In general, protruding chin refers to the case where the lower jaw or mouth protrudes forward, and the face is long. To accurately classify the protruding chin, it can be divided into two; Macrogenia and Mandibular Prognathism.
In the case of Macrogenia, only the jaw tip can be corrected by genioplasty. Still, for Mandibular Prognathism, lower jaw surgery that is pushing the mandible in, or a two-jaw surgery that is pushing both maxilla and mandible in is needed.
When the occlusion is normal but only the chin structure is developed. If the lower chin grew forward or downward and looks like a protruding chin, it can be simply corrected by chin reduction surgery.
This method is performed when the length of the face is average, but it is in the case of a Mandibular Prognathism. It is a surgical method that can move the lower jaw backward using a technique that affects less of a burden to the jaw joint and protects lower jaw nerves at the same time.
At this time, the sagittal split ramus osteotomy (SSRO) is performed to cut and overlap the posterior part of the jaw bone to fix the protruding lower jaw.
In the case of long or short faces, it requires an upper jaw surgery at the same time with the lower jaw surgery, which called two jaw surgery (or so-called double jaw surgery).
Two jaw surgery, or double jaw surgery, is a surgery that the lower jaw osteotomy is done simultaneously with an upper jaw osteotomy that is cutting an upper jaw from the upper teeth to the lower part of the nose.
In the case of a protruding chin with a long face, the upper jaw is receded, so the upper jaw is moved forward, and the lower jaw is moved backward simultaneously to reduce the long face.
However, in the case of a protruding chin with a short face, the surgery to move the upper jaw forward and downward is performed because the lower jaw is smaller than the upper jaw and looks receding. In contrast, the lower jaw can be moved back according to the position of the upper jaw.