title: Evaluation of "all-on-four" concept and alternative designs with 3D finite element analysis method.
abstract: OBJECTIVE
  The aim of the present study was to evaluate the effect of the forces on the implant and supporting alveolar ridge in "all on four" concept and alternative designs using finite element analysis.
  
  
  METHODS
  Different treatment alternatives with various implant designs were performed in an edentulous mandible. In Design 1, implants were placed according to "All-on-Four" concept; Design 2, two long (13 mm long, 4 mm diameter) and two short (7 mm long, 4 mm diameter) implants; Design 3, four long and two short implants; and Design 4, two long and four short implants were placed vertically. A force of 100 N for each tooth, a total of 300 N load was applied. Finite element analysis was used to evaluate and compare the different designs.
  
  
  RESULTS
  The stress concentration within the cortical bone was significantly higher than the trabecular bone around the neck of the implants. The maximum stress values were located around the cortical bone of the distal implant for all designs. The reduction in the number of implants did not diminish the success of the design.
  
  
  CONCLUSIONS
  In the presence of vertically resorbed posterior mandibula, although the "all on four" concept is a feasible approach clinically, short implants had decreased the amount of force transmitted to the supporting bone.
authors.affiliation: Department of Prosthetic Dentistry, Faculty of Dentistry, Cumhuriyet University, Sivas, Turkey.
authors.forename: Derya
authors.initials: D
authors.lastname: Özdemir Doğan
authors.forename: Nilufer Tulin
authors.initials: NT
authors.lastname: Polat
authors.forename: Serkan
authors.initials: S
authors.lastname: Polat
authors.forename: Emre
authors.initials: E
authors.lastname: Şeker
authors.forename: Esma Başak
authors.initials: EB
authors.lastname: Gül
mesh_terms: D000539:Alveolar Process / Q000473:pathology; D001696:Biomechanical Phenomena; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D007575:Jaw, Edentulous / Q000534:rehabilitation; D008334:Mandible / Q000000981:diagnostic imaging* / Q000601:surgery; D011857:Radiographic Image Interpretation, Computer-Assisted; D012984:Software; D014057:Tomography, X-Ray Computed
chemical_list: D015921:Dental Implants