Can I get a chin implant before orthognathic surgery?

Good question, and one that is not asked enough to be honest with you.  I've worked with many oral surgeons who specialize in orthognathic surgery, and the most important thing is finding someone who has a working relationship with the person who is planning on doing your double jaw surgery.  There are many questions that need to be answered - how long will you have your braces on? When did they put them in and when are they thinking that you will have adequate alignment for the jaw surgery? Often times if you are having your lower jaw advanced and rotated (which I am guessing is your problem as you are asking about a chin implant), it will help align the vector of the chin at the same time.  Sometimes it wont. But your oral surgeon would be able to tell you this and I would hate to see you go through a chin implant, only to have to have it removed once you undergo orthognathic surgery because now you are over projected.  The other question you need to ask is if they do surgery on your upper jaw, will it change the position of your nose.  This is often overlooked and you should ask about.  As you can see, making sure that before any consultation you find from your oral surgeon someone who they work with frequently is best as this is really a "team approach" question.  Hope this helped. 

  It is probably best to undergo the double jaw surgery first, and then placement of a chin implant at that time or any time thereafter. Chin implants are composed of Silastic, and are manufactured in a large array of sizes and shapes is best determined at the time the consultation and examination. For more information and many diagrams of the chin implants, placed in the link and the video below

As a general rule you should wait to have any chin augmentation to either at the time of orthognathic surgery or after. But this question needs more information such as pictures and the plan of orthognathic surgery to provide a more informed answer.