Lower jaw surgery
The back of the lower jaw is split in the region of the wisdom teeth on both sides and under general anaesthesia. Dr Defrancq advises getting the wisdom teeth removed at least six months prior to this corrective surgery. An incision of two to three cm is made inside the mouth underneath and beyond your last molars. The bone is fixed in its new position by three screws on both sides, which are inserted through a tiny external skin incision located slightly anterior and inferior of the angle of the jaw. This stab incision is about two mm, to aid the screw driver. This stab incision heals without any noticeable scar. At the end of the operation, two tiny little drains are inserted into the gums to prevent swelling and after-bleeding. Those mini-drains are taken out the next day in the office. The tissues are stitched back in place with dissolvable stitches. The stitches can be taken out after one week. If they are not taken out, they take three to five weeks to dissolve.
The lower jaw can be too small or too long to fit the upper jaw. The lower jaw can then be lengthened (advanced), shortened (setback), or slightly rotated to adjust to the upper jaw and face.
The whole procedure is carried out in about 45 to 60 minutes. It permits the lower jaw to be advanced, pushed back, or rotated with adequate overlapping bone contact for healing.
Some setting of the bite is often mandatory after surgery. This is achieved with two elastic bands on brackets just to guide and set the bite.
The operation is frequently carried out together with upper jaw surgery (more than 40% of the cases). This is called a Bi-Maxillary Osteotomy (M&M). Bi-maxillary osteotomies take about two and a half hours to complete and may be carried out in conjunction with chin surgery (3/4h) or other adjunctive surgery as indicated.
Frequently asked questions
- Is it necessary to wire the jaws together?
No, not at all. The healing of the jaws goes through the screws and plates, which are necessary to keep the ‘voluntary fracture’ immobile. After surgery, some elastics can be used for a couple of weeks just to guide the occlusion. This is certainly the final tuning.
- What about postoperative facial swelling?
This is highly variable. During surgery, you are given intravenous steroids during the anaesthesia. The tendency for swelling varies from person to person. There is usually more swelling in younger patients. People with blond hair are more likely to experience swelling than people with dark hair. After one week, 1/3 of the swelling has gone, and after three weeks, at least 2/3 has gone. The mini-drains are put in place for this purpose and are removed the next day.
- Is it possible to speed up the swelling resorption?
Yes, it is. After a few days, you can apply a lymph drainage massage carried out by a specialised physiotherapist. This is even more helpful after a La Fort I.
- What about facial bruising?
Facial bruising is possible as well. Your face will gradually show all the colours of the rainbow, from blue to yellow, and by gravity it sinks from your face to your clavicle. However, this is nothing to worry about, since the yellow disappears completely in a couple of weeks.
- What about diet?
Patients require a light diet for some days. Spaghetti and hamburgers are possible after a few days. We recommend making a quality broth soup with meat. You can add mixed potatoes and vegetables to the soup. We advise you to eat small quantities, but frequently. The best is to eat six to eight small meals for the first few days, rather than just three times! The most important thing is to drink a lot of fluid, at least half a litre a day.
- Is there any sensory nerve damage?
The sensory nerve to the lower lip runs into the lower jaw in the region of the osteotomy bone cuts. During surgery, this nerve is always visible and protected. Following the surgery, all patients should expect some numbness of the lower lip, but this improves over a period of days, weeks, or months. About 5% of the patients experience some degree of permanent altered sensation. Younger patients are not particularly concerned about this. For older people this can be more cumbersome, since with ageing, sensibility becomes part of the overall self-image. However, it never leads to a disability and it is not a reason to renounce the surgery. The sensory nerve of the tongue lies close to the osteotomy cuts in the soft tissue and is retracted away from the operation site. Altered sensation associated with this traction is rare and usually temporary if it does occur.
- What about motor nerves?
A branch of the facial nerve innervates the mimic muscles of the face and lip. Injury to this facial nerve, which supplies movement of the lower lip muscles, has been reported. This may produce some weakness of the lower lip, which is more noticeable when the patient smiles. This is very exceptional and is hardly ever permanent. This is an extremely rare complication.
- What about relapse?
Long-term complications include relapse. It can be related to your age or type of mandible. Most relapses are unnoticed by the patient. It is uncommon for a relapse to affect the achieved cosmetic improvement adversely, but it can compromise the occlusion.
- What about elastics?
Some setting of the bite is often mandatory after surgery. This is usually achieved with two elastics on brackets, just to guide and set the bite.
- What about blood transfusion?
No blood transfusion is required.
- Is a hospital stay necessary?
Usually one night.
- Screw fixation or plate-screw fixation?
This is a matter of surgical preferences. The screw fixation goes through completely. The plates are usually fixed with mono-cortical screwing, so there is less risk of harm to the sensory nerve. However, this is merely a matter of habit. The plates often need to be removed after some months for a diversity of reasons, including infection and cumbersome discomfort. Plates are more difficult to install than bicortical screws.