title: A three-dimensional finite element study on the stress distribution pattern of two prosthetic abutments for external hexagon implants.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the mechanical behavior of two different straight prosthetic abutments (one- and two-piece) for external hex butt-joint connection implants using three-dimensional finite element analysis (3D-FEA).
  
  
  METHODS
  Two 3D-FEA models were designed, one for the two-piece prosthetic abutment (2 mm in height, two-piece mini-conical abutment, Neodent) and another one for the one-piece abutment (2 mm in height, Slim Fit one-piece mini-conical abutment, Neodent), with their corresponding screws and implants (Titamax Ti, 3.75 diameter by 13 mm in length, Neodent). The model simulated the single restoration of a lower premolar using data from a computerized tomography of a mandible. The preload (20 N) after torque application for installation of the abutment and an occlusal loading were simulated. The occlusal load was simulated using average physiological bite force and direction (114.6 N in the axial direction, 17.1 N in the lingual direction and 23.4 N toward the mesial at an angle of 75° to the occlusal plan).
  
  
  RESULTS
  The regions with the highest von Mises stress results were at the bottom of the initial two threads of both prosthetic abutments that were tested. The one-piece prosthetic abutment presented a more homogeneous behavior of stress distribution when compared with the two-piece abutment.
  
  
  CONCLUSIONS
  Under the simulated chewing loads, the von Mises stresses for both tested prosthetic-abutments were within the tensile strength values of the materials analyzed which thus supports the clinical use of both prosthetic abutments.
authors.affiliation: Department of Prosthodontics, Latin American Institute of Dental Research and Education, ILAPEO, Curitiba, Paraná, Brazil.|PhD Student, São Leopoldo Mandic College, Campinas, São Paulo, Brazil.
authors.forename: Wagner
authors.initials: W
authors.lastname: Moreira
authors.affiliation: Department of Prosthodontics, Latin American Institute of Dental Research and Education, ILAPEO, Curitiba, Paraná, Brazil.
authors.forename: Caio
authors.initials: C
authors.lastname: Hermann
authors.affiliation: Department of Mechanical Engineering, Federal University of Paraná, Curitiba, Paraná, Brazil.
authors.forename: Jucélio Tomás
authors.initials: JT
authors.lastname: Pereira
authors.affiliation: Department of Mechanical Engineering, Federal University of Paraná, Curitiba, Paraná, Brazil.
authors.forename: Jean Anacleto
authors.initials: JA
authors.lastname: Balbinoti
authors.affiliation: Department of Prosthodontics, Latin American Institute of Dental Research and Education, ILAPEO, Curitiba, Paraná, Brazil.|Department of Odontotécnica, Niterói School of Dentistry, Fluminense Federal University, Niterói, Rio de Janeiro, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Tiossi
keywords: Dental implant-abutment interface; dental implants; finite element analysis; platform switching