Orthognathic surgery

Orthognathic surgery is surgery that corrects the position of the jaw bones —the upper jaw (maxilla), the lower jaw (mandible) or both— when they are not properly aligned with each other or with the rest of the skull. Its goals are both functional (bite, chewing, breathing) and aesthetic (balance of the profile and face). It is a core procedure of oral and maxillofacial surgery.

History

The first mandibular osteotomy is attributed to Simon Hullihen in the United States in 1849. The modern technique owes much to Hugo Obwegeser and Richard Trauner, who in 1957 described the sagittal split osteotomy of the mandibular ramus, still the reference technique for moving the lower jaw. In the following decades the Le Fort I osteotomy became standard for the upper jaw, as did operating on both jaws at once. In the 21st century, 3D virtual planning and custom guides and plates have greatly increased precision.

Indications

• Mandibular prognathism or class III (forward lower jaw or underdeveloped upper jaw).
• Retrognathia or class II (receding lower jaw and chin).
• Open bite: the front teeth do not meet when closing.
• Facial asymmetry of skeletal origin.
• Obstructive sleep apnoea in selected cases, by advancing both jaws.

It is performed once facial growth has finished and the skeletal discrepancy is too large to be corrected with orthodontics alone.

Techniques

• Le Fort I osteotomy: separates the upper jaw at the level of the nasal floor to advance, set back, raise, lower or rotate it.
• Sagittal split osteotomy: splits the mandibular ramus to advance, set back or rotate the lower jaw.
• Bimaxillary surgery: combines both.
• Bony genioplasty: adjusts the position of the chin and is often added.

The bones are fixed with titanium mini-plates and screws, and all incisions are inside the mouth. Treatment is always coordinated with the orthodontist, who prepares the teeth before surgery and fine-tunes the bite afterwards.

Risks and complications

The most common issue is altered sensation in the lower lip and chin, due to the proximity of the inferior alveolar nerve, which usually recovers within months. Other possible complications include bleeding, infection, temporomandibular joint discomfort, partial relapse (the bones tend to move slightly back towards their original position) and the need for later adjustments.

Recovery and results

It requires one or two days in hospital. Swelling is significant for the first two or three weeks, and a liquid and then soft diet is followed for several weeks. The final result is seen at six to twelve months, once post-operative orthodontics is complete, and it is permanent.