A sliding genioplasty is a versatile procedure that can change both the horizontal and vertical dimensions of the chin. The vertical height of the chin can be increased, stay the same or even be decreased based on the aesthetics needs of the chin with the genioplasty is fixed into its new position.
Generally speaking, a jumping genioplasty will decrease vertical height but increase chin projection. A sliding genioplasty will predominately add projection to the chin. Depending on how the genium is cut and fixated, some vertical height may appear to increase with a sliding genioplasty. However, a sliding maneuver will predominately add projection, not vertical height.
You should see a board certified plastic surgeon to discuss what you best options are.
Talk to your craniofacial surgeon or oral maxillofacial surgeon who will know about the many different types and nuances of genioplasty. They can show you exactly what your options are. Every case is different in terms of exactly where the bone is cut, where the bone is moved, what the angles are...so every patient gets a different operation. Your surgeon can tell you exactly what can and cant be done, what should and shouldn't be done....