Orthognathic Surgery

Understanding Orthognathic Surgery

Orthognathic surgery, commonly known as corrective jaw surgery, is a specialized dental and medical procedure performed to correct significant irregularities of the jaw bones and teeth. These irregularities often lead to functional problems such as difficulty chewing, speaking, or breathing, as well as aesthetic concerns. The term "orthognathic" derives from Greek words "orthos" (straight) and "gnathos" (jaw), accurately reflecting its purpose: to align the jaws properly. This complex intervention requires meticulous planning and a multidisciplinary approach, typically involving an oral and maxillofacial surgeon, an orthodontist, and the patient's general dentist.

The primary goal of orthognathic surgery is to achieve a harmonious and functional relationship between the maxilla (upper jaw), mandible (lower jaw), and the dentition. Unlike orthodontics alone, which repositions teeth within existing jaw structures, orthognathic surgery repositions the actual bone segments. This allows for correction of discrepancies that are too severe to be addressed by braces or other orthodontic appliances alone, establishing a stable occlusion and improving overall facial balance.

Indications and Candidacy

Candidates for orthognathic surgery typically present with skeletal malocclusions that manifest as significant discrepancies between the upper and lower jaws. These conditions are often developmental but can also result from trauma or congenital defects. Common indications include:

• Prognathism (Class III Malocclusion): Where the lower jaw protrudes significantly beyond the upper jaw, often resulting in an "underbite."
• Retrognathism (Class II Malocclusion): Where the lower jaw is set back relative to the upper jaw, leading to an "overbite" or recessed chin.
• Open Bite: A condition where the front teeth do not meet when the back teeth are together, making it difficult to incise food. This can be anterior (front teeth) or posterior (back teeth).
• Crossbite: Where the upper teeth sit inside the lower teeth, often unilaterally, affecting chewing efficiency.
• Facial Asymmetry: Significant imbalances in the facial structure due to disproportionate jaw growth.
• Sleep Apnea: In some cases, repositioning the jaws can open the airway and alleviate obstructive sleep apnea.
• Temporomandibular Joint (TMJ) Dysfunction: While not a primary treatment, some severe malocclusions contributing to TMJ pain may be addressed.

Comprehensive assessment involves clinical examination, dental models, photographs, and advanced imaging such as panoramic radiographs, cephalometric radiographs, and 3D cone-beam computed tomography (CBCT) scans. The planning phase also includes a psychological evaluation to ensure the patient has realistic expectations and a clear understanding of the process.

Surgical Procedures and Techniques

Orthognathic surgery encompasses several specific procedures, which can be performed on the upper jaw, lower jaw, or both, sometimes simultaneously. The choice of procedure depends on the specific skeletal deformity identified during the diagnostic phase. All incisions for these procedures are typically made inside the mouth, leaving no visible external scars.

• Lefort I Osteotomy: This procedure is used to correct issues with the upper jaw (maxilla). The surgeon makes an incision above the roots of the upper teeth, detaches the maxilla, and then repositions it. The maxilla can be moved forward, backward, upward, or downward, and sometimes rotated to correct asymmetries or open bites. Once repositioned, it is secured with small titanium plates and screws.
• Bilateral Sagittal Split Osteotomy (BSSO): This is the most common procedure for correcting lower jaw (mandible) discrepancies. Incisions are made on the inside of the cheeks, and the mandible is split sagittally (lengthwise) on both sides behind the molar teeth. The front segment containing the teeth is then moved forward or backward to achieve the desired occlusion and facial profile. Fixation is typically achieved with titanium screws and sometimes plates.
• Genioplasty: Often performed in conjunction with other orthognathic procedures, genioplasty reshapes the chin bone. This involves detaching a segment of the chin bone and repositioning it forward, backward, or vertically to enhance facial harmony and achieve a more balanced profile.
• Segmental Osteotomies: Less commonly, specific segments of the jaw containing only a few teeth may be moved to correct localized discrepancies.

Post-surgically, patients typically experience swelling, discomfort, and temporary numbness. A period of jaw immobilization or restricted movement, often involving elastics, is necessary to allow for bone healing and stabilization. Orthodontic treatment usually continues for several months after surgery to fine-tune the bite.

Patient Journey and Recovery

The patient journey through orthognathic surgery is a significant commitment that typically spans several years. It generally begins with a comprehensive orthodontic phase (pre-surgical orthodontics) to align the teeth within their respective jaws, ensuring they will fit together properly after the skeletal correction. This phase can last from 12 to 24 months.

Following surgical planning, the operation itself is performed under general anesthesia in a hospital setting. The immediate recovery period involves an overnight or several-day stay in the hospital, depending on the extent of the surgery. Pain management, swelling control, and nutritional support (often liquid or soft diet) are critical during this time.

Full recovery of sensation and function can take several weeks to months. Swelling gradually subsides over the first few weeks, though minor residual swelling can persist for several months. Numbness in the lips, chin, or cheeks is common temporarily, and in some cases, can be permanent, although this is less frequent. Patients gradually transition back to a normal diet and activities as advised by their surgeon. The final phase involves post-surgical orthodontics to refine the bite and ensure stability, followed by retention with retainers. Regular follow-up appointments with both the orthodontist and surgeon are essential to monitor progress and maintain the results.