3D mandibular positioning after rapid maxillary expansion in Class II malocclusion

Abstract

This study investigated, using cone beam computed tomography (CBCT), the spatial mandibular positioning after rapid maxillary expansion (RME) in Class II Division 1 malocclusion. This prospective study evaluated 17 children (mean initial age 10.36 years old) presenting Class II, Division 1 malocclusion and skeletal maxillary constriction that underwent to RME Haas' protocol. CBCT was performed before treatment (T1), immediately after the stabilization of expander screw (T2) and after the retention period of 6 months (T3). The scans were managed in Dolphin Imaging ® 11.0 software, where landmarks (right and left condylion, right and left gonion, and menton) were positioned and measured in relation to sagittal, coronal and axial plane to verify, respectively, transverse, anteroposterior and vertical displacement of the mandible. Paired Student's t-test was used to identify significant differences (p<0.05) between T1 and T2, T2 and T3, and T1 and T3. After RME, right and left gonion moved downward (1.11 mm and 0.89 mm) and menton displaced downward (1.90 mm) and backward (1.50 mm). During the retention period, only anteroposterior displacement was significant, with the right and left gonion (0.97 mm and 1.26 mm) and the menton (2.29 mm) moving forward. Three-dimensional assessment of the mandible in Class II Division 1 patients subjected to RME showed a transitory backward and downward mandibular positioning, without any lateral displacement. The 6-month retention period allowed the mandible shifting significantly forward, exhibiting a more anterior position compared with the initial condition, even remaining in a more downward direction.

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

“…Samples were characterized as having either dental [18][19][20] or skeletal discrepancies. 16,17,21,22 Transverse maxillary deficiency was reportedly present in the sample of part of the studies. 16,19,21,22 All subjects in the included studies were treated with RME, either as a sole treatment approach, 16,21,22 or associated with other appliances, such as passive transpalatal arches.…”

“…Finally, seven clinical trials met the eligibility criteria and were considered for this systematic review. [16][17][18][19][20][21][22] A summary of the key methodological data and study characteristics can be found in Table 2. Study samples were observed during the mixed dentition phase and presented a wide spectrum of Class II malocclusions.…”

“…16,19,21,22 All subjects in the included studies were treated with RME, either as a sole treatment approach, 16,21,22 or associated with other appliances, such as passive transpalatal arches. [17][18][19] The subjects were observed for varying periods of time, according to different outcomes, which related to either skeletal [16][17][18][19]21,22 or dental characteristics. [18][19][20] Methodological appraisal of the selected studies is presented in Table 3.…”

“…[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.…”

Morphological Changes of Condyles and Helkimo Clinical Dysfunction Index in Patients Treated with Herbst - Orthodontic Appliance

“…1). As transversal maxillary deficiency frequently occurs in Class II malocclusions (23), rapid maxillary expansion was performed during the first 2 weeks after placement of the Herbst appliance (one turn on the first day and half a turn on subsequent days until clinical correction was achieved (1)).…”