Three-Dimensional Finite Element Analysis of Varying Diameter and Connection Type in Implants with High Crown-Implant Ratio

Abstract The aim of this study was to evaluate the effect of varying the diameter, connection type and loading on stress distribution in the cortical bone for implants with a high crown-implant ratio. Six 3D models were simulated with the InVesalius, Rhinoceros 3D 4.0 and SolidWorks 2011 software programs. Models were composed of bone from the posterior mandibular region; they included an implant of 8.5 mm length, diameter Ø 3.75 mm or Ø 5.00 mm and connection types such as external hexagon (EH), internal hexagon (IH) and Morse taper (MT). Models were processed using the Femap 11.2 and NeiNastran 11.0 programs and by using an axial force of 200 N and oblique force of 100 N. Results were recorded in terms of the maximum principal stress. Oblique loading showed high stress in the cortical bone compared to that shown by axial loading. The results showed that implants with a wide diameter showed more favorable stress distribution in the cortical bone region than regular diameter, regardless of the connection type. Morse taper implants showed better stress distribution compared to other connection types, especially in the oblique loading. Thus, oblique loading showed higher stress concentration in cortical bone tissue when compared with axial loading. Wide diameter implant was favorable for improved stress distribution in the cortical bone region, while Morse taper implants showed lower stress concentration than other connections.

摘要 本研究旨在评估高冠种植体比例的种植体，其直径、连接类型及载荷参数变化对皮质骨应力分布的影响。本研究采用InVesalius、Rhinoceros 3D 4.0及SolidWorks 2011三款软件构建6组三维模型。模型取材于下颌后区骨组织，包含长度为8.5mm、直径分别为Ø3.75mm与Ø5.00mm的种植体，连接方式涵盖外六角（external hexagon, EH）、内六角（internal hexagon, IH）与莫氏锥度（Morse taper, MT）三种类型。模型通过Femap 11.2与NeiNastran 11.0软件进行后处理，并分别施加200N轴向载荷与100N斜向载荷。本研究以最大主应力作为结果观测指标。相较于轴向载荷，斜向载荷下皮质骨的应力水平显著更高。结果表明，无论连接类型如何，宽直径种植体在皮质骨区域的应力分布均优于常规直径种植体。莫氏锥度种植体的应力分布表现优于其他连接类型，在斜向载荷工况下尤为突出。综上，相较于轴向载荷，斜向载荷下皮质骨组织的应力集中程度更高；宽直径种植体可有效改善皮质骨区域的应力分布，而莫氏锥度种植体的应力集中程度低于其他连接类型的种植体。