What is Orthognathic Jaw Surgery?

Treatments & Care

22 September 2021

Two surgeons holding up an xray of a patient’s jaw to assess them for jaw surgery.

Some orthodontic patients require a combination of orthodontics and jaw surgery to gain the best outcome for their bite, jaw position and facial appearance. The jaw surgery may involve repositioning the upper or lower jaw or both simultaneously. The upper jaw may also be expanded and the chin shape and position may also be modified.

Why Would You Need Orthognathic Surgery?

Some bite problems are due to significant differences in the upper and lower jaw positions. In patients with severe underbite, overbite or cross bite, the amount of orthodontic tooth movement needed to get the teeth to fit may be beyond the range of safe tooth movement. It could also leave the individual with a poor appearance due to lip flattening, or excessive or deficient jaw protrusion. Some people born with a cleft lip and palate, or deformities related to injury or uneven growth of the left and right side of the jaw may choose to have jaw surgery. For others, jaw surgery is used to improve breathing problems such as sleep apnoea and make biting and chewing easier.

What is Involved in Jaw Surgery?

The surgery is performed by an oral and maxillofacial oral surgeon. The planning of the surgery usually involves joint input from the surgeon and the orthodontist to ensure the best cosmetic outcome is achieved in addition to a good bite. Orthodontic appliances are often used to align teeth in preparation for surgery and fit the teeth in their best possible position for after the surgery. Depending on the type of jaw correction, the surgery may be performed early in the course of orthodontic appliance treatment or well through the orthodontic course. During the planning stage, 3D x-rays and photographs are taken and software is used to construct sophisticated surgical guides and titanium fixation plates to hold the jaws in the desired positions. Moreover, this software assists the clinicians in predicting how a patient’s face will look after surgery.

Patients are placed under a general anaesthetic for the surgery which can take up to three to five hours. Most of the incisions are made inside the mouth to avoid facial scarring. Tiny screws (smaller than the size of a bracket for braces) and custom printed titanium plates are used to hold the jawbone in place and reduce the pain from moving around immediately after surgery. In some cases, extra bone transferred from the hip, rib, lower jaw or chin may be required to assist in repositioning the jaw.

There are different forms of jaw surgery. The main forms of surgery include maxillary osteotomy, mandibular osteotomy, bimaxillary osteotomy and genioplasty.

Maxillary Osteotomy

Surgery undertaken on the upper jaw to improve:

An upper jaw that protrudes or recedes
Tooth display at rest and during smiling when the upper jaw is too short and people do not show their teeth
A gummy smile by reducing the height of the upper jaw
An open bite when the molars interfere in the bite preventing the front teeth from meeting
A crossbite when the bottom teeth sit further out than the top teeth and the upper jaw is expanded

The surgeon makes an incision in the gums above the upper teeth then cuts into the bone of the upper jaw so that it can be moved to align with the bottom jaw.

Mandibular Osteotomy

This surgery is performed on the lower jaw that may either protrude or recede. The incision is made behind the molars and the bone of the lower jaw is moved forward or back and held in place with plates or screws.

Bimaxillary Osteotomy

This form of surgery involves both the top and bottom jaws. The same processes are used as the maxillary and mandibular osteotomy surgeries. This surgery is needed when a more complex rearrangement in the jaw positions are required, including bringing both jaws forward to improve sleep apnea.

Genioplasty

Genioplasty surgery involves correcting deformities of the chin such as a weak, strong, long or asymmetrical chin. An incision is made in the gums to cut into the chin bone and move it to a new position. Printed titanium plates or screws hold the bone in position.

After any type of jaw surgery, patients will usually stay in hospital for two to five nights, depending on the complexity of the surgery. They take antibiotics to reduce the risk of an infection, and receive advice on how to care for the incisions and what to eat during their recovery. A liquid diet is needed for the first few days after surgery to allow the stitches to heal and the jawbone to recover.

What are the Risks Involved with Jaw Surgery?

Jaw surgery is generally safe but like any type of surgery, there are risks involved.

Pain

Everyone has a different pain threshold, but most patients need strong pain medications for the first two or three days post-surgery. For the week following, over the counter pain medication is usually needed to reduce the discomfort.

Movement of the Jaw

Most patients will have a reduced range of movement of the lower jaw in the first few weeks after surgery. Within three months, the majority of patients will regain their pre-surgical mobility. However, in some individuals this may take up to a year. Most patients are guided through home exercises to make it easier to return to normal function but on rare occasions, a referral to a physiotherapist may need to be considered.

Bleeding

In the first day or two after surgery, there is a risk of bleeding. Keeping the head raised on pillows and not rinsing the mouth too vigorously reduces the risks.

Swelling and Bruising

As with most surgery, swelling and bruising of the area is to be expected. The most swelling usually occurs two days after surgery then slowly subsides, however it can take four weeks for all swelling and bruising to disappear.

The swelling can make it difficult to open the mouth properly. But also, the elastic bands between the teeth supporting the lower jaw and moving it into the desired position will restrict movement in the face and jaw in the short term.

Nerve Damage

Some people will experience temporary numbness or altered sensation around the lips and chin, while a very small number may experience nerve damage. During surgery, nerves may be stretched or moved which can affect sensation in the lips, cheeks, chin and palate. The majority of patients recover full sensation with time. Patients over the age of 40 are more likely to be affected.

Sinus

The nasal sinus is usually affected for a few weeks following surgery on the upper jaw, but usually returns to normal function within a few months. Individuals with long standing sinus problems may take longer to recover sound sinus health.