title: Evaluation of Platform Switching on Crestal Bone Stress in Tapered and Cylindrical Implants: A Finite Element Analysis.
abstract: OBJECTIVE
  To analyze and compare the stress distribution around tapered and cylindrical implants and investigate how different abutment diameters influence crestal bone stress levels.
  
  
  METHODS
  Six finite element models of an abutment (5 mm, 4.3 mm, and 3.5 mm in diameter) and supporting implants (tapered and cylindrical) were designed. A vertical force of 100 N and a 15-degree oblique force of 100 N were applied separately on the occlusal surface, and von Misses stresses were evaluated in the cortical and cancellous bone.
  
  
  RESULTS
  Higher stress was observed under oblique loading than under vertical loading of both tapered and cylindrical implants. Tapered implants demonstrated more stress under both vertical and oblique loading. Platform switching reduced peri-implant crestal bone stress in all models under vertical and oblique forces. The peri-implant crestal bone around tapered implants experienced 4.8% more stress under vertical loading and 35% more stress under oblique loading in comparison to bone around cylindrical implants (2.62 MPa with vertical loading, 8.11 MPa under oblique loading). Oblique loads resulted in much higher stress concentrations in the peri-implant crestal bone than vertical loads (238% in cylindrical and 308% in tapered implants). When the abutment diameter decreased, both models showed reductions of stress in the crestal bone under both types of loading.
  
  
  CONCLUSIONS
  In this finite element analysis, tapered implants increased crestal bone stress upon loading, and platform switching minimized the stress transmitted to the crestal bone in both tapered and parallel wall implants.
authors.forename: Amir Alireza
authors.initials: AA
authors.lastname: Rasouli-Ghahroudi
authors.forename: Allahyar
authors.initials: A
authors.lastname: Geramy
authors.forename: Siamak
authors.initials: S
authors.lastname: Yaghobee
authors.forename: Afshin
authors.initials: A
authors.lastname: Khorsand
authors.forename: Hosnieh
authors.initials: H
authors.lastname: Yousefifakhr
authors.forename: Amirreza
authors.initials: A
authors.lastname: Rokn
authors.forename: Ahmad
authors.initials: A
authors.lastname: Soolari
mesh_terms: D000539:Alveolar Process / Q000502:physiology*; D001696:Biomechanical Phenomena; D001732:Bite Force; D003198:Computer Simulation; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D015921:Dental Implants; D017267:Dental Prosthesis Design; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008954:Models, Biological; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D015921:Dental Implants