J Dent Rehabil Appl Sci.  2019 Sep;35(3):132-142. 10.14368/jdras.2019.35.3.132.

Finite element analysis of the effect of novel Lock Screw system preventing abutment screw loosening

• Im ES
• Kim JE
• Kim JH
• Park YB

• KMID: 2463622
• DOI: http://doi.org/10.14368/jdras.2019.35.3.132

Abstract

PURPOSE
The purpose of this finite element analysis study is to introduce the novel Lock screw system and analyze its mechanical property to see if it can prevent abutment screw loosening.
MATERIALS AND METHODS
The Lock screw is a component tightened on the inside of the implant abutment which applies compressive force to the abutment screw head. To investigate the effect, modeling was done using CAD program and it was analyzed by finite element analysis under various load conditions. First, the preload was measured according to the tightening torque of the abutment screw then it was compared with the theoretical value to verify the analytical model. The validated analytical model was then divided into those with no external load and those with 178 N, and the tightening torque of the lock screw was changed to 10, 20, 30 Ncm respectively to examine the property of stress distribution on the implant components.
RESULTS
Using Lock screw under various loading conditions did not produce equivalent stresses beyond the yield strength of the implant components. In addition, the axial load was increased at the abutment-abutment screw interface.
CONCLUSION
The use of Lock screw does not exert excessive stress on the implant components and may increase the frictional force between the abutment-abutment screw interface, thus it is considered to prevent loosening of the abutment screw.

Keyword

finite element analysis; abutment screw loosening; preload; friction force; axial loading

MeSH Terms

Finite Element Analysis*
Friction
Head
Torque

Figure

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  Fig. 1 Components of implant and Lock screw. (A) Fixture, (B) Abutment, (C) Abutment screw, (D) Lock screw, (E), (F) Finite element model

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  Fig. 2 Boundary condition.

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  Fig. 3 Axial load according to different tightening torque of Lock screw.

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  Fig. 4 von Mises stress distribution according to tightening torque of Lock screw. (A - D) No external load, (E - H) Under external load.

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  Fig. 5 Normal stress of abutment screw and abutmentabutment screw interface under external load.

Reference

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