Finite-element analysis of stress on dental implant prosthesis.
BACKGROUND
Understanding how clinical variables affect stress distribution facilitates optimal prosthesis design and fabrication and may lead to a decrease in mechanical failures as well as improve implant longevity.


OBJECTIVE
In this study, the many clinical variations present in implant-supported prosthesis were analyzed by 3-D finite element method.


METHODS
A geometrical model representing the anterior segment of a human mandible treated with 5 implants supporting a framework was created to perform the tests. The variables introduced in the computer model were cantilever length, elastic modulus of cancellous bone, abutment length, implant length, and framework alloy (AgPd or CoCr). The computer was programmed with physical properties of the materials as derived from the literature, and a 100N vertical load was used to simulate the occlusal force. Images with the fringes of stress were obtained and the maximum stress at each site was plotted in graphs for comparison.


RESULTS
Stresses clustered at the elements closest to the loading point. Stress increase was found to be proportional to the increase in cantilever length and inversely proportional to the increase in the elastic modulus of cancellous bone. Increasing the abutment length resulted in a decrease of stress on implants and framework. Stress decrease could not be demonstrated with implants longer than 13 mm. A stiffer framework may allow better stress distribution.


CONCLUSIONS
The relative physical properties of the many materials involved in an implant-supported prosthesis system affect the way stresses are distributed.
Rubo
José Henrique
JH
Department of Prosthodontics, Bauru School of Dentistry, University of São Paulo, Bauru, SP, Brazil. jrubo@fob.usp.br
Capello Souza
Edson Antonio
EA
D001732:Bite Force; D015519:Bone Density; D003198:Computer Simulation; D000044:Dental Abutments; D003722:Dental Alloys; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D003799:Dental Stress Analysis / Q000379:methods*; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D007568:Jaw / Q000033:anatomy & histology / Q000502:physiology; D008954:Models, Biological
D003722:Dental Alloys; D015921:Dental Implants