Fig. 8. Maximum von Mises stress value in implant bodies (MPa)
Fig. 8. Maximum von Mises stress value in implant bodies (MPa)
Fig. 7. Von Mises stress distribution in implant bodies. (right: buccal side, left: lingual side)
Fig. 7. Von Mises stress distribution in implant bodies. (right: buccal side, left: lingual side)
Fig. 6. Largest maximum principle stress value in cortical bone (MPa)
Fig. 6. Largest maximum principle stress value in cortical bone (MPa)
Fig. 5. Distribution of the maximum principle stress in the surrounding bone (occlusal view)
Fig. 5. Distribution of the maximum principle stress in the surrounding bone (occlusal view)
Fig. 4. Distribution of the maximum principle stress in the surrounding bone (right: buccal side, left: lingual side)
Fig. 4. Distribution of the maximum principle stress in the surrounding bone (right: buccal side, left: lingual side)
Fig. 3. Assembly of implant and bone models. A static load of 100 N was applied obliquely from the buccal side to the occlusal plane of the superstructure at 30 to the long axis of the implant
Fig. 3. Assembly of implant and bone models. A static load of 100 N was applied obliquely from the buccal side to the occlusal plane of the superstructure at 30 to the long axis of the implant
Fig. 2. Models of different implant body lengths
Fig. 2. Models of different implant body lengths
Fig. 1. Three-dimensional CAD model. (upper: a abutment screw, b superstructure, c implant body; Lower: bone model)
Fig. 1. Three-dimensional CAD model. (upper: a abutment screw, b superstructure, c implant body; Lower: bone model)
Young’s modulus (GPa)Poisson’s ratioReferenceAbutment screw (Ti-6Al-4V)1100.33[19]Superstructure (gold alloy)96.60.35[20]Cortical bone130.3[21]Cancellous bone1.370.3[21]Implant body (cpTi)1100.34 Implant body (TiZr)97.30.36 Table 1 Mechanical properties of each model component
Araki, H., Nakano, T., Ono, S. et al. Three-dimensional finite element analysis of extra short implants focusing on implant designs and materials. Int J Implant Dent 6, 5 (2020). https://doi.org/10.1186/s40729-019-0202-6
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Received: 20 August 2019
Accepted: 11 December 2019
Published: 29 January 2020
DOI: https://doi.org/10.1186/s40729-019-0202-6
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Department of Fixed Prosthodontics, Osaka University Graduate School of Dentistry, Osaka, 565-0871, Japan
Haruka Araki, Tamaki Nakano, Shinji Ono & Hirofumi Yatani
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This research was supported by Grants-in-Aid for Scientific Research T15K204780 and T15K111560 from the Japan Society for the Promotion of Science.
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Within the limitations of this study, the following conclusions were drawn.
The stress distribution in the cortical bone and implant body was smaller in the TL implant than in the BL implant.
The TiZr alloy had a lower elastic modulus than cpTi, and the stress distribution generated in the cortical bone and implant body was also lower.
The stress distribution generated in the cortical bone an...
Clinically, it is generally considered that the crown length increases proportionally when the length of the implant body decreases because of alveolar bone resorption. However, most previous studies performing FEA of short implants have analyzed them with a standard crown length [38]. In this study, the distance from the tip of the implant body to the occlusal plane was standardized to make the a...
The difference in the implant body structure between the submerged and non-submerged implants greatly affected the stress distribution. Since the TL implant body lies above the bone level rather than level with the crestal bone, it was found that the stress concentrates above the apex of the alveolar bone, regardless of the material type. As a result, the maximum stress value in the cortical bone ...
Overloading, which is one of the factors contributing to bone resorption around an implant body, can lead to complications because force is applied beyond the prosthodontic or biological tolerance [23]. It is believed that when stress of a certain magnitude is applied to the bone, microscopic bone destruction occurs resulting in bone resorption [24, 25]. Because implants do not have buffering mech...
The distribution of the maximum principal stress in the cortical bone concentrated on the neck of the implant body. In the TL implants, tensile stress was concentrated on the buccal side and compressive stress on the lingual side. In the BL implants, tensile stress concentration was observed on the lingual side. The distributions were similar between the cpTi and TiZr implants (Figs. 4 and 5). Th...
To validate the accuracy of the FEA model, microstrain of the surrounding bone were compared with the results of in vitro experiment measured with strain gauge [22]. In the literature, it was reported that microstrain of 59.3876 ± 24.7185 μe at the neck of implant and 17.3456 ± 12.9147 μe at the apical occurred in a bovine bone under an oblique load of 120 N. Under the same conditi...
TL and BL three-dimensional computer-aided design (CAD) implant models were created using the CAD function in computer-aided engineering software (SolidWorks 2014, Dassault Systèmes SolidWorks Corporation, MA, USA), and they were created with reference to conical connection implant used clinically. The connection part of superstructure has a tapered 15° conical shape without any special locking ...
Dental implants are widely used as a treatment option to replace a defective prosthesis. In recent years, treatment using short implants, which are ≤ 8 mm in length, has been increasing in cases with vertical bone resorption [1]. It is thought that this will become more popular as the number of patients who require minimally invasive treatment, such as older patients and those with chronic d...
When using short implants, fracture of the implant body and bone resorption are a concern because stress concentrates on and around a short implant. The purpose of this research is to investigate the differences in stress distribution between tissue level (TL) and bone level (BL) implant body designs, and between commercially pure titanium (cpTi) and the newer titanium–zirconium (TiZr) alloy in ...
Within the limitations of this study, the following conclusions were drawn.
The stress distribution in the cortical bone and implant body was smaller in the TL implant than in the BL implant.
The TiZr alloy had a lower elastic modulus than cpTi, and the stress distribution generated in the cortical bone and implant body was also lower.
The stress distribution generated in the cortical bone and ...
Clinically, it is generally considered that the crown length increases proportionally when the length of the implant body decreases because of alveolar bone resorption. However, most previous studies performing FEA of short implants have analyzed them with a standard crown length [38]. In this study, the distance from the tip of the implant body to the occlusal plane was standardized to make the a...
The difference in the implant body structure between the submerged and non-submerged implants greatly affected the stress distribution. Since the TL implant body lies above the bone level rather than level with the crestal bone, it was found that the stress concentrates above the apex of the alveolar bone, regardless of the material type. As a result, the maximum stress value in the cortical bone ...
