ORCID Profile
0000-0002-3773-5612
Current Organisation
Western Sydney University - Penrith Campus
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Mechanical engineering | Numerical modelling and mechanical characterisation | Nanomanufacturing | Biomechanical engineering | Nanomaterials | Nanotechnology | Microtechnology | Mining engineering | Composite and hybrid materials
Expanding Knowledge in the Physical Sciences | Expanding Knowledge in Engineering | Expanding Knowledge in the Medical and Health Sciences |
Publisher: Trans Tech Publications, Ltd.
Date: 07-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.268-270.853
Abstract: Bioceramics have rapidly emerged as one of major biomaterials in modern biomedical applications because of its outstanding biocompatibility. However, one drawback is its low tensile strength and fracture toughness due to brittleness and inherent microstructural defects, which to a certain extent prevents the ceramics from fully replacing metals used as load-bearing prostheses. This paper aims to model the crack initiation and propagation in ceramic fixed partial denture, namely dental bridge, by using two recently developed methods namely continuum-to-discrete element method (CDEM) in ELFEN and extended finite element methods (XFEM) in ABAQUS. Unlike most existing studies that typically required prescriptions of initial cracks, these two new approaches will model crack initiation and propagation automatically. They are applied to a typical prosthodontic ex le, thereby demonstrating their applicability and effectiveness in biomedical applications.
Publisher: Elsevier BV
Date: 12-2022
DOI: 10.1016/J.JMBBM.2022.105483
Abstract: The fibula free flap (FFF) has been extensively used to repair large segmental bone defects in the maxillofacial region. The reconstruction plate plays a key role in maintaining stability and load-sharing while the fibula unites with adjacent bone in the course of healing and remodeling. However, not all fibula flaps would fully unite, and fatigue of prosthetic devices has been recognized as one major concern for long-term load-bearing applications. This study aims to develop a numerical approach for predicting the fatigue life of the reconstruction plate by taking into account the effect of ongoing bone remodeling. The patient-specific mandible reconstruction with a prosthetic system is studied in this work. The 3D finite element model with heterogeneous material properties obtained from clinical computerized tomography (CT) data is developed for bone, and eXtended Finite Element Method (XFEM) is adopted for the fatigue analysis of the plate. During the remodeling process, the changing apparent density and Young's modulus of bone are simulated in a step-wise fashion on the basis of Wolff's law, which is correlated with the specific clinical follow-up. The maximum biting forces were considered as the driving force on the bone remodeling, which are measured clinically at different time points (4, 16 and 28 months) after reconstruction surgery. Under various occlusal loadings, the interaction between fatigue crack growth and bone remodeling is investigated to gain new insights for the future design of prosthetic devices. The simulation results reveal that appropriate remodeling of grafted bone could extend the fatigue life of fixation plates in a positive way. On the other hand, the rising occlusal load associated with healing and remodeling could lead to fatigue fracture of fixation plate and potentially cause severe bone resorption. This study proposes an effective approach for more realistically predicting fatigue life of prosthetic devices subject to a tissue remodeling condition in-silico. It is anticipated to provide a guideline for deriving an optimal design of patient-specific prosthetic devices to better ensure longevity.
Publisher: Wiley
Date: 13-04-2017
DOI: 10.1002/CNM.2779
Abstract: Design of prosthetic implants to ensure rapid and stable osseointegration remains a significant challenge, and continuous efforts have been directed to new implant materials, structures and morphology. This paper aims to develop and characterise a porous titanium dental implant fabricated by metallic powder injection-moulding. The surface morphology of the specimens was first examined with a scanning electron microscope (SEM), followed by microscopic computerised tomography (μ-CT) scanning to capture its 3D microscopic features non-destructively. The nature of porosity and pore sizes were determined statistically. A homogenisation technique based on the Hills-energy theorem was adopted to evaluate its directional elastic moduli, and the conservation of mass theorem was employed to quantify the oxygen diffusivity for bio-transportation feature. This porous medium was found to have pore sizes varying from 50 to 400 µm and the average porosity of 46.90 ± 1.83%. The anisotropic principal elastic moduli were found fairly close to the upper range of cortical bone, and the directional diffusivities could potentially enable radial osseous tissue ingrowth and vascularisation. This porous titanium successfully reduces the elastic modulus mismatch between implant and bone for dental and orthopaedic applications, and provides improved capacity for transporting oxygen, nutrient and waste for pre-vascular network formation. Copyright © 2016 John Wiley & Sons, Ltd.
