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
Â
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. 6. Loading of implant off-axially
Fig. 6. Loading of implant off-axially
Fig. 5. Loading of implant axially
Fig. 5. Loading of implant axially
Fig. 4. Installation of strain gauges on surfaces of epoxy resin adjacent to mini implants
Fig. 4. Installation of strain gauges on surfaces of epoxy resin adjacent to mini implants
Fig. 3. Lava Ultimate Restorative crown on the two mini implants.
Fig. 3. Lava Ultimate Restorative crown on the two mini implants.
Fig. 2. Metal crown supported on two mini implants
Fig. 2. Metal crown supported on two mini implants
Fig. 1.
Fig. 1. a Standard, b short-wide, and c single-piece mini implants
Crown
Implant type
Axial
Off-axial
P-value
Mean
SD
...
Axial
Off-axial
P value
Mean
SD
Mean
SD
...
Lava Ultimate
crowns
Metal
crowns
P value
Mean
SD
Mean
...
Load
Crown type
Standard
Short-wide
Double mini
P value
...
Standard
Short-wide
Double mini
P value
Mean
SD
Mean
...
Elfadaly, L.S., Khairallah, L.S. & Al Agroudy, M.A. Peri-implant biomechanical responses to standard, short-wide, and double mini implants replacing missing molar supporting hybrid ceramic or full-metal crowns under axial and off-axial loading: an in vitro study.
Int J Implant Dent 3, 31 (2017). https://doi.org/10.1186/s40729-017-0094-2
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Received: 14 Februar...
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...
The authors L.S.Elfadaly, L.S.Kheirallah, and M.A.Alagroudy state that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Fixed Prosthodontics, Cairo University, Giza, Egypt
Lamiaa Said Elfadaly, Lamiaa Sayed Khairallah & Mona Atteya Al Agroudy
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Gracis S, Nicholls J, Chalupnik J, Yuodelis R. Shock-absorbing behavior of five restorative materials used on implants. Int J Prosthodont. 1990;4:282–91.
Skalak R. Biomechanical considerations in osseointegrated prostheses. J Prosthet Dent. 1983;49:843–8.
Misch C. Clinical biomechanics in implant dentistry, Contemporary Implant Dentistry. 3rd ed. 2008. p. 543–56. mosby,inc.
Lundgren D, La...
Himmlova L, Dostalova T, Kacovsky A, Konvickova S. Influence of implant length and diameter on stress distribution: a finite element analysis. J Prosthet Dent. 2004;91(1):20–5.
Shetty S, Puthukkat N, Bhat S, Shenoy K. Short implants: a new dimension in rehabilitation of atrophic maxilla and mandible. Journal of Interdisciplinary Dentistry. 2014;4(2):66.
Misch C, Bidez M. Contemporary implant d...
Barbier L, Vander SJ, Krzesinski G, Schepers E, Van der Perre G. Finite element analysis of non-axial versus axial loading of oral implants in the mandible of the dog. J Oral Rehabil. 1998;25(11):847–58.
Saime S, Murat C, Emine Y. The influence of functional forces on the biomechanics of implant-supported prostheses—a review. J Dent. 2002;30:271–82.
Balshi T, Hernandez R, Pryszlak M, Range...
Mazor Z, Lorean A, Mijiritsky E, Levin L. Replacement of a molar with 2 narrow diameter dental implants. Implant Dent. 2012;21(1):36–8.
Atwood D. Postextraction changes in the adult mandible as illustrated by micrographs of midsagittal sections and serial cephalometric roentgenograms. J Prosthet Dent. 1963;13:810–24.
Felice P, Pellegrino G, Checchi L, Pistilli R, Esposito M. Vertical augment...
Within the limitations of this in vitro study, the following conclusions could be drawn:
Implant design, superstructure material, and load direction significantly affect peri-implant microstrains.
The recorded compressive and tensile microstrains for the tested designs were within the physiologic loading range, as they did not exceed the compressive or tensile strength of the bone-implant interf...
