Orthognathic Surgery

Orthognathic surgery is an operation that corrects the position of the jaws when the upper and lower jaw do not match each other or the face. The name comes from the Greek "ortho" (straight) and "gnathos" (jaw). It is also known as corrective jaw surgery.

Crowded teeth can be corrected with braces (orthodontics). But if the problem is not in the teeth but in the jawbones themselves — for example, when the lower jaw is too far forward or back relative to the upper jaw — braces alone are not enough. In that case the jawbones are moved into the right position surgically, and the final fit of the teeth is achieved with orthodontics. This is why orthognathic surgery is a treatment carried out jointly by an oral and maxillofacial surgeon and an orthodontist.

The operation is done both for function (biting, chewing, speech and sometimes breathing) and for facial balance. In most patients, both improve together.

Patients usually come either because they notice something about their profile or because of problems with chewing and biting. The main situations are:

• Lower jaw too far forward: The lower teeth close in front of the upper teeth and the chin is prominent in profile.
• Lower jaw too far back: The chin is set back and the profile looks "chinless"; some patients also snore and stop breathing during sleep.
• Open bite: When the teeth are closed, the front teeth do not touch; biting into food is difficult.
• Jaw asymmetry: The chin is shifted to one side and the face looks asymmetric from the front.
• Vertical problems: Too much gum showing when smiling, or a lower face that is too short or too long.
• Obstructive sleep apnoea: In suitable patients, moving the jaws forward is considered as an option to widen the airway.
• Jaw growth problems after cleft lip and palate.

Even without a clear difference in appearance, the jaw structure may be the cause in patients with chewing and biting problems.

Orthognathic surgery is usually done after jaw growth has finished. An operation done while the jaw is still growing can be undone by later growth. Jaw growth usually finishes earlier in girls than in boys; the timing is decided with X-rays and growth monitoring. There is no upper age limit; general health is what matters.

Because general anaesthesia is needed, heart, lung and bleeding conditions, medicines and smoking are assessed before treatment. Because the treatment is long and runs alongside orthodontics, it is important to discuss your expectations about the process from the start.

1. Assessment. The face is examined from the front and in profile: facial proportions, midline, asymmetry, lips, nose and chin. Facial photographs, skull X-rays and a 3D CT scan are taken; the bite and the jaw joints are assessed.
2. Pre-surgical orthodontics. The teeth are aligned with braces so that they will meet correctly once the jaws are in their new position. This stage usually takes 12–18 months. During this time the bite may temporarily look worse; this is part of the plan.
3. 3D virtual planning. The CT scan and an intraoral scan are combined on a computer. How many millimetres and in which direction the jaws will move is planned on screen, and the result can be previewed. From this plan, custom surgical splints are produced to help position the jaws as planned during surgery.
4. Surgery. It is done under general anaesthesia from inside the mouth; there are no incisions on the face. The jawbones are separated along planned lines, moved to their new position and fixed with small titanium plates and screws.
5. Hospital stay and early recovery. After the operation you are monitored in hospital for a short time. In the first weeks: a liquid and soft diet, regular check-ups and, if needed, elastics attached to the teeth to guide the bite.
6. Post-surgical orthodontics. Once the bones have healed, the teeth are fine-tuned with braces; this usually takes from a few months to a year. After the braces are removed, retainers are used to maintain the result.

The extent of the operation depends on the source of the problem:

• Upper jaw surgery: The upper jawbone is separated and moved forward, back, up or down. It is used for too much gum showing when smiling, open bite and a set-back upper jaw.
• Lower jaw surgery: The lower jaw is separated at its back sections and moved forward or back.
• Double jaw surgery: In many patients both jaws are involved, so the upper and lower jaw are corrected in the same operation.
• Chin surgery (genioplasty): The chin bone is moved forward, back or sideways to reshape it. It can be done alone or together with other operations.

In conventional planning, jaw movements are calculated on plaster models. In 3D virtual planning, bone, teeth and soft tissues are seen together on a computer. Complex situations such as asymmetry can be assessed in more detail in three dimensions, the match between the planned movement and the operation is strengthened, and the likely result can be discussed with the patient before surgery. The on-screen simulation shows a target; the final appearance of the soft tissues can vary from person to person.

Orthognathic surgery is a major operation and its risks should be known in advance:

• Swelling and bruising: This is expected; it is greatest in the first days, most of it goes within a few weeks, and mild swelling can continue to fade for months.
• Numbness: Numbness of the lower lip and chin after lower jaw surgery, and of the upper lip and palate after upper jaw surgery, is common. In most patients it improves markedly within months; in some, partial numbness can be permanent.
• Relapse: The jaws moving back a little towards their old position over time. Post-surgical orthodontics and check-ups are important to monitor this.
• Infection, bleeding or problems with the plates and screws; rarely, the plates need to be removed
• Temporary nasal congestion after upper jaw surgery
• Changes in jaw joint symptoms
• Risks related to general anaesthesia

Some of these risks are reduced by careful planning, good coordination between the surgical and orthodontic team and following the instructions during recovery. The risks specific to you are discussed in detail at the examination.

• First 2–3 days. Swelling is at its greatest. Cold compresses, rest with your head raised, the recommended medicines. A liquid diet. After upper jaw surgery, avoid blowing your nose.
• First 2 weeks. Swelling and bruising go down markedly. The diet stays liquid or puréed, and oral care follows the instructions. For most patients, returning to desk work or school can be planned towards the end of this period.
• 6–8 weeks. Much of the bone healing is complete. On your surgeon's advice you move on to soft solid foods; avoid heavy sports and activities with a risk of impact.
• The following months. Remaining swelling fades, sensation slowly returns and the bite takes its final form with post-surgical orthodontics.