Bi-Jaw Surgery (Double Jaw Surgery)

Bi-Jaw Surgery, also known as Double Jaw Surgery or BIMAX Jaw Surgery, is a type of orthognathic surgery that addresses jaw abnormalities involving both the upper (maxilla) and lower (mandible) jaws. This procedure aims to correct issues related to jaw alignment, shape, and function, and it can be performed for cosmetic or functional reasons. Bi-Jaw Surgery involves cutting both the upper and lower jaws and repositioning them as needed, either forward or backward, to achieve improved facial balance and function.

Bi-Jaw Surgery is recommended when cases involve complex jaw abnormalities that cannot be adequately corrected with single-jaw procedures like LeFort Osteotomy or Bilateral Sagittal Split Osteotomy (BSSO). Common situations where Bi-Jaw Surgery is needed include:

1. Severe malalignment of both the upper and lower jaws.
2. Correction of issues like deep bite, underbite, open bite, overlapping jaws, and asymmetrical jaws.
3. Misaligned teeth due to incorrect jaw size or position.
4. Severe temporomandibular joint ( TMJ ) disorders with impaired jaw function.
5. Moderate to severe obstructive sleep apnea.
6. Gummy smile caused by an underdeveloped mandible.
7. Severe maxillary (upper jaw) underdevelopment is often seen in congenital deformities like cleft lip and palate.
8. Cases requiring a comprehensive approach to correct both aesthetic and functional skeletal issues.
9. Bi-Jaw Surgery is often combined with chin surgery or genioplasty for improved facial aesthetics.

It is essential to confirm that skeletal growth is complete in both boys and girls before performing orthognathic surgery, typically around 15 to 16 years in girls and 17 to 18 years in boys. Keep in mind that upper jaw (maxillary) growth usually ceases about two years before lower jaw (mandibular) growth is completed.

Successful Bi-Jaw Surgery relies on thorough preoperative planning, which includes several investigations such as:

1. 3D CT scan of the face.
2. Frontal and lateral photos of the face.
3. Cephalometric X-ray of the face for soft tissue and bony measurements.

Dental impressions to aid in diagnosis.

1. Cephalometric X-rays are particularly crucial as they reveal abnormal growth patterns of the upper and lower jaws concerning the cranial base. Following these investigations, a detailed analysis of skeletal, dental, and soft tissue findings is conducted. Dental models are created, and mock surgery is performed to fabricate acrylic occlusal splints used intraoperatively for precise repositioning of the maxilla.

In many cases, patients may require pre-surgical orthodontic treatment lasting approximately 7 to 10 months. This treatment may continue after the surgery, depending on the individual case’s requirements.

Several factors and conditions may contraindicate Bi-Jaw Surgery, including:

1. Major medical comorbidities.
2. Cardiac diseases.
3. Presence of active dental infections.
4. Patients in the active growth phase.
5. Psychiatric diseases or uncontrolled seizure disorders.
6. Significant disparities between patient and surgeon goals and expectations.
7. Smoking or substance abuse habits.
8. Questionable blood supply to the maxilla and mandible, as seen in patients who have undergone multiple surgeries (e.g., cleft palate) or have a history of radiation therapy.

The surgical procedure of Bi-Jaw Surgery typically involves the following steps:

1. Anesthesia: The procedure is performed under general anesthesia with nasal endotracheal intubation.
2. Local anesthesia with lidocaine and epinephrine may also be used to minimize blood loss.
3. Intraoral Incision: Incisions are made inside the mouth to avoid visible facial scars.
4. One jaw is repositioned at a time during the surgery.
5. Jaw Repositioning: Depending on the patient’s needs, one or both jaws are repositioned, either brought forward or backward.
6. Bone grafts may be used to enlarge the jaw or parts of the bone may be removed for reduction.
7. Fixation: Titanium screws and plates are used to securely hold the repositioned jaws in place.
8. Elastic bands and wires may also be used for stabilization.
9. Sequence: The surgeon decides whether to work on the upper jaw (maxilla) or lower jaw (mandible) first.
10. The sequence can vary among surgeons, but it’s commonly preferred to perform BSSO first and then LeFort osteotomy for upper jaw correction.
11. Bilateral Sagittal Split Osteotomy (BSSO) : For BSSO, the surgeon makes cuts behind the last molar teeth diagonally and lengthwise down the jawbone, allowing the front of the jaw to move as one unit.
12. LeFort Osteotomy : For LeFort Osteotomy, the upper jaw is cut above the level of the tooth roots, separated from the skull and facial bones, and carefully positioned.
13. Care is taken to avoid damage to teeth during the separation.
14. Fixation of Maxilla: The surgically moved maxilla is fixed to the native facial bones using plates and screws.
15. Closure: Incisions inside the mouth are closed in layers using absorbable sutures.
16. Stabilization: The jaws are not wired shut for extended periods; instead, bone segments are fixed rigidly.

The recovery period for Bi-Jaw Surgery typically includes:

1. Overnight monitoring in the post-operative recovery room.
2. Common postoperative side effects include facial swelling and bruising, which usually subside within a week. Ice packs may be used to minimize swelling.
3. The patient is typically discharged from the hospital after 3 to 4 days and instructed to follow up after a week.
4. Early postoperative occlusal changes may occur due to edema and muscle adaptation.
5. A strict postoperative regimen is advised, along with thorough oral hygiene practices, including the use of a soft toothbrush and antibacterial mouth rinse.

To promote faster recovery after Bi-Jaw Surgery, the following measures are often recommended:

1. Soft diet for 4 to 6 weeks, starting with liquids for about a week.
2. One-week antibiotic treatment.
3. Placement of soft elastics between the upper and lower jaws to maintain the upper jaw’s new position.
4. Patients are instructed to avoid forceful nose blowing for three weeks.

Orthodontists play a critical role in Bi-Jaw Surgery, both before and after the procedure. Pre-surgical orthodontic treatment may be necessary for several months, and post-surgical orthodontics aims to ensure that the teeth settle into their final occlusion. The duration of postoperative orthodontic treatment varies based on individual cases, surgical plans, and desired occlusal outcomes.

While Bi-Jaw Surgery is generally considered safe and reliable, there are potential complications, which may include:

1. Bleeding.
2. Infective complications such as abscess formation.
3. Anterior open bite in the early or late postoperative period.
4. Dental and periodontal injuries.
5. Oro nasal fistula.
6. Partial or total nerve injury to the infraorbital nerve, leading to sensory loss in the upper lip , cheeks, and nose.
7. Alterations in facial appearance, including changes in nasal tip position and widening of alar bases.
8. Increased nasal airway resistance due to the constriction of the internal nasal valve with maxillary superior repositioning.
9. Pain and congestion, with rare infections leading to maxillary sinusitis.
10. Non-union of bony segments.
11. Unfavorable fractures of the upper or lower jaw.
12. Partial or total nerve injury to the inferior alveolar nerve, resulting in sensory loss in the lower lip and teeth.
13. Temporomandibular joint (TMJ) dysfunction or condylar malposition.
14. Malocclusion: If malocclusion results from improper placement of the maxilla, hardware failure, or condylar malposition, revision surgery may be necessary.
15. Retraction of the gingiva.
16. Rare complications, such as maxillary necrosis, unilateral blindness, and oculomotor nerve palsy, may occur.

Patients considering Bi-Jaw Surgery should undergo a thorough evaluation by Dr. Amit to discuss potential risks and benefits specific to their individual circumstances.