Orthodontics is the specialized field of dentistry focused on correcting improper bites, known as malocclusions, and aligning crooked teeth. A common source of confusion is whether the appliances only affect the position of the teeth or if they can also change the underlying jaw structure. The answer involves a clear distinction between moving individual teeth within the bone and altering the entire skeletal framework of the upper and lower jaws. While traditional braces are primarily designed for the former, the full scope of orthodontic treatment, often combined with specialized devices, can address both dental and skeletal alignment issues.
How Braces Facilitate Dental Alignment
Traditional fixed braces work by applying continuous, gentle force to guide teeth into new positions within the jawbone. This movement relies on bone remodeling, a biological mechanism occurring around the tooth root, which is held in its socket by the periodontal ligament (PDL).
When a brace exerts pressure, it compresses the PDL on one side of the root and stretches it on the opposite side. This triggers a cellular response involving osteoclasts, which break down alveolar bone tissue on the compressed side, and osteoblasts, which deposit new bone tissue on the tension side.
This slow process of bone resorption and deposition is why orthodontic adjustments are typically spaced several weeks apart. This mechanism, referred to as dental alignment, involves the tooth moving within its existing bone housing and is the primary function of standard braces.
Skeletal Correction: Moving the Jaw Structure
The movement achieved by traditional braces is limited to repositioning teeth within the alveolar bone; they do not change the size or relationship of the upper jaw (maxilla) and lower jaw (mandible). Correcting a skeletal malocclusion, where the jaws themselves are misaligned, requires specialized orthopedic appliances or surgical intervention.
Functional Appliances for Growing Patients
For growing patients, functional appliances modify jaw growth and change the relationship between the maxilla and the mandible. Devices like the Herbst, Twin Block, or Bionator work by posturing the lower jaw forward, harnessing natural growth to guide the bone structure into a harmonized position. Specialized devices, such as palatal expanders, can also physically widen the maxilla to address a narrow upper arch.
These non-brace tools apply forces directly to the bone plates, leading to changes in the overall facial structure. However, once skeletal growth has finished, these functional appliances are no longer effective for major jaw movement.
In adult patients with severe skeletal discrepancies, the only way to physically change the relationship of the jaws is through orthognathic surgery. This procedure involves repositioning the jaw bones and is often performed in conjunction with braces to align the teeth on the newly positioned jaws.
The Role of Patient Age
The feasibility of achieving skeletal correction depends entirely on the patient’s age and remaining growth potential. Non-surgical changes to the jaw structure are only possible in children and adolescents whose bones and growth plates are still actively developing. During this period, an orthodontist can use orthopedic appliances to redirect the direction or magnitude of the jaw’s natural development.
For example, a functional appliance can encourage the mandible to grow more forward in a growing patient with a recessed lower jaw. Once the adolescent growth spurt is complete and the bones have matured, major jaw repositioning without surgery is no longer an option.
While dental movement—the shifting of individual teeth within the bone—remains possible at any age, the rate of this movement is often slower in adults. Adult bone is denser and bone remodeling activity is less rapid compared to the developing bones of a young person.