Villefort Regina Furbino, Tribst João Paulo Mendes, Dal Piva Amanda Maria de Oliveira, Borges Alexandre Luiz, Binda Nívia Castro, Ferreira Carlos Eduardo de Almeida, Bottino Marco Antonio, von Zeidler Sandra Lúcia Ventorim
Biotechnology Program, Federal University of Espírito Santo, Rede Nordeste de Biotecnologia (RENORBIO), Vitória, Espírito Santo, Brazil.
Post-Graduate Program in Restorative Dentistry (Prosthodontic), Department of Dental Materials and Prosthodontics, Institute of Science and Technology, São Paulo State University (Unesp/SJC), São José dos Campos, SP, Brazil.
PLoS One. 2020 Oct 30;15(10):e0241589. doi: 10.1371/journal.pone.0241589. eCollection 2020.
Implant-retained custom-milled framework enhances the stability of palatal obturator prostheses. Therefore, to evaluate the mechanical response of implant-retained obturator prostheses with bar-clip attachment and milled bars, in three different materials under two load incidences were simulated. A maxilla model which Type IIb maxillary defect received five external hexagon implants (4.1 x 10 mm). An implant-supported palatal obturator prosthesis was simulated in three different materials: polyetheretherketone (PEEK), titanium (Ti:90%, Al:6%, V:4%) and Co-Cr (Co:60.6%, Cr:31.5%, Mo:6%) alloys. The model was imported into the analysis software and divided into a mesh composed of nodes and tetrahedral elements. Each material was assumed isotropic, elastic and homogeneous and all contacts were considered ideal. The bone was fixed and the load was applied in two different regions for each material: at the palatal face (cingulum area) of the central incisors (100 N magnitude at 45°); and at the occlusal surface of the first left molar (150 N magnitude normal to the surface). The microstrain and von-Mises stress were selected as criteria for analysis. The posterior load showed a higher strain concentration in the posterior peri-implant tissue, near the load application side for cortical and cancellous bone, regardless the simulated material. The anterior load showed a lower strain concentration with reduced magnitude and more implants involving in the load dissipation. The stress peak was calculated during posterior loading, which 77.7 MPa in the prosthetic screws and 2,686 με microstrain in the cortical bone. For bone tissue and bar, the material stiffness was inversely proportional to the calculated microstrain and stress. However, for the prosthetic screws and implants the PEEK showed higher stress concentration than the other materials. PEEK showed a promising behavior for the bone tissue and for the integrity of the bar and bar-clip attachments. However, the stress concentration in the prosthetic screws may represent an increase in failure risk. The use of Co-Cr alloy can reduce the stress in the prosthetic screw; however, it increases the bone strain; while the Titanium showed an intermediate behavior.
种植体固位的定制铣削框架可增强腭部阻塞器假体的稳定性。因此，为了评估采用杆夹式连接和铣削杆的种植体固位阻塞器假体在三种不同材料、两种加载情况下的力学响应，进行了模拟。一个患有IIb型上颌骨缺损的上颌骨模型植入了5颗外六角种植体（4.1×10毫米）。模拟了三种不同材料的种植体支持的腭部阻塞器假体：聚醚醚酮（PEEK）、钛合金（Ti:90%，Al:6%，V:4%）和钴铬合金（Co:60.6%，Cr:31.5%，Mo:6%）。将模型导入分析软件，并划分为由节点和四面体单元组成的网格。每种材料均假定为各向同性、弹性和均匀的，且所有接触均视为理想状态。骨组织固定，每种材料在两个不同区域施加载荷：在中切牙的腭面（切缘区）（大小为100 N，角度为45°）；以及在左上颌第一磨牙的咬合面（垂直于表面大小为150 N）。选择微应变和冯·米塞斯应力作为分析标准。无论模拟材料如何，后牙加载时在种植体周围后部组织中，靠近皮质骨和松质骨的载荷施加侧显示出较高的应变集中。前牙加载时应变集中较低，大小减小，更多种植体参与载荷消散。在后牙加载过程中计算出应力峰值，在修复螺钉中为77.7 MPa，在皮质骨中为2686 με微应变。对于骨组织和杆，材料刚度与计算出的微应变和应力成反比。然而，对于修复螺钉和种植体，PEEK显示出比其他材料更高的应力集中。PEEK在骨组织以及杆和杆夹连接的完整性方面表现出良好的性能。然而，修复螺钉中的应力集中可能意味着失败风险增加。使用钴铬合金可降低修复螺钉中的应力；然而，它会增加骨应变；而钛合金表现出中间性能。
