Double jaw surgery, formally known as bimaxillary orthognathic surgery, corrects significant skeletal and functional discrepancies of the face. The decision to undergo this operation often stems from a need to address issues that cannot be resolved with orthodontics alone. Given the complexity of simultaneously operating on two major facial bones, patients naturally question the degree of risk involved. This article provides an objective assessment of the potential complications, separating the immediate surgical risks from the challenges encountered during recovery.
Understanding Double Jaw Surgery
Double jaw surgery repositions both the maxilla (upper jaw) and the mandible (lower jaw) during the same operation. This procedure achieves a proper dental bite (occlusion) and improves facial symmetry and functional capabilities. It is typically reserved for correcting severe skeletal imbalances, such as those causing a significant overbite, underbite, or facial asymmetry.
The surgical process involves distinct cuts, or osteotomies, for each jaw. For the maxilla, a LeFort I osteotomy is most commonly performed, separating the upper jaw from the base of the skull and allowing three-dimensional movement. The mandible is typically addressed with a Bilateral Sagittal Split Osteotomy (BSSO), which divides the bone lengthwise to allow the jaw to be advanced or set back.
These movements are necessary to correct functional problems like difficulty chewing, chronic temporomandibular joint (TMJ) pain, or severe obstructive sleep apnea. Once the jaws are moved into their planned position, they are stabilized using small titanium plates and screws. These provide rigid fixation to allow the bone segments to heal.
Immediate Surgical Risks and Complications
The most serious risks associated with double jaw surgery occur during the operation or immediately afterward. As with any major operation, complications related to general anesthesia exist, though they are rare in otherwise healthy patients. Advanced anesthetic monitoring and planning minimize this systemic risk.
Excessive bleeding (hemorrhage) is a specific concern because the jaw bones and surrounding soft tissues are highly vascularized. While modern techniques, including induced hypotensive anesthesia, help control blood loss, significant bleeding may necessitate a blood transfusion in a small percentage of cases. Damage to the neurovascular structures is another intraoperative risk.
Nerve injury is perhaps the most frequently discussed complication, particularly affecting the inferior alveolar nerve (IAN) in the lower jaw. This nerve provides sensation to the lower lip, chin, and gums. Temporary numbness or altered sensation, known as paresthesia, is extremely common following the BSSO procedure due to nerve stretching or bruising. Although sensation often returns gradually over several months, a persistent, complete loss of sensation in the chin area can occur in an estimated 10 to 20% of cases involving the IAN.
Infection at the surgical site is a risk following any procedure that involves cutting bone. An infection of the bone, known as osteomyelitis, is a rare but serious complication requiring aggressive antibiotic treatment and potentially the removal of the hardware. Less common risks include injury to adjacent tooth roots (approximately 0.19% chance) or aseptic necrosis, where a small segment of the upper jaw loses blood supply (around 0.2% chance). New or exacerbated jaw joint (TMJ) symptoms can sometimes develop post-operatively, even though the surgery is intended to correct underlying skeletal issues.
Navigating Post-Operative Recovery Challenges
Challenges during the recovery period involve the body’s ability to heal and maintain the new jaw position. Severe facial swelling and bruising are universal experiences, typically peaking within the first 48 hours following the procedure. Managing the swelling is paramount during this initial phase because a rapid increase can potentially compromise the patient’s airway, necessitating close monitoring.
Bone healing issues, specifically non-union or malunion, occur when the repositioned bone segments fail to fuse correctly or heal in the wrong position. Non-union, where the bone does not heal, is reported in a small percentage of cases (0.5% to 1%) and requires a second surgery. Relapse, the tendency for the jaw segments to shift back toward their original position, is a risk influenced by muscle memory and the direction of the bone movement.
Hardware-related problems, such as irritation from the titanium plates and screws, can manifest months after the surgery. In some patients, the hardware becomes palpable, causes discomfort, or becomes the site of a late-stage infection, requiring a separate procedure for removal. The reported rate for hardware removal ranges widely, from around 3.6% to over 27.5%, depending on the study and specific fixation method used.
Nutritional challenges are a significant aspect of recovery, as patients are restricted to a liquid or soft diet for several weeks to allow bone segments to stabilize. This restricted intake often leads to temporary weight loss, averaging around four kilograms. Strict adherence to the modified diet is necessary to prevent excessive force on the healing bone and to avoid damaging the surgical sites.
Patient Strategies for Minimizing Risk
The most significant step a patient can take to minimize surgical risk is the careful selection of an Oral and Maxillofacial Surgeon (OMFS) experienced in orthognathic procedures. A highly skilled surgeon’s expertise in meticulous pre-operative planning and advanced surgical techniques directly correlates with lower complication rates. Patients should inquire about the surgeon’s specific experience with double jaw cases.
Strict compliance with pre-operative instructions, such as smoking cessation, is important for optimizing the body’s healing capacity and reducing the risk of complications. Smoking significantly compromises blood flow, which is necessary for bone regeneration. Addressing any underlying health conditions before the operation further reduces systemic risks.
Following the operation, patient diligence is crucial for a successful outcome and involves adherence to a demanding post-operative regimen. This includes maintaining excellent oral hygiene, following the prescribed medication schedule for pain and infection, and strictly adhering to all dietary and physical activity restrictions. Consistent attendance at all scheduled follow-up appointments allows the surgical team to monitor the healing process and identify potential complications like relapse or infection at the earliest possible stage.