Mandibular asymmetry is a condition where the two sides of the lower jaw, or mandible, are not mirror images of each other. This imbalance can affect facial appearance as well as functions like speaking and chewing. While minor facial asymmetry is common, more significant imbalances can lead to functional and aesthetic concerns that require correction. Addressing these issues involves a coordinated approach of both orthodontics and surgery to restore balance.
Evaluating the Need for Surgical Correction
Mandibular asymmetry can stem from developmental or genetic factors where one side of the jaw grows differently than the other. Examples include hemifacial microsomia (underdevelopment) and unilateral condylar hyperplasia (overgrowth). Acquired causes include facial trauma or degenerative joint diseases like osteoarthritis that alter the jaw’s structure.
A misaligned jaw can lead to functional problems such as an improper bite (malocclusion), which causes inefficient chewing and premature tooth wear. Other issues include temporomandibular joint (TMJ) pain, clicking sounds, and difficulty with speech. Aesthetically, a deviated chin or uneven jawline can disrupt facial harmony and be a source of concern.
Determining if surgery is the right solution is a collaborative effort between an oral and maxillofacial surgeon and an orthodontist. The evaluation begins with a clinical examination of the face and jaw. Advanced imaging, such as panoramic X-rays and three-dimensional (3D) CT scans, provides a precise map of the underlying skeletal structure. These tools allow the clinical team to measure the exact degree of asymmetry and confirm if surgical correction is the necessary path forward.
The Orthognathic Surgical Procedure
Surgical correction of mandibular asymmetry is a type of orthognathic surgery performed by an oral and maxillofacial surgeon. The most common technique is the Bilateral Sagittal Split Osteotomy (BSSO). This approach allows the surgeon to move the jaw forward, backward, or rotationally to achieve a symmetrical position.
During the BSSO procedure, the surgeon makes incisions through the bone of the lower jaw on both sides. These cuts are made behind the molars, running down toward the lower edge of the jawbone. This technique allows the tooth-bearing portion of the mandible to be separated from the jaw joint and base. The central segment can then be repositioned into its planned, symmetrical alignment with the upper jaw.
The entire procedure is performed from inside the mouth to minimize visible scarring. Once the jaw is in its corrected position, it is stabilized with small, medical-grade titanium plates and screws. These permanent fixtures hold the bone segments together, providing the stability needed for the bone to mend.
In cases of significant asymmetry, other procedures may be performed simultaneously. A genioplasty can reshape or reposition an asymmetric chin. If the upper jaw (maxilla) is also misaligned, a Le Fort I osteotomy might be performed to reposition it, addressing the entire facial structure for a more balanced result.
The Patient Journey: Preparation and Recovery
The process begins with pre-surgical orthodontics, which involves wearing braces for 12 to 18 months. An orthodontist aligns the teeth within each jaw, removing dental compensations the body made to accommodate the asymmetry. This step ensures the upper and lower teeth will fit together correctly after surgery.
After surgery, a hospital stay of one to two days is required for monitoring. The first few days at home involve significant facial swelling, which peaks around the third day. Pain is managed with prescribed medication, and patients receive instructions on caring for the surgical sites to prevent infection.
Dietary modification is a key part of recovery. For the first several weeks, a liquid diet is necessary to avoid putting any pressure on the newly positioned jaw. This gradually transitions to a soft, non-chew diet that may include items like mashed potatoes, yogurt, and smoothies. This restriction can last for six to eight weeks as the jawbone heals, during which time strenuous exercise must be avoided.
Patients use special mouth rinses and a soft toothbrush to maintain oral hygiene without disturbing the incisions. Regular follow-up appointments with the surgeon monitor healing. Most patients return to school or work within two to four weeks, though full functional recovery takes several months.
Expected Functional and Aesthetic Results
Successful surgery provides significant functional and aesthetic improvements. Functionally, establishing a correct bite makes chewing more efficient and comfortable, reducing strain on the teeth. Many patients experience a resolution of jaw joint pain, clicking, and other TMJ symptoms.
Aesthetically, correcting the skeletal imbalance creates a more symmetric lower face. The surgery centers a deviated chin, balances the jawline, and improves the overall facial profile. These changes can have a positive impact on a patient’s self-esteem.
Maintaining the outcome requires a final phase of post-surgical orthodontics. This involves several more months in braces to fine-tune the bite. After the braces are removed, lifelong wear of retainers at night is necessary to prevent teeth from shifting and to preserve the corrected jaw alignment.