Parametric analysis of the strength in the ''Toronto'' osseous-prosthesis system.
OBJECTIVE
The aim of this work is to analyze how the different distributions of the chewing load could be related to dental prosthesis fractures of the Toronto restoration via the fulfilment of a virtual parametric model. Moreover investigation about implant positions and perspectives in comparison with a virtual medial plane was made to evaluate the incidence of screw and prosthesis breakage.


METHODS
Finite element analysis of the lower jaw was performed to underline parameters and mechanical features of dental implants connected with the fractures of the prosthetic restoration. Jaw virtual model and 3D fixtures (Global Sweden and Martina) were created by Cosmos-Solid Works. Matlab was used to recreate the distribution of an unspecific chewing phase analyzing the overall load on the fixtures of the lower jaw.


RESULTS
Four virtual 3D models were performed with Matchad 14, for data analysis. The study investigated frontal and horizontal planes and vertical direction of the occlusal forces. Data results showed how position and perspective of fixtures strongly influenced the stress distribution upon the bone of the jaw; safeguard of prostheses elements like cantilever, passing screws, and dental implants are strictly related to a correct selection of the dental implant position.


CONCLUSIONS
The 3D geometry of the jaw is an important condition for the choice of position, number, diameter and length of dental implants used for Toronto prostheses. This study would suggest a virtual ''method'' to help the surgeon choosing a correct model for a prosthetic rehabilitation evaluating position, perspective, and stress distribution of the chewing strengths.
Cicciù
M
M
Department of Oral Surgery, I.C.P. Dental School University of Milan, Milan, Italy. acromarco@yahoo.it
Risitano
G
G
Maiorana
C
C
Franceschini
G
G
D016301:Alveolar Bone Loss / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D001732:Bite Force; D001863:Bone Screws; D003198:Computer Simulation; D017076:Computer-Aided Design; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D019544:Equipment Failure Analysis; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D007568:Jaw / Q000502:physiology; D008409:Mastication / Q000502:physiology*; D003765:Models, Dental