Effect of chewing and cutting condition for V-shape three-dimensional titanium miniplate for fixation of mandibular angle fractures (MAFs)

PurposeMiniplate shapes determine the fixation stability to promote best healing and osseointegration process of mandibular fracture. In clinical treatment, the common method used two straight-type miniplate or I-shape miniplate; sometimes this method is not stable enough or limited by the fracture geometry and caused high risk of failure due to screw loosening. This paper aims to investigate a new type of miniplate called V-shape miniplate design as an alternative to the standard straight plate based on total displacement, von Mises stress, stress transfer parameter (STP) and strain energy density transfer parameters (SEDPTs) for two types of bite force condition, which is cutting and chewing condition.Design/methodology/approachThe 3D fixation models were constructed and the finite element (FE) simulation is based on the two-bite force load that ranges from 50 to 700 N based on cutting and chewing bite force condition using ANSYS Workbench 19.2.FindingsIn result comparison, the maximum loading of the V-shape miniplate can reduce deformation by 5.9%, reduce stress by 0.58% reduce strain by 8.1% in cutting condition while reducing deformation by 6.43%, reduce stress by 15.25%, reduce strain by 10.1% in chewing condition. To assess the stress transfer behavior of miniplates fixations to the mandibular bone, the STP and SEDPT were evaluated at the normal cortex screw and the locking head screw. In the simulation, the locking head screw is vertical to the bone structure while the cortex screw is 95 degrees to the bone structure, as a result, the STP value for locking head screw is 1.0073 while in cortex screw is 0.7408.Research limitations/implicationsMeanwhile, the SEDPT value for locking head screw is 2.7574 and 1.8412 for cortex screw.Practical implicationsClinically, V-shape miniplate has shown factual data that can be used for prototyping. STP and SEDTP values provide evidence of how fixation stability is better than I-shape miniplate.Originality/valueIn conclusion, the newly designed V-shape miniplate has overall better stability than the standard I-shape miniplate, and the locking head screw has the STP value closer to 1 than the standard cortex screw; it means the locking screw is better in reducing the stress shielding.

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A biomechanical study of a novel biomimetic hip implant.

10.32920/ryerson.14647719 ◽

2021 ◽

Author(s):

Shaheen Khurshid

Keyword(s):

Three Dimensional ◽

Stress Shielding ◽

Stress Transfer ◽

Biomechanical Study ◽

Von Mises Stress ◽

Fe Model ◽

Polyamide 12 ◽

Hip Stems ◽

Von Mises ◽

Three Dimensional Finite Element

A three dimensional finite element (FE) model of a novel carbon fibre polyamide 12 composite hip stem was used to compare with two commerically available (Exeter and Omnifit) hip stems to minimize stress shielding and bone resorption. A virtual axial load of 3000N was applied to the FE model which replicated the experimental study. Strain and stress distributions were computed and compared with experimental results. Experimentally, three hip stems had their distal portions rigidly mounted and had strain gauges placed along the surface at 3 medial and 3 lateral locations. From the FE analysis, the von mises stress range for the composite hip stem was 200% and 45% lower than that in the Omnifit and Exeter implants, respectively. The aggregate average difference between FE and experimental microstrains for four proximal strain gauge locations were 7.5% (composite), 11.5% (Exeter), 14.6% (Omnifit), and the composite hip stem's stiffness (1982N/mm) was lower than the metallic hip stem stiffnesses (Exter, 2460N/mm; Omnifit, 2543 N/mm). This study showed considerable improvement in stress transfer to bone tissue.

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A biomechanical study of a novel biomimetic hip implant.

10.32920/ryerson.14647719.v1 ◽

2021 ◽

Author(s):

Shaheen Khurshid

Keyword(s):

Three Dimensional ◽

Stress Shielding ◽

Stress Transfer ◽

Biomechanical Study ◽

Von Mises Stress ◽

Fe Model ◽

Polyamide 12 ◽

Hip Stems ◽

Von Mises ◽

Three Dimensional Finite Element

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A personalized mandibular implant with supporting and porous structures designed with topology optimization – a case study of canine

Rapid Prototyping Journal ◽

10.1108/rpj-11-2017-0231 ◽

2019 ◽

Vol 25 (2) ◽

pp. 417-426 ◽

Cited By ~ 5

Author(s):

