Short answer: A jaw deformity is a mismatch between the lower and upper jaws in terms of size, position or symmetry. A jaw positioned too far back or forward, open bite and crossbite are the most common types. Causes include genetic predisposition and habits that continue in childhood. During growth, development is guided with orthodontic appliances; after growth is complete, orthodontics and, when necessary, jaw surgery are used.
Some problems with tooth alignment stem only from the position of the teeth, while others are rooted in the structure of the jawbones. A jaw deformity refers to a mismatch between the lower and upper jaws in size, position or symmetry and is also called a skeletal jaw anomaly in medicine. This condition can affect not only appearance but also biting, chewing, speaking and sometimes breathing. Below we give an overview of the types of jaw deformities, their possible causes, symptoms and treatment options.
What types of jaw deformity are there?
Jaw deformities are usually classified according to the relationship of the jaws in the front-to-back, vertical and side-to-side directions. The most widely used classification in orthodontics is based on the front-to-back relationship between the upper and lower jaws.
Class II: a lower jaw set back or an upper jaw too far forward
In this type, the lower jaw is positioned back relative to the upper jaw, or the upper jaw has developed too far forward. In profile, the chin may look set back and the upper front teeth may stick out noticeably. Deep bite, in which the upper front teeth overlap the lower front teeth excessively, often accompanies this picture.
Class III: a lower jaw too far forward or an upper jaw set back
In this type, the lower jaw is positioned forward relative to the upper jaw, or the upper jaw has not developed sufficiently. When the mouth is closed, the lower front teeth may sit in front of the upper front teeth; this is commonly known as an "underbite". The facial profile may take on a concave appearance.
Vertical and side-to-side deformities
In open bite, the front teeth do not touch even though the back teeth are in contact; conversely, in deep bite the front teeth overlap each other excessively. In crossbite, some of the upper teeth close inside the lower teeth; this is often associated with a narrow upper jaw. Some people may have facial asymmetry because one side of the jaw has developed differently from the other. Often several of these types are present together.
Causes: genetics and habits
In a significant proportion of jaw deformities, genetic predisposition is decisive. Similar jaw structures within the same family are common, especially with a forward lower jaw. The growth rate, direction and size of the jawbones are largely shaped by heredity.
That said, environmental factors can also guide jaw development. Prolonged thumb or pacifier sucking in childhood, pushing the tongue between the teeth during swallowing and constant mouth breathing can contribute especially to open bite and a narrow upper jaw. Nasal obstruction due to enlarged adenoids or tonsils can make mouth breathing persistent. Early loss of baby teeth, blows to the jaw area and certain syndromes are among other possible causes.
What are the symptoms of a jaw deformity?
The most obvious sign of a jaw deformity is that the upper and lower teeth do not fit together normally when the mouth is closed. In addition, the following signs may indicate the need for an assessment:
- Difficulty biting off food with the front teeth or chewing with the back teeth
- Difficulty producing certain sounds, or a lisp
- Inability to close the lips without strain and constant mouth breathing
- A chin that sits noticeably back or forward in profile
- Facial asymmetry, the jaw shifting to one side when smiling
- Uneven wear on some teeth, sounds or a feeling of strain in the jaw joint
The presence of these signs alone does not mean a diagnosis; similar findings can also result from the position of the teeth alone. Whether the problem is skeletal or dental is determined by the dentist with records such as an intraoral examination and a cephalometric X-ray.
What are the orthodontic treatment options?
The form of orthodontic treatment depends largely on whether the patient is still growing. Treatments applied while the jawbones are still growing can influence the direction and amount of growth to a certain extent. For this reason, organizations such as the Turkish Orthodontic Society and the American Association of Orthodontists recommend that children have their first orthodontic assessment at around age 7. You can also find information on early orthodontic approaches in our article at what age can clear aligners be used.
The main methods used in growing children are:
- Rapid maxillary expansion appliances: Use the growth line in the middle of the palate to correct a narrow upper jaw and the related crossbite.
- Functional appliances: Hold the lower jaw in a forward position to support forward development of a lower jaw that is set back.
- Face mask and extraoral appliances: Used to guide or restrict growth of the upper jaw.
In patients whose growth is complete or nearly complete, orthodontic treatment often has a "camouflage" aim. In this approach, the jawbones themselves are not changed; the position of the teeth is adjusted to balance the skeletal mismatch. In mild and moderate skeletal problems, this method can give satisfying results both functionally and aesthetically. In suitable cases, this alignment can also be done with clear aligners; however, it is important to know that clear aligners do not change bone structure. We covered this topic in detail in our article do clear aligners correct jaw structure.
Which situations require surgery?
In people whose growth is complete, when the mismatch between the jaws is pronounced, orthognathic surgery, that is, jaw surgery, may be considered for a stable and balanced result. In such cases, moving the teeth alone can push the teeth to the limits of the bone and may not provide the desired balance in facial appearance.
Orthognathic surgery is a process planned jointly by an orthodontist and a jaw surgeon. In most cases, pre-surgical orthodontic treatment first brings the teeth into the correct position relative to the jawbones. Then, in an operation under general anesthesia, the upper jaw, lower jaw or both are moved to the planned position. After the operation, the final adjustments to the bite are made with orthodontic treatment. The timing of surgery is usually determined by the completion of facial growth; this varies between girls and boys and requires an individual assessment.
The decision to operate is always assessed together with detailed records, facial analysis and the patient's expectations. In many people with a mild mismatch, a functional bite can be achieved with orthodontic treatment without the need for surgery.
Why is early diagnosis important?
Early diagnosis is important because some jaw discrepancies noticed during growth can be guided with simpler methods, and the need for more extensive treatment later may be reduced. If you notice mouth breathing, continued thumb sucking, an underbite or marked crowding in your child, you do not need to wait for all the permanent teeth to erupt before an orthodontic examination. To better understand dental and jaw terms, you can browse our dental glossary.
Jaw and bite assessment in Ankara
If you have a question about your child's jaw structure or your own, the first step is a detailed orthodontic examination and the necessary X-ray records. At our clinic in Park Oran Ofis, next to Panora Mall in Çankaya, our orthodontist assesses whether the problem is dental or skeletal and, when necessary, shares joint planning options with jaw surgery with you.
Frequently asked questions
Does a jaw deformity correct itself?
Jaw deformities of skeletal origin usually do not correct themselves; they may even become more pronounced with growth. Stopping habits such as thumb sucking early can contribute to the correction of some mild open bites. Monitoring of the condition and the need for treatment are determined by an orthodontic examination.
Can jaw deformities be treated without surgery in adults?
In mild and moderate mismatches, a functional bite can be achieved with camouflage orthodontics that adjusts the position of the teeth. In pronounced skeletal mismatches, orthognathic surgery may give a more balanced result. Which option is suitable is assessed with the dentist after the records have been examined.
When should I take my child to an orthodontist?
Orthodontic associations recommend that the first assessment be done at around age 7. Not every child needs to start treatment at this age, but growth-related problems can be noticed early and monitored. If there are signs such as an underbite or mouth breathing, you can come in even earlier.
