Sagittal and vertical maxillary effects after surgically assisted rapid maxillary expansion (SARME) using Haas and Hyrax expanders

Division of Plastic Surgery, Federal University of São Paulo, São Paulo, Brazil.
Journal of Craniofacial Surgery (Impact Factor: 0.68). 12/2007; 18(6):1322-6. DOI: 10.1097/scs.0b013e3180a772a3
Source: PubMed


The purpose of this study was to evaluate the effect of surgically assisted rapid maxillary expansion on the sagittal and vertical maxillary planes. Thirty-three adult patients aged between 18 and 40 years who required surgically assisted rapid maxillary expansion were included in this study. They were divided into two groups: the Haas type expander (16) and the Hyrax type expander (17). All patients were subjected to subtotal LeFort I osteotomy with pterygomaxillary disjunction. Lateral cephalometric radiographs were taken during the preoperative assessment (T1), soon after completion of the expansion (T2), and 4 months after the end of the expansion (T3). The following cephalometric measures were obtained in each of the three radiographs for all the patients: SNA, SN palatal plane, Frankfurt horizontal plane. NA, CF-A, CF-NA, Nperp-A, CF-A, Frankfurt horizontal plane-ANS, and Frankfurt horizontal plane-PNS. Statistically significant changes were observed in the cephalometric measures: SNA, Frankfurt horizontal plane, NA, Nperp-A in the patients in the Haas group, and CF-A in the patients in the Hyrax group, demonstrating anterior displacement of the maxilla. The cephalometric measures SN.palatal plane, CF-A, CF-NA, Frankfurt horizontal plane-ANS, and Frankfurt-PNS plane that evaluated vertical displacement did not show changes in either group. The surgically assisted rapid maxillary expansion caused anterior displacement of the maxilla in both groups, but only the Haas group had statistical significance. Neither the Haas group nor the Hyrax group showed vertical displacement of the maxilla. When Hyrax and Haas groups were compared, there were no statistically significant differences for sagittal and vertical changes.

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    ABSTRACT: Surgically assisted rapid maxillary expansion is the treatment of choice for correcting maxillary transverse deficiency in adults. Traditionally, the appliance for expansion is tooth-borne and tissue-tooth-borne devices (Hyrax and Haas). Although a number clinical and radiographic studies have evaluated the surgically assisted rapid maxillary expansion, only limited information is available to study the transverse movement of the midpalatal suture with computed tomography. Forty adult patients of both sexes, ranging in age from 18 to 38 years, with bilateral transverse maxillary deficiency were operated on. Twenty patients had Hyrax expander, and 20 had Haas expander. Under general anesthesia, subtotal Le Fort I osteotomy was performed including pterygomaxillary dysjunction. The width of the midpalatal suture opening was measured at the anterior edge of the midpalatal suture and at the junction of the midpalatal suture and palatal bones, using computed tomography in axial acquisition, obtained in the preoperative period and immediately after the end of expansion. A digital caliper was used to measure Haas and Hyrax distance on the central jackscrew preoperatively and postoperatively. The proportion between the midpalatal suture expansion and the amount of expansion on the jackscrew was evaluated. The mean of midpalatal suture opening and screw opening for Haas group was 5.19 and 8.78 mm, and for the Hyrax group, 5.85 and 8.51 mm, respectively. Both groups showed parallel-shaped separation of the midpalatal opening with no significant difference in the anterior and posterior portion. Midpalatal/jackscrews opening proportion was greater in the Hyrax group (69,2%) than in the Haas group (60%).
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    ABSTRACT: The aim of this study was to evaluate the effects of laser therapy on bone regeneration in the midpalatal anterior suture (MPAS) after surgically assisted rapid maxillary expansion (SARME). Thirteen patients aged between 18 and 33 years old with maxillary transverse deficiency (> or =7.0 mm) were evaluated. All patients underwent subtotal Le Fort I osteotomy with separation of the pterygomaxillary suture with the use of Hyrax expander, and were divided into 2 groups: control group (n = 6) and laser group (n = 7). A GaAlAs laser (P = 100 mW, lambda = 830 nm, Ø = 0.06 cm(2)) was used. The laser was applied in 8 treatment sessions with intervals of 48 hours. Each treatment session consisted of laser applications, per point (E = 8.4J, ED = 140J/cm(2)), at 3 points on the MPAS, and total dose of E = 25.2 J, ED = 420 J/cm(2). Digital radiographs were taken before the surgical procedure and at 1-, 2-, 3-, 4-, and 7-month follow-up visits. Optical density analysis of the regenerated bone was performed using Adobe Photoshop 8.0 software. Bone regeneration associated with the use of laser after SARME showed a statistically significant difference. A higher mineralization rate was found in the laser group (26.3%, P < .001) than the control group. Low-level laser irradiation (GaAlAs) accelerates bone regeneration in MPAS after SARME. However, the optical density measurements after 7 months of follow-up were lower in comparison with the preoperative measurements.
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