Orthognathic, or surgery of the jaws is indicated when there is a skeletal malocclusion with teeth misalignment, airway obstructive problems, and facial disproportions.
In the long term this problem affects your masticatory system, including teeth wear, gum recession, temporomandibular derangements, not to say self esteem problems, and when there is a narrow airway, breathing problems such as Obstructive Sleep Apnea.
The cause of these misalignments is typically an abnormal growth pattern or even a congenital cause. In some instances, they can be as a consequence of facial trauma or oncologic surgical resections.
When the reason for a malposition of teeth is a skeletal problem, dentists and orthodontists who detect it will refer you to a specialist to treat this condition surgically, since it´s a skeletal problem.
You might think of orthognathic surgery as orthopedic surgery of the facial bones, that not only corrects malocclusion (hence improving your bite and breathing pattern) but also, last but not least, substantially improves facial aesthetics. It has a component of aesthetic surgery of the facial bones.
It is of the utmost importance in order to obtain a good result, a good communication between your orthodontist and your orthognathic surgeon, so that both approaches are well aligned. This symbiosis is necessary before and after your surgery. It will help you understand the steps taken and the chronogram of your treatment.