Planning for Bi-Jaw Surgery

Preoperative surgical planning is the key to successful surgery

A) Investigations

• 3D CT scan of the face
• Frontal and lateral photos of the face
• Cephalometric X-Ray of the face for soft tissue and bony measurements.
• Dental impressions are obtained to aid in formulating a diagnosis.

Out of all the mentioned investigations, Cephalometric X-rays are very important as it reveals abnormal growth patterns of the upper and lower jaws about the cranial base.

B) Analysis

Then a detailed analysis of the skeletal, dental, and soft tissue findings is done by Dr. Amit Agarwal and the orthodontist. Dental models are made and a mock surgery is done and acrylic occlusal splints are fabricated. These occlusal splints are used intraoperatively to accurately reposition the osteotomized maxilla.

C) Presurgical Orthodontic Treatment

In many cases, pre-surgical orthodontic treatment for about 7 to 10 months is required, which may be continued after the surgery depending on the case requirement.

16 Steps for Surgical Procedure of Bi-Jaw Surgery

• This procedure is performed under general anesthesia with nasal endotracheal intubation. Local anesthesia (lidocaine 1% with 1:100,000 epinephrine) is also used to decrease blood loss.
• The incision is made inside the mouth to prevent visible scars on the face. One jaw is repositioned at a time during the surgery.
• In case of a jaw enlargement, a bone graft may be placed between the cut ends of the bone fragments to increase the size of the jaw and in case of a jaw reduction, some part of the bone may be removed.
• Titanium screws & plates are used to hold the jaws in position. Elastic bands and wires are as well used to keep the jaws in position.
• It is the surgeon's preference to decide whether the upper jaw needs to be worked upon first or the lower jaw. Dr. Amit Agarwal prefers to do BSSO first and then Lefort osteotomy.

Bilateral Sagittal Split Osteotomy (BSSO)

The surgeon makes cuts behind the last molar teeth diagonally and lengthwise down the jawbone so the front of the jaw can move as one unit.

• The cuts are made on the sides-right and left. 'Osteotomes' which are the separators, are used to split the jaw through these cut edges.
• To establish an improved bite, the protruding jaw can be moved backward or a retruded lower jaw can be moved forward.
• Therefore, once the jaws are separated, the lower jaw can be moved to its corrected position and fixed through screws & plates, with intraoral wiring done on the teeth for better positioning of the lower jaw in proper occlusion/bite.
• The incision is closed in layers with absorbable sutures

For LeFort Osteotomy

The upper jaw is cut above the level of the tooth roots & separated from the skull and facial bone.

• A lot of care is taken to know the location of the apices of the tooth and the pterygoid plates posteriorly while cutting.
• Proper clinical examination & X-rays are required to prevent damage to the teeth due to the maxillary separation.
• Temporary inter-maxillary fixation with elastics is done over pre-surgically made occlusion wafers.
• The surgically moved maxilla is fixed with the native bones of the face with the help of plates and screws and the incision is closed in layers with absorbable sutures.
• The jaws are not wired & shut for long, and the bone segments are fixed rigidly.

Risks and Complications of Bi-Jaw Surgery

Bi-Jaw/ Bi-Max surgery is a safe and reliable surgery but can lead to a few complications which are described below-

• Bleeding.
• Infective complications such as Abscess formation
• Anterior open bite in the early or late postoperative period
• Dental and periodontal injuries
• Oro nasal fistula
• Partial or total nerve injury to the infraorbital nerve with sensory loss to the upper lip, cheeks, and nose
• Alterations in the appearance of the face including widening of alar bases and changes in nasal tip position.
• Increased nasal airway resistance due to constriction of internal nasal valve with maxillary superior repositioning
• Pain and congestion with rare infections leading to maxillary sinusitis
• Non-union of bony segments
• Unfavorable fractures of the upper or lower jaw.
• Partial or total nerve injury to the inferior alveolar nerve with sensory loss to the lower lip and teeth
• TMJ dysfunction or condylar malposition
• Malocclusion- If the aetiology of the malocclusion is related to improper placement of the maxilla, failed hardware, or condylar malposition, revision surgery is indicated.
• Retraction of the gingiva.
• Rarest complication of Necrosis of the maxilla, unilateral blindness and Occulomotor nerve palsy.