Orthognathic surgery (orthognathic surgery) is the surgical correction of the position, shape or size of the upper and/or the lower jaws.

Problems which can be corrected with orthognathic surgery include jaws that are too large, too small, too far forward, too far back or crooked (asymmetric).

These problems include:

• Mandibular retrognothia (lower jaw too short) – This results in the lower teeth being too far behind the upper teeth.
• Mandibular prognothia (lower jaw too low) – This results in the lower teeth being too far forward of the upper teeth.
• Maxillary retrognothia (upper jaw too far back).
• Maxillary prognothia (upper jaw too far forward).
• Vertical maxillary excess (upper jaw too tall vertically with excessive display of upper tooth and gum below the upper lip).
• Vertical maxillary deficiency (upper jaw too short vertically with little upper tooth displayed below the upper lip).
• Transverse maxillary deficiency (upper jaw too narrow, leading to dental cross-bite).
• Transverse maxillary excess (upper jaw too wide, leading to dental scissors-bite).
• Anterior open bite (vertical open bite between the upper and lower front teeth, making incising food and chewing difficult or impossible).
• Posterior open bite (vertical open bite between the upper and lower back teeth, making chewing in this region impossible).
• Facial and jaw asymmetry, including deviation of the dental and jaw midlines to one side and/or tilting of the occlusal (bite) plane up or down on one side.
• Orthognathic surgery is also an effective treatment for snoring and obstructive sleep apnoea, by moving the lower and/or the upper jaw forward to improve the pharyngeal (throat) airway.

Disharmony of the jaw position is most often associated with dental malocclusion (the teeth are not in the correct position and do not meet correctly).

Symptoms and Signs

Symptoms and signs which might indicate a need for orthognathic surgery include:

• Difficulty biting or chewing food
• Difficulty with speech (for example, a lisp)
• Receding jaw or chin
• Protruding jaw or chin
• Jaw pain
• Facial or jaw asymmetry
• Open bite (space between the upper and lower front or back teeth when the mouth is closed)
• Difficulty getting the upper and lower lips together without muscular effort
• Chronic mouth breathing with dry mouth and inflamed gums
• Snoring or obstructive sleep apnoea

Diagnosis

A careful examination and assessment of the face, temporomandibular joints, mouth and teeth is carried out.  This is supplemented with clinical photographs, x-rays and plaster models of the teeth.  Computer aided analysis of these records is carried out and this leads to the production of a provisional treatment plan.

Treatment

Treatment almost always consists of a combination of orthodontic treatment, carried out by a specialist orthodontist, and orthognathic surgery, carried out by a specialist oral & maxillofacial surgeon.

Staging of Treatment

The treatment usually proceeds in stages:

1. Pre-surgical orthodontic treatment

• Usually fixed orthodontic braces on the upper and lower teeth.
• Sometimes it is necessary to remove teeth to allow the orthodontic treatment objective to be achieved.
• It may be necessary to remove impacted wisdom teeth at this stage.
• The orthodontist aligns the teeth so that the orthognathic surgery can be carried out accurately and the teeth meet in the correct position following surgery.
• This phase of treatment usually takes between 9 and 18 months, but depending on the circumstances, this can be shorter or longer.

2. Orthognathic surgery

• Surgery is carried out with the braces still on the teeth.
• Prior to surgery, the surgeon simulates the surgery on computer to formulate the correct treatment plan, and carries out mock surgery on plaster models of the patient’s teeth. Templates are constructed to allow two jaws to be positioned correctly at the time of surgery.
• Surgery is carried out under general anaesthetic in hospital in a fully equipped operating theatre.  The hospital staff are very experienced at looking after jaw surgery patients.
• Options for orthognathic surgery are discussed carefully with the patient before the surgical treatment plan is approved. Options include:

a) Surgery to lengthen the lower jaw
b) Surgery to shorten the lower jaw
c) Surgery to reposition the chin
d) Surgery to reposition the upper jaw
e) Surgery to re-shape the upper jaw
f) Sometimes it is necessary to consider bone grafting the surgical sites, especially in the upper jaw.

• At surgery the bones are held together with titanium mini plates and screws.    Following surgery it is usual to spend one, two or three post-operative nights in hospital before being allowed home.

3. Post-Surgical orthodontic treatment

• Following the surgery, the orthodontic treatment is continued so that the correct occlusion (bite) is achieved.  This phase of treatment usually takes between 3 and 9 months, but can take longer in certain circumstances.  Following the removal of the braces, the orthodontist will provide retainers, which must be worn according to the orthodontist’s instructions.

Diet

For the first few days after the surgery, a puree diet is required. Following this soft food may be consumed until 6 weeks after surgery, following which a normal diet is gradually resumed.  Diet information is provided close to the time of surgery.

Swelling

It is usual to experience swelling and bruising following surgery.  The maximum swelling is usually about 48 hours after surgery and resolves over several weeks.

Pain

Post-operative pain is usually well controlled with non sterioid analgesics and Paraecetemol.

Strong analgesics are available but are usually not needed.

Return to Normal Activity

• It is usual to require two to four weeks following surgery to convalesce before returning to normal activities.
• After single jaw surgery (upper or lower), return to school or work can often be contemplated after one to two weeks, with two jaw surgery (upper and lower jaws) two to three weeks is more usual.
• Contact sport should be avoided for up to three months following surgery.