I need to have orthognathic surgery to advance my lower jaw. As I don't show my upper teeth the surgery should include lowering the maxilla. This worries me because the maxilla will have to come down about 8mm. I would like to know if it would be possible for me to grow the bone needed for the implant or the bone will need to be taken from my hip. I would like to know if the bone used for the implant could be reabsorbed.