Kangjie Cheng ◽

Yunfeng Liu ◽

Chunyan Yao ◽

Wenquan Zhao ◽

Xu Xu

Keyword(s):

Topology Optimization ◽

Optimal Design ◽

Three Dimensional ◽

Fem Analysis ◽

Von Mises Stress ◽

Content Type ◽

Optimized Model ◽

Supporting Structures ◽

External Shape

Purpose The purpose of this study is to obtain a titanium mandibular implant that possesses a personalized external shape for appearance recovery, a supporting structure for physiological loading and numerous micro-pores for accelerating osseointegration. Design/methodology/approach A three-dimensional intact mandibular model of a beagle dog was created from cone-beam computerized tomography scans. A segment of the lower jaw bone was resected and replaced by a personalized implant with comprehensive structures including a customized external shape, supporting structures and micro-pores, which were designed by topology optimization. Then with FEM analysis, the stress, displacement distribution and compliance of the designed implant were compared with the non-optimized model. The weight of the optimized implant that was fabricated by SLM with titanium alloy powder was measured and contrasted with the predicted non-optimized model for evaluating the viability of the design. Findings The FEM results showed the peaks of von Mises stress and displacement on the optimized implant were much lower than those of the implant without optimization. With topology optimization, the compliance of the implant decreased significantly by 53.3 per cent, and a weight reduction of 37.2 per cent could be noticed. Originality/value A design strategy for personalized implant, with comprehensive structures and SLM as the fabrication method, has been developed and validated by taking a canine mandible as the case study. With comprehensive structures, the implant presented good biomechanical behaviors thanks to the most appropriate supporting structures obtained by optimal design. The topological optimal design combined with SLM printing proved to be an effective method for the design and fabrication of personalized implant with complex structures.

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Finite element prediction of stress transfer in h-BN sheet nanocomposites

International Journal of Structural Integrity ◽

10.1108/ijsi-02-2017-0014 ◽

2018 ◽

Vol 9 (1) ◽

pp. 2-16

Author(s):

Konstantinos Spanos ◽

Androniki Tsiamaki ◽

Nicolaos Anifantis

Keyword(s):

Finite Element ◽

Hexagonal Boron Nitride ◽

Matrix Material ◽

Three Dimensional ◽

Stress Transfer ◽

Content Type ◽

The Matrix ◽

Element Approach ◽

Solid Finite Elements ◽

Heterogeneous Region

Purpose The purpose of this paper is to implement a micromechanical hybrid finite element approach in order to investigate the stress transfer behavior of composites reinforced with hexagonal boron nitride (h-BN) nanosheets. Design/methodology/approach For the analysis of the problem, a three-dimensional representative volume element, consisting of three phases, has been used. The reinforcement is modeled discretely using spring elements of specific stiffness while the matrix material is modeled as a continuum medium using solid finite elements. The third phase, the intermediate one, known as the interface, has been simulated by appropriate stiffness variations which define a heterogeneous region affecting the stress transfer characteristics of the nanocomposite. Findings The results show a good agreement with corresponding ones from the literature and also the effect of a number of factors is indicated in stress transfer efficiency. Originality/value This is the first time that such a modeling is employed in the stress transfer examination of h-BN nanocomposites.

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Morphological Study of the Newly Designed Cementless Femoral Stem

BioMed Research International ◽

10.1155/2014/692328 ◽

2014 ◽

Vol 2014 ◽

pp. 1-11 ◽

Cited By ~ 8

Author(s):

Mohd Yusof Baharuddin ◽

Sh-Hussain Salleh ◽

Ahmad Hafiz Zulkifly ◽

Muhammad Hisyam Lee ◽

Alias Mohd Noor

Keyword(s):