Overloading, which is one of the factors contributing to bone resorption around an implant body, can lead to complications because force is applied beyond the prosthodontic or biological tolerance [23]. It is believed that when stress of a certain magnitude is applied to the bone, microscopic bone destruction occurs resulting in bone resorption [24, 25]. Because implants do not have buffering mech...
The distribution of the maximum principal stress in the cortical bone concentrated on the neck of the implant body. In the TL implants, tensile stress was concentrated on the buccal side and compressive stress on the lingual side. In the BL implants, tensile stress concentration was observed on the lingual side. The distributions were similar between the cpTi and TiZr implants (Figs. 4 and 5). Th...
To validate the accuracy of the FEA model, microstrain of the surrounding bone were compared with the results of in vitro experiment measured with strain gauge [22]. In the literature, it was reported that microstrain of 59.3876 ± 24.7185 μe at the neck of implant and 17.3456 ± 12.9147 μe at the apical occurred in a bovine bone under an oblique load of 120 N. Under the same conditi...
TL and BL three-dimensional computer-aided design (CAD) implant models were created using the CAD function in computer-aided engineering software (SolidWorks 2014, Dassault Systèmes SolidWorks Corporation, MA, USA), and they were created with reference to conical connection implant used clinically. The connection part of superstructure has a tapered 15° conical shape without any special locking ...
Dental implants are widely used as a treatment option to replace a defective prosthesis. In recent years, treatment using short implants, which are ≤ 8 mm in length, has been increasing in cases with vertical bone resorption [1]. It is thought that this will become more popular as the number of patients who require minimally invasive treatment, such as older patients and those with chronic d...
When using short implants, fracture of the implant body and bone resorption are a concern because stress concentrates on and around a short implant. The purpose of this research is to investigate the differences in stress distribution between tissue level (TL) and bone level (BL) implant body designs, and between commercially pure titanium (cpTi) and the newer titanium–zirconium (TiZr) alloy in ...
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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Sevimay M, Turhan F, Kilicarslan MA, Eskitascioglu G. Three-dimensional finite element analysis of the effect of different bone quality on stress distr...
Matsunaga S, Ide Y. Morphological characteristics of peri-implant trabecular bone using μ-CT and its mechanical evaluation. BONE. 2009;23:289–92 [in Japanese].
Yokoyama M. Modeling techniques and stress analysis in finite element methods. Tokyo: Yokendo; 2007. p. 1–22 [in Japanese].
Sato Y, Shindoi N, Hosokawa R, Tsuga K, Akagawa Y. A biomechanical effect of wide implant placement and offse...
Morita Y, Qian L, Todo M, Matsushita Y, Arakawa K, Koyano K. Stress and strain distribution analyses of porcine mandibular periodontium by experimental mechanics and finite element analysis. Jpn J Clin Biomech. 2009;30:7–13 [in Japanese].
Taira S. Modern material mechanics. Tokyo: Ohmsha; 2011. p. 235–8 [in Japanese].
Morita Y. Experimental study on displacement and strain distributions arou...
Frost HM. Wolff’s Law and bone’s structural adaptations to mechanical usage: an overview for clinicians. Angle Orthod. 1994;64:175–88.
Duyck J, Rønold HJ, Van Oosterwyck H, Naert I, Vander Sloten J, Ellingsen JE. The influence of static and dynamic loading on marginal bone reactions around osseointegrated implants: an animal experimental study. Clin Oral Implants Res. 2001;12:207–18.
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...
Fig. 15. Load supporting area in the superstructures
Fig. 15. Load supporting area in the superstructures
Fig. 14. The distribution of equivalent stress around the no. 36 implant in the finite element analysis (FEA) models
Fig. 14. The distribution of equivalent stress around the no. 36 implant in the finite element analysis (FEA) models
Fig. 13. The distribution of equivalent stress around the peri-implant bone in the finite element analysis (FEA) models
Fig. 13. The distribution of equivalent stress around the peri-implant bone in the finite element analysis (FEA) models
Fig. 12. The strain around the no. 36 implant in the finite element analysis (FEA) models
Fig. 12. The strain around the no. 36 implant in the finite element analysis (FEA) models
Fig. 11. The strain around the no. 36 implant in the experimental models
Fig. 11. The strain around the no. 36 implant in the experimental models
Fig. 10. The displacement of the three implants
Fig. 10. The displacement of the three implants
Fig. 9. The displacement of the implants under loading in finite element analysis (FEA) models
Fig. 9. The displacement of the implants under loading in finite element analysis (FEA) models
Fig. 8. The displacement of the implants under loading in experimental models
Fig. 8. The displacement of the implants under loading in experimental models
Fig. 7. A finite element analysis (FEA) model. (a) Buccal load, (b) central load, and (c) lingual load
Fig. 7. A finite element analysis (FEA) model. (a) Buccal load, (b) central load, and (c) lingual load
Fig. 6. Loading test in the experimental model
Fig. 6. Loading test in the experimental model
Fig. 5. Application of strain gauges
Fig. 5. Application of strain gauges
Fig. 4. Experimental model. (a) Buccal load, (b) central load, and (c) lingual load
Fig. 4. Experimental model. (a) Buccal load, (b) central load, and (c) lingual load
Fig. 3. Three different models with different placements
Fig. 3. Three different models with different placements
Models
Mean difference
P value
Straight
B-offset
−58.94
...
Models
Mean difference
P value
Straight
B-offset
−402.94
...
Models
Loading
Strain (με)
Strain M
Strain B
Strain D
...
Models
Mean difference
P value
Straight
B-offset
−25.14
...
Models
Mean difference
P value
Straight
B-offset
1524.82
...
Models
Loading
Strain (με)
Strain M
Strain B
Strain D
...
Models
Displacement (μm)
Buccal loading
Central loading
Lingual loading
Buccal offse...
Models
Displacement (μm)
Buccal loading
Central loading
Lingual loading
Buccal offse...
Material
Young’s modulus (MPa)
Poisson’s ratio
Artificial cancellous bone
6.29
0.3
Artificial cortical bone
13.73
0.3
Implant and superstructure
108,000
0.3
Table 1 Mechanical properties of materials used in the FEA models
Shimura, Y., Sato, Y., Kitagawa, N. et al. Biomechanical effects of offset placement of dental implants in the edentulous posterior mandible. Int J Implant Dent 2, 17 (2016). https://doi.org/10.1186/s40729-016-0050-6
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Received: 18 January 2016
Accepted: 13 June 2016
Published: 17 June 2016
DOI: https://doi.org/10.1186/s40729-016-0050-6
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were m...
