Micromotion and Stress Distribution of Immediate Loaded Implants: A Finite Element Analysis

Background: Primary stability and micromotion of the implant fixture is mostly influenced by its macrodesign. Purpose: To assess and compare the peri-implant stress distribution and micromotion of two types of immediate loading implants, immediate loaded screw (ILS) Nisastan and Xive (DENTSPLY/Friadent, Monnheim, Germany), and to determine the best macrodesign of these two implants by finite element analysis. Methods: In this experimental study, the accurate pictures of two fixtures (ILS: height = 13, diameter = 4 mm and Xive: height = 13, diameter = 3.8 mm) were taken by a new digital camera (Nikon Coolpix 5700 [Nikon, Japan], resolution = 5.24 megapixel, lens = 8x optical, 4x digital zoom). Following accurate measurements, the three-dimensional finite element computer model was simulated and inserted in simulated mandibular bone (D-2) in SolidWorks 2003 (SolidWork Corp., MA, USA) and Ansys 7.1 (Ansys, Inc., Canonsburg, PA, USA). After loading (500 N, 75 degrees above horizon), the displacement was displayed and von Mises stress was recorded. Results: It was found that the primary stability of ILS was greater (152 mu m) than Xive (284 mu m). ILS exhibited more favorable stress distribution. Maximum stress concentration found in periapical bone around Xive (approximate to 30 MPa) was lesser than Nisastan (approximate to 37 MPa). Conclusions: Macrodesign of ILS leads to better primary stability and stress distribution. Maximum stress around Xive was less.