Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran.
Department of Prosthodontics, Faculty of Dentistry, Islamic Azad University Isfahan (Khorasgan) Branch, Isfahan, Iran.
J Prosthodont. 2017 Jun;26(4):289-295. doi: 10.1111/jopr.12388. Epub 2015 Dec 14.
Depending on esthetic, anatomical, and functional aspects, in implant-prosthetic restoration of a completely edentulous jaw, the selection of implant type is highly important; however, bone- and tissue-level implants and their stress distribution in bone have not yet been comparatively investigated. Hence, finite element analysis was used to study the influence of cantilever length in a fixed prosthesis on stress distribution in peri-implant bone around these two types of oral implants.
A 3D edentulous mandible was modeled. In simulations, a framework with four posterior cantilever lengths and two types of implants, bone-level and tissue-level, was considered. A compressive load was applied to the distal regions of the cantilevers, and the von-Mises stress of peri-implant bone was investigated. The independent t-test and the Pearson correlation coefficient analyzed the results (α = 0.05).
Stresses in the cortical bone around the bone-level implants were greater than those in the tissue-level implants with the same cantilever length. In addition, by extending the cantilever length, the stress values in peri-implant bone increased. Therefore, when the cantilever was at its maximum length, the maximum stress was in cortical bone and around the bone-level distal implants.
The results of the present study indicate that treatment with tissue-level implants is potentially more advantageous than with bone-level implants for implant-supported fixed prostheses.
在全口无牙颌的种植 - 修复体中，根据美观、解剖和功能方面的要求，种植体类型的选择非常重要；然而，尚未对骨内和黏膜下种植体及其在骨内的应力分布进行比较研究。因此，本研究采用有限元分析来研究两种类型的口腔种植体周围固定义齿的悬臂长度对种植体周围骨的应力分布的影响。
建立了一个 3D 无牙颌下颌骨模型。在模拟中，考虑了具有四个后牙悬臂长度和两种类型的种植体（骨内和黏膜下）的支架。在悬臂的远端区域施加压缩载荷，并研究了种植体周围骨的 von-Mises 应力。采用独立样本 t 检验和 Pearson 相关系数分析结果（α = 0.05）。
骨内种植体周围皮质骨的应力大于相同悬臂长度的黏膜下种植体周围皮质骨的应力。此外，随着悬臂长度的延长，种植体周围骨的应力值增加。因此，当悬臂达到最大长度时，最大应力位于皮质骨和骨内种植体的远端。
本研究结果表明，对于种植体支持的固定义齿，黏膜下种植体治疗的潜在优势大于骨内种植体。
