgeons, who perform the surgery, work with one another in the treatment of retrognathia.
To avoid retrognathia in particular, and jaw deformities in general, physicians advise patients to observe good dental hygiene. People who are very active in sports may want to wear protective headgear. Since infant injury is considered a major factor in the occurrence of the condition, parents might want to check for any jaw damage whenever the child falls or otherwise bangs up that area.
I am blessed with good teeth. I never had to have braces, and when I had my wisdom teeth removed, my oral surgeon said if everyone had teeth like mine, that he would be out of a job. He said my bite was as close to perfect as he had ever seen, and even asked to take a cast of my bite so he could show people what a correct bite was supposed to look like! I knew I had always had straight teeth, but had no idea I had a textbook bite. Live and learn.
My sister had to have her bite corrected, though. She had to wear that headgear. Her teeth were straight, but her bite was out of alignment. She had to wear the headgear at night for like two years, and had to wear a retainer for three.
My cousin had maxillary retrognathia. Hers was hereditary, and not caused by lack of good hygiene or anything like that. She actually had to have surgery and had part of her lower jaw broken and pieces removed from each side to bring it into line with her upper jaw. She had to have her mouth wired shut for about six weeks.
She lost about 35 pounds, and she really didn't have it to lose, but she said it was the thinnest she had ever been, so she wasn't terribly upset. She had never been overweight in her life, so I didn't understand that, but I know she was glad when she could finally open her mouth again!