Hi Amimelly.
I can completely understand where you're coming from. A lot of our patients express the same wish and understandably so.
The simple difference between jaw surgery and chin surgery is the fact that jaw surgery corrects the disturbed tooth relationships along with the face profile, and has the potential to give a greater degree of change than chin surgery.
Chin surgery has the sole purpose of improving the profile and is independent of the the way the teeth meet. The only limitation is the amount of correction that can be achieved with sliding genioplasty.
What limits the amount of augmentation we can achieve with a sliding genioplasty is the distance how much we can slide the chin segment forward without losing bone contact with the jaw bone above. Maintaining bony contact with the parent bone is essential for good healing.
This means that we can only slide the chin forward for a distance which is equal to the width of the chin bone. This is different for different individuals and needs to be measured precisely on the x-ray so that the surgery can be planned accordingly.
The approximate width is usually in the range of 8-12 mm. So, to give you a rough estimate, a chin advancement of up to 10 mm, or 1 cm, can be safely performed in most cased with genioplasty alone.
I have performed several corrections greater than 10 mm also in my practice. But this needs to be planned according to the patient's individual measurements.
Hope this helps. Take care.