Transverse expansion of the maxilla was first done in 1860 by means of an orthodontic appliance. In the following decennia, the orthodontic treatment evolved. The theory of distraction was first published in 1905 by Codivilla . The combined surgical and orthodontic treatment for maxillary expansion was introduced in 1938 for skeletally matured patients. The first successful use of distraction on the femur of a significant group of patients was published in 1990 . In 1999, the first bone-borne distractor was introduced .
Once skeletal maturity has been reached, orthodontic treatment alone cannot provide a stable widening of the constricted maxilla in cases of deficiencies of more than 5 mm. In general, an orthodontist can camouflage transverse discrepancies less than 5 mm with orthopedic forces alone . Tooth extractions for alignment of dental arches are often unnecessary . As mentioned before, surgically assisted rapid maxillary expansion (SARME) is a form of distraction that was applied before its biological healing principles were known . Physicians have to decide between two methods of expansion: SME (slow maxillary expansion) and RME (rapid maxillary expansion). Applying SME, the maxilla is broadened by 0.5 to 1 mm per week; meanwhile, using RME demands an expansion of 0.6 to 0.8 mm three times a day. Both methods have advantages and disadvantages . The surgically assisted rapid maxillary expansion is a method which, using combined orthodontic-oral surgical treatment, leads to a distinctive extension of the midline palatal suture. Thereby, it is possible to avoid extractions, widen the nasal floor and support the change from oral to nasal breathing .
SARME is considered a procedure with little risk of serious complications; however, several complications are mentioned in the literature, varying from life threatening epistaxis to a cerebrovascular accident, skull base fracture with reversible oculomotor nerve pareses and orbital compartment syndrome [8–10]. Less serious complications reported are postoperative hemorrhage, pain, sinusitis, palatal tissue irritation/ulceration, asymmetrical expansion, nasal septum deviation, periodontal problems and relapse .
In 1976 Bell and Epker, as well as Neubert in 1989, described the surgically assisted maxillary expansion, all using an oscillating saw that injured the mucous membrane of the maxillary sinus . Unfortunately, only a little information exists on how to preserve this mucous sinus membrane during the intervention. However, in 2001 Vercelotti described a new technique in osseous surgery which overcame the limits of traditional instrumentation in oral bone surgery by modifying and improving conventional ultrasound technology. Therefore, Vercelotti is known as the inventor of piezosurgery [13, 14], a technique that allows the soft tissue to rest and a tendency for less bleeding [15–17]. It transmits a special modular ultrasonic vibration frequency on the scalpel. Not only is this technique clinically effective, but histological and histomorphometric evidence of wound healing and bone formation in experimental animal models has shown that tissue response is more favorable in piezosurgery than it is in conventional bone-cutting techniques, such as with diamond or carbide rotary instruments . Voltage applied to a polarized piezoceramic causes it to expand in the direction of and contract perpendicular to polarity. A frequency of 25 to 29 kHz is used because the micromovements that are created at this frequency (ranging between 60 and 210 μm) cut only mineralized tissue; neurovascular tissue and other soft tissue is cut at frequencies higher than 50 kHz [19–22].
Piezoelectric devices are an innovative ultrasonic technique for safe and effective osteotomy or osteoplasty compared with traditional hard and soft tissue methods that use rotating instruments because of the absence of macrovibrations, ease of use and control, and safer cutting, particularly in complex anatomical areas. Its physical and mechanical properties have several clinical advantages: precise cutting, sparing of vital neurovascular bundles and better visualization of the surgical field. Piezoelectric bone surgery seems to be more efficient in the first phases of bony healing; it induces an earlier increase in bone morphogenetic proteins, controls the inflammatory process better, and stimulates remodeling of bone as early as 56 days after treatment .
SARME is reported to be performed under either general or local anesthesia, but with differences in surgical technique. Pterygo-maxillary separation is not recommended by those who have performed SARME under local anesthesia, as it is performed blindly and can produce profuse bleeding from the descending palatine bundle that is not easily controlled without a maxillary down-fracture [24, 25]. Separation of the pterygoid junction is thus particularly useful if greater posterior expansion is desired . The use of ultrasonic vibrations for fracture of the pterygoid plates during orthognathic surgery has been recently reported by Ueki et al. . In other words, the scope of the study is to answer the question of whether a surgically assisted rapid maxillary expansion using Piezosurgery® (Mectron, Carasco, Italy) without using saws and chisels is as effective as one applying conventional procedures.