Objective: To determine by low-dose computed tomography (CT) protocol the dental and periodontal effects of rapid maxillary expansion (RME). Materials and Methods: The sample comprised 17 subjects (7 males and 10 females), with a mean age at first observation of 11.2 years. Each patient underwent expansion of 7 mm. Multislice CT scans were taken before rapid palatal expansion (T0), at the end of the active expansion phase (T1), and after a retention period of 6 months (T2). On scanned images, measurements were performed at the dental and periodontal levels. Mean differences between measurements at T0, T1, and T2 were examined through analysis of variance (ANOVA) for repeated measures with post-hoc tests. Results: All interdental transverse measurements were significantly increased at both T1 and T2 with respect to T0. In the evaluation of T0-T1 changes, periodontal measurements were significant on the buccal aspect of banded teeth with a reduction in alveolar bone thickness corresponding to the mesial (−0.5 mm; P < .05) and distal (−0.4 mm; P < .05) roots of the right first molar and to the mesial root of the left first molar (−0.3 mm; P < .05). In the evaluation of overall T0-T2 changes, the lingual bone plate thickness of both first molars was found to be significantly increased (+0.6 mm; P < .05). Conclusions: RME therapy induces a significant increase in the transverse dimension of the maxillary arch in growing subjects without causing permanent injury to the periodontal bony support of anchoring teeth discernible on CT imaging.

Introduction:The aim of this study was to apply low-dose computed tomography (CT) to evaluate treatment and posttreatment effects produced by rapid maxillary expansion (RME) at the levels of the midpalatal suture and the pterygoid processes. Methods: A sample of 17 subjects (7 boys, 10 girls; mean age, 11.2 years) was analyzed. Multi-slice CT scans were taken before RME, at the end of the active expansion phase, and after a retention period of 6 months. Statistical analysis was performed with ANOVA for repeated measures with post-hoc tests. Results: The amounts of opening of the midpalatal suture during the active phase of expansion were 3.01, 2.17, and 1.15 mm for the anterior, middle, and posterior suture widths, respectively. Pterygoid width also showed a statistically significant increase (1.49 mm). In the postretention period, all transverse measurements had significant decreases except for pterygoid width. Conclusions: At the end of the retention phase after RME therapy, the transverse width of the midpalatal suture was similar to the pretreatment width, whereas the width between the pterygoid processes was significantly increased. (Am J Orthod Dentofacial Orthop 2008;134:389-92)

Introduction the aim of this study was to evaluate the differences between 2 regions of maxillary voxel-based registration and to test the reproducibility of the registration. Methods 3D models were built for before treatment (T1) and after treatment (T2) Cone Beam CTs for 16 growing subjects. Landmarks were labeled in all T2 models of the maxilla, and voxel-based registration was performed independently by two observers, at two different times, using two different reference regions: 1) the Maxilla region (MAX) included the maxillary bone clipped inferiorly at the dentoalveolar processes, superiorly at the plane passing through the right and left orbitale points, laterally at the zygomatic processes through the orbitale point, and posteriorly at a plane passing through the distal surface of the second molars. 2) the Palate and Infra-zygomatic region (PIZ) had different posterior and anterior limits (at the plane passing through the distal of the first molar and distal of the canines, respectively). The differences between the registration regions were measured by comparing the distances between corresponding landmarks in the T2 registered models and comparing corresponding x,y,z coordinates from corresponding landmarks. Statistical analysis of the differences between T2 surface models was performed by evaluating the means and standard deviations of the distances between landmarks and by testing the agreement between coordinates from corresponding landmarks (ICC and Bland-Altman method). Results The means of the differences between landmarks from PIZ to MAX 3D T2 surface models for all of the regions of reference, times of registrations and observers combinations were smaller than 0.5 mm. The ICC and the Bland-Altman plots indicated adequate concordance. Conclusions Both regions of regional maxillary registration (MAX and PIZ) showed similar results and adequate intra- and inter-observer reproducibility.

The aim of the present study was to analyze the variations of maxillary arch size and of palatal morphology in subjects with prolonged mouth-breathing due to allergic rhinitis when compared with a control group with normal breathing pattern by using a three-dimensional analysis on digital casts

Objective: To assess the scientific evidence that rapid maxillary expansion (RME) causes Adverse Effects on the midpalatal suture, vertical dimension, dental and periodontal structures in growing subjects. Materials and Methods: Electronic databases were searched for articles dated through December 2011. The quality of the studies was ranked on a 13-point scale in which 1 was the low end of the scale and 13 was the high end. Results: Thirty relevant articles were identified. The amount of midpalatal suture opening ranged from 1.6 to 4.3 mm in the anterior region and from 1.2 to 4.4 mm in the posterior region. At the end of the active phase, RME resulted in slight inferior movement of the maxilla (SN-PNS +0.9 mm; SN-ANS +1.6 mm), increased tipping of anchored teeth from 3.4u to 9.2u and bending of the alveolar bone from 5.1u to 11.3u. In the long term, RME did not modify the facial growth patterns, and no significant changes on dentoalveolar structures were observed. Of the 30 studies, 2 were medium-high quality, 8 were medium quality, and 20 were low quality. Conclusions: RME always opened the midpalatal suture in growing subjects. The vertical changes were small and transitory. In the long-term evaluation, an uprighting of anchored teeth was observed and periodontal structures were not compromised. (Angle Orthod. 2013;83:172-182.)