Chin Surgery, Genioplasty
Minor corrections can be corrected by contouring with a bur. Vertical reduction over 3-4mm often required making a cut in the mid portion of the chin to retain the natural shape of the chin. Simply shaving if off from the bottom may leave an undesired and unnatural appearance of the chin. 3-D imaging with office CT scan can help surgeons and patients visualize their facial bones in great detail to aid with diagnosis and planning.
Reduction Genioplasty Asymmetry
For this type of bony asymmetry after a reduction sliding genioplasy, burring would be a good contouring technique. (at least based on what is seen in this one picture)