Jang Yeol Lee

The concept of orthognathic surgery for the dentofacial deformity of skeletal Cl III patients was firstly introduced over 100 years ago by Dr. Blair with ostectomy and modified in late 1950's to osteotomies divided into SSRO(Sagittal Split Ramus Osteotomy) and IVRO(Intraoral Vertical Ramus Osteotomy). For the last decades, tremendous development has been made not only in the surgical technique itself but also in the manner of whole management of these surgical procedures including the initial treatment planning and post operative care. Improvement of surgical instruments has made possible surgery of maxilla more extended and accurate, eventually the position of mandible became more ideal and stable. Furthermore use of mini-screw in orthodontic field makes pre and post surgical orthodontics more predictable and target-oriented.
Despite of these developments of surico-orthodontics in Cl III patients, long-term stability after surgery is still one of the biggest concerns for orthodontists and surgeons as well. There are many factors influencing the post-operative stability. In SSRO, the location of proximal segment will affect the initial stability right after mandibular set-back and it is highly related to the management of proximal segment in the operation room and method of fixation. In IVRO, the supra-hyoid muscles and lateral pterygoid muscle can affect the initial stability and the protocol for post-operative physical therapy is very crucial. Afterwards the forces induced by the muscles attached to the proximal and distal segments gradually affect the long-term stability of mandible in both different techniques. Many studies have revealed that these representative two techniques for mandibular set-back surgery for Cl III are enough secure and stable under the control of these various factors to the relapse. Another issue regarding orthognathic surgery for Class III is long-term stability of surgery-first approach. New concept of the different sequence conducting surgery before orthodontic treatment can be beneficial and attractive to patients and doctors. But the precise understanding of the procedure and reliable post-op stability should be guaranteed to accept this new way of surgical-orthodontics.
In this presentation, various relapse factors in Cl III surgery will be reviewed throughout the past and recent studies and the long-term stability of SSRO and IVRO will be compared. Also, a new approach with differential sequence of surgical orthodontics will be introduced and the long-term stability as well as initial change of surgery-first approach will be shown. Additionally, the different post-operative change following surgery-first approach with SSRO and IVRO will be discussed together.