Orthognathic surgery, commonly known as jaw surgery, is a specialized procedure performed to correct irregularities of the jaw bones. This treatment addresses problems rooted in the size, shape, or position of the upper jaw (maxilla) and lower jaw (mandible). It is typically recommended when orthodontic treatments, such as braces or aligners, are insufficient to realign the bite due to a significant structural discrepancy. By surgically repositioning one or both jaws, the procedure aims to improve the function of the bite and the overall balance of the facial structure.
Addressing Severe Skeletal Alignment Issues
Jaw surgery is most frequently indicated for correcting severe skeletal malocclusion, which is a misalignment of the bite caused by a discrepancy in the jaw bones themselves. This condition is distinct from dental malocclusion, where the teeth are simply crowded or crooked but the underlying jaw structure is normal. When the jaw bones are disproportionate, the upper and lower teeth cannot meet correctly.
One common indication is a severe Class II malocclusion, often described as a significant overbite, where the lower jaw is underdeveloped or recessed relative to the upper jaw. This skeletal positioning causes the lower teeth to sit far behind the upper teeth, making biting and chewing difficult. The opposite, a Class III malocclusion, involves an underbite where the lower jaw protrudes excessively, often due to mandibular overgrowth or maxillary underdevelopment.
These skeletal discrepancies prevent proper meshing of the dental arches, which is necessary for efficient chewing and long-term dental health. Correcting a Class III malocclusion may involve moving the lower jaw backward, the upper jaw forward, or a combination of both. For a Class II correction, the surgeon typically uses a bilateral sagittal split osteotomy to advance the lower jaw into a balanced position. This skeletal repositioning creates a stable, functional occlusion that minimizes wear on the teeth and jaw joints.
Restoring Essential Functions Like Breathing and Eating
The physical positioning of the jaw bones impacts several life-sustaining functions, particularly breathing during sleep. An underdeveloped or recessed lower jaw can cause the tongue and associated soft tissues to collapse backward into the throat, leading to Obstructive Sleep Apnea (OSA). This condition causes repeated pauses in breathing, resulting in poor oxygen saturation and significant health risks.
For patients with moderate to severe OSA, Maxillomandibular Advancement (MMA) is often performed. This involves surgically moving both the upper and lower jaws forward, which physically pulls the soft palate, tongue base, and other airway structures. By repositioning the entire skeletal framework, the surgery permanently enlarges the posterior airway space, providing the most effective surgical treatment for OSA.
Jaw alignment also plays a direct role in eating and speaking. Severe discrepancies prevent proper mastication, or the grinding and shearing of food necessary for efficient digestion. For example, an open bite, where the front teeth do not overlap, makes it impossible to bite into food like sandwiches. Jaw surgery can significantly improve speech clarity by establishing the correct spatial relationship between the upper and lower dental arches, allowing for precise tongue and lip movements.
Repairing Damage from Trauma and Congenital Conditions
Beyond developmental growth issues, jaw surgery is frequently required to repair acute damage or correct structural abnormalities present from birth. Severe facial trauma, resulting from accidents or injuries, can cause complex fractures of the upper and lower jaw bones. Surgery is necessary to realign the fractured segments of bone and fix them in place with small plates and screws.
Restoring the pre-injury alignment is paramount to ensure the patient can regain normal biting and chewing function and maintain facial symmetry. This type of reconstructive maxillofacial surgery often involves multiple procedures to rebuild the bone structure and restore the integrity of the dental occlusion. The goal is to stabilize the jaw to allow for proper bone healing and prevent long-term functional deficits.
Congenital conditions also require surgical intervention to normalize function and form. Conditions such as cleft lip and palate often result in significant underdevelopment or asymmetry of the upper jaw (maxilla). Patients with certain craniofacial syndromes may also exhibit severe growth deficiencies or asymmetries of the mandible. Orthognathic and reconstructive procedures are employed to lengthen, widen, or reposition the jaw bones, establishing a functional bite and a more balanced facial structure.