Regarding the effect of superstructure material on induced microstrains, generally, different implant designs supporting Lava Ultimate crowns showed higher mean microstrain values(1927.3 ± 1536.6 μɛ), in comparison with those supporting metal crowns (1313.7 ± 973.1 μɛ).Theoretical considerations [44, 45] and in vitro experiments [46,47,48,49] suggest that an occlusal material with ...
Regarding the effect of direction of loading on induced microstrains, it was shown that changing the position of occlusal loading had a considerable effect on the amount of distribution of stresses where axial loading generated even distribution of load around the implant in comparison to off-axial loading where stresses were more pronounced in the area of load application. This might be due to th...
Previous studies have shown that direct correlations exist between microstrain magnitudes and bone stability/instability conditions. This has been summarized by Frost, when bone is loaded below about 2000 microstrains, bone can easily repair what little microdamage occurs. Yet, when pathologic overloading occurs (over 4000 microstrains), stress and strain gradients exceed the physiologic tolerance...
To replace a missing lower molar in compromised ridge, different treatment options were suggested, using either a standard size implant with surgical procedures, short-wide implant, or two mini implants. Concerning the use of mini implant, splinted multiple implants increase the surface area that interfaces with the bone to lessen the per square millimeters of force borne by the bone [11]. The imp...
Results revealed that standard implant showed the statistically significantly highest mean microstrain values (3362.4 ± 757.4 μɛ). Double mini implant showed statistically significantly lower mean microstrain values (801.6 ± 251.4 μɛ), while short-wide implant showed the statistically significantly lowest mean microstrain values (697.6 ± 79.7 μɛ), with a P value
Data were presented as mean and standard deviation (SD) values. Data were explored for normality by checking data distribution and histograms, calculating mean and median values, and finally using Kolmogorov-Smirnov and Shapiro-Wilk tests of normality. Stress data showed non-parametric distribution, so the Kruskal-Wallis test was used to compare between the types of implants. The Mann-Whitney U te...
Each crown was cemented to its corresponding implant-abutment assembly using temporary cement (Cavex Temporary Cement, Cavex, Holland).
Each implant received 4 strain gauges (Kowa strain gages, Japan) placed on the mesial, distal, buccal, and lingual surfaces of the epoxy resin adjacent to the implants. At these selected sites, the thickness of the epoxy resin surrounding each implant was reduced...
In the present study, the following materials were used: titanium root form endosseous implants of standard diameter and length (4-mm platform, 3.8-mm diameter,12-mm length, fixture bevel 0.2Â mm, Super Line System, Dentium, USA), short-wide implant (7-mm platform, 5.8-mm diameter, 7-mm length, Super Line System, Dentium, Seoul, Korea) with 1.5-mm machined surface and 5.5-mm threaded surface that ...
There are several factors that affect force magnitudes in peri-implant bone. The application of functional forces induces stresses and strains within the implant prosthesis complex and affect the bone remodeling process around implants [8, 9].
While there are several methods of measuring strain, the most common is with a strain gauge, a device whose electrical resistance varies in proportion to t...
The molars are one of the first teeth to be lost over lifetime; thus, their replacement is frequently needed. Implantation is generally the preferred choice to replace a missing single tooth avoiding vital teeth preparation and bridge fabrication [1].
The mandibular bone loss occurs as knife-edge residual ridge where there is marked narrowing of the labiolingual diameter of the crest of the ridge...
The aim of this study was to evaluate the biomechanical response of the peri-implant bone to standard, short-wide, and double mini implants replacing missing molar supporting either hybrid ceramic crowns (Lava Ultimate restorative) or full-metal crowns under two different loading conditions (axial and off-axial loading) using strain gauge analysis.
Three single-molar implant designs, (1) single, ...
Fig. 6. Loading of implant off-axially
Fig. 6. Loading of implant off-axially
Fig. 5. Loading of implant axially
Fig. 5. Loading of implant axially
Fig. 4. Installation of strain gauges on surfaces of epoxy resin adjacent to mini implants
Fig. 4. Installation of strain gauges on surfaces of epoxy resin adjacent to mini implants
Fig. 3. Lava Ultimate Restorative crown on the two mini implants.