Publisher: Informa UK Limited
Date: 23-03-2016
Publisher: Springer Science and Business Media LLC
Date: 12-07-2016
DOI: 10.1038/SREP28816
Abstract: Healing large bone defects, especially in weight-bearing locations, remains a challenge using available synthetic ceramic scaffolds. Manufactured as a scaffold using 3D printing technology, Sr-HT-Gahnite at high porosity (66%) had demonstrated significantly improved compressive strength (53 ± 9 MPa) and toughness. Nevertheless, the main concern of ceramic scaffolds in general remains to be their inherent brittleness and low fracture strength in load bearing applications. Therefore, it is crucial to establish a robust numerical framework for predicting fracture strengths of such scaffolds. Since crack initiation and propagation plays a critical role on the fracture strength of ceramic structures, we employed extended finite element method (XFEM) to predict fracture behaviors of Sr-HT-Gahnite scaffolds. The correlation between experimental and numerical results proved the superiority of XFEM for quantifying fracture strength of scaffolds over conventional FEM. In addition to computer aided design (CAD) based modeling analyses, XFEM was conducted on micro-computed tomography (μCT) based models for fabricated scaffolds, which took into account the geometric variations induced by the fabrication process. Fracture strengths and crack paths predicted by the μCT-based XFEM analyses correlated well with relevant experimental results. The study provided an effective means for the prediction of fracture strength of porous ceramic structures, thereby facilitating design optimization of scaffolds.
Publisher: Informa UK Limited
Date: 30-12-2015
DOI: 10.1080/10255842.2015.1124268
Abstract: This study aims to establish a new computational framework that allows modeling transient oxygen diffusion in tissue scaffolds more efficiently. It has been well known that the survival of cells strongly relies on continuous oxygen/nutrient supply and metabolite removal. With optimal design in scaffold architecture, its ability to sustain long distance oxygen supply could be improved considerably. In this study, finite element based homogenization procedure is first used to characterize the initial effective biotransport properties in silico. These initial properties are proper indicators to prediction of the on-going performance of tissue scaffolds over time. The transient model by adopting an edge-based smoothed finite element method with combination of mass-redistributed method is then established to more efficiently simulate the transient oxygen transfer process in tissue scaffolds. The proposed new method allows large time steps to model the oxygen diffusion process without losing numerical accuracy, thereby enhancing the computational efficiency significantly, in particular for the design optimization problems which typically require numerous analysis iterations. A number of different scaffold designs are examined either under net diffusion without cell seeding, or under cellular oxygen/nutrient uptake with or without considering cell viability. The association between the homogenized effective diffusivity of net scaffold microstructures and corresponding transient diffusion and time-dependent cellular activities is ulged. This study provides some insights into scaffold design.
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.ACTBIO.2013.05.009
Abstract: Effective and reliable clinical uses of dental ceramics necessitate an insightful analysis of the fracture behaviour under critical conditions. To better understand failure characteristics of porcelain veneered to zirconia core ceramic structures, thermally induced cracking during the cooling phase of fabrication is studied here by using the extended finite element method (XFEM). In this study, a transient thermal analysis of cooling is conducted first to determine the temperature distributions. The time-dependent temperature field is then imported to the XFEM model for viscoelastic thermomechanical analysis, which predicts thermally induced damage and cracking at different time steps. Temperature-dependent material properties are used in both transient thermal and thermomechanical analyses. Three typical ceramic structures are considered in this paper, namely bi-layered spheres, squat cylinders and dental crowns with thickness ratios of either 1:2 or 1:1. The XFEM fracture patterns exhibit good agreement with clinical observation and the in vitro experimental results obtained from scanning electron microscopy characterization. The study reveals that fast cooling can lead to thermal fracture of these different bi-layered ceramic structures, and cooling rate (in terms of heat transfer coefficient) plays a critical role in crack initiation and propagation. By exploring different cooling rates, the heat transfer coefficient thresholds of fracture are determined for different structures, which are of clear clinical implication.
