Max D Pereira

Universidade Federal de São Paulo, San Paulo, São Paulo, Brazil

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Publications (4)2.83 Total impact

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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%).
    Journal of Craniofacial Surgery 04/2008; 19(2):433-8. · 0.69 Impact Factor
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    ABSTRACT: 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.
    Journal of Craniofacial Surgery 12/2007; 18(6):1322-6. · 0.69 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate the behavior of the transverse dimension of the maxilla after surgically assisted rapid expansion with and without using a transpalatal arch fixed retention. Sixty cast models of the maxilla and 60 posteroanterior radiographs from 30 adult subjects, 16 male subjects and 14 female subjects, were evaluated. The subjects were 18.1 to 53.2 years old (mean age, 27.3 years), had been submitted to surgically assisted rapid maxillary expansion, and were using the expansion appliance for four months. The subjects were randomly assigned into two groups of 15 subjects. One group, called the group with retention, received a transpalatal arch fixed retention and another group, which received no retention, was called the group without retention. The assessments were performed at two time points: at the removal of the expansion appliance (T1) and 6 months after the removal of the expansion appliance (T2). In the cast models, interpremolar distances (A-A1) and intermolar distances (B-B1) were measured and in the posteroanterior radiographs, maxillomandibular discrepancy was used. A reduction in the distances A-A1 (-0.76 mm) and B-B1 (-1.54 mm) was observed among the time points studied in the group without retention and this difference was statistically significant. In the group with retention, the difference between the time points T1 and T2 was not statistically significant. The assessment of the maxillomandibular difference showed an increase between the time points T1 and T2 in the group with retention (1.54 mm) and the group without retention (0.84 mm), which means a reduction in the maxillary width in the posteroanterior radiograph. In the comparison between the groups, the assessment of the cast models and the assessment of the posteroanterior radiograph showed no statistically significant difference in any of the variables studied.
    Journal of Craniofacial Surgery 08/2007; 18(4):860-5. · 0.69 Impact Factor
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    ABSTRACT: Mandible fractures can result in esthetic, functional and financial problems and their epidemiological patterns have changed in many locations. This study was carried out to detect these changes, aiming to compare data of patients with mandible fractures treated at the Sao Paulo Hospital (UNIFESP-EPM) from June 1999 to March 2002 with data of patients treated from January 1991 to March 1996. Information on most affected gender and age, most often fractured mandible segment, associated injuries, treatment and complications of 98 victims of mandible fracture admitted from June 1999 to March 2002 were compared to the same data of 166 patients treated from January 1991 to March 1996. the most affected gender and age ranges remain the same. Aggressions surpassed traffic accidents as the main etiology. Incidence of associated injuries and multiple fractures in the mandible decreased, a fact probably related to the change in etiology. The most affected segment is still the body of the mandible. The most used type of treatment in both samples was internal rigid fixation with miniplates and the number of complications decreased, due to the higher standard of patient care. Mandible fractures in the São Paulo population have undergone epidemiological changes and this knowledge enables local authorities to establish adequate measures for prevention and treatment.
    Revista da Associação Médica Brasileira 01/2004; 50(4):417-21. · 0.77 Impact Factor