Department of Clinical Sciences and Translational Medicine, University of Rome 'Tor Vergata', Via Collazia 29, 00183, Rome, Italy.
Department of Dentistry UNSBC, Tirana, Albania.
BMC Oral Health. 2019 Feb 13;19(1):31. doi: 10.1186/s12903-019-0724-6.
Maxillary protraction with facemask (FM) is an orthopedic approach for treatment of Class III growing patients. Aim of the present investigation was to analyze tension loads produced by two different facial mask (FM) designs on facial skin of subject with skeletal Class III.
A three-dimensional (3D) geometry of Delaire and Petit FM models were reconstructed from the original Computer Aided Design (CAD) 3D prototype using software package (ANSYS 5.7). A traction load of 9.8 N inclined of 30° to the occlusal plane was applied combining analytical FM models with a 3D facial model. Resulting stresses and deformations on the skin layer were tested through the von Mises yield criterion.
Overall tensions were mostly developed on the chin area, while lower stresses were observed on forehead area for both FM designs. When Delaire FM model was tested, maximum stresses were observed on the upper border of the chin cup corresponding to the inferior lip and to marginal gingiva of lower incisors. After Petit FM application, maximum stresses were more extensively localized at the level of both upper border and central area of the chin. Stresses measured on the chin area were significantly higher with Petit FM when compared with Delaire FM (44 KPa versus 29 KPa, respectively).
Delaire FM determined lower stresses and tensile tensions than Petit FM model. Highest tensions were observed at the level of chin cup area for both Delaire and Petit FM. Stresses following Delaire FM application were mostly observed on the upper border of the chin cup, while Petit FM determined stresses more extensively distributed to the central area of the chin.
上颌骨牵引面具（FM）是治疗 III 类生长患者的一种矫形方法。本研究旨在分析两种不同面弓（FM）设计对上颌骨 III 类骨骼患者面部皮肤产生的张力负荷。
使用软件包（ANSYS 5.7）从原始计算机辅助设计（CAD）3D 原型重建 Delaire 和 Petit FM 模型的三维（3D）几何形状。将 9.8N 的牵引负荷以 30°的角度倾斜于咬合平面施加于分析 FM 模型与 3D 面部模型相结合。通过 von Mises 屈服准则测试皮肤层上的应变和变形。
两种 FM 设计的整体张力主要集中在下颌区域，而前额区域的张力较低。当测试 Delaire FM 模型时，最大的应力出现在下巴杯的上边缘，对应于下唇和下切牙的边缘牙龈。应用 Petit FM 后，最大的应力更广泛地集中在下巴的上边缘和中央区域。与 Delaire FM 相比，Petit FM 在下巴区域测量的应力明显更高（分别为 44KPa 和 29KPa）。
Delaire FM 确定的应力和拉伸张力低于 Petit FM 模型。对于 Delaire 和 Petit FM，最高的张力出现在下巴杯区域。Delaire FM 应用后的应力主要出现在下巴杯的上边缘，而 Petit FM 则确定了更广泛分布于下巴中央区域的应力。