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.JMBBM.2018.10.015
Abstract: An increase in non-enzymatic collagen matrix cross-links, such as advanced glycation end-products (AGEs), is known to be a major complication in human mineralized tissues, often causing abnormal fractures. However, degradation of mechanical properties in relation to AGEs has not been fully elucidated at the material level. Here, we report nanoscale time-dependent deformation and dimensional recovery of human tooth dentin that has undergone glycation induced by x-ray irradiation. The reduction in enzymatic collagen cross-linking and the increased level of AGEs with concomitant growth of disordered collagen matrix diminished creep deformation recovery in the lower mineralized target region. However, the elevated AGEs level alone did not cause a reduction in time-dependent deformation and its recovery in the higher mineralized target region. In addition to the elevated AGEs level, the degradation of the mechanical properties of mineralized tissues should be assessed with care in respect to multiple parameters in the collagen matrix at the molecular level.
Publisher: Elsevier BV
Date: 12-2202
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.JMBBM.2015.08.010
Abstract: The principle of minimal intervention dentistry (MID) is to limit removal of carious tooth tissue while maximizing its repair and survival potential. The objective of this study is to explore the fracture resistance of a permanent molar tooth with a fissure carious lesion along with three clinical restoration procedures, namely one traditional and two conservative approaches, based upon MID. The traditional restoration employs extensive surgical removal of enamel and dentine about the cavity to eliminate potential risk of further caries development, while conservative method #1 removes significantly less enamel and infected dentine, and conservative method #2 only restores the overhanging enamel above the cavity and leaves the infected and affected dentine as it was. An extended finite element method (XFEM) is adopted here to analyze the fracture behaviors of both two-dimensional (2D) and three-dimensional (3D) modeling of these four different scenarios. It was found that the two conservative methods exhibited better fracture resistance than the traditional restorative method. Although conservative method #2 has less fracture resistance than method #1, it had significantly superior fracture resistance compared to other restorations. More important, after cavity sealing it may potentially enhance the opportunity for remineralization and improved loading bearing capacity and fracture resistance.
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.JMBBM.2018.08.034
Abstract: This study aimed to develop a simple and efficient numerical modeling approach for characterizing strain and total strain energy in bone scaffolds implanted in patient-specific anatomical sites. A simplified homogenization technique was developed to substitute a detailed scaffold model with the same size and equivalent orthotropic material properties. The effectiveness of the proposed modeling approach was compared with two other common homogenization methods based on periodic boundary conditions and the Hills-energy theorem. Moreover, experimental digital image correlation (DIC) measurements of full-field surface strain were conducted to validate the numerical results. The newly proposed simplified homogenization approach allowed for fairly accurate prediction of strain and total strain energy in tissue scaffolds implanted in a large femur mid-shaft bone defect subjected to a simulated in-vivo loading condition. The maximum discrepancy between the total strain energy obtained from the simplified homogenization approach and the one obtained from detailed porous scaffolds was 8.8%. Moreover, the proposed modeling technique could significantly reduce the computational cost (by about 300 times) required for simulating an in-vivo bone scaffolding scenario as the required degrees of freedom (DoF) was reduced from about 26 million for a detailed porous scaffold to only 90,000 for the homogenized solid counterpart in the analysis. The simplified homogenization approach has been validated by correlation with the experimental DIC measurements. It is fairly efficient and comparable with some other common homogenization techniques in terms of accuracy. The proposed method is implicating to different clinical applications, such as the optimal selection of patient-specific fixation plates and screw system.
