title: The effect of placement depth of platform-switched implants on periimplant cortical bone stress: a 3-dimensional finite element analysis.
abstract: OBJECTIVE
  The purpose of this study was to evaluate periimplant bone stress distribution for platform-switched implants placed at different depths relative to the bone crest, maintaining the occlusal plane at the same level.
  
  
  METHODS
  Sections of posterior mandibular bone blocks comprising cortical and cancellous bones were simulated in a computer-aided design software. A platform-switched implant was simulated and placed at 1.0 mm supracrestal to 1.8 mm subcrestal positions at 0.1 mm intervals. All bone and implant materials were presumed to be homogenous and isotropic. Conical gold crowns were designed for each model, maintaining the occlusal plane at the same level. Models were analyzed under axial and nonaxial loads.
  
  
  RESULTS
  Cortical bone stress increased only slightly from equicrestal to 0.8 mm subcrestal positions, whereas supracrestal and deeper subcrestal positions resulted in higher stress values. Subcrestal positions showed maximum stress concentration away from crestal bone.
  
  
  CONCLUSIONS
  It can be concluded that shallow subcrestal placement of 2-stage platform-switched implants only slightly increases the stress within the cortical bone.
authors: Dental Implants Research Center, Department of Prosthodontics, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: Mansour
authors: M
authors: Rismanchian
authors: Navid
authors: N
authors: Askari
authors: Soufia
authors: S
authors: Shafiei
mesh_terms: D000497:Alloys; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D017076:Computer-Aided Design; D003442:Crowns; D003722:Dental Alloys / Q000737:chemistry; D059605:Dental Implant-Abutment Design; D003758:Dental Implantation, Endosseous / Q000379:methods; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry; D019094:Dental Prosthesis, Implant-Supported; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008334:Mandible / Q000473:pathology / Q000601:surgery*; D008954:Models, Biological; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry
chemical_list: D000497:Alloys; D003722:Dental Alloys; D015921:Dental Implants; D003764:Dental Materials; D006047:Gold Alloys; C031462:titanium alloy (TiAl6V4); D014025:Titanium