Maxillary–mandibular aesthetic orthognathic surgery

Introduction

The three fundamental procedures of orthognathic surgery—maxillary LeFort I osteotomy and its variations, mandibular bilateral sagittal split osteotomy, and osseous genioplasty—give the surgeon an incredible ability to safely disassemble the facial skeleton and reposition it to achieve the desired occlusion and facial appearance. Although functional occlusion can be achieved with either maxillary surgery alone or mandibular surgery alone, it is the ability to operate on both the maxilla and the mandible that gives the surgeon the greatest latitude to optimize the aesthetic facial form. The aesthetic appearance may be compromised with single-jaw surgery, even though the occlusal goals may be met. However, the ability to operate on both jaws simultaneously and reliably came much later.

Obwegeser described the bilateral sagittal split osteotomy (BSSO) in 1955, and mandibular surgery was used to solve a variety of dentofacial skeletal deformities even when the primary deformity was in the maxilla. A decade later, in 1965, Obwegeser described repositioning of the maxilla in a stable and consistent manner. Thus for the next decade or more, maxillary skeletal deformities were corrected by repositioning the maxilla via the LeFort I procedure to the mandible, and mandibular deformities were corrected by repositioning the mandible via the BSSO procedure to the maxilla. However, when both maxillary and mandibular deformities were identified, surgeons staged the procedures because of the complexity of presurgical planning, the technical difficulties in executing the procedures, and the time required to complete each of the procedures. While Obwegeser initially described the simultaneous two-jaw procedure in 1970, it took many years before it would become a routine procedure as it is today. One must remember that in those early years, the lack of instrumentation, the availability of only a drill to perforate the bone and an osteotome to sequentially complete the osteotomy, and the instability of wire osteosynthesis hampered the surgeon’s confidence in sectioning both jaws simultaneously. With time, the understanding of the need to appropriately align and level the dental arches before surgery to ensure postoperative stability and the development of plate/screw fixation were perhaps the two most important factors that increased the confidence of the surgeon that maxillary and mandibular deformities can be corrected in a single operation. As the maxillary and mandibular procedures are described in individual chapters, the focus of this chapter will be the indications for two-jaw surgery, planning, and operative sequencing.