Graduate student, Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan Republic of China.
Associate Professor, Department of Mold and Die Engineering, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan Republic of China.
J Prosthet Dent. 2019 Oct;122(4):376-382. doi: 10.1016/j.prosdent.2018.10.008. Epub 2019 Apr 1.
A unidiameter abutment attached to a large-diameter implant has been reported to result in an unexpectedly high failure rate, inconsistent with the general understanding of dental implant mechanics.
The purpose of this finite element analysis study was to investigate the mechanical mechanism underlying these unexpected failures with the hypothesis that the cold welding or interference fit interface between abutment and implant increases the failure probability of a large-diameter implant system with a unidiameter abutment.
A conical implant system with different abutment gingival heights and implant diameters was analyzed for 3 contact conditions of the abutment-implant interface (bond and frictional coefficients of 0.3 and 0.7). A computer model was created using computed tomography images, and an oblique load of 100 N was applied to the abutment to determine the mechanical effect of the implant diameter and gingival height under the 3 contact conditions.
When the abutment-implant interface was bonded, the peak stress of the abutment increased and that of the bone decreased with increasing implant diameter. When friction was applied to the abutment-implant interface, the peak stress of the implant, screw, and bone decreased with increasing implant diameter. Furthermore, the peak stress of the implant system and bone increased when the abutment gingival height increased under all contact conditions.
Cold wielding or interference fit at the abutment-implant interface can prevent a screw fracture; however, it puts high stress on the unidiameter abutment neck when the implant diameter is increased. Screw loosening may lead to a slide between the abutment and implant, considerably increasing the stress of the screw. A system with a narrow diameter implant may cause an implant fracture rather than an abutment fracture when friction is applied to the abutment-implant interface.
已报道，与大直径种植体相连的单直径基台会导致出乎意料的高失败率，这与人们对牙科种植体力学的普遍理解不一致。
本有限元分析研究的目的是探讨这些意外失败的力学机制，并提出假设，即基台和种植体之间的冷焊接或过盈配合界面会增加大直径种植体系统中单直径基台的失败概率。
分析了不同基台牙龈高度和种植体直径的圆锥形种植体系统，共分析了 3 种基台-种植体界面接触条件（粘结和摩擦系数分别为 0.3 和 0.7）。使用计算机断层扫描图像创建计算机模型，并在基台上施加 100 N 的斜向载荷，以确定 3 种接触条件下种植体直径和牙龈高度对种植体的力学影响。
当基台-种植体界面粘结时，随着种植体直径的增加，基台的峰值应力增加，而骨的峰值应力降低。当基台-种植体界面施加摩擦力时，随着种植体直径的增加，种植体、螺钉和骨的峰值应力降低。此外，在所有接触条件下，随着基台牙龈高度的增加，种植体系统和骨的峰值应力增加。
基台-种植体界面的冷焊接或过盈配合可以防止螺钉断裂；然而，当种植体直径增加时，它会使单直径基台颈部承受高应力。螺钉松动可能导致基台和种植体之间发生滑动，从而大大增加螺钉的应力。当在基台-种植体界面施加摩擦力时，与小直径种植体系统相比，大直径种植体系统可能导致种植体断裂而不是基台断裂。
