Baratieri Carolina, Alves Matheus, Sant'anna Eduardo Franzotti, Nojima Matilde da Cunha Gonçalves, Nojima Lincoln Issamu
Department of Orthodontics, Dental School, University of Rio de Janeiro, RJ, Brazil.
Braz Dent J. 2011;22(5):428-34. doi: 10.1590/s0103-64402011000500014.
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.
本研究采用锥形束计算机断层扫描（CBCT），调查了安氏II类1分类错牙合畸形患者快速上颌扩弓（RME）后下颌的空间位置。这项前瞻性研究评估了17名患有安氏II类1分类错牙合畸形且上颌骨狭窄的儿童（平均初始年龄10.36岁），他们接受了RME Haas矫治方案。在治疗前（T1）、扩弓螺旋稳定后即刻（T2）以及6个月保持期后（T3）进行CBCT扫描。扫描图像在Dolphin Imaging® 11.0软件中进行处理，在该软件中确定并测量标志点（右侧和左侧髁突点、右侧和左侧角点以及颏下点）相对于矢状面、冠状面和轴面的位置，以分别验证下颌骨的横向、前后向和垂直位移。采用配对学生t检验来确定T1与T2、T2与T3以及T1与T3之间的显著差异（p<0.05）。RME后，右侧和左侧角点向下移动（分别为1.11 mm和0.89 mm），颏下点向下移动（1.90 mm）并向后移动（1.50 mm）。在保持期内，只有前后向位移显著，右侧和左侧角点（分别为0.97 mm和1.26 mm）以及颏下点（2.29 mm）向前移动。对接受RME的安氏II类1分类患者的下颌骨进行三维评估显示，下颌骨出现暂时的向后和向下移位，无任何侧向移位。6个月的保持期使下颌骨显著向前移位，与初始状态相比呈现出更靠前的位置，即使仍处于更靠下的方向。