Yuta Shimura, Yuji Sato, Noboru Kitagawa, and Miyuki Omori declare that they have no competing interests.
YS drafted the manuscript. YS, NK, and MO contributed advice for the manuscript. All authors read and approved the final manuscript.
Department of Geriatric Dentistry, Showa University, 2-1-1 Kitasenzoku, Ota-ku, Tokyo, 145-8515, Japan
Yuta Shimura, Yuji Sato, Noboru Kitagawa & Miyuki Omori
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We are sincerely grateful for the assistance we received from the teaching staff of the Geriatric Dentistry course at Showa University Dental Hospital; Professor Takashi Miyazaki and the late Akihiro Fujishima of the Department of Conservative Dentistry, Division of Oral Biomaterials and Engineering; Professor Masanori Nakamura of the Department of Oral Anatomy and Developmental Biology; and Profe...
Yoshino A. Effects of ratio of superstructure length to fixture length on the strain of the bone surfaces surrounding the implant. J Jpn Soc Oral Implantol. 2001;14:398–413. in Japanese.
Rangert B, Jemt T, Jörneus L. Forces and moments on Branemark implants. Int J Oral Maxillofac Implants. 1989;4:241–7.
Sato Y. Discussion of offset arrangement in implants. Quintessence Dent Implantol. 2000;...
Nishioka RS, de Vasconcellos LG, de Melo Nishioka LN. External hexagon and internal hexagon in straight and offset implant placement: strain gauge analysis. Implant Dent. 2009;18:512–20.
Nishioka RS, de Vasconcellos LG, de Melo Nishioka GN. Comparative strain gauge analysis of external and internal hexagon, Morse taper, and influence of straight and offset implant configuration. Implant Dent. 2...
Frost HM. Wolff’s Law and bone’s structural adaptations to mechanical usage: an overview for clinicians. Angle Orthod. 1994;64:175–88.
Duyck J, Rønold HJ, Van Oosterwyck H, Naert I, Vander Sloten J, Ellingsen JE. The influence of static and dynamic loading on marginal bone reactions around osseointegrated implants: an animal experimental study. Clin Oral Implants Res. 2001;12:207–18.
Qu...
In the present study, which aimed to verify the biomechanical effects of offset placement on peri-implant bone, we created multiple finite element models and models where implants were actually placed. We compared the compressed displacement as well as the strain and stress distribution in the peri-implant bone between both kinds of models, and the results can be summarized as follows:
Central lo...
Concentration of stress in the loading-side peri-implant bone was observed in all placements and for both the experimental and the FEA models. Considerable stress was also found to be concentrated in the no. 36 peri-implant bone in buccal loading with buccal offset and lingual loading with lingual offset. Similar to the strain results, stress was observed in a large range under conditions where th...
Similar trends were observed in the direction and magnitude of displacement between placements. Buccal loading exhibited considerable motion towards the buccal rotation/tilting of the implant bodies, and lingual loading exhibited little motion towards lingual displacement. This corresponds to the fact that there was more compressed displacement during buccal loading than during lingual loading.
I...
Moreover, considering the possibility of error while using an implant placement guide, we created many FEA models for each placement to compare the accuracy between the same placement models used with different FEA models.
Most studies verifying the usefulness of offset placement used a single technique for analysis [8–19]. Therefore, the results regarding the usefulness of offset placement var...
Reported studies verifying the effects of offset placement include ones where implant bodies were embedded in rectangular experimental models [11–14], ones where rectangular bone models were constructed with FEA models [15, 16], and ones where FEA models were constructed from CT data on human mandibles [17, 18]. The artificial mandible models used in the present study were type II in the Lekholm...
Figure 11 and Table 4 show the strain, by loading site, in the implant part corresponding to the first molar in the experimental models during the application of a 100-N vertical load.
Considerable compressive strain was observed with the load-side strain gauges in all placements, and similar trends were observed between placements. As much as about 4500 με of compressive strain was observed...
Figures 8 and 9 and Tables 2 and 3 show the results for the compressed displacement of the implants, by loading site, during the application of a 100-N vertical load in each of the models.
In all placements, the compressed displacement in the experimental models and FEA models was greatest with buccal loading and smallest with central loading at the three loading points. For both the experiment...
The places on the experimental models where the strain gauges were applied were represented as coordinate points on the FEA models, and the strain in the FEA models was calculated by dividing the change in length between before and after loading by the length of the strain gauges.
An equivalent stress occurring in the peri-implant bone during loading was observed and assessed in a buccolingual cr...
Implant displacement under loading conditions was 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 0.5 mm/s on the ...
Four two-wire strain gauges (KFR-02N-120-C1-11, Kyowa Electronic Instruments, Tokyo, Japan) were applied to the no. 36 peri-implant bone surface [21]. The surface of the measurement site was polished with no. 320 sandpaper and then wiped clean with acetone, following which they were adhered with a special adhesive (CC-33A, Kyowa Electronic Instruments, Tokyo, Japan). The strain gauges were applied...
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 (Fig. 1). The model was composed of a two-layer structure of artificial cortical bone (urethane resin) and artificial cancellous bone (urethane resin foam).
Using the anatomical crown w...
Bone remodeling to maintain osseointegration between the 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. The concentration of stress at the bone-implant interface, caused...
Offset placement may not necessarily be more biomechanically effective than straight placement in edentulous posterior mandibles.
Proper implant placement is very important for long-term implant stability. Recently, numerous biomechanical studies have been conducted to clarify the relationship between implant placement and peri-implant stress. The placement of multiple implants in the edentulous posterior mandible has been studied by geometric analysis, three-dimensional finite element analysis (FEA), model experimentation, ...
Fig. 8. Distribution of occlusal force in models. a Im67, b Im6, c Im4567, d Im456, e MT67, and f MT7. R right TMJ, L left TMJ, 4 first premolar, 5 second premolar, 6 first molar, and 7 second molar. Numbers within circles indicate implant superstructure
Fig. 8. Distribution of occlusal force in models. a Im67, b Im6, c Im4567, d Im456, e MT67, and f MT7. R right TMJ, L left TMJ, 4 first prem...
