Figure 12. Equivalent stresses at (a) the neck and (b) the tip of the implant.
Figure 12. Equivalent stresses at (a) the neck and (b) the tip of the implant.
Figure 11. The distribution of equivalent stress (MPa) around the first molar.
Figure 11. The distribution of equivalent stress (MPa) around the first molar.
Figure 10. Displacement in the inferior-superior direction (z-axis). (a) The contact model and (b) the fixation model.
Figure 10. Displacement in the inferior-superior direction (z-axis). (a) The contact model and (b) the fixation model.
Figure 9. Displacement in the mesiodistal direction (y-axis). (a) The contact model and (b) the fixation model.
Figure 9. Displacement in the mesiodistal direction (y-axis). (a) The contact model and (b) the fixation model.
Figure 8. Displacement in the buccolingual direction (x-axis). (a) The contact model and (b) the fixation model.
Figure 8. Displacement in the buccolingual direction (x-axis). (a) The contact model and (b) the fixation model.
Figure 7. The displacement of the three implants. (M) Mesial side, (D) Distal side, (B) Buccal side, and (L) Lingual side are shown.
Figure 7. The displacement of the three implants. (M) Mesial side, (D) Distal side, (B) Buccal side, and (L) Lingual side are shown.
Figure 6. Implant displacement under loading conditions.
Figure 6. Implant displacement under loading conditions.
Figure 5. An FEA model. (a) Buccal loading, (b) central loading, and (c) lingual loading are shown.
Figure 5. An FEA model. (a) Buccal loading, (b) central loading, and (c) lingual loading are shown.
Figure 4. An experimental model loading test.
Figure 4. An experimental model loading test.
Figure 3. An experimental model. (a) Buccal loading, (b) central loading, and (c) lingual loading are shown.
Figure 3. An experimental model. (a) Buccal loading, (b) central loading, and (c) lingual loading are shown.
Figure 2. Three implants were embedded in an artificial mandible.
Figure 2. Three implants were embedded in an artificial mandible.
Figure 1. An artificial mandible.
Figure 1. An artificial mandible.
Model
Loading points
Buccal loading
Central loading
Lingual loading
Average
The neck of the implant
Contact model
No. 34
9.62
...
Source
Sum of squares
df
Mean squared
F
value
p
value
The neck of the implant
A: Boundary conditions
64.725
1
...
Source
Sum of squares
df
Mean squared
F
value
p
value
Contact model
A: Observed area
22.324
1
22.324
...
Source
Sum of squares
df
Mean squared
F
value
p
value
Contact model
A: Observed area
116.630
1
116.63...
Source
Sum of squares
df
Mean squared
F
value
p
value
Contact model
A: Observed area
16.346
1
16.346
...
Model
Loading
Average
Buccal loading
Central loading
Lingual loading
Experimental model
2.49
4.76
4.90
4.05
...
Material
Young’s modulus (MPa)
Poisson ratio
Artificial cancellous bone
628
0.3
Artificial cortical bone
1,373
...
Omori, M., Sato, Y., Kitagawa, N. et al. A biomechanical investigation of mandibular molar implants: reproducibility and validity of a finite element analysis model.
Int J Implant Dent 1, 10 (2015). https://doi.org/10.1186/s40729-015-0011-5
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Received: 07 January 2015
Accepted: 24 March 2015
Published: 28 April 2015
DOI: https://doi.org/10.1186/s40729-015-...
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0), which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and in...
Miyuki Omori, Yuji Sato, Noboru Kitagawa, Yuta Shimura and Manabu Ito declare that they have no competing interests.
MO drafted the manuscript. YS contributed advice regarding the manuscript. All authors have read and approved the final manuscript.
Department of Geriatric Dentistry, Showa University, School of Dentistry, 2-1-1 Kitasenzoku, Ota-ku, Tokyo, 145-8515, Japan
Miyuki Omori, Yuji Sato, Noboru Kitagawa, Yuta Shimura & Manabu Ito
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The authors would like to express their deep appreciation to the teaching staff of the Geriatric Dentistry course at Showa University Dental Hospital for their help and cooperation. This study was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology (Showa University Grant-in-Aid for Scientific Research (C)) (Grant Number 2546...
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Qu...
finite element analysis
computed tomography
coefficient of variation
computer-aided design/computer-aided manufacturing
analysis of variance
With the objective of verifying the reproducibility and validity of three-dimensional finite element models, we fabricated finite element models and multiple models in which implants were embedded in artificial mandibles and compared implant displacements under various loading conditions; the results obtained produced the following conclusions:
The CVs as calculated from the amount of displacemen...