Fig. 3. Lava Ultimate Restorative crown on the two mini implants.
Fig. 2. Metal crown supported on two mini implants
Fig. 2. Metal crown supported on two mini implants
Fig. 1. a Standard, b short-wide, and c single-piece mini implants
Crown
Implant type
Axial
Off-axial
P-value
Mean
SD
...
Axial
Off-axial
P value
Mean
SD
Mean
SD
...
Lava Ultimate
crowns
Metal
crowns
P value
Mean
SD
Mean
...
Load
Crown type
Standard
Short-wide
Double mini
P value
...
Standard
Short-wide
Double mini
P value
Mean
SD
Mean
...
Elfadaly, L.S., Khairallah, L.S. & Al Agroudy, M.A. Peri-implant biomechanical responses to standard, short-wide, and double mini implants replacing missing molar supporting hybrid ceramic or full-metal crowns under axial and off-axial loading: an in vitro study.
Int J Implant Dent 3, 31 (2017). https://doi.org/10.1186/s40729-017-0094-2
Download citation
Received: 14 Februar...
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...
The authors L.S.Elfadaly, L.S.Kheirallah, and M.A.Alagroudy state that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Fixed Prosthodontics, Cairo University, Giza, Egypt
Lamiaa Said Elfadaly, Lamiaa Sayed Khairallah & Mona Atteya Al Agroudy
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Gracis S, Nicholls J, Chalupnik J, Yuodelis R. Shock-absorbing behavior of five restorative materials used on implants. Int J Prosthodont. 1990;4:282–91.
Skalak R. Biomechanical considerations in osseointegrated prostheses. J Prosthet Dent. 1983;49:843–8.
Misch C. Clinical biomechanics in implant dentistry, Contemporary Implant Dentistry. 3rd ed. 2008. p. 543–56. mosby,inc.
Lundgren D, La...
Himmlova L, Dostalova T, Kacovsky A, Konvickova S. Influence of implant length and diameter on stress distribution: a finite element analysis. J Prosthet Dent. 2004;91(1):20–5.
Shetty S, Puthukkat N, Bhat S, Shenoy K. Short implants: a new dimension in rehabilitation of atrophic maxilla and mandible. Journal of Interdisciplinary Dentistry. 2014;4(2):66.
Misch C, Bidez M. Contemporary implant d...
Barbier L, Vander SJ, Krzesinski G, Schepers E, Van der Perre G. Finite element analysis of non-axial versus axial loading of oral implants in the mandible of the dog. J Oral Rehabil. 1998;25(11):847–58.
Saime S, Murat C, Emine Y. The influence of functional forces on the biomechanics of implant-supported prostheses—a review. J Dent. 2002;30:271–82.
Balshi T, Hernandez R, Pryszlak M, Range...
Mazor Z, Lorean A, Mijiritsky E, Levin L. Replacement of a molar with 2 narrow diameter dental implants. Implant Dent. 2012;21(1):36–8.
Atwood D. Postextraction changes in the adult mandible as illustrated by micrographs of midsagittal sections and serial cephalometric roentgenograms. J Prosthet Dent. 1963;13:810–24.
Felice P, Pellegrino G, Checchi L, Pistilli R, Esposito M. Vertical augment...
Within the limitations of this in vitro study, the following conclusions could be drawn:
Implant design, superstructure material, and load direction significantly affect peri-implant microstrains.
The recorded compressive and tensile microstrains for the tested designs were within the physiologic loading range, as they did not exceed the compressive or tensile strength of the bone-implant interf...
Regarding the effect of superstructure material on induced microstrains, generally, different implant designs supporting Lava Ultimate crowns showed higher mean microstrain values(1927.3 ± 1536.6 μɛ), in comparison with those supporting metal crowns (1313.7 ± 973.1 μɛ).Theoretical considerations [44, 45] and in vitro experiments [46,47,48,49] suggest that an occlusal material with ...
Regarding the effect of direction of loading on induced microstrains, it was shown that changing the position of occlusal loading had a considerable effect on the amount of distribution of stresses where axial loading generated even distribution of load around the implant in comparison to off-axial loading where stresses were more pronounced in the area of load application. This might be due to th...
Previous studies have shown that direct correlations exist between microstrain magnitudes and bone stability/instability conditions. This has been summarized by Frost, when bone is loaded below about 2000 microstrains, bone can easily repair what little microdamage occurs. Yet, when pathologic overloading occurs (over 4000 microstrains), stress and strain gradients exceed the physiologic tolerance...
To replace a missing lower molar in compromised ridge, different treatment options were suggested, using either a standard size implant with surgical procedures, short-wide implant, or two mini implants. Concerning the use of mini implant, splinted multiple implants increase the surface area that interfaces with the bone to lessen the per square millimeters of force borne by the bone [11]. The imp...
Results revealed that standard implant showed the statistically significantly highest mean microstrain values (3362.4 ± 757.4 μɛ). Double mini implant showed statistically significantly lower mean microstrain values (801.6 ± 251.4 μɛ), while short-wide implant showed the statistically significantly lowest mean microstrain values (697.6 ± 79.7 μɛ), with a P value
Data were presented as mean and standard deviation (SD) values. Data were explored for normality by checking data distribution and histograms, calculating mean and median values, and finally using Kolmogorov-Smirnov and Shapiro-Wilk tests of normality. Stress data showed non-parametric distribution, so the Kruskal-Wallis test was used to compare between the types of implants. The Mann-Whitney U te...
Each crown was cemented to its corresponding implant-abutment assembly using temporary cement (Cavex Temporary Cement, Cavex, Holland).
Each implant received 4 strain gauges (Kowa strain gages, Japan) placed on the mesial, distal, buccal, and lingual surfaces of the epoxy resin adjacent to the implants. At these selected sites, the thickness of the epoxy resin surrounding each implant was reduced...
In the present study, the following materials were used: titanium root form endosseous implants of standard diameter and length (4-mm platform, 3.8-mm diameter,12-mm length, fixture bevel 0.2Â mm, Super Line System, Dentium, USA), short-wide implant (7-mm platform, 5.8-mm diameter, 7-mm length, Super Line System, Dentium, Seoul, Korea) with 1.5-mm machined surface and 5.5-mm threaded surface that ...
There are several factors that affect force magnitudes in peri-implant bone. The application of functional forces induces stresses and strains within the implant prosthesis complex and affect the bone remodeling process around implants [8, 9].
While there are several methods of measuring strain, the most common is with a strain gauge, a device whose electrical resistance varies in proportion to t...
The molars are one of the first teeth to be lost over lifetime; thus, their replacement is frequently needed. Implantation is generally the preferred choice to replace a missing single tooth avoiding vital teeth preparation and bridge fabrication [1].
The mandibular bone loss occurs as knife-edge residual ridge where there is marked narrowing of the labiolingual diameter of the crest of the ridge...
The aim of this study was to evaluate the biomechanical response of the peri-implant bone to standard, short-wide, and double mini implants replacing missing molar supporting either hybrid ceramic crowns (Lava Ultimate restorative) or full-metal crowns under two different loading conditions (axial and off-axial loading) using strain gauge analysis.
Three single-molar implant designs, (1) single, ...
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 ±â€...
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
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Figure 15. Load supporting area in the superstructures
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Figure 14. The distribution of equivalent stress around the no. 36 implant in the finite element analysis (FEA) models
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Figure 13. The distribution of equivalent stress around the peri-implant bone in the finite element analysis (FEA) models
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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
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Figure 9. The displacement of the implants under loading in finite element analysis (FEA) models
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Figure 8. The displacement of the implants under loading in experimental models
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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
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Figure 6. Loading test in the experimental model
Figure 5. Application of strain gauges
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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 ...
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Strain on the peri-implant bone
Strain in the experimental models
Figure 11Â and Table 4Â 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 3Â 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...