Fig. 7. Initializing models altering the load displacement curves of springs
Fig. 7. Initializing models altering the load displacement curves of springs
Fig. 6. Springs for opposing teeth and TMJs and load directions. Arrows indicate loads, arrowheads indicate restricted nods, and spiral lines indicate springs
Fig. 6. Springs for opposing teeth and TMJs and load directions. Arrows indicate loads, arrowheads indicate restricted nods, and spiral lines indicate springs
Fig. 5. Distribution of occlusal force in the natural teeth model displayed in Fig.4
Fig. 5. Distribution of occlusal force in the natural teeth model displayed in Fig.4
Fig. 4. Three-dimensional finite element model with natural teeth and no defect
Fig. 4. Three-dimensional finite element model with natural teeth and no defect
Fig. 3. Load displacement curves of natural teeth in FE model
Fig. 3. Load displacement curves of natural teeth in FE model
Fig. 2. Load displacement curves of springs
Fig. 2. Load displacement curves of springs
Fig. 1. Three-dimensional finite element model. The tooth roots and implant bodies are displayed with permeability. a Im67, b Im6, c Im4567, d Im456, e MT67, and f MT7
Fig. 1. Three-dimensional finite element model. The tooth roots and implant bodies are displayed with permeability. a Im67, b Im6, c Im4567, d Im456, e MT67, and f MT7
Material
Modulus of elasticity (MPa)
Poisson ratio
References
Cortical bone
140,000
...
Yoshitani, M., Takayama, Y. & Yokoyama, A. Significance of mandibular molar replacement with a dental implant: a theoretical study with nonlinear finite element analysis.
Int J Implant Dent 4, 4 (2018). https://doi.org/10.1186/s40729-018-0117-7
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Received: 13 March 2017
Accepted: 08 January 2018
Published: 27 February 2018
DOI: https://doi.org/10.1186/s407...
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were m...
Author Masazumi Yoshitani, Yoshiyuki Takayama, and Atsuro Yokoyama state that there are no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Division of Oral Functional Science, Department of Oral Functional Prosthodontics, Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo, 060-8648, Japan
Masazumi Yoshitani & Atsuro Yokoyama
Removable Prosthodontics, Hokkaido University Hospital, Hokkaido University, Kita-14, Nishi-5, Kita-Ku, Sapporo, 060-8648, Japan
Yoshiyuki Takayama
You can also sear...
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Kasai K, Takayama Y, Yokoyama A. Distribution of occlusal forces during occlusal adjustment of dental implant prostheses: a nonlinear finite element analysis considering the ...
Chappuis V, Buser R, Bragger U, Bornstein MM, Salvi GE, Buser D. Long-term outcomes of dental implants with a titanium plasma-sprayed surface: a 20-year prospective case series study in partially edentulous patients. Clin Implant Dent Relat Res. 2013;15:780–90.
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Within the limitations of this theoretical study, we demonstrated that restoration with the same number of implants as missing teeth shows almost symmetric occlusal force distribution, and it produced less biomechanically stress for a unilateral defect of the mandible. However, if restoration of a missing second molar with an implant is impossible or difficult, then an SDA with implants may also b...
It should be noted that our results were obtained under conditions of vertical loading by bilaterally balanced muscle activity with tight intercuspation in the correct mandibular position because the horizontal displacement of the premolars and molars was restrained. The actual distribution of occlusal forces may differ due to individual differences in the material properties of the soft tissue. A...
Occlusal adjustment is usually performed to obtain symmetrical occlusal force distribution in natural dentition. However, occlusal force distribution among natural teeth and implants depends on occlusal force because of the difference of displaceability between a natural tooth and an implant [14, 15]. Therefore, we evaluated the result of the analysis from viewpoints of symmetry of occlusal force ...
FEA is useful for mechanical simulations of a living body and has been used in implant dentistry research under careful consideration of the analysis conditions [32, 33]. Although some reports have demonstrated that bone density varies according to bone type and location, the material properties of the mandible were homogenous and isotropic in this study. However, the effect of this difference was...
In model Im456 (Fig. 8d), under loads 100 and 200 N, the occlusal force at the premolars on the defect side was larger than that in model Im4567 (shown in Fig. 8c). The occlusal force was also larger than that in model MT7 (shown in Fig. 6f). However, the occlusal force at the second premolar under load 200 N was 34.5 N, which was slightly smaller than the occlusal force at the second molar ...
In model Im6 (Fig. 8b), the occlusal force at the second premolar under loads 100, 200, 400, and 800 N were 18.3, 37.0, 38.8, and 70.2 N, respectively. The occlusal force was larger than that in model Im67 (shown in Fig. 8a), while it was approximately equivalent to that in model MT7 (shown in Fig. 8f). Under loads 100 and 200 N, the occlusal force at the second premolar on the defect side w...
The distributions of occlusal force are shown in Fig. 8. In model MT67 (Fig. 8e), the occlusal force at the first premolar on the defect side was 10.0–86.5 N, which was 1.2–15.0-fold larger than that on the natural dentition side. The occlusal force at the second premolar on the defect side was 24.6–190.1 N, which was 2.6–8.3-fold larger than on the natural dentition side. The occlusal...
Analysis was performed according to the report by Kayumi et al. [15]. In linear finite element analysis (FEA), all teeth maintain perfect contact with antagonists with no stress on occlusal surfaces before loading. However, there must be some occlusal force on the occlusal surface when a mandible is in the intercuspal position. Since the displaceabilities of osseointegrated implants, natural teeth...
Nonlinear characteristics according to the load displacement curve of teeth [21,22,23,24] and cartilage [30] were given to the springs for the opposing teeth and TMJs, respectively (Fig. 2). The nonlinear elasticity of the springs on the teeth and implants simulated displaceability of opposing natural teeth at compression and separation of the occlusal surface from opposing teeth at tension.
The...
The 3D FEMs were constructed based on those reported by Kasai et al. [14], Kayumi et al. [15] and consisted of a mandible, natural teeth with the periodontal ligament (PDL), and titanium implant(s) with superstructures in the left premolar and molar regions.
The surface of the mandible was generated using measurements of a commercially available model (QS7, SOMSO) of the dentate mandible with a 3...
From the viewpoint of occlusal force distribution, when a second molar defect remains without prosthesis, the force might concentrate in the implant, residual teeth, or temporomandibular joints (TMJs). Therefore, the aim of this study was to investigate occlusal force distribution in SDA in the mandible with/without an implant using a three-dimensional (3D) finite element model (FEM).
