J Adv Prosthodont.  2016 Aug;8(4):304-312. 10.4047/jap.2016.8.4.304.

A two-short-implant-supported molar restoration in atrophic posterior maxilla: A finite element analysis

• Song HY
• Huh YH
• Park CJ
• Cho LR

• KMID: 2349339
• DOI: http://doi.org/10.4047/jap.2016.8.4.304

Abstract

PURPOSE
The aim of this study was to investigate the stress distribution of 2-short implants (2SIs) installed in a severely atrophic maxillary molar site.
MATERIALS AND METHODS
Three different diameters of internal connection implants were modeled: narrow platform (NP), regular platform (RP), and wide platform (WP). The maxillary first molars were restored with one implant or two short implants. Three 2SI models (NP-oblique, NP-vertical, and NP-horizontal) and four single implant models (RP and WP in a centered or cantilevered position) were used. Axial and oblique loadings were applied on the occlusal surface of the crown. The von Mises stress values were measured at the bone-implant, peri-implant bone, and implant/abutment complex.
RESULTS
The highest stress distribution at the bone-implant interface and the peri-implant bone was noticed in the RP group, and the lowest stress distribution was observed in the 2SI groups. Cantilevered position showed unfavorable stress distribution with axial loading. 2SI types did not affect the stress distribution in oblique loading. The number and installation positions of the implant, rather than the bone level, influenced the stress distribution of 2SIs. The implant/abutment complex of WP presented the highest stress concentration while that of 2SIs showed the lowest stress concentration.
CONCLUSION
2SIs may be useful for achieving stable stress distribution on the surrounding bone and implant-abutment complex in the atrophic posterior maxilla.

Keyword

Bone level; Finite element analysis; Implant diameter; Short implant

MeSH Terms

Bone-Implant Interface
Crowns
Finite Element Analysis*
Maxilla*
Molar*

Figure

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  Fig. 1 Two short implants (2SI) supporting single molar restoration in atrophic posterior maxilla. (A) Buccal and palatal positioned implants, (B) Customized abutment on 2SI, (C) Definitive single crown, (D) Panoramic radiographs of 2SI.

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  Fig. 2 Schematic diagram of implant inserted in maxillary first molar area. (A) Buccal view, (B) Mesial view.

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  Fig. 3 Configurations of models. (A) NP-oblique, (B) NP-vertical, (C) NP-horizontal, (D) RP-cantilever, (E) WP-cantilever, (F) RP-center, (G) WP-center.

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  Fig. 4 von Mises stress distribution in three conditions of 2SIs under axial loading. (A) Stress distribution at implant-bone interface of buccal position implant, (B) Stress distribution at implant-bone interface of palatal position implant, (C) Stress distribution at peri-implant bone, (D) Stress distribution at implant-abutment complex.

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  Fig. 5 von Mises stress distribution in three conditions of 2SIs implants under oblique loading. (A) Stress distribution at implant-bone interface of buccal position implant, (B) Stress distribution at implant-bone interface of palatal position implant, (C) Stress distribution at peri-implant bone, (D) Stress distribution at implant-abutment complex.

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  Fig. 6 von Mises stress distribution in four conditions of single implants under axial loading. (A) Stress distribution at implant-bone interface of implant, (B) Stress distribution at peri-implant bone, (C) Stress distribution at implant-abutment complex. Left: RP implant, Right: WP implant.

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  Fig. 7 von Mises stress distribution in four conditions of single implants under oblique loading. (A) Stress distribution at implant-bone interface of implant, (B) Stress distribution at peri-implant bone, (C) Stress distribution at implant-abutment complex. Left: RP implant, Right: WP implant.

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  Fig. 8 von Mises stress distribution by the bone conditions (stepped and flat bone) under axial loading. (A) Stress distribution at implant-bone interface of implants in stepped bone condition, (B) Stress distribution at peri-implant bone in stepped bone condition, (C) Stress distribution at implant-bone interface of implants in flat bone condition, (D) Stress distribution at peri-implant bone in flat bone condition.

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  Fig. 9 von Mises stress distribution by the bone conditions (stepped and flat bone) under oblique loading. (A) Stress distribution at implant-bone interface of implants in stepped bone condition, (B) Stress distribution at peri-implant bone in stepped bone condition, (C) Stress distribution at implant-bone interface of implants in flat bone condition, (D) Stress distribution at peri-implant bone in flat bone condition.

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