Thank you for your picture. Dr. Apply has done a very nice job explaining lip incompetence as it relates to your chin contour. In my opinion,can achieve improved profile and better lip competence with a sliding genioplasty. Best wishes.
Your chin loks and functions the way it does because of the relationship between the bone and its overlying soft tissue pad. Your chin bone is horizontally short but vertically long. As a result the soft tissue chin pad sits up higher on it than normal and is also unsupported. As a result when you try and close your mouth the soft tissue chin pad tenses up to try and achieve lip competence. What you need is a sliding genioplasty that brings the chin forward as well as vertically shortens it. This will both improve your side profile, help with lip competence and establish a better bone-soft tissue relationship.