I see lots of information on chin augmentation but have yet to see any articles on...
A protruding chin can be treated with a procedure called a sliding genioplasty. With this procedure the bony chin is cut and slid back. The chin is held in the new position with a small bone plate and screws. There are no incisions or scars on the face. An incision is made in the mouth inside the lower lip.
Sometimes when the chin is moved back, fullness under the chin can occur. Depending on how severe this fullness is, it may be improved with liposuction. The liposuction can be done at the same time or at a later time as a staged procedure.
One word of caution: this is a difficult procedure. Make sure your surgeon has experience doing sliding genioplasties. I recommend consulting with a surgeon who is an ASAPS member.