title: Micromotion and stress distribution of immediate loaded implants: a finite element analysis.
abstract: BACKGROUND
  Primary stability and micromotion of the implant fixture is mostly influenced by its macrodesign.
  
  
  OBJECTIVE
  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 microm) than Xive (284 microm). ILS exhibited more favorable stress distribution. Maximum stress concentration found in periapical bone around Xive ( approximately 30 MPa) was lesser than Nisastan ( approximately 37 MPa).
  
  
  CONCLUSIONS
  Macrodesign of ILS leads to better primary stability and stress distribution. Maximum stress around Xive was less.
authors.affiliation: Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Fazel
authors.forename: S
authors.initials: S
authors.lastname: Aalai
authors.forename: M
authors.initials: M
authors.lastname: Rismanchian
authors.forename: P
authors.initials: P
authors.lastname: Sadr-Eshkevari
mesh_terms: D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology; D003198:Computer Simulation; D017076:Computer-Aided Design; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry; D017267:Dental Prosthesis Design; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008334:Mandible / Q000502:physiology; D008954:Models, Biological; D009068:Movement; D010781:Photography; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: D015921:Dental Implants; D003764:Dental Materials; D014025:Titanium