Publisher: Trans Tech Publications, Ltd.
Date: 05-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.553.299
Abstract: Intraoperative periprosthetic femoral fractures (IPPFF) occur in approximately 3-5% of all cementless total hip arthroplasty (THA) surgeries. This study aimed to identify the critical impaction load to cause an IPPFF during implant implementation. This critical load may be used as a guideline for surgeons as well as a parameter for the design of future surgical tools and procedures. This study concerned a single femur of a healthy 60 year old female with an anatomical femoral stem implant, thus the effects of patient specific variables (such as osteoporosis, amount of bone resorption, bone damage, implant geometry, age and gender) were not considered. The eXtended Finite Element Method (XFEM) was used to analyse the fracture. From CT scan data, a user-defined subroutine is used to assign heterogeneous isotropic material properties to the femur. It was computed that IPPFF would take place at an impaction load of 18.5 kN.
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.JMBBM.2018.12.038
Abstract: Dental adhesive provides effective retention of filling materials via adhesive-dentin hybridization. The use of co-monomers, such as 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP), is thought to be crucial for hybridization owing to their ionic-binding to calcium and co-polymerization in the polymerizable adhesives. Optimal hybridization partly depends on the mechanical properties of polymerized adhesives, which are likely to be proportional to the degree of conversion ratio. This study assessed the correlation between polymerization quality and mechanical properties at the adhesive-dentin interfaces in the presence or absence of 10-MDP. In situ Raman microspectroscopy and nanoindentation tests were used concurrently to quantify the degree of conversion ratio and dynamic mechanical properties across the adhesive-dentin interfaces. Despite the excellent diffusion and apparent higher degree of co-polymerization, 10-MDP reduced the elastic modulus of the interface. The higher viscoelastic properties of the adhesive are suggestive of poor polymerization, namely polymerization linearity related to the long carboxyl chain of 10-MDP. Such reduced mechanical integrity of hybridization could also be associated with the inhibition of nano-layering between 10-MDP and mineralized tissue in the presence of hydroxyethyl methacrylate (HEMA). This potential drawback of HEMA necessitates further qualitative/quantitative characterization of adhesive-dentin hybridization using a HEMA-free/low concentration experimental 10-MDP monomer, which theoretically possesses superior chemical bonding potential to the current HEMA-rich protocol.
Publisher: Elsevier BV
Date: 03-2016
DOI: 10.1016/J.DENTAL.2015.11.018
Abstract: This study aimed to in idually quantify the effects of various design parameters, including margin thickness, convergence angle of abutment, and bonding conditions on fracture resistance of resin bonded glass dental crown systems (namely, glass simulated crown). An in vitro experimental test and an in silico computational eXtended Finite Element Method (XFEM) were adopted to explore crack initiation and propagation in glass simulated crown models with the margin thickness ranging from 0.8 to 1.2mm, convergence angle from 6° to 12°, and three different bonding conditions, namely non-bonded (NB), partially bonded (PB), fully bonded (FB). The XFEM modeling results of cracking initiation loads and subsequent growth in the glass simulated crown models were correlated with the experimental results. It was found that the margin thickness has a more significant effect on the fracture resistance than the convergence angle. The adhesively bonded state has the highest fracture resistance among these three different bonding conditions. Crowns with thicker margins, smaller convergence angle and fully bonded are recommended for increasing fracture resistance of all-ceramic crowns. This numerical modeling study, supported by the experimental tests, provides more thorough mechanical insight into the role of margin design parameters, thereby forming a novel basis for clinical guidance as to preparation of tapered abutments for all-ceramic dental crowns.
Publisher: Wiley
Date: 29-08-2019
DOI: 10.1002/CNM.3245
Abstract: Biofabricated nanostructured and microstructured scaffolds have exhibited great potential for nerve tissue