J Korean Acad Prosthodont.  2012 Jan;50(1):36-43.

Evaluation of the stress distribution in the external hexagon implant system with different hexagon height by FEM-3D

• Park SJ
• Kim JH
• Kim SY
• Yun MJ
• Ko SM
• Huh JB

Abstract

PURPOSE
To analyze the stress distribution of the implant and its supporting structures through 3D finite elements analysis for implants with different hexagon heights and to make the assessment of the mechanical stability and the effect of the elements.
MATERIALS AND METHODS
Infinite elements modeling with CAD data was designed. The modeling was done as follows; an external connection type Phi 4.0 mm x11.5 mm Osste(R) USII (Osstem Co., Pusan, Korea) implant system was used, the implant was planted in the mandibular first molar region with appropriate prosthetic restoration, the hexagon (implant fixture's external connection) height of 0.0, 0.7, 1.2, and 1.5 mm were applied. ABAQUS 6.4 (ABAQUS, Inc., Providence, USA) was used to calculate the stress value. The force distribution via color distribution on each experimental group's implant fixture and titanium screw was studied based on the equivalent stress (von Mises stress). The maximum stress level of each element (crown, implant screw, implant fixture, cortical bone and cancellous bone) was compared.
RESULTS
The hexagonal height of the implant with external connection had an influence on the stress distribution of the fixture, screw and upper prosthesis and the surrounding supporting bone. As the hexagon height increased, the stress was well distributed and there was a decrease in the maximum stress value. If the height of the hexagon reached over 1.2 mm, there was no significant influence on the stress distribution.
CONCLUSION
For implants with external connections, a hexagon is vital for stress distribution. As the height of the hexagon increased, the more effective stress distribution was observed.

Keyword

Finite element; Dental implant; External hexagon; Abutment screw

MeSH Terms

Dental Implants
Molar
Plants
Prostheses and Implants
Titanium
Dental Implants
Titanium

Figure

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  Fig. 1 Schematic representation of models.

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  Fig. 2 Schematic representation of experimental model (Unit; mm).

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  Fig. 3 Reference points of cervical portion. A: implant area with shearing force at cervix, B: cortical bone area with shearing force at cervix, C: implant area with compressive force at cervix, D: cortical bone area with compressive force at cervix.

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  Fig. 4 The stress contour in model. A: hexagonal height 0.0 mm, B: hexagonal height 0.7 mm, C: hexagonal height 1.2 mm, D: hexagonal height 1.5 mm.

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  Fig. 5 von Mises stresses in the fixture and abutment screw under hexagonal height. A: hexagonal height 0.0 mm, B: hexagonal height 0.7 mm, C: hexagonal height 1.2 mm, D: hexagonal height 1.5 mm.

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  Fig. 6 The stress contour of the bone under hexagonal height. A: hexagonal height 0.0 mm, B: hexagonal height 0.7 mm, C: hexagonal height 1.2 mm, D: hexagonal height 1.5 mm.

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  Fig. 7 The stress contour of the fixture under hexagonal height. A: hexagonal height 0.0 mm, B: hexagonal height 0.7 mm, C: hexagonal height 1.2 mm, D: hexagonal height 1.5 mm.

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  Fig. 8 The stress contour of the titanium screw under hexagonal height. A: hexagonal height 0.0 mm, B: hexagonal height 0.7 mm, C: hexagonal height 1.2 mm, D: hexagonal height 1.5 mm.

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