Dental implant treatment has been frequently applied in dental practice as the most important prosthodontic procedure with long-term predictability to restore oral function, maintain occlusion, and improve the quality of life (QoL) of a patient [1]. Clinically, dental implants are mainly applied to correct mandibular distally extended edentulism [2]. However, implant placement in the molar region ...
Dental implants are frequently applied to unilateral defects in the mandible. However, implant placement in the molar region of the mandible can be difficult due to anatomical structure. The aim of this study was to evaluate the distribution of occlusal force in a mandibular shortened dental arch (SDA) with implants.
Three-dimensional finite element (FE) models of the mandible with varying number...
Fig. 3. Proportion of dental implant FEA articles with a validation. (Left) Among totally 522 FEA articles of dental implants which we were able to access English full text up to January 2017, there are only 47 articles with a validation. (Right) The articles with a validation were categorized according to their validation method as follows levels: A, in vivo (human bodies); B, performed in vivo...
Fig. 2. Hierarchy of validations based on their similarity to real biomechanical behaviors. The articles (n = 47) were categorized according to their validation method as follows: in vivo experiments in humans (n = 1) and other animals (n = 3), model experiments (n = 32), others’ clinical data and past literature (n = 9), and other software (n = 2)
Fig. 2. Hierarchy ...
Fig. 1. Flowchart of literature review. An electronic literature search of PubMed was conducted up to January 2017 using the Medical Subject Headings “dental implants” and “finite element analysis.” After accessing the full texts, the context of each article was searched using the words “valid” and “validation” and articles in which these words appeared were read to determine whe...
Ranking
Authors
Year
FE model
FEM geometry reference
Material properties of tissues a...
Chang, Y., Tambe, A.A., Maeda, Y. et al. Finite element analysis of dental implants with validation: to what extent can we expect the model to predict biological phenomena? A literature review and proposal for classification of a validation process.
Int J Implant Dent 4, 7 (2018). https://doi.org/10.1186/s40729-018-0119-5
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Received: 05 November 2017
Accepte...
Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were m...
Yuanhan Chang, Abhijit Anil Tambe, Yoshinobu Maeda, Masahiro Wada, and Tomoya Gonda declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
Yuanhan Chang, Yoshinobu Maeda, Masahiro Wada & Tomoya Gonda
Mahatma Gandhi Vidyamandir’s Karmaveer Bhausaheb Hiray Dental College & Hospital, Mumbai Agra Road, Panchwati, Nashik, Maharashtra, India
Abhijit Anil Tambe
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Gass SI. Decision-adding m...
High-level validation of FEA using in vivo experiments is still rare in the dental implant field.
It is necessary to clearly indicate the validation process of the model when a study using FEA is presented.
The hierarchy proposed in this study based on the evidence level of the validations can be applied to evaluate the clinical significance of studies using FEA.
To explain or analyze the mechanical properties involved in biological phenomena such as motor tasks (mastication, walking, or heart contraction), a time-dependent finite element model may provide a more realistic view. However, if time-dependent performance criteria are considered (the most common is to clarify the influence of musculoskeletal structure on function or the performance of a motor t...
Because of the limitations of computer technology, most FEA models [75,76,77,78,79] simplify the skeletal muscle architecture in terms of a uniform fiber length, pennation angle, and line of action and represent the architecture using a Hill-based muscle model. However, how well the modeling of skeletal muscles as one-dimensional strings represents the behavior of the full three-dimensional muscle...
Table 1 shows all studies in the literature that considered the need for validation of FEAs. According to these studies, we established a hierarchy based on the evidence level of the validations (A to G, i.e., high to low) (Fig. 2).
Level A: validation using living humans
Level B: validation using living heterogeneous animals
Levels C and D: validation using homogenous and heterogeneous bone
...
Level E: model experiment performed using artificial materials (n = 23) [14, 25, 26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46]
Artificial materials such as acrylic resin, polyurethane, or plastic bone models were commonly used as embedded “bone” implants in validation experiments. Level E includes the use of special materials and specific methods to measure the force di...
We classified all validation processes based on their similarity to real biomechanical behaviors into the following hierarchy (levels A to G) (Fig. 2):
Level A: performed in vivo (human bodies) (n = 1) [10]
The top level of the hierarchy, level A, includes in vivo methods of FEA validation conducted in humans. In 2006, Heckmann et al. [10] quantified the degree of stress that occurs in the...
In total, 601 articles were obtained from the PubMed electronic search using the Medical Subject Headings “dental implants” and “finite element analysis.” After excluding articles for which the full text could not be accessed (n = 69) and that were not written in English (n = 10), 522 articles remained. These articles were searched using the terms “validation,” “validity,” ...
FEA studies with validation have recently become more common in the biomechanical field. FEA validations can be divided into two types: (1) direct validation, which involves experiments on the quantities of interest (from basic material characterizations to hierarchical system analysis such as model experiments and in vitro experiments), and (2) indirect validation, which involves the use of liter...
Finite element analysis (FEA) has been applied to investigate dental implant designs, the structure and material of the superstructure, and the stability of the surrounding bone [1, 2]. According to PubMed, only 10 FEA studies of dental implants were published in 1990, while 102 papers were published in 2014.
FEA has become an increasingly useful tool in the past few decades. In the medical field...
A literature review of finite element analysis (FEA) studies of dental implants with their model validation process was performed to establish the criteria for evaluating validation methods with respect to their similarity to biological behavior. An electronic literature search of PubMed was conducted up to January 2017 using the Medical Subject Headings “dental implants” and “finite element...
Models
Mean difference
P value
Straight
B-offset
−58.94
0.855
Straight
L-offset
270.67
0.061
B-offset
L-offset
329.61
0.020
Models
Mean difference
P value
Straight
B-offset
−402.94
0.007
Straight
L-offset
−323.79
0.029
B-offset
L-offset
79.16
0.772
Table 7 Means and standard deviations (SD) of strain around the no. 36 implant (με) in the finite element analysis (FEA) models
Models
Loading
Strain (με)
Strain M
Strain B
Strain D
Strain L
Buccal offset
Buccal loading
−222.34 ± 158.56
−934.84 ± 76.82
252.11 ± 103.72
−98.32 95.94
Central loading
−336.26 ± 94.27
−477.17 ±...
