Recent protocol of the sendai surgery- first (SSF) approach: Clinical and scientific perspectives

The treatment protocol of Surgery-First has gradually evolved, since our team employed it for the first time twenty-years ago. In this article, we describe every step of the current Sendai Surgery-First (SSF) approach pro-tocol, in detail. Two major differences between the recent and old protocol, exists, which are (1) In the recent protocol, placement of brackets and pas-sive surgical wires is no longer required before jaw surgery, and (2) only sur-gical hooks are needed to be bonded to the lateral teeth. Further, the duration of surgical splint use has been significantly shortened. Instead of a surgical splint, a posterior build-up in the maxillary dentition is used to secure a vertical stop. These considerations allow patients to undergo treat-ment in a more comfortable manner. However, the skeletal anchorage sys-tem (SAS) using the orthodontic miniplate for postoperative orthodontics remains unchanged. Based on many SSF approach cases, we have confirmed that the SAS can predictably improve unstable and complicated occlusion immediately after surgery, and reliably achieve treatment goals. Therefore, our SSF approach has the distinguishing feature of having a wider range of indications than other Surgery-First approaches. Furthermore, in regard to scientific perspectives, dynamic systemic changes in bone metabolic activity of the SSF approach is also discussed. The C-reactive protein levels increase immediately after surgery, followed by an increase in the C-terminal telopep-tide type I collagen levels, which is associated with osteoclastic activity, indi-cating bone resorption. After this, alkaline phosphatase, and bone-specific alkaline phosphatase levels, which are associated with osteoblastic activity, increase with a peak at 1 month and then decrease gradually to preoperative levels by 6 months. During the early postoperative period, osteocalcin-posi-tive cells, such as osteogenic precursors, appear in the peripheral blood and are involved in the bone healing process after surgery through the systemic acceleration phenomenon. Therefore, orthognathic surgery induces regional and systemic accelerated phenomena, which, in turn, causes rapid orthodon-tic tooth movement, resulting in reduced treatment duration with the SSF approach. (Semin Orthod 2022; 28:258-288) (c) 2022 Published by Elsevier Inc.