Three Dimensional ◽

Stress Shielding ◽

Femoral Stem ◽

Medullary Canal ◽

Stem Design ◽

Asian Patients ◽

Cementless Femoral Stem ◽

Fixation Stability ◽

Flare Index ◽

Metaphyseal Region

A morphology study was essential to the development of the cementless femoral stem because accurate dimensions for both the periosteal and endosteal canal ensure primary fixation stability for the stem, bone interface, and prevent stress shielding at the calcar region. This paper focused on a three-dimensional femoral model for Asian patients that applied preoperative planning and femoral stem design. We measured various femoral parameters such as the femoral head offset, collodiaphyseal angle, bowing angle, anteversion, and medullary canal diameters from the osteotomy level to 150 mm below the osteotomy level to determine the position of the isthmus. Other indices and ratios for the endosteal canal, metaphyseal, and flares were computed and examined. The results showed that Asian femurs are smaller than Western femurs, except in the metaphyseal region. The canal flare index (CFI) was poorly correlated (r<0.50) to the metaphyseal canal flare index (MCFI), but correlated well (r=0.66) with the corticomedullary index (CMI). The diversity of the femoral size, particularly in the metaphyseal region, allows for proper femoral stem design for Asian patients, improves osseointegration, and prolongs the life of the implant.

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FE simulation of sealing ability for premium connection based on ISO 13679 CAL IV tests

International Journal of Structural Integrity ◽

10.1108/ijsi-11-2019-0125 ◽

2020 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Yihua Dou ◽

Yufei Li ◽

Yinping Cao ◽

Yang Yu ◽

Jiantao Zhang ◽

...

Keyword(s):

Finite Element ◽

Contact Pressure ◽

Thermal Cycle ◽

Three Dimensional ◽

Element Model ◽

Helix Angle ◽

Von Mises Stress ◽

Content Type ◽

Von Mises ◽

Three Dimensional Finite Element

PurposeTo maintain the well integrity, the strength and sealing ability of premium connection should be in the safe scope. ISO 13679 is widely used for evaluating the ability of tubing and casing connection all over the world. FE is adopted to simulate the ISO 13679 tests.Design/methodology/approachBecause of the disadvantage of experiment such as long period, high cost and high requirement on the facility, considering the convenience and universality of finite element method, as well as the contacting nonlinearity and material nonlinearity, three-dimensional finite element model of a certain type of premium connection is established with the consideration of helix angle. The loads exerted on the premium connection are the loads in series B test and thermal cycle test of ISO 13679. The distributions of Von Mises stress and contact pressure in various cases were studied.FindingsThe results showed that the bending load has a great influence on the distribution of Von Mises stress and contact pressure for premium connection. The Von Mises stress and contact pressures on the sealing surface are smaller on the tension side and greater on the compression side. With increasing axial compression load, the contact pressures on the tension side are too small, which may lead to sealing failure. The influence of temperature on the performance of premium connection cannot be ignored when choosing or designing premium connections. Both the Von Mises stress and contact pressure decrease slightly during a period of thermal cycle. Although the performance of the premium connection is good in a period of thermal cycle, its performance in a long period should be evaluated. Finite element simulation can effectively simulate the ISO 13679 test procedure and obtain the stress and contact pressure distribution. It can be used as a reference for evaluating the performance of premium connections.Originality/valueConsidering the convenience and universality of finite element method, as well as the contacting nonlinearity and material nonlinearity, three-dimensional finite element model of a certain type of premium connection is established with the consideration of helix angle.

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Effects of occlusal scheme on All-on-Four abutments, screws and prostheses: A three-dimensional finite element study

Journal of Oral Implantology ◽

10.1563/aaid-joi-d-19-00334 ◽

2020 ◽

Author(s):

Nurullah Türker ◽

Hümeyra Tercanlı Alkış ◽

Steven J Sadowsky ◽

Ulviye Şebnem Büyükkaplan

Keyword(s):

Finite Element ◽

Three Dimensional ◽

Good Prognosis ◽

Von Mises Stress ◽

Element Analysis ◽

Group Function ◽

Occlusal Contact ◽

Maximum Deformation ◽

Contact Points ◽

Von Mises

An ideal occlusal scheme plays an important role in a good prognosis of All-on-Four applications, as it does for other implant therapies, due to the potential impact of occlusal loads on implant prosthetic components. The aim of the present three-dimensional (3D) finite element analysis (FEA) study was to investigate the stresses on abutments, screws and prostheses that are generated by occlusal loads via different occlusal schemes in the All-on-Four concept. Three-dimensional models of the maxilla, mandible, implants, implant substructures and prostheses were designed according to the All-on-Four concept. Forces were applied from the occlusal contact points formed in maximum intercuspation and eccentric movements in canine guidance occlusion (CGO), group function occlusion (GFO) and lingualized occlusion (LO). The von Mises stress values for abutment and screws and deformation values for prostheses were obtained and results were evaluated comparatively. It was observed that the stresses on screws and abutments were more evenly distributed in GFO. Maximum deformation values for prosthesis were observed in the CFO model for lateral movement both in the maxilla and mandible. Within the limits of the present study, GFO may be suggested to reduce stresses on screws, abutments and prostheses in the All-on-Four concept.

