Two Jaw Surgery : Bimaxillary Osteotomy

It is very common for patients to require both upper and lower jaw surgery done together. If so, they are done in the one operation.


Why is 2 jaw surgery or bimaxillary surgery done?

Sometimes it is not possible to correct the bite or facial problems in the one jaw. If the bite discrepancy is large, it is often more stable to divide the movements between the 2 jaws. In addition, by reducing the amount of movement or change required per jaw this may result in less excessive or unfavourable facial or soft tissue changes. Sometimes, one jaw is asymmetric while the other jaw has a length problem, and in order to have a more pleasing face, the problems need to be corrected in both jaws. Each patient is different and will require a specialized design or treatment plan. Dr Lim will assess and design the surgery depending on bite and face. Sometimes one jaw surgery is all that is required and other times, 2 jaw surgery may be needed. If 2 jaw surgery is required, they are done in the one operation. Occasionally, a 2 Stage Approach may be needed. Sometimes an upper jaw expansion surgery called “Surgically Assisted Rapid Maxillary Expansion” may be required followed by 12 months orthodontics , then bimaxillary surgery as a second stage procedure. 


What is involved in the planning of jaw surgery?

At initial consultation Dr Lim will clinically assess the bite and face together with x-rays and plaster models of the teeth to arrive at a facial plan.

Surgical Work-up

At the surgical work-up appointment, a few weeks prior to surgery, precise records are taken to allow a detailed plan and simulation of the surgery in the laboratory. Dr Lim will take facial measurements and the models of the teeth are assessed. Dr Lim will also take specialised Facial recordings including a face-bow and wax record of the patient’s bite. Dr Lim will then translate the detailed plan using computerized planning software where x-rays of the patient’s face are scanned in and merged with facial photographs and she will manipulate the software to predict the planned movements and a final treatment plan is determined. 

Computerised Planning

Dr Lim a  computer software program where facial x-rays are merged with clinical photos to plan and predict the facial changes. The facial plan will be communicated to the patient and orthodontist to arrive at an orthodontic and surgical plan.

Laboratory Surgery Simulation

The stone models of the teeth are mounted onto a mechanical jaw (articulator). Model surgery is then performed and accuracy is optimized by using a specialised measuring block platform with a digital gauge and allows measurements in 3 dimensions. Surgical Splints are fabricated. The splints allow accurate duplication of the planned movements during the operation. For Bimaxillary surgery, there will be 2 splints. One for the first jaw against the unoperated jaw. The second for the second operated jaw against the new first jaw position.

How is 2 jaw surgery  or Bimaxillary surgery done?

Both jaws are operated on in the one surgical session. See details in earlier section on upper jaw surgery and lower jaw surgery.