**3. Surgically Assisted Rapid Maxillary Expansion (SARME)**

The areas of resistance to lateral forces in the midface are the pyriform aperture (anterior), the zygomatic buttress (lateral), the pterygoid junction (posterior) and the midpalatal synostosis suture (median). Many surgical interventions and techniques have been developed by the identification of these areas of resistance. Surgery assisted maxillary expansion procedures have conventionally been grouped into 2 categories:


**Advantages of SARME** over orthodontic therapy and segmental Le Fort procedures include decreased risk of periodontal damage, improved esthetics when smiling, improved nasal air flow, and decreased risk of avascularity. SARME is also a relatively simple procedure and is associated with minimal morbidity. Intraoperative complications are uncommon and there is also less chance of avascularity leading to aseptic necrosis than with segmental Le Fort I procedures. [29, 30] Brown [12] was probably the first who described a technique of SARME with midpalatal splitting. [31] In 1961, Haas described the downward and forward movement of the maxilla that occurs during rapid maxillary expansion because of the location of the craniomaxillofacial sutures. He believed that the hemimaxillas separated from each other develop tipping rather than separating in a parallel fashion due to the strength of the zygomatic buttresses. [32]

Most methods consider the zygomaticomaxillary junction the major site of resistance and perform a corticotomy through the zygomatic-maxillary buttress from the pyriform rim to the maxillopterygoid junction. The midpalatal suture is historically considered the major place of resistance. The pterygoid plates are also a considerable site of resistance but because of the increased risk of injuring the pterygoid plexus by the osteotomy, some chose not to, without losing much mobility. By not releasing the pterygoid junction, the pattern of opening of the maxillary halves is more V-shaped with the point of the V located dorsally [33-37].

Isaacson and Ingram [38] and Isaacson et al. [39] mention that historically, the midpalatal suture was thought to be the area of resistance to expansion, but the facial skeleton increases its resistance to expansion as it ages and matures, and that the major site of resistance is not the midpalatal suture but the remaining maxillary articulations. Wertz stated that resistance of the zygomatic arch prevents parallel opening of the midpalatal suture [40]. Many surgeons release the midpalatal suture to improve mobility and to prevent deviation of the nasal septum. Several authors describe two paramedian palatal osteotomies from the posterior nasal spine to a point just posterior to the incisive canal [41-43].

In 1975 and 1976 Bell and Epker demonstrated that the area of increased facial skeletal resistance to expansion was indeed not the midpalatal suture, but the zygomaticotemporal, zygomaticofrontal and zygomaticomaxillary sutures. [44, 45] On the other hand, Shetty concluded that exclusive use of bilateral zygomaticomaxillary buttress osteotomies to facilitate SARME was inadequate. They therefore concluded that complete midpalatal and pterygo‐ maxillary osteotomies were essential for predictable maxillary expansion in adults. [46]

There is a lack of consensus among orthodontists and surgeons about the indications for SARME. Although maxillary expansion may be required for many patients, an accurate diagnosis of maxillary transverse distraction is somewhat ambiguous. This is further compli‐ cated by case reports in the literature about orthodontic maxillary expansion or other forms of expansion in adults. The following have been reported in the literature as indications for SARME, all applying to a skeletally mature patient with a constricted maxillary arch.