Table 6 Tukey’s test for strain L in the experimental models
Models
Mean difference
P value
Straight
B-offset
−25.14
0.999
Straight
L-offset
168.04
0.948
B-offset
L-offset
193.18
0.932
Table 5 Tukey’s test for strain B in the experimental models
Models
Mean difference
P value
Straight
B-offset
1524.82
0.044
Straight
L-offset
−503.40
0.670
B-offset
L-offset
−2028.22
0.007
Table 4 Means and standard deviations (SD) of strain around the no. 36 implant (με) in the experimental models
Models
Loading
Strain (με)
Strain M
Strain B
Strain D
Strain L
Buccal offset
Buccal loading
−599.33 ± 595.46
−4507.35 ± 1192.62
1164.77 ± 169.94
−148.09 ± 174.19
Central loading
−697.29 ± 651.92
−2526.69 ± 5...
Models
Displacement (μm)
Buccal loading
Central loading
Lingual loading
Buccal offset
72.24 ± 1.43
28.24 ± 1.86
28.02 ± 1.41
Straight
68.49 ± 5.24
31.43 ± 1.23
40.18 ± 1.29
Lingual offset
49.63 ± 2.03
26.39 ± 0.37
38.44 ± 1.46
Table 2 Means and standard deviations (SD) of displacement of the implants (μm) under loading in experimental models
Models
Displacement (μm)
Buccal loading
Central loading
Lingual loading
Buccal offset
54.60 ± 8.53
37.39 ± 5.53
40.22 ± 4.24
Straight
80.66 ± 7.47
52.92 ± 1.07
63.03 ± 3.69
Lingual offset
53.11 ± 4.35
40....
Table 1 Mechanical properties of materials used in the FEA models
Material
Young’s modulus (MPa)
Poisson’s ratio
Artificial cancellous bone
6.29
0.3
Artificial cortical bone
13.73
0.3
Implant and superstructure
108,000
0.3
Figure 15. Load supporting area in the superstructures
Figure 14. The distribution of equivalent stress around the no. 36 implant in the finite element analysis (FEA) models
Figure 13. The distribution of equivalent stress around the peri-implant bone in the finite element analysis (FEA) models
Figure 12. The strain around the no. 36 implant in the finite element analysis (FEA) models
Figure 11. The strain around the no. 36 implant in the experimental models
Figure 9. The displacement of the implants under loading in finite element analysis (FEA) models
Figure 8. The displacement of the implants under loading in experimental models
Figure 7. A finite element analysis (FEA) model. (a) Buccal load, (b) central load, and (c) lingual load
Figure 7. A finite element analysis (FEA) model. (a) Buccal load, (b) central load, and (c) lingual load
Figure 6. Loading test in the experimental model
Figure 5. Application of strain gauges
Figure 4. Experimental model. (a) Buccal load, (b) central load, and (c) lingual load
Figure 3. Three different models with different placements
Figure 2. Three implants were embedded in an artificial mandible
Figure 1. An artificial mandible
References
Frost HM. Wolff’s Law and bone’s structural adaptations to mechanical usage: an overview for clinicians. Angle Orthod. 1994;64:175–88.
Duyck J, Rønold HJ, Van Oosterwyck H, Naert I, Vander Sloten J, Ellingsen JE. The influence of static and dynamic loading on marginal bone reactions around osseointegrated implants: an animal experimental study. Clin Oral Implants Res. 200...
In addition, there was not a significantly less strain site by offset placement. Anitua et al. have reported that offset placement did not affect marginal bone loss around the implant in the oral cavity of the living body. Overloading of the peri-implant bone has been reported to result in bone resorption, and the concentration of considerable stress in the load-side peri-implant bone observ...
Thus, compressed displacement exhibited the same trend in the experimental models and FEA models. The results of both models may be reliable. When the effects of offset placement are considered, there is the concept of the load-supporting area (Fig. 15) put forth by Sato. The load-supporting area is the area surrounded by the lines connecting the implant peripheries, and if a loading point falls w...
In previous studies verifying the usefulness of offset placement, one set of FEA models was created and analyzed by changing the conditions or settings. Few studies used different FEA models with the same placement models. In the present study, we carried out the same experiments with both the models to verify the validity of each analysis.
Moreover, considering the possibility of error while usi...
Strain in the FEA models also exhibited considerable compressive strain on the loading side, similar to the experimental models. In terms of quantitative data for comparison with the experimental models, the length of the places where the strain gauges were applied was measured on the FEA models and the strain was calculated from the length before and after loading and compared with the expe...
Discussion
Experimental models
Reported studies verifying the effects of offset placement include ones where implant bodies were embedded in rectangular experimental models, ones where rectangular bone models were constructed with FEA models, and ones where FEA models were constructed from CT data on human mandibles. The artificial mandible models used in the present study were type II in the ...
Strain on the peri-implant bone
Strain in the experimental models
Figure 11 and Table 4 show the strain, by loading site, in the implant part corresponding to the first molar in the experimental models during the application of a 100-N vertical load.
Considerable compressive strain was observed with the load-side strain gauges in all placements, and similar trends were observed between pl...
A strain gauge (2630-100, Instron Japan, Kanagawa, Japan) was attached between the worktable and jig, and the change in the distance between the worktable and jig was measured under the assumption that it would be the same as the implant displacements under loading conditions (Fig. 6). Measurements were taken five times at each loading site, and the mean of the five measurements was considered the...
FEA software (Mechanical Finder®, Research Center of Computational Mechanics, Tokyo, Japan) was used to construct three-dimensional FEA models from the resulting CT data. The mesh was constructed of tetrahedral elements, and the total numbers of nodes and elements were approximately 260,000 and 1,400,000, respectively. FEA models were prepared with appropriate physical properties (Table 1) determ...
Preparation of the superstructure
Using the anatomical crown width as a reference, it was determined that the occlusal surface view of the superstructure would be trapezoidal with a 7-mm buccolingual width in the mesial first premolar section, a 10-mm buccolingual width in the distal first molar section, and a 26-mm mesiodistal width (Fig. 4). The vertical dimension was 8 mm; the upper 4 mm was t...
Compressed displacement
Figures 8 and 9 and Tables 2 and 3 show the results for the compressed displacement of the implants, by loading site, during the application of a 100-N vertical load in each of the models.
In all placements, the compressed displacement in the experimental models and FEA models was greatest with buccal loading and smallest with central loading at the three loading points....
Methods
Fabrication of the experimental model
Artificial mandibular bone
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 (Fig. 1). The model was composed of a two-layer structure of artificial cortical bone (urethane resin) and ar...