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Stereotactic radiosurgery versus stereotactic radiotherapy for patients with vestibular schwannoma: a Leksell Gamma Knife Society 2000 debate

Journal of Neurosurgery ◽

10.3171/jns.2000.93.supplement_3.0090 ◽

2000 ◽

Vol 93 (supplement_3) ◽

pp. 90-92 ◽

Cited By ~ 48

Author(s):

Mark E. Linskey

Keyword(s):

Gamma Knife ◽

Stereotactic Radiotherapy ◽

Three Dimensional ◽

Late Recurrence ◽

Vestibular Schwannomas ◽

Tumor Control ◽

Complication Rates ◽

Content Type ◽

Single Fraction ◽

Fine Print

✓ By definition, the term “radiosurgery” refers to the delivery of a therapeutic radiation dose in a single fraction, not simply the use of stereotaxy. Multiple-fraction delivery is better termed “stereotactic radiotherapy.” There are compelling radiobiological principles supporting the biological superiority of single-fraction radiation for achieving an optimal therapeutic response for the slowly proliferating, late-responding, tissue of a schwannoma. It is axiomatic that complication avoidance requires precise three-dimensional conformality between treatment and tumor volumes. This degree of conformality can only be achieved through complex multiisocenter planning. Alternative radiosurgery devices are generally limited to delivering one to four isocenters in a single treatment session. Although they can reproduce dose plans similar in conformality to early gamma knife dose plans by using a similar number of isocenters, they cannot reproduce the conformality of modern gamma knife plans based on magnetic resonance image—targeted localization and five to 30 isocenters. A disturbing trend is developing in which institutions without nongamma knife radiosurgery (GKS) centers are championing and/or shifting to hypofractionated stereotactic radiotherapy for vestibular schwannomas. This trend appears to be driven by a desire to reduce complication rates to compete with modern GKS results by using complex multiisocenter planning. Aggressive advertising and marketing from some of these centers even paradoxically suggests biological superiority of hypofractionation approaches over single-dose radiosurgery for vestibular schwannomas. At the same time these centers continue to use the term radiosurgery to describe their hypofractionated radiotherapy approach in an apparent effort to benefit from a GKS “halo effect.” It must be reemphasized that as neurosurgeons our primary duty is to achieve permanent tumor control for our patients and not to eliminate complications at the expense of potential late recurrence. The answer to minimizing complications while maintaining maximum tumor control is improved conformality of radiosurgery dose planning and not resorting to homeopathic radiosurgery doses or hypofractionation radiotherapy schemes.

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Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis

Scientific Reports ◽

10.1038/s41598-021-93821-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Niksa Mohammadi Bagheri ◽

Mahmoud Kadkhodaei ◽

Shiva Pirhadi ◽

Peiman Mosaddegh

Keyword(s):

