Comparison between all-on-four and all-on-six treatment concepts and framework material on stress distribution in atrophic maxilla: A prototyping guided 3D-FEA study

Published Date
Materials Science and Engineering: C
1 December 2016, Vol.69:715–725, doi:10.1016/j.msec.2016.07.059

Author 

• Cláudia Lopes Brilhante Bhering ^a
• Marcelo Ferraz Mesquita ^a
• Daniel Takanori Kemmoku ^b
• Pedro Yoshito Noritomi ^b
• Rafael Leonardo Xediek Consani ^a
• Valentim Adelino Ricardo Barão ^a,,,

• aDepartment of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Piracicaba, Sao Paulo, Brazil
• bRenato Archer Information Technology Center, Campinas, Sao Paulo, Brazil

Received 14 March 2016. Revised 14 June 2016. Accepted 20 July 2016. Available online 21 July 2016. 

Highlights

• •
  All-on-four and all-on-six concepts for the rehabilitation of maxilla were evaluated.
• •
  CoCr, Ti and Zr materials were used as framework materials.
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  Prototypes were successfully used to guide finite element model construction.
• •
  All-on-six approach and stiffer frameworks had favorable biomechanical behavior.
• •
  Ti framework and all-on-four concept had the most concerning results.

Abstract

We evaluated two treatment concepts for the rehabilitation of moderate atrophic maxilla with dental implants (all-on-four and all-on-six) and the effect of framework material on the stress distribution of implant-support system. A three-dimensional finite element model based on a prototype was built to simulate an entirely edentulous maxilla with moderate sinus pneumatization that was rehabilitated with a full-arch fixed dental prosthesis. Four standard implants were positioned according to the all-on-four concept and four standard implants and two short implants were placed according to the all-on-six concept. Three framework materials were evaluated: cobalt-chrome (CoCr), titanium (Ti) and zirconia (Zr), totalizing six groups. A unilateral oblique force of 150 N was applied to the posterior teeth. The von Mises (σ_VM), maximum (σ_max) and minimum (σ_min) principal stress and displacements were obtained. All-on-six showed smaller σ_min, σ_VM and σ_max values on the cortical bone, implants and trabecular bone, respectively. All-on-four exhibited higher displacement levels. Ti presented the highest stress values on the cortical bone, implants, abutments, prosthetic screws and displacement levels. In conclusion, the all-on-six approach and framework stiffer materials showed the most favorable biomechanical behavior. However, the stress values did not exceed the bone resistance limits for both treatment concepts.

Graphical abstract

Keywords

• All-on-four
• All-on-six
• Short implant
• Framework material
• Finite elements analysis

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  Corresponding author at: Av. Limeira, 901, Piracicaba, Sao Paulo 13414-903, Brazil.
  
  

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