Sagittal and vertical effects of rapid maxillary expansion in Class I, II, and III occlusions

Abstract

Objective: To evaluate and compare the skeletal vertical and sagittal effects of the Hyrax expander in Class I, II, and III patients. Materials and Methods: One hundred and eighty-three patients (91 females, 92 males) with a mean age of 8.7 years and with maxillary bilateral cross-bite and maxillary hypoplasia were analyzed retrospectively. They were divided into three groups according to their skeletal class. Sixty-five patients were skeletal Class I, 55 were skeletal Class II, and 63 were skeletal Class III. For each patient a lateral cephalogram was obtained before treatment and at the end of the retention period. Changes in the groups during the observation period were calculated, compared, and statistically analyzed with a t-test. Results: In terms of vertical effects, a statistically significant increase in the anterior vertical dimension was observed only in Class III patients. No statistically significant changes were observed in the posterior vertical dimension in any of the groups. In terms of sagittal effects, in Class I patients the maxilla and the mandible moved forward, but not in a statistically significant way, and the ANB angle showed a statistically significant decrease, but its change was less modified. In Class II patients the maxilla moved forward, but not in a statistically significant way, while the mandible moved forward in all of the patients in a statistically significant manner. The ANB decreased, statistically improving the skeletal classification. In Class III patients the maxilla moved forward in a statistically significant manner; the mandible showed a downward and backward rotation, improving the skeletal classification. Conclusions: The data obtained in this study permit us to confirm that rapid maxillary expansion can be used in all of the skeletal classes with good vertical and sagittal results. (Angle Orthod. 2011;81:298-303.)

Skeletal growth changes in Class II subjects treated with slow palatal expansion

“…Mandibular length, which was measured by a straight line from the condylion to the gnathion, showed a significant increase within the observation period in the two groups, indicating an actual significant growth during the observation period. In agreement with the findings of this study, Farronato et al [19] found a significant decrease in ANB angle in subjects with Class II malocclusion after maxillary rapid expansion. The change in ANB angle in their sample was 0.2 greater than that found in this study.…”

“…The SNB angle was not significantly changed during the observation period in the present treated sample, and the change was also not significantly different compared with that in the control group. Although Farranato et al [19] and Lima Filho and de Oliveira Ruellas [20] found significant increases in the SNB angle after rapid maxillary expansion in their Class II sample, those two studies did not include a control group. Because the SNB angle is influenced by the changes in three pointsdsella, nasion, and point Bdthe continuous displacement of the nasion and point B may explain the nonsignificant change in this angle.…”

Three-dimensional evaluation of upper airway following rapid maxillary expansion: A CBCT study

“…Farronato et al 7 reported that the mandibular position changes in various directions when RME is applied to patients with different malocclusions. These differences in mandibular position may affect the OP airway size, shape, and volume.…”

“…5,6 Furthermore, RME is known to affect the position of the mandible, which may also change the size and volume of the oropharyngeal (OP) airway. 7 The effects of RME over nasal size and volume have been researched with various procedures such as lateral and anteroposterior radiographs, [8][9][10][11][12] acoustic rhinometric methods [13][14][15][16] and multislice computed tomography. [17][18][19][20] Recent advances in cone beam computed tomography (CBCT) and related software have made it possible to visualize and measure the upper airway as a solid structure.…”

Rapid maxillary expansion effects in Class II malocclusion: A systematic review

“…[13][14][15] However, such observations have mostly relied upon clinical experience, and the research intended to analyze that question is controversial and presents diverse study methods. [16][17][18][19][20][21][22] Therefore, the objective of this investigation was to evaluate the effectiveness of rapid maxillary expansion (RME) on the sagittal dental or skeletal parameters of growing children with Class II malocclusion through a systematic review of available clinical trials.…”