J Adv Prosthodont.  2016 Apr;8(2):131-136. 10.4047/jap.2016.8.2.131.

Effects of crown retrieval on implants and the surrounding bone: a finite element analysis

• Ozkir SE
• Unal SM
• Yurekli E
• Güven S

• KMID: 2176653
• DOI: http://doi.org/10.4047/jap.2016.8.2.131

Abstract

PURPOSE
The aim of this study was to observe stress concentration in the implant, the surrounding bone, and other components under the pull-out force during the crown removal.
MATERIALS AND METHODS
Two 3-dimensional models of implant-supported conventional metal ceramic crowns were digitally constructed. One model was designed as a vertically placed implant (3.7 mm × 10 mm) with a straight abutment, and the other model was designed as a 30-degree inclined implant (3.7 mm × 10 mm) with an angled abutment. A pull-out force of 40 N was applied to the crown. The stress values were calculated within the dental implant, the abutment, the abutment screw, and the surrounding bone.
RESULTS
The highest stress concentration was observed at the coronal portion of the straight implant (9.29 MPa). The stress concentrations at the cortical bone were lower than at the implants, and maximum stress concentration in bone structure was 1.73 MPa. At the abutment screws, the stress concentration levels were similiar (3.09 MPa and 3.44 MPa), but the localizations were different. The stress at the angled abutment was higher than the stress at the straight abutment.
CONCLUSION
The pull-out force, applied during a crown removal, did not show an evident effect in bone structure. The higher stress concentrations were mostly observed at the implant and the abutment collar. In addition, the abutment screw, which is the weakest part of an implant system, also showed stress concentrations. Implant angulation affected the stress concentration levels and localizations. CLINICAL IMPLICATIONS: These results will help clinicians understand the mechanical behavior of cement-retained implant-supported crowns during crown retrieval.

Keyword

Implant; FEA; Retrievability; Crown

MeSH Terms

Ceramics
Crowns*
Dental Implants
Finite Element Analysis*
Ceramics
Dental Implants

Figure

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  Fig. 1 Stress concentrations (in Pa) on the implant collar of the straight abutment. The highest stress values were observed in this portion.

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  Fig. 2 Stress concentrations (in Pa) on the abutment screw of the straight abutment. The stress was concentrated on the 1/3 apical portion of the screw.

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  Fig. 3 Stress concentrations (in Pa) on the straight abutment.

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  Fig. 4 Stress concentrations (in Pa) in the surrounding bone.

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  Fig. 5 Stress concentrations (in Pa) on the implant collar of the angled abutment.

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  Fig. 6 Stress concentrations (in Pa) on the abutment screw of the angled abutment. The stress was concentrated on the 1/3 coronal portion of the screw.

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  Fig. 7 Stress concentrations (in Pa) on the angled abutment.

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  Fig. 8 Stress concentrations (in Pa) in the surrounding bone of the inclined implant.

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