Effects of abutment screw preload and preload simulation techniques on dental implant lifetime
Megha Satpathy, Rose M. Jose, Yuanyuan Duan, Jason A. Griggs
Abstract
Background: This study aimed to investigate how the predicted implant fatigue lifetime is affected by the loss of connector screw preload and the finite element analysis method used to simulate preload. Methods: A dental implant assembly (DI1, Biomet-3i external hex; Zimmer Biomet) was scanned using microcomputed tomography and measured using Mimics software (Materialise) and an optical microscope. Digital replicas were constructed using SolidWorks software (Dassault Systèmes). The material properties were assigned in Abaqus (Dassault Systèmes). An external load was applied at 30° off-axial loading. Eight levels of connector screw preload (range, 0-32 Ncm) were simulated for DI1. This assembly and an additional model (DI2) having a longer and narrower screw were compared regarding their fatigue limits (using fe-safe software [Dassault Systèmes]) for 2 preloading methods: (1) adding preload torque or (2) adding bolt axial tension. Results: s recommendation and dropped precipitously between 80% and 70% preload. Adding a preload torque on the screw resulted in a more uniform stress distribution on the screw compared with bolt axial tension, especially for DI2, which had a longer and narrower screw than DI1. Conclusions: A substantial loss of preload can be accommodated without compromising the fatigue resistance of this dental implant. Computer models should be constructed using torque instead of a bolt axial tension.