Department of Mechanical Engineering, Yildiz Technical University, Yildiz, Istanbul, Turkey.
Faculty of Dentistry, Department of Orthodontics, Akdeniz University, Antalya, Turkey.
Comput Methods Biomech Biomed Engin. 2024 Jan-Mar;27(1):56-66. doi: 10.1080/10255842.2023.2170712. Epub 2023 Feb 1.
Skeletal orthopedic expansion of maxilla is accepted as a reliable method for the treatment of transverse maxillar deficiency in growing patients. The aim of the study was to evaluate the effects of different palatal distractor positions on the expansion, stress and displacement patterns of the structures of craniofacial complex in surgical assisted rapid maxillary expansion without pterygomaxillary disjunction (PTMD) with the help of finite element analysis(FEA). Four facial skeleton models with different distractor positions (first premolar, second premolar, first molar, second molar regions) were created. In all finite element models median and lateral osteotomies were performed, without PTMD. Stress distribution was evaluated after 5 mm activation of the transpalatal distraction in all models using the nonlinear solution method in FEA. Unilateral displacement(mm) and stress distribution(MPa) were measured in three directions (x, y, and z axes) of craniofacial and maxillofacial structures in the symmetrical finite element models. In all models, the unilateral transverse displacements of the anterior teeth were greater than those of the posterior teeth, and the greatest displacement was at the central incisor level. The greatest displacement values at the central incisor level, at the anterior nasal spine(ANS) and at the posterior nasal spine(PNS) levels was measured in Model-IV, III, II and I, respectively. Mean elemental stress(von Mises stress) in the medial pterygoid plate, screw and lateral pterygoid plate regions from highest to lowest was measured in Model-IV, III, II and I, respectively. The maxilla performed outward rotation and tipping movement in all models during the expansion period. Among the distractor positions, the second molar region was found to be the most advantageous one in terms of expansion pattern. Considering the patient's anatomy and clinical conditions, placing the palatal distractor as posteriorly as possible will result in more effective maxillary expansion.
上颌骨的骨骼矫形扩展被认为是治疗生长患者横向上颌骨不足的可靠方法。本研究旨在借助有限元分析（FEA）评估不同腭部牵开器位置对上颌骨手术辅助快速扩展（不进行翼上颌分离）中颅面复合体结构的扩展、应力和位移模式的影响。创建了四个具有不同牵开器位置（第一前磨牙、第二前磨牙、第一磨牙、第二磨牙区域）的面骨模型。在所有有限元模型中，均进行了正中及侧方截骨术，而不进行翼上颌分离。在所有模型中，使用非线性求解方法在经腭骨牵开器激活 5mm 后评估应力分布。在对称有限元模型中，在三个方向（x、y 和 z 轴）测量颅面和颌面结构的单侧位移（mm）和应力分布（MPa）。在所有模型中，前牙的单侧横向位移大于后牙，最大位移位于中切牙水平。在前切牙水平、前鼻棘（ANS）和后鼻棘（PNS）水平，最大位移值分别在模型 IV、III、II 和 I 中测量。在翼内板、螺钉和翼外板区域的平均元素应力（von Mises 应力）从高到低分别在模型 IV、III、II 和 I 中测量。在上颌骨扩展期间，所有模型中上颌均发生向外旋转和倾斜运动。在牵开器位置中，第二磨牙区域在扩展模式方面被认为是最有利的位置。考虑到患者的解剖结构和临床情况，尽可能将腭部牵开器放置在更靠后的位置将导致更有效的上颌骨扩展。