Clinical Data ◽

Three Dimensional ◽

Element Model ◽

Von Mises Stress ◽

Patient Specific ◽

Average Error ◽

Constant Thickness ◽

Arc Length ◽

Implementation Techniques ◽

Von Mises

AbstractThe implementation of intracorneal ring segments (ICRS) is one of the successfully applied refractive operations for the treatment of keratoconus (kc) progression. The different selection of ICRS types along with the surgical implementation techniques can significantly affect surgical outcomes. Thus, this study aimed to investigate the influence of ICRS implementation techniques and design on the postoperative biomechanical state and keratometry results. The clinical data of three patients with different stages and patterns of keratoconus were assessed to develop a three-dimensional (3D) patient-specific finite-element model (FEM) of the keratoconic cornea. For each patient, the exact surgery procedure definitions were interpreted in the step-by-step FEM. Then, seven surgical scenarios, including different ICRS designs (complete and incomplete segment), with two surgical implementation methods (tunnel incision and lamellar pocket cut), were simulated. The pre- and postoperative predicted results of FEM were validated with the corresponding clinical data. For the pre- and postoperative results, the average error of 0.4% and 3.7% for the mean keratometry value ($$\text {K}_{\text{mean}}$$ K mean ) were predicted. Furthermore, the difference in induced flattening effects was negligible for three ICRS types (KeraRing segment with arc-length of 355, 320, and two separate 160) of equal thickness. In contrast, the single and double progressive thickness of KeraRing 160 caused a significantly lower flattening effect compared to the same type with constant thickness. The observations indicated that the greater the segment thickness and arc-length, the lower the induced mean keratometry values. While the application of the tunnel incision method resulted in a lower $$\text {K}_{\text{mean}}$$ K mean value for moderate and advanced KC, the induced maximum Von Mises stress on the postoperative cornea exceeded the induced maximum stress on the cornea more than two to five times compared to the pocket incision and the preoperative state of the cornea. In particular, an asymmetric regional Von Mises stress on the corneal surface was generated with a progressive ICRS thickness. These findings could be an early biomechanical sign for a later corneal instability and ICRS migration. The developed methodology provided a platform to personalize ICRS refractive surgery with regard to the patient’s keratoconus stage in order to facilitate the efficiency and biomechanical stability of the surgery.

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Agent-Based Modeling Demonstrates How Local Chemotactic Behavior Can Shape Biofilm Architecture

mSphere ◽

10.1128/msphere.00285-19 ◽

2019 ◽

Vol 4 (3) ◽

Cited By ~ 4

Author(s):

Emily G. Sweeney ◽

Andrew Nishida ◽

Alexandra Weston ◽

Maria S. Bañuelos ◽

Kristin Potter ◽

...

Keyword(s):

Helicobacter Pylori ◽

Three Dimensional ◽

Structural Features ◽

Agent Based Modeling ◽

Emergent Properties ◽

Cellular Interactions ◽

Biofilm Growth ◽

Content Type ◽

Agent Based ◽

H Pylori

ABSTRACTBacteria are often found living in aggregated multicellular communities known as biofilms. Biofilms are three-dimensional structures that confer distinct physical and biological properties to the collective of cells living within them. We used agent-based modeling to explore whether local cellular interactions were sufficient to give rise to global structural features of biofilms. Specifically, we asked whether chemorepulsion from a self-produced quorum-sensing molecule, autoinducer-2 (AI-2), was sufficient to recapitulate biofilm growth and cellular organization observed for biofilms ofHelicobacter pylori, a common bacterial resident of human stomachs. To carry out this modeling, we modified an existing platform, Individual-based Dynamics of Microbial Communities Simulator (iDynoMiCS), to incorporate three-dimensional chemotaxis, planktonic cells that could join or leave the biofilm structure, and cellular production of AI-2. We simulated biofilm growth of previously characterizedH. pyloristrains with various AI-2 production and sensing capacities. Using biologically plausible parameters, we were able to recapitulate both the variation in biofilm mass and cellular distributions observed with these strains. Specifically, the strains that were competent to chemotax away from AI-2 produced smaller and more heterogeneously spaced biofilms, whereas the AI-2 chemotaxis-defective strains produced larger and more homogeneously spaced biofilms. The model also provided new insights into the cellular demographics contributing to the biofilm patterning of each strain. Our analysis supports the idea that cellular interactions at small spatial and temporal scales are sufficient to give rise to larger-scale emergent properties of biofilms.IMPORTANCEMost bacteria exist in aggregated, three-dimensional structures called biofilms. Although biofilms play important ecological roles in natural and engineered settings, they can also pose societal problems, for example, when they grow in plumbing systems or on medical implants. Understanding the processes that promote the growth and disassembly of biofilms could lead to better strategies to manage these structures. We had previously shown thatHelicobacter pyloribacteria are repulsed by high concentrations of a self-produced molecule, AI-2, and thatH. pylorimutants deficient in AI-2 sensing form larger and more homogeneously spaced biofilms. Here, we used computer simulations of biofilm formation to show that localH. pyloribehavior of repulsion from high AI-2 could explain the overall architecture ofH. pyloribiofilms. Our findings demonstrate that it is possible to change global biofilm organization by manipulating local cell behaviors, which suggests that simple strategies targeting cells at local scales could be useful for controlling biofilms in industrial and medical settings.

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