Stress patterns on implants in prostheses supported by four or six implants: a three-dimensional finite element analysis.
OBJECTIVE
Using the three-dimensional finite element method (FEM), this study compared the biomechanical behavior of the "All-on-Four" system with that of a six-implant-supported maxillary prosthesis with tilted distal implants. The von Mises stresses induced on the implants under different loading simulations were localized and quantified.


METHODS
Three-dimensional models representing maxillae restored with an "All-on-Four" and with a six-implant-supported prosthesis were developed in three-dimensional design software and then transferred into FEM software. The models were subjected to four different loading simulations (full mouth biting, canine disclusion, load on a cantilever, load in the absence of a cantilever). The maximum von Mises stresses were localized and quantified for comparison.


RESULTS
In both models, in all loading simulations, the peak stress points were always located on the neck of the distal tilted implant. The von Mises stress values were higher in the "All-on-Four" model (7% to 29%, higher, depending on the simulation). In the presence of a cantilever, the maximum von Mises stress values increased by about 100% in both models.


CONCLUSIONS
The stress locations and distribution patterns were similar in the two models. The addition of implants resulted in a reduction of the maximum von Mises stress values. The cantilever greatly increased the stress.
Silva
Guilherme Carvalho
GC
Department of Restorative Dentistry, School of Dentistry, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil. guilhermeccs@ufmg.br
Mendonça
José Alfredo
JA
Lopes
Luiza Randazzo
LR
Landre
Janés
J
D001641:Bicuspid; D001696:Biomechanical Phenomena; D001732:Bite Force; D003198:Computer Simulation; D003481:Cuspid; D000044:Dental Abutments; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003779:Denture Design; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008437:Maxilla / Q000473:pathology; D008954:Models, Biological; D012984:Software; D013314:Stress, Mechanical; D013499:Surface Properties
D015921:Dental Implants