Verri Fellippo Ramos, Santiago Joel Ferreira, Almeida Daniel Augusto, de Souza Batista Victor Eduardo, Araujo Lemos Cleidiel Aparecido, Mello Caroline Cantieri, Pellizzer Eduardo Piza
Int J Oral Maxillofac Implants. 2017 Jul/Aug;32(4):e191-e198. doi: 10.11607/jomi.5472.
The aim of this study was to use three-dimensional finite element analysis to analyze the stress distribution transferred by single implant-supported prostheses placed in the anterior maxilla using different connections (external hexagon, internal hexagon, or Morse taper), inclinations of the load (0, 30, or 60 degrees), and surgical techniques for placement (monocortical/conventional, bicortical, or bicortical with nasal floor elevation).
Nine models representing a bone block of this region were simulated by computer-aided design software (InVesalius, Rhinoceros, SolidWorks). Each model received one implant, which supported a cemented metalloceramic crown. Using FEMAP software, finite elements were discretized while simulating a 178-N load at 0, 30, and 60 degrees relative to the long axis of the implant. The problem was solved in NEi Nastran software, and postprocessing was performed in FEMAP. Von Mises stress and maximum principal stress maps were made.
The von Mises stress analysis revealed that stress increased with increasing inclination of the load, from 0 to 30 to 60 degrees. Morse taper implants showed less stress concentration around the cervical and apical areas of the implant. The bicortical technique, associated or not with nasal floor elevation, contributed to decreasing the stress concentration in the apical area of the implant. Maximum principal stress analysis showed that the increase in inclination was proportional to the increase in stress on the bone tissue in the cervical area. Lower stress concentrations in the cortical bone were obtained with Morse taper implants and the bicortical technique compared with other connections and surgical techniques, respectively.
Increasing the inclination of the applied force relative to the long axis of the implant tended to overload the peri-implant bone tissue and the internal structure of the implants. The Morse taper connection and bicortical techniques seemed to be more favorable than other connections or techniques, respectively, for restoring the anterior maxilla.
本研究旨在使用三维有限元分析，分析在上颌前部植入的单颗种植体支持的修复体，采用不同连接方式（外六角、内六角或莫氏锥度）、不同载荷倾斜度（0°、30°或60°）以及不同种植手术技术（单皮质/传统、双皮质或双皮质加鼻底提升）时所传递的应力分布情况。
通过计算机辅助设计软件（InVesalius、Rhinoceros、SolidWorks）模拟该区域的九块骨块模型。每个模型植入一颗种植体，其上支持一个粘结式金属烤瓷冠。使用FEMAP软件离散有限元，同时模拟相对于种植体长轴呈0°、30°和60°的178 N载荷。在NEi Nastran软件中求解该问题，并在FEMAP中进行后处理。绘制冯·米塞斯应力图和最大主应力图。
冯·米塞斯应力分析显示，随着载荷倾斜度从0°增加到30°再到60°，应力增大。莫氏锥度种植体在种植体颈部和根尖区域周围的应力集中较小。双皮质技术，无论是否联合鼻底提升，均有助于降低种植体根尖区域的应力集中。最大主应力分析表明，倾斜度的增加与颈部骨组织应力的增加成正比。与其他连接方式和手术技术相比，莫氏锥度种植体和双皮质技术分别在皮质骨中获得了更低的应力集中。
相对于种植体长轴增加作用力的倾斜度往往会使种植体周围骨组织和种植体内部结构过载。对于上颌前部修复，莫氏锥度连接和双皮质技术似乎分别比其他连接方式或技术更具优势。
