Thank you for your question. Deciding on whether to have just sub mental lipo or a chin implant really depends on what your goals are. If what you're looking for is more of a defined jaw line, than an implant is probably the way to go. An implant can give the jaw a bit more projection and often patients feel like it gives that more of a finished appearance.
It depends upon your present bone structure. If your lower jaw is wide enough and a 'division' is obvious between your face and neck; then liposuction can help somewhat. But most individuals need some increased structure/bone width definition. Talk to the Maxillofacial surgeon