What Is Jaw Recession?

A sharp lower jaw and chin set the lower third of the face. When the mandible sits too far back, the chin loses its projection and the jawline goes soft, a condition known clinically as mandibular retrognathia, and informally as a recessed chin or weak chin. The opposite happens in mandibular prognathism, where the lower jaw juts forward past the upper. Both sit on a spectrum of jaw projection, and both shape the face in ways that are hard to mask without surgery. This page walks through what each looks like, what causes them, and what the treatment options are.

Chin Recession or Retrognathia

Retrognathia, previously known as Mandibular Retrognathia, or Jaw recession is described as a small sized mandible associated with with chin recession (1). Mandibular Recession is a multi-factorial condition caused by genetic, epigenetic, and environmental factors (2). Genetic retrognathia can be evaluated prenatally, through a detailed USG. The fetal subtype is usually associated with syndromes like Pierre-Robin's Syndrome, and Treacher Collins Syndrome (3). However, it can also develop in adolescents and young adults. This subtype is strongly associated with Temporomandibular disk displacement, especially displacement of the anterior disk (4). Temporomandibular disorders can affect mandibular mobility and cause multiple problems such as mandibular deviation and retrusion. When these consequences arise in adolescents, they lead to retrognathia as the mandible of the adolescents is not completely formed and ossified (5). This retrognathia can only be treated surgically or with fillers.

Causes of Retrognathia

Retrognathia can develop as a result of syndromes mentioned above. It can also develop due to facial trauma causing improper development of jaw, facial surgery to remove a tumor near or on the mandible, TMJ disorders, and poor oral posture. Proper oral posture simply means resting the tongue on the roof of the mouth. This helps with normal spacing of teeth and normal sizing of the jaw. When children grow up without doing so, their upper jaw develops in three dimensions, lower jaw narrows and retracts/deviates to the side. This can cause retrognathia, overcrowding of teeth, and temporomandibular joint problems(6). TMJ disorders, as mentioned above, also cause retrognathia, leading to a prominent chin recession. Poor oral posture in children is mostly due to conditions like enlargement of tonsils, frequent infections and allergies. All these issues cause children to breath through their mouth, preventing the resting of the tongue on the upper palate. Along with that, thumb sucking and overuse of pacifiers in children can also cause poor oral posture. Nasal breathing training, in the absence of occlusion, and myofunctional therapy, and allergy treatment can help with development of proper oral posture in children.

Aesthetic Effects and Treatment of Retrognathia

A recessed chin pulls the lower third out of balance with the rest of the face. In adolescents that imbalance can wear on self-image, and in severe cases the retrusion is large enough that the airway is compromised and the patient needs intubation before any cosmetic step is considered.

When breathing is not the issue, the fix is cosmetic. Surgeons reshape or advance the chin through genioplasty, place an alloplastic chin implant, or build projection with hyaluronic-acid filler. Each option targets the same problem from a different angle: filler is fastest and reversible, an implant adds permanent volume, and genioplasty moves the underlying bone. Demand has tracked the modern preference for a defined jawline, and the American Society for Aesthetic Plastic Surgery now lists chin work among its more commonly requested cosmetic procedures.

Chin Protrusion or Prognathism

Prognathism, or the Habsburg jaw, can be described as the anteroposterior discrepancy between the lower jaw and the upper jaw. It can be of three different types; alveolar, mandibular, and maxillary(8). Amongst them, maxillary prognathism or skeletal Class III malocclusion with a prognathic mandible is the most severe craniofacial disorder(9). Due to the severe nature of the disease and its subtypes, proper evaluation is required to determine which type of prognathism is present.

Causes of Prognathism

It is the protrusion of the mandible, or the lower jaw, ahead of the upper jaw, causing a discrepancy. Just like retrognathia, mandibular prognathism is also multifactorial in origin. However, genetic disorders like Crouzon Syndrome, or Down Syndrome are associated with prognathism (10). It can also be caused by inbreeding, like in the Habsburg Family, from which it gets its name. Poor oral posture also plays an important role in the development of prognathism, along with the elevation of GH, Acromegaly, and hypertrophied tonsils in children.

Treatment of Prognathism

Taking into consideration the disturbance of facial balance, prognathism can cause dysmorphia and self-consciousness in patients. Just like retrognathia, prognathism can cause many self-image issues in it’s patients, along with physical complications. Treatment of prognathism requires a mixture of orthognathic or maxillofacial surgery and orthodontic surgery (11). Since protrusion or retraction can affect the teeth development and structure, it is important to perform orthodontic surgery as well. Malocclusion and misalignment is treated with surgery, and depending on type or severity of prognathism, surgery is performed on either or both of the jaws. As most patients are already self conscious and not comfortable with massive scars, doctors make the incision at the gums and insert plates and screws to fix the discrepancy between the jaws. Overall, Retrognathia and Prognathism are severe craniofacial diseases which can affect the physical appearance and self-image of the affected individuals. Both of them are multifactorial diseases, caused by genetics, epigenetic, or environmental factors and timely diagnosis is needed for appropriate treatment. Environmental factors like oral posture are crucial for development of these disorders. Maintaining good oral posture can help reduce the risk factors of both prognathism and retrognathia. Cosmetic, orthognathic, and orthodontic surgeries can treat these defects. It is important for the mental health of these patients to treat these conditions, as these conditions affect the ideal beauty factor of their face.