Background
Bone remodeling to maintain osseointegration between the bone and implant is absolutely essential to ensure favorable results and long-term stability in implant treatment. Bone remodeling requires that various stresses generated around the bone caused by the occlusal load applied to the implant be within an appropriate range. The concentration of stress at the bone-implant interface,...
Biomechanical effects of offset placement of dental implants in the edentulous posterior mandible
Abstract
Background
Proper implant placement is very important for long-term implant stability. Recently, numerous biomechanical studies have been conducted to clarify the relationship between implant placement and peri-implant stress. The placement of multiple implants in the edentulous posterio...
Figure 8. Distribution of the occlusal forces. Left column: model-T, right column: model-I, “Natural dentition” indicates the results in model-N under the load during occlusal adjustment
Figure 7. Load-displacement curve of the left canine
Figure 6. FE model with natural dentition (model-N). Tooth root is displayed with permeability
Figure 5. Schematic diagram for each phase of the load-displacement curve after occlusal adjustment of implants. a: Before loading, only anterior natural teeth were in contact with opposing teeth. Occlusal forces were not yet exerted anywhere. b: When a slight load caused the displacement of the mandible upward by the distance corresponding to the gap, i.e., the quantity of occlusal adjust...
Figure 4. Occlusal adjustment was simulated by altering the load-displacement curves of the springs
Figure 3. Load-displacement curves of the springs
Figure 2. Boundary conditions to verify the displaceability of teeth (a) and analyze the distribution of occlusal forces (b). Arrows: loads, triangles: restricted nodes, zigzags: springs
Figure 1. Finite element models (model-I and model-T). The tooth roots and the implant bodies are displayed with permeability
Occlusal adjustment (model)
___
___
___
___
4
5
6
7
Adj40N (model-T)
25.0
26.0
13.0
12.0
Adj200N (model-T)
30.0
37.0
23.5
24.0
Adj40N (model-I)
39.4
41.0
42.8
43.5
Adj200N (model-I)
70.9
75.4
79.9
81.6
Materials
Modulus of elasticity (MPa)
Poisson ratio
Enamel
80,000
0.3
Dentin
17,600
0.25
Inplant (titanium)
117,000
0.32
Superstructure (gold alloy)
94,000
0.3
Cortical bone
14,000
0.3
Cancellous bone
7,900
0.3
Since it was far larger than that of the teeth and implants (Fig. 3), the TMJs and ramus of the mandible were displaced upward and the most posterior implants became fulcrums of the rotation of the mandible. On the other hand, posterior implants were considered to be separated from opposing teeth and implants when the load was less than that exerted during occlusal adjustment. However, becau...
Thus, the “occlusal adjustment” performed on the FE models in this study was not a clinical procedure itself but a procedure to set the models in the state of the ICP under various occlusal loads.
This problem can be clarified by the definition of the ICP itself. Although load and deformation of the bone, joints, periodontal ligaments, and teeth in the ICP depend on the amount of the oc...
Discussion
FE models
The FE models in this study were based on those reported by Kasai et al. The material properties of the soft tissues such as the PDL and the TMJ, which were mainly deformed in the analysis, were considered to be crucial, because the aim of this study was to investigate the distribution of occlusal forces on the teeth, implants, and TMJs. In Figs. 3 and ...
Under Load200N, 20.3 % of the occlusal force was distributed at the molar site implants and 14.0 % of the occlusal force was distributed at the premolar site implants. The POF in the TMJ was larger than that in model-N. Under Load800N, the POF at the molar site implants was 36.3 %. However, almost no occlusal force occurred at the premolar site implants and anterior teeth. The POF in the TMJ wa...
Results
Displaceability of teeth
The load-displacement curve of the left canine under vertical load indicated two-phase displacement as shown in Fig. 7.
Model-T
The results of model-T are shown in Fig. 8. Adj40N resulted in the concentration of approximately 25 % of the occlusal force at the most posteriorly located implant on each side. In other words, about half of the total occlusal force...
Loading conditions
The loading conditions assumed intercuspal clenching. On the assumption that occlusal force was generated by the contractile force of four bilateral masticatory muscles, the masseter, temporalis, mesial, and lateral pterygoid muscles, the loading points and the directions of the loads were determined based on the report by Korioth and Hannam and anatomical findi...
Boundary conditions of the model and simulation of occlusal adjustment
The boundary conditions used to verify the displaceability of teeth and analyze the distribution of occlusal forces are shown in Fig. 2a, b, respectively. In the former model, a vertical load was applied to the left canine with the restriction of nodes on the bottom of the mandible (Fig. 2a). FE analysis was pe...
Methods
Finite element model
Three-dimensional finite element (FE) models were based on those reported by Kasai et al. and consisted of a mandible, natural teeth with periodontal ligaments, and titanium implants with superstructures. All elements were homogenous and isotropic. In the models, eight implants replaced all of the premolars and molars (Fig. 1).
The mass/volume and ...
Background
Dental implants have been widely used to restore or maintain occlusion, function, and esthetics and are particularly effective for partially edentulous jaws. However, the difference of the displaceability of the implants and natural teeth with periodontal ligaments (PDLs) may cause a problem in an arch that includes both implants and teeth. There is controversy about ...
Effect of bite force in occlusal adjustment of dental implants on the distribution of occlusal pressure: comparison among three bite forces in occlusal adjustment
Abstract
Background
The purpose of this study was to investigate the influence of occlusal forces (the contractile force of masticatory muscles) exerted during occlusal adjustment on the distribution of the forces among teeth, i...
Figure 6. Figure 6. a–d Von Mises stress distribution on bone. From a to d: L-M, ZL-M, L-V, and ZL-V respectively. The stress concentration occurred in the cortical bone around the neck of the implant. Groups L-M and ZL-M were quite similar and reduced stress
Figure 5. a–d Von Mises stress distribution on abutment. From a to d: L-M, ZL-M, L-V, and ZL-V respectively. Von Mises stresses were relatively similar and concentrated at the coronal part of the abutment in all groups
Figure 5. a–d Von Mises stress distribution on abutment. From a to d: L-M, ZL-M, L-V, and ZL-V respectively. Von Mises stresses were relatively similar and concentrated ...
