Stress and strain patterns of 1-piece and 2-piece implant systems in bone:  a 3-dimensional finite element analysis.
BACKGROUND
The transition from implant to abutment is solid in 1-piece (1P) and broken in 2-piece (2P) implant designs. This difference may affect occlusal load distribution and marginal bone response.


OBJECTIVE
To determine whether 1P and 2P implants with equivalent geometries exhibited stresses and strains differently under applied loading conditions.


METHODS
Design software simulated 1P and 2P implants restored with metal copings and embedded in 3 cylindrical bone block models that varied in dimensions, density, and percentage of bone-to-implant contact. Three-dimensional, finite element analysis simulated occlusal loading. Experiments evaluated stresses and strains relative to implant design and (1) periimplant bone thickness, (2) cortical bone thickness, (3) magnitude and direction of occlusal loading, and (4) % bone-to-implant contact.


RESULTS
Implants with equivalent dimensions exhibited comparable stresses and strains in all experimental conditions. Implant diameter and periimplant bone thickness influenced stress levels. Only small-diameter (3.0 mm) 1P implants in low-density bone exhibited stress levels that might adversely affect marginal bone stability.


CONCLUSIONS
Implant diameter and periimplant bone thickness influenced load distribution in bone, but the type of implant-abutment transition had no significant effect. Small-diameter 1P implants should be limited to dense bone to minimize stress concentrations.
Department of Oral Rehabilitation, The Maurice and Gabriela Goldschleger School of Dental Medicine, University of Tel Aviv, Tel Aviv, Israel. drzeev@ormianer.com
Zeev
Z
Ormianer
Arial
A
Ben Amar
Mariusz
M
Duda
Sharon
S
Marku-Cohen
Israel
I
Lewinstein
D001696:Biomechanical Phenomena; D001732:Bite Force; D015519:Bone Density; D003198:Computer Simulation; D000044:Dental Abutments; D015921:Dental Implants; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis / Q000379:methods*; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D016348:Osseointegration; D013314:Stress, Mechanical
D015921:Dental Implants