Department of Orthodontics and Dentofacial Orthopaedics, Maulana Azad Institute of Dental Sciences, 110002 New Delhi, India.
Department of Orthodontics and Dentofacial Orthopaedics, Maulana Azad Institute of Dental Sciences, 110002 New Delhi, India.
Int Orthod. 2023 Dec;21(4):100813. doi: 10.1016/j.ortho.2023.100813. Epub 2023 Sep 28.
Various designs of mini-implants assisted rapid palatal expander (MARPE) appliances can impact treatment effectiveness through their biomechanical effects. The purpose of the study was to study the stress distribution and displacement with four different designs of the MARPE appliance on the craniofacial complex.
A 3D finite element model of the craniofacial complex was created from CBCT DICOM data, comprising four distinct groups. Each group consisted of one 4-hole expansion screw positioned between the second premolar and first molar in all models. Group 1 used four single-cortical mini-implants (1.5×8mm) engaging only the palatal cortex. Group 2 employed four mini-implants (1.5×11mm) engaging both the palatal and nasal cortices. Group 3 had monocortical implants on the palatal slopes, while Group 4 was similar to group 3 with implants in the acrylic wings. Comparisons between groups were made for anchorage (groups 1 and 2), mini-implant position (groups 1 and 3) and surface effect (groups 3 and 4). Von Mises stresses and displacements at various skeletal and dental points were evaluated using ANSYS software.
The highest stresses were observed in the maxillary, pterygoid and zygomatic bones, as well as in the mid- palatal suture in all four groups. Downward and forward rotation of the craniofacial complex was noted. Group 2 showed greater skeletal expansion than group 1. Among groups 1 and 3, group 3 showed a better stress distribution. Group 4 showed less dentoalveolar rotation than group 3.
The MARPE appliances had an impact on the craniofacial complex with stresses on the mid-palatal suture, maxillary bone, pterygoid bones and anterior teeth. Clockwise rotation of the maxilla, zygomatic bones and dentition was noted, while the pterygoid bones and pterygoid suture were displaced backwards. MARPE with bicortical anchorage produces better skeletal expansion. Placing implants on the palatal slopes with acrylic wings results in better skeletal expansion with less clockwise rotation of the dentition.
微型种植体支抗快速腭扩展器（MARPE）的各种设计可以通过生物力学效应影响治疗效果。本研究的目的是研究四种不同设计的 MARPE 矫治器对上颌面部复合体的应力分布和位移。
从 CBCT DICOM 数据创建了一个包含四个不同组的颅面复合体的 3D 有限元模型。每个组都由一个位于所有模型中第二前磨牙和第一磨牙之间的四孔扩张螺钉组成。第 1 组使用四个仅与腭侧皮质结合的单皮质微型种植体（1.5×8mm）。第 2 组使用四个同时与腭侧和鼻侧皮质结合的微型种植体（1.5×11mm）。第 3 组在腭侧斜坡上有单皮质种植体，而第 4 组与第 3 组相似，种植体位于丙烯酸翼上。组间比较包括锚固（第 1 组和第 2 组）、微型种植体位置（第 1 组和第 3 组）和表面效应（第 3 组和第 4 组）。使用 ANSYS 软件评估各种骨骼和牙齿点的 Von Mises 应力和位移。
在四个组中，上颌骨、翼状骨和颧骨以及所有骨骼和牙齿点的中腭缝都观察到最高的应力。颅面复合体出现向下和向前旋转。第 2 组的骨骼扩张大于第 1 组。在第 1 组和第 3 组中，第 3 组显示出更好的应力分布。第 4 组的牙牙槽旋转小于第 3 组。
MARPE 矫治器对上颌面部复合体产生影响，在上腭缝、上颌骨、翼状骨和前牙上产生应力。观察到上颌骨、颧骨和牙齿的顺时针旋转，而翼状骨和翼状缝向后移位。具有双皮质锚固的 MARPE 产生更好的骨骼扩张。在带有丙烯酸翼的腭侧斜坡上放置种植体可实现更好的骨骼扩张，同时减少牙齿的顺时针旋转。
