Wang M H, Ge Z L, Tian L, Li P R, Che Y Q
Department of Orthodontics, School of Stomatology, Lanzhou University, Lanzhou 730000, China.
Zhonghua Kou Qiang Yi Xue Za Zhi. 2017 Nov 9;52(11):678-683. doi: 10.3760/cma.j.issn.1002-0098.2017.11.006.
To evaluate the transverse displacement, stress distribution and tendency of change in tooth, alveolar bone and mid-palatal suture using three kinds of rapid maxillary expansion methods. Cone-beam CT image data was obtained by scanning skulls of a volunteer. Three-dimensional models of maxillary complex were re-established using Mimics and Geomagic Studio and models of Hyrax expander, Haas expander and miniscrew-assisted rapid palatal expander (MARPE) were established using ANSYS Workbench. Stress distribution, displacement and tendency of change in tooth, alveolar bone and mid-palatal suture were evaluated. Hyrax expander brought 0.105 mm lateral displacement of crown, 0.022 mm mid-palatal suture width increase, wedge opening and clockwise rotation tendency of maxilla. Haas expander created uniform stress distribution, 0.216 mm lateral displacement of crown, and 0.031 mm mid-palatal suture width increase. In MARPE model, the lateral displacement of crown was 0.267 mm, and mid-palatal suture width increased 0.315 mm. The maximum of mid-palatal suture expansion and stress distribution appeared in the middle region, and maxilla had tendency of counterclockwise rotation. The lateral changes of teeth and bones brought by MARPE were the most significant. Haas expander had some advantages in comparison with Hyrax.
使用三种快速上颌扩弓方法评估牙齿、牙槽骨和腭中缝的横向位移、应力分布及变化趋势。通过扫描一名志愿者的颅骨获取锥形束CT图像数据。使用Mimics和Geomagic Studio重建上颌复合体的三维模型，并使用ANSYS Workbench建立Hyrax扩弓器、Haas扩弓器和微螺钉辅助快速腭扩弓器（MARPE）的模型。评估牙齿、牙槽骨和腭中缝的应力分布、位移及变化趋势。Hyrax扩弓器使牙冠产生0.105 mm的侧向位移，腭中缝宽度增加0.022 mm，上颌出现楔状开口和顺时针旋转趋势。Haas扩弓器产生均匀的应力分布，牙冠侧向位移0.216 mm，腭中缝宽度增加0.031 mm。在MARPE模型中，牙冠侧向位移为0.267 mm，腭中缝宽度增加0.315 mm。腭中缝扩张和应力分布的最大值出现在中部区域，上颌有逆时针旋转趋势。MARPE引起的牙齿和骨骼的侧向变化最为显著。与Hyrax相比，Haas扩弓器具有一些优势。
