As part of pre-surgical planning, xrays and 3D scans of your skull and face will be made. This can then be used to approximate the changes to your face as a result of the surgery.
Some patients may benefit from correcting a single jaw, some both jaws. The decision on which jaw should be treated can sometimes be very obvious. For cases that are borderline, pre-surgical simulation can be helpful.
There are computer programs that can produce simulations of what your face should look like after surgery with reasonable accuracy. These simulations can allow you to compare what surgery can achieve on only the upper jaw, only the lower jaw or both jaws.
How your soft tissue (skin, muscle and fat) will drape over the bone cannot be fully accounted for by the software, leading to some differences in how your face will look like after the surgery. There is also variation across ethnic groups.
Immediately after the surgery, there will be swelling of the overlying soft tissues that may distort what the final result will look like. This often resolves with time but it may be alarming for patients in the beginning.
In the end, predictions are just that - predictions. Jaw surgery is a major operation that carries risks, so you should do your homework and work with your surgeon and orthodontist closely during the pre-surgical phase to reduce any guesswork.
Looking at cases that have been treated previously can also give you a reasonable idea of what to expect. Ask your oral surgeon or plastic surgeon if they can provide this.