The equivalent stress values of the contact model were higher at the implant neck than the tip, and the stress generation range was also broader. However, in the fixation model, the implant neck and tip had substantially equivalent values and the stress generation range was also narrower than that of the contact model. This shows that under immediate loading conditions, there is a high likelihood ...
It has been reported that when micromovement of an implant occurs, an ingrowth of soft tissue occurs after the implant is embedded; therefore, it is difficult to achieve osseointegration [32-34]. Brunski et al. [35] reported that when immediate loading or early loading is carried out, micromovements of the implant should be controlled to 100 μm or less and excessive movement of the implant not o...
In the experimental and contact models, the absolute values of displacement under loading were different, but aspects of the displacement under loading conditions caused by differences in the loading points were similar and showed similar tendencies. The correlation coefficient of the two was 0.925, representing a significant and strong correlation (p
In the experimental model, an implant cavity 3.0 mm in diameter was formed prior to embedding an implant 3.75 mm in diameter. In theory, the threads were completely mechanically fitted to the artificial mandibular bone. It does not osseointegrate, but does represent the circumstances of immediate loading in a state of full contact with the bone. The contact model reproduced the state of contact ...
When a three-dimensional FEA is used to analyze the mechanics of peri-implant bone, it is ideal to construct an FEA model that approximates the material properties and structures of an actual mandible. Moreover, the results should be compared with the behavior of an implant in an actual mandible. However, in an actual oral cavity, individual differences exist resulting from bone morphology and phy...
Central loading resulted in the lowest equivalent stress value, while buccal and lingual loading showed substantially similar values (Figure 12b). In the bone surrounding the implant tip, the loading point was a significant factor for the equivalent stress value (p
At all three loading sites, no. 36 had the greatest displacement; the more mesial the implant, the less the displacement, and the distal portions showed a sinking displacement (Figure 10). Central loading resulted in the least displacement; buccal and lingual loading showed substantially similar displacements. Compared with the contact model, the fixation model demonstrated less displacement, but...
Figure 6 and Table 2 show the results for implant displacement under 100 N of vertical loading at each loading point and in each model.
The implant displacement under loading conditions in the experimental model and the two FEA models showed a tendency to exhibit the smallest values under central loading; substantially similar values were exhibited in buccal and lingual loading. Buccal loading...
Regarding displacement under loading, a one-way analysis of variance (ANOVA) was used to investigate statistically significant differences between the loading sites. A three-way ANOVA was used to investigate statistically significant differences in three-dimensional implant displacements under loading conditions. The assessment site, dental formula, and loading point were used as intra-subject par...
Implant displacement measurements under loading conditions were measured using an Instron-type universal testing machine (Instron‐5500R®, Instron Japan, Kanagawa, Japan) for the experimental model. The experimental models were placed on the worktable of an Instron-type universal testing machine, and compression tests were performed using a conical jig. A vertical load was applied at a rate of 0...
The experimental models were fixed in a micro-CT scanner (inspeXio SMX-90CT, SHIMADZU, Kyoto, Japan) and scanned under the following imaging conditions: tube voltage, 90 kV; tube current, 109 nA; and slice thickness, 100 μm. FEA software (Mechanical Finder®, Research Center of Computational Mechanics, Tokyo, Japan) was used to construct three-dimensional FEA models from the resulting computed...
An artificial mandibular bone (P9-X.1135, Nissin Dental Products, Kyoto, Japan) with free-end edentulism of the left mandibular first premolar (no. 34), second premolar (no. 35), and first molar (no. 36) was used (Figure 1). The model is composed of a two-layer structure of artificial cortical bone (urethane resin) and artificial cancellous bone (urethane resin foam).
Using the anatomical crown ...
With the purpose of verifying the reproducibility and validity of a three-dimensional finite element model, the displacements of implants embedded in an experimental model and in three-dimensional FEA models constructed from the experimental model were compared under various loading conditions.
Bone remodeling to maintain osseointegration between bone and implant is absolutely essential to ensure favorable results and long-term stability in implant treatment [1,2]. Bone remodeling requires that various stresses generated around the bone caused by the occlusal load applied to the implant be within an appropriate range. Concentrations of stress at the bone-implant interface, which are caus...
Three-dimensional finite element analysis (FEA) is effective in analyzing stress distributions around dental implants. However, FEA of living tissue involves many conditions, and the structures and behaviors are complex; thus, it is difficult to ensure the validity of the results. To verify reproducibility and validity, we embedded implants in experimental models and constructed FEA models; implan...