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
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...
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The authors declare that they have no competing interests.
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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You can also search for this author in PubMed Google Scholar
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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.
Gottlow J, Dard M, Kjellson F, Obrecht M, Sennerby L. Evaluation of a new titanium-zirconium dental implant: a biomechanical and histological comparative study in the mini pig. Clin Implant Dent Relat Res. 2012;14:538–45.
Jimbo R, Naito Y, Galli S, Berner S, Dard M, Wennerberg A. Biomechanical and histomorphometrical evaluation of TiZr alloy implants: an in vivo study in the rabbit. Clin Implan...
Yamanishi Y, Yamaguchi S, Imazato S, Nakano T, Yatani H. Influences of implant neck design and implant–abutment joint type on peri-implant bone stress and abutment micromovement: three-dimensional finite element analysis. Dent Mater. 2012;28:1126–33.
Harel N, Eshkol-Yogev I, Piek D, Livne S, Lavi D, Ormianer Z. Bone microstrain values of 1-piece and 2-piece implants subjected to mechanical lo...
Lee TJ, Ueno T, Nomura N, Wakabayashi N, Hanawa T. Titanium-zirconium binary alloy as dental implant material: analysis of the influence of compositional change on mechanical properties and in vitro biologic response. Int J Oral Maxillofac Implants. 2015;31:547–54.
Al-Nawas B, Brägger U, Meijer HJA, Naert I, Persson R, Perucchi A. A double-blind randomized controlled trial (RCT) of titanium-13...
Renouard F, Nisand D. Impact of implant length and diameter on survival rates. Clin Oral Implants Res. 2006;17(Suppl 2):35–51.
Lee SA, Lee CT, Fu MM, Elmisalati W, Chuang SK. Systematic review and meta-analysis of randomized controlled trials for the management of limited vertical height in the posterior region: short implants (5 to 8 mm) vs longer implants (> 8 mm) in vertically augmented site...
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 ...
Fig. 5. Osteoblasts with an orientation tendency after 24 h of rotation (phallacidin fluorescence staining). On the left side with 200× and on the right side with 400× magnification. The yellow arrows show the orientation of the cells. The red arched arrow within the coloured circle shows the direction of rotation. The dashed white line oriented to the right stands for the resulting centrifug...
Fig. 4. Randomly orientated osteoblasts without influence of rotation (phallacidin fluorescence staining). On the left side with 200× and on the right side with 400× magnification. The white X on the coloured circle marks the location upon the plate where the osteoblasts were located. The red X marks the centre of the plate
Fig. 4. Randomly orientated osteoblasts without influence of rotati...
centrifugal force and the glass plates’ dimensions. For example, at a distance of 25 mm from the centre of the upper plate, the shear forces’ value is 8.33 dyn/cm2, together with an additional centrifugal force that has a value of 0.55 dyn/cm2
Fig. 3. Diagram for visualisation of the calculation of shear stress rates taking into account the centrifugal force and the glass plates’ dim...
earing gap and bottom plate are shown on the left side; rotation speed = 200 rpm; colour code bar (left edge) showing shear force values [Pa] [1 Pa = 10 dyn/cm2]; flow direction presented by arrows
Fig. 2. Side view of a computerized simulation, showing the flow chambers’ lower compartment and the flow profile in between the two plates; shearing gap and bottom plate are shown on ...
Fig. 1. Three-dimensional illustration (a–e) and photography (f) of the experimental setup with the components marked numerical. a as the lower plate); 2 Rotating glass panel [60 mm diameter (cell bearing)]; 3 Titanium axis. b4 Liquid medium (red). cGearwheel with set screw. eng ring with additional set screw
Fig. 1. Three-dimensional illustration (a–e) and photography (f) of the experim...
Culture medium/additives
Manufacturer
Order no.
Concentration
Dulbecco’s modified Eagle medium (DMEM) with l-glutamine, plus 4.5 g glucose,...
Component
Manufacturer
Order no.
Large petri dish
Becton Dickinson, Franklin Lakes, NJ, USA
...
Kämmerer, P.W., Thiem, D.G.E., Alshihri, A. et al. Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up.
Int J Implant Dent 3, 22 (2017). https://doi.org/10.1186/s40729-017-0085-3
Download citation
Received: 27 February 2017
Accepted: 22 May 2017
Published: 31 May 2017
DOI: https://doi.org/10.1186/s40729-017-0085-3
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...
Correspondence to
D. G. E. Thiem.
Department of Oral and Maxillofacial Surgery, Facial Plastic Surgery, University Medical Centre Rostock, Schillingallee 35, 18057, Rostock, Germany
P. W. Kämmerer & D. G. E. Thiem
Department of Prosthetic and Biomaterial Sciences, King Saud University, Riyadh, Saudi Arabia
A. Alshihri
Harvard School of Dental Medicine, Boston, MA, USA
A. Alshihri
Department of Oral and Maxillofacial Surge...
The authors thank the Department of Hydraulic Machines, Faculty of Mechanical Engineering, Technical University of Munich, Germany, for helping with the computerised simulations.
Nothing to declare
The datasets supporting the conclusions of this article are available at the repository of the University Medical Centre Mainz, Germany, and can be provided on request.
PK had substantial contributio...
Papadaki M, Eskin SG. Effects of fluid shear stress on gene regulation of vascular cells. Biotechnol Prog. 1997;13(3):209–21.
James NL, Harrison DG, Nerem RM. Effects of shear on endothelial cell calcium in the presence and absence of ATP. FASEB J. 1995;9(10):968–73.
Kämmerer PW, Lehnert M, Al-Nawas B, Kumar VV, Hagmann S, Alshihri A, et al. Osseoconductivity of a specific streptavidin-biot...
Hughes-Fulford M. Signal transduction and mechanical stress. Sci STKE. 2004;2004(249):RE12.
Ruel J, Lemay J, Dumas G, Doillon C, Charara J. Development of a parallel plate flow chamber for studying cell behavior under pulsatile flow. ASAIO J. 1995;41(4):876–83.
Kazakidi A, Sherwin SJ, Weinberg PD. Effect of Reynolds number and flow division on patterns of haemodynamic wall shear stress near br...
Becker J, Kirsch A, Schwarz F, Chatzinikolaidou M, Rothamel D, Lekovic V, et al. Bone apposition to titanium implants biocoated with recombinant human bone morphogenetic protein-2 (rhBMP-2). A pilot study in dogs. Clin Oral Investig. 2006;10(3):217–24.
Hung CT, Allen FD, Pollack SR, Brighton CT. What is the role of the convective current density in the real-time calcium response of cultured bon...
Ehrlich PJ, Lanyon LE. Mechanical strain and bone cell function: a review. Osteoporos Int. 2002;13(9):688–700.
Vaughan TJ, Haugh MG, Mcnamara LM. A fluid-structure interaction model to characterize bone cell stimulation in parallel-plate flow chamber systems. J R Soc Interface. 2013;10(81):20120900.
Weinbaum S, Cowin SC, Zeng Y. A model for the excitation of osteocytes by mechanical loading-in...
To create fluid shear stress under in vitro conditions, several flow chambers have been developed in the past. The experimental setup of the flow chamber in the centre of this study offers advantages such as simplicity to assemble and ease of use as well as the creation of reproducible fluid shear forces on cells. Due to the new design, different cell types could be simultaneously analysed under r...
Besides, in the model reported in this study, microscopic examinations are possible after completing the experiment only. Nevertheless, an advantage of the new flow chamber is the possibility of testing different cell colonies simultaneously in one single experiment by placing cells in different radial locations on the spinning disc. Due to the current flow gradient from the centre to the peripher...
Due to the fact that constant flows were generated within the parallel flow chamber only, the situations of in vitro experiments differ from in vivo setting where dynamic flow profiles are particular [33]. As the constant laminar flow profile is not physiological in bones [34], vessels and other tissues [35], the informative value of the experimental setting is limited but it could be used for var...
The aim of this study was to establish a new FSS model that is easy to use as well as simple to assemble in order to create reproducible fluid shear forces on cells close to implant material surfaces. Todays’ commonly used commercial flow devices differ in geometry and function, which makes comparisons between experiments difficult [4, 10, 26, 27]. The benefits of this novel testing device are r...
in which ρ = density, h = height, ω = angular velocity and r = radius.
Figure 3 shows the respective physical force and its dependence on a bigger radius and higher rotational speed. The results of this study indicate that the centrifugal force represents only a little proportion of effective forces. Hence, the centrifugal forces’ impacts on the tested cells are considered to be insignifican...
Our analysis was focused on two main aspects:
Simulation of the fluid flow characteristics as well as quantification of the arising shear forces at the plate/plate flow chamber with reliable reproducibility
Assessment of the impact of fluid shear stress on osteoblast cells in terms of altered cell morphology and intracellular structural changes
The computational fluid dynamic analysis and the q...
For constant and fully developed laminar flow between the two parallel plates, the magnitude of the wall shear stress (τ) in between was calculated by formula 1:
in which η is the dynamic fluid viscosity (dyn/cm2), r is the radius of the plate (cm), ω stands for angular velocity and H for height (vertical distance in between the two plates).
To get information whether the flow is laminar or t...
A three-dimensional illustration and photography of the plate/plate flow chamber model is shown in Fig. 1. A detailed list of used parts can be found in Appendix 1.
The circulation within the flow chamber was generated by an externally attached electric motor, which rotates up to 500 rounds per minute (rpm). A commercial grade 4 pure medical titanium gear shaft (length = 40 mm, diameter =...
Therefore, the aim of the present study was to establish a new cell chamber model for FSS simulation and stimulation. In addition to its ease of use, the reported model in this study should meet the requirements of a simple design, generating reproducible flow characteristics next to laminar flows and clearly defined flow gradients on implant surfaces.
Cells can be influenced by different mechanostimuli, which lead to an activation of cellular and inter-cellular responses. These reactions may be caused by either a direct stimulation of the cell body (mechanoreception) or indirect cellular stimulation (response) [1,2,3]. Extracellular fluid movement induces fluid shear stress (FSS) that can result in different cellular processes including prolife...
Mechanostimuli of different cells can affect a wide array of cellular and inter-cellular biological processes responsible for dental implant healing. The purpose of this in vitro study was to establish a new test model to create a reproducible flow-induced fluid shear stress (FSS) of osteoblast cells on implant surfaces.
As FSS effects on osteoblasts are detectable at 10 dyn/cm2, a custom-made f...
Fig. 5. Osteoblasts with an orientation tendency after 24 h of rotation (phallacidin fluorescence staining). On the left side with 200× and on the right side with 400× magnification. The yellow arrows show the orientation of the cells. The red arched arrow within the coloured circle shows the direction of rotation. The dashed white line oriented to the right stands for the resulting centrifug...
Fig. 4. Randomly orientated osteoblasts without influence of rotation (phallacidin fluorescence staining). On the left side with 200× and on the right side with 400× magnification. The white X on the coloured circle marks the location upon the plate where the osteoblasts were located. The red X marks the centre of the plate
Fig. 4. Randomly orientated osteoblasts without influence of rotati...
to account the centrifugal force and the glass plates’ dimensions. For example, at a distance of 25 mm from the centre of the upper plate, the shear forces’ value is 8.33 dyn/cm2, together with an additional centrifugal force that has a value of 0.55 dyn/cm2
Fig. 3. Diagram for visualisation of the calculation of shear stress rates taking into account the centrifugal force and the glas...
e in between the two plates; shearing gap and bottom plate are shown on the left side; rotation speed = 200 rpm; colour code bar (left edge) showing shear force values [Pa] [1 Pa = 10 dyn/cm2]; flow direction presented by arrows
Fig. 2. Side view of a computerized simulation, showing the flow chambers’ lower compartment and the flow profile in between the two plates; shearing gap...
Fig. 1. Three-dimensional illustration (a–e) and photography (f) of the experimental setup with the components marked numerical. a lower plate); 2 Rotating glass panel [60 mm diameter (cell bearing)]; 3 Titanium axis. b4 Liquid medium (red). cwheel with set screw. e ring with additional set screw
Fig. 1. Three-dimensional illustration (a–e) and photography (f) of the experimental setup w...
Culture medium/additives
Manufacturer
Order no.
Concentration
Dulbecco’s modified Eagle medium (DMEM) with l-glutamine, plus 4.5 g glucose,...
Component
Manufacturer
Order no.
Large petri dish
Becton Dickinson, Franklin Lakes, NJ, USA
...
Kämmerer, P.W., Thiem, D.G.E., Alshihri, A. et al. Cellular fluid shear stress on implant surfaces—establishment of a novel experimental set up.
Int J Implant Dent 3, 22 (2017). https://doi.org/10.1186/s40729-017-0085-3
Download citation
Received: 27 February 2017
Accepted: 22 May 2017
Published: 31 May 2017
DOI: https://doi.org/10.1186/s40729-017-0085-3
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...
Correspondence to
D. G. E. Thiem.
Department of Oral and Maxillofacial Surgery, Facial Plastic Surgery, University Medical Centre Rostock, Schillingallee 35, 18057, Rostock, Germany
P. W. Kämmerer & D. G. E. Thiem
Department of Prosthetic and Biomaterial Sciences, King Saud University, Riyadh, Saudi Arabia
A. Alshihri
Harvard School of Dental Medicine, Boston, MA, USA
A. Alshihri
Department of Oral and Maxillofacial Surge...
The authors thank the Department of Hydraulic Machines, Faculty of Mechanical Engineering, Technical University of Munich, Germany, for helping with the computerised simulations.
Nothing to declare
The datasets supporting the conclusions of this article are available at the repository of the University Medical Centre Mainz, Germany, and can be provided on request.
PK had substantial contributio...
Papadaki M, Eskin SG. Effects of fluid shear stress on gene regulation of vascular cells. Biotechnol Prog. 1997;13(3):209–21.
James NL, Harrison DG, Nerem RM. Effects of shear on endothelial cell calcium in the presence and absence of ATP. FASEB J. 1995;9(10):968–73.
Kämmerer PW, Lehnert M, Al-Nawas B, Kumar VV, Hagmann S, Alshihri A, et al. Osseoconductivity of a specific streptavidin-biot...
Hughes-Fulford M. Signal transduction and mechanical stress. Sci STKE. 2004;2004(249):RE12.
Ruel J, Lemay J, Dumas G, Doillon C, Charara J. Development of a parallel plate flow chamber for studying cell behavior under pulsatile flow. ASAIO J. 1995;41(4):876–83.
Kazakidi A, Sherwin SJ, Weinberg PD. Effect of Reynolds number and flow division on patterns of haemodynamic wall shear stress near br...
Becker J, Kirsch A, Schwarz F, Chatzinikolaidou M, Rothamel D, Lekovic V, et al. Bone apposition to titanium implants biocoated with recombinant human bone morphogenetic protein-2 (rhBMP-2). A pilot study in dogs. Clin Oral Investig. 2006;10(3):217–24.
Hung CT, Allen FD, Pollack SR, Brighton CT. What is the role of the convective current density in the real-time calcium response of cultured bon...
Ehrlich PJ, Lanyon LE. Mechanical strain and bone cell function: a review. Osteoporos Int. 2002;13(9):688–700.
Vaughan TJ, Haugh MG, Mcnamara LM. A fluid-structure interaction model to characterize bone cell stimulation in parallel-plate flow chamber systems. J R Soc Interface. 2013;10(81):20120900.
Weinbaum S, Cowin SC, Zeng Y. A model for the excitation of osteocytes by mechanical loading-in...
To create fluid shear stress under in vitro conditions, several flow chambers have been developed in the past. The experimental setup of the flow chamber in the centre of this study offers advantages such as simplicity to assemble and ease of use as well as the creation of reproducible fluid shear forces on cells. Due to the new design, different cell types could be simultaneously analysed under r...
Besides, in the model reported in this study, microscopic examinations are possible after completing the experiment only. Nevertheless, an advantage of the new flow chamber is the possibility of testing different cell colonies simultaneously in one single experiment by placing cells in different radial locations on the spinning disc. Due to the current flow gradient from the centre to the peripher...
Due to the fact that constant flows were generated within the parallel flow chamber only, the situations of in vitro experiments differ from in vivo setting where dynamic flow profiles are particular [33]. As the constant laminar flow profile is not physiological in bones [34], vessels and other tissues [35], the informative value of the experimental setting is limited but it could be used for var...
The aim of this study was to establish a new FSS model that is easy to use as well as simple to assemble in order to create reproducible fluid shear forces on cells close to implant material surfaces. Todays’ commonly used commercial flow devices differ in geometry and function, which makes comparisons between experiments difficult [4, 10, 26, 27]. The benefits of this novel testing device are r...
in which ρ = density, h = height, ω = angular velocity and r = radius.
Figure 3 shows the respective physical force and its dependence on a bigger radius and higher rotational speed. The results of this study indicate that the centrifugal force represents only a little proportion of effective forces. Hence, the centrifugal forces’ impacts on the tested cells are considered to be insignifican...
Our analysis was focused on two main aspects:
Simulation of the fluid flow characteristics as well as quantification of the arising shear forces at the plate/plate flow chamber with reliable reproducibility
Assessment of the impact of fluid shear stress on osteoblast cells in terms of altered cell morphology and intracellular structural changes
The computational fluid dynamic analysis and the q...
For constant and fully developed laminar flow between the two parallel plates, the magnitude of the wall shear stress (τ) in between was calculated by formula 1:
in which η is the dynamic fluid viscosity (dyn/cm2), r is the radius of the plate (cm), ω stands for angular velocity and H for height (vertical distance in between the two plates).
To get information whether the flow is laminar or t...
A three-dimensional illustration and photography of the plate/plate flow chamber model is shown in Fig. 1. A detailed list of used parts can be found in Appendix 1.
The circulation within the flow chamber was generated by an externally attached electric motor, which rotates up to 500 rounds per minute (rpm). A commercial grade 4 pure medical titanium gear shaft (length = 40 mm, diameter =...
Therefore, the aim of the present study was to establish a new cell chamber model for FSS simulation and stimulation. In addition to its ease of use, the reported model in this study should meet the requirements of a simple design, generating reproducible flow characteristics next to laminar flows and clearly defined flow gradients on implant surfaces.
Cells can be influenced by different mechanostimuli, which lead to an activation of cellular and inter-cellular responses. These reactions may be caused by either a direct stimulation of the cell body (mechanoreception) or indirect cellular stimulation (response) [1,2,3]. Extracellular fluid movement induces fluid shear stress (FSS) that can result in different cellular processes including prolife...
Mechanostimuli of different cells can affect a wide array of cellular and inter-cellular biological processes responsible for dental implant healing. The purpose of this in vitro study was to establish a new test model to create a reproducible flow-induced fluid shear stress (FSS) of osteoblast cells on implant surfaces.
As FSS effects on osteoblasts are detectable at 10 dyn/cm2, a custom-made f...
Figure 5. Osteoblasts with an orientation tendency after 24 h of rotation (phallacidin fluorescence staining). On the left side with 200× and on the right side with 400× magnification. The yellow arrows show the orientation of the cells. The red arched arrow within the coloured circle shows the direction of rotation. The dashed white line oriented to the right stands for the r...
Figure 4. Randomly orientated osteoblasts without influence of rotation (phallacidin fluorescence staining). On the left side with 200× and on the right side with 400× magnification. The white X on the coloured circle marks the location upon the plate where the osteoblasts were located. The red X marks the centre of the plate
Figure 3. Diagram for visualisation of the calculation of shear stress rates taking into account the centrifugal force and the glass plates’ dimensions. For example, at a distance of 25 mm from the centre of the upper plate, the shear forces’ value is 8.33 dyn/cm2, together with an additional centrifugal force that has a value of 0.55 dyn/cm2
Figure 2. Side view of a computerized simulation, showing the flow chambers’ lower compartment and the flow profile in between the two plates; shearing gap and bottom plate are shown on the left side; rotation speed = 200 rpm; colour code bar (left edge) showing shear force values [Pa] [1 Pa = 10 dyn/cm2]; flow direction presented by arrows
Figure 1. Three-dimensional illustration (a–e) and photography (f) of the experimental setup with the components marked numerical. a 1 Lower petri dish (s’ bottom serving as the lower plate); 2 Rotating glass panel [60 mm diameter (cell bearing)]; 3 Titanium axis. b 4 Liquid medium (red). c 5 Reversed upper petri dish. d 6 Gearwheel with set screw. e 7 Closing; 8 Electronic motor device and ...
References
Ehrlich PJ, Lanyon LE. Mechanical strain and bone cell function: a review. Osteoporos Int. 2002;13(9):688–700.
Vaughan TJ, Haugh MG, Mcnamara LM. A fluid-structure interaction model to characterize bone cell stimulation in parallel-plate flow chamber systems. J R Soc Interface. 2013;10(81):20120900.
Weinbaum S, Cowin SC, Zeng Y. A model for the excitation of osteocytes by mec...
Besides, in the model reported in this study, microscopic examinations are possible after completing the experiment only. Nevertheless, an advantage of the new flow chamber is the possibility of testing different cell colonies simultaneously in one single experiment by placing cells in different radial locations on the spinning disc. Due to the current flow gradient from the centre to the pe...
Due to the fact that constant flows were generated within the parallel flow chamber only, the situations of in vitro experiments differ from in vivo setting where dynamic flow profiles are particular. As the constant laminar flow profile is not physiological in bones, vessels and other tissues, the informative value of the experimental setting is limited but it could be used for various cell...
Further on, the simulations indicated that the flow profile in between the two plates was not influenced by peripheral turbulences alongside the peripheral regions. To verify a cellular realignment towards the shear direction, cells were microscopically examined prior and after exposure to shear forces for 24 h upon a spinning disc at a speed level of 200 rpm. Even if not sufficiently ...
Discussion
The aim of this study was to establish a new FSS model that is easy to use as well as simple to assemble in order to create reproducible fluid shear forces on cells close to implant material surfaces. Todays’ commonly used commercial flow devices differ in geometry and function, which makes comparisons between experiments difficult. The benefits of this novel testing device are...
Regarding the upper compartment, peripheral turbulent flow along the outer edges was similar to the fluid movements within the area in between the plates. At the top, the turbulent flow directed from the centre to the periphery whereas the turbulences at the bottom were orientated in reverse to that. Moreover, the effect of the shear forces on the osteoblast cells was also influenced by the centri...
Results
Our analysis was focused on two main aspects:
Simulation of the fluid flow characteristics as well as quantification of the arising shear forces at the plate/plate flow chamber with reliable reproducibility
Assessment of the impact of fluid shear stress on osteoblast cells in terms of altered cell morphology and intracellular structural changes
Evaluation of the f...
Test procedure
The experimental process involved three steps. First, a count of n = 50.000 commercially available osteoblasts (PromoCell, Heidelberg, Germany) per millilitre of culture medium were cultured on the bottom of the cell-bearing surface (glass panel). Therefore, cells were seeded in a culture medium (cf. Appendix 2 for a detailed composition) at 37 °C. Prior to the test proce...
Analytical formula for evaluating the flow characteristics
Frequently used flow chambers are characterised by an internal fluid flow along a stationary cell-bearing surface, whereas the osteoblast test cells of this newly developed model are circulating within a resting culture medium.
For constant and fully developed laminar flow between the two parallel plates, the magnitude of the wall sh...
Methods
Experimental setup
A three-dimensional illustration and photography of the plate/plate flow chamber model is shown in Fig. 1. A detailed list of used parts can be found in Appendix 1.
The circulation within the flow chamber was generated by an externally attached electric motor, which rotates up to 500 rounds per minute (rpm). A commercial grade 4 pure medical titanium gear shaft (len...
Abstract
Background
Mechanostimuli of different cells can affect a wide array of cellular and inter-cellular biological processes responsible for dental implant healing. The purpose of this in vitro study was to establish a new test model to create a reproducible flow-induced fluid shear stress (FSS) of osteoblast cells on implant surfaces.
Methods
As FSS effects on osteoblasts are detectabl...