School of Health and Life Sciences, Pontifical Catholic University of Rio Grande Doo Sul, Av. Ipiranga 6681, Predio 06 Bairro: Partenon, Porto Alegre, RS, 90619-900, Brazil.
Department of Oral Surgery, State University of Western Parana, Cascavel, Parana, Brazil.
Oral Maxillofac Surg. 2023 Dec;27(4):647-654. doi: 10.1007/s10006-022-01111-9. Epub 2022 Aug 15.
It is known that a correct transverse maxillary dimension is a key factor for a stable occlusion, which brings functional and esthetic benefits for the patient. In patients presenting maxillary atresia and the completion of bone growth, a highly recommended option for correction is the surgically assisted rapid maxillary expansion (SARME) associated with the Hyrax appliance. The objective of this study was to evaluate the influence of tooth anchorage variations of the Hyrax appliance in SARME through finite element analysis, evaluating which anchorage option might be associated with more effective orthopedic results with less undesired side effects.
Five different dental anchoring conditions for the Hyrax appliance were simulated through FE analysis applying premolars and molars as anchorage, having the same force applied by the activation of the Hyrax screw (0.5 mm) in all groups. The maxillary displacement results (axes X, Y, and Z) and generated stresses for both teeth and maxillary bone were calculated and represented using a color scale.
All groups presented significant bone displacement and stress concentration on anchoring teeth, with the group presenting anchorage in the 1st and 2nd molars showing the greatest maxillary horizontal displacement (axis X) and suggesting the lowest tendency of dental vestibular inclination.
Variations in dental anchorage might substantially affect the maxillary bone and teeth displacement outcome. The protocol for the Hyrax apparatus in SARME applying the 1st and 2nd molars as anchorage might generate less tilting and inclination of the anchoring teeth.
众所周知，正确的横向上颌尺寸是稳定咬合的关键因素，这为患者带来了功能和美观上的好处。对于上颌发育不全的患者，在骨骼生长完成后，推荐使用外科辅助快速上颌扩展（SARME）联合 Hyrax 矫治器进行矫正。本研究旨在通过有限元分析评估 Hyrax 矫治器的牙支抗变化对 SARME 的影响，评估哪种支抗选择可能与更有效的矫形效果相关，同时副作用更小。
通过有限元分析模拟了 Hyrax 矫治器的五种不同牙支抗条件，在前磨牙和磨牙上施加相同的支抗，通过激活 Hyrax 螺钉（0.5mm）在所有组中施加相同的力。计算并以颜色刻度表示上颌位移结果（X、Y 和 Z 轴）和牙齿及上颌骨产生的应力。
所有组均表现出明显的骨位移和支抗牙的应力集中，以第一和第二磨牙作为支抗的组表现出最大的上颌水平位移（X 轴），并提示牙齿前庭倾斜的趋势最低。
牙支抗的变化可能会显著影响上颌骨和牙齿的位移结果。在 SARME 中应用第一和第二磨牙作为支抗的 Hyrax 器械方案可能会产生较少的支抗牙倾斜和倾斜。