Figure 4. a–d Von Mises stress distribution on implant. From a to d: L-M, ZL-M, L-V, and ZL-V respectively
Figure 4. a–d Von Mises stress distribution on implant. From a to d: L-M, ZL-M, L-V, and ZL-V respectively
Figure 3. a–d Maximum principal stress distribution on crown restoration. From a to d: L-M, ZL-M, L-V, and ZL-V respectively
Figure 3. a–d Maximum principal stress distribution on crown restoration. From a to d: L-M, ZL-M, L-V, and ZL-V respectively
Figure 2. The graph of the interaction of the materials and restoration design
Group
N
Mean (N)
Standard deviation
Minimum
Maximum
L-M
12
2891.88a
410.12
2079.74
3486.96
L-V
12
2077.37bc
356.59
1220.96
2493.39
ZL-M
12
1750.28c
314.96
1084.36
2163.95
ZL-V
12
2202.55b
503.14
1292.20
2912.81
Material
Young’s modulus (GPa)
Poisson ratio
Reference
E.max CAD
95
0.20
[1]
Vita Suprinity
65
0.23
[2]
Vita VM 11
65
0.23
*
E.max Ceram
64
0.23
[4]
Implant and abutment
114
0.34
[5]
Cortical bone
13.7
0.3
[5]
Spongious bone
1
0.3
[5]
Figure 1. Crown restoration design
Groups
N
Materials
L-M
12
IPS e-max CADIPS e.max CAD glaze
L-V
12
IPS e-max CADe.max Ceram DentinIPS e.max Ceram Glaze
ZL-M
12
Vita SuprinityVita Akzent Plus
ZL-V
12
Vita SuprinityVM-11Vita Akzent Plus
Material
Chemical composition (%)
Coefficient of thermal expansion (10−6 K−1)
Flexural strength (MPa)
Manufacturer
IPS e.max CAD; lithium disilicate glass ceramic (LDS)
SiO2 (57–80), Li2O (11–19), K2O (0–13), P2O5 (0–11), ZrO2 (0–8), ZnO (0–8), Al2O3 (0–5), MgO (0–5), coloring oxides (0–8)
10.2
360
Ivoclar Vivadent
IPS e.max Ceram; low-fusing nan...
Conclusions
Within the limitation of the present study, it can be concluded that the restoration design affected the failure load of ceramics. Monolithic design had a statistically significant effect on the failure load of two different ceramics (LDS > ZLS). Veneer application had opposite effects on two different ceramics which increased the failure load of ZLS and reduced it for LDS witho...
Zheng et al. compared the stress distribution of the same veneering ceramic on different cores and concluded that the zirconia core was clearly different from other materials with higher tensile stresses at the veneer core interface because the increasing differences between the elasticity modulus of the core and the veneer transmitted higher stress concentrations to the cores. Con...
Veneer application provided additional strength to the ZLS crowns in contrast to the LDS crowns. The higher failure load of the veneered ZLS crowns (2202.55 N; group L-V 2077.37 N) may be associated with the higher flexural strength of the veneering porcelain VM-11 (100 MPa; emax Ceram 90 MPa). These veneered groups had a statistically significant difference from the monoli...
Similar results were presented in a study of Traini et al. as it was concluded that ZLS was comparable to that of existing zirconia-based ceramics and was suitable for oral function even in the posterior regions. In the literature, there have been few studies on this ceramic and a limited number of them include the failure load of the material. In one of these studi...
In literature, it has been stated that the failure load of LDS crowns was higher than veneered zirconia and could be comparable with metal ceramic systems. Doğan et al. evaluated the fracture strength of different CAD/CAM-manufactured crowns and concluded that the monolithic LDS crowns had the highest fracture resistance. Present study confirmed as monolithic LDS crowns demonstrated so satisfying...
Discussion
Implant-supported restorations have been accepted as an alternative treatment for the rehabilitation of edentulous spaces. Despite the high success rates, implant failures are inevitable and classified as early or late implant failures. Late implant failures are observed after prosthetic restoration which is primarily related to biomechanical complications. Since occlusal loads are t...
Results
Descriptive analysis (mean, standard deviation (SD), minimum, maximum) of the groups is presented in Table 4.
Group L-M exhibited the highest failure load values (2891.88 N ± 410.12 N), and the lowest values were observed in group ZL-M (1750.28 N ± 314.96 N). Two-way ANOVA indicated a statistically significant difference between materials and veneering technique (p = 0.00 < ...
Statistical analysis
The statistical analysis was performed with SPSS 24.0 (SPSS Inc, Chicago, USA). The Kolmogorov–Smirnov normality test was used to evaluate whether the data distribution of the groups was normal. The homogeneity of the variances was analyzed by Levene’s test. Since test results indicated that data distribution of the groups was normal and the variances were homogenous,...
All crowns were subjected to a combination firing that included crystallization and glaze firing according to each manufacturer’s guidelines in the ceramic furnace (Vita Vacumat 6000 M, Vita Zahnfabrik, Bad Sackingen, Germany).
For veneered restorations, the design mode was changed to “split,” and the core was constructed in 0.6-mm thickness. In group L-V (n = 12), e.max ...
Methods
Preparation of test groups
This study tested the current glass ceramic ZLS by comparing LDS with monolithic and conventional veneering techniques in implant-supported crowns: group L-M: lithium disilicate ceramic (monolithic), group L-V: lithium disilicate ceramic (conventional veneering), group ZL-M: zirconia-reinforced lithium silicate ceramic (monolithic), group ZL-V: zirconia-reinf...
Background
Implants have been successfully used to replace missing teeth for many years. Notwithstanding the high success rates, complications such as screw loosening and/or fracture, prosthesis fracture, and even implant fracture are inevitable. The reasons of the complication may be related to decreased proprioception and low tactile sensitivity which makes implant-supported crowns more susc...
Abstract
Background
Present study compared the failure load of CAD/CAM-manufactured implant-supported crowns and the stress distribution on the prosthesis-implant-bone complex with different restoration techniques.
Methods
The materials were divided into four groups: group L-M: lithium disilicate ceramic (LDS, monolithic), group L-V: LDS ceramic (veneering), group ZL-M: zirconia-reinforced l...
Finite Element Analysis (FEA) atau Analisis Elemen Terbatas adalah metode numerik yang dipakai untuk memecahkan model matematis suatu struktur atau sistem. FEA meramal tanggapan struktur (contoh, deru, O-ring, seal) terhadap daya-daya yang diterapkan, suhu, dan getaran. Input ke model adalah properti bahan, geometri bahan, dan kondisi sekeliling.
Properti tegangan-regangan yang dipunyai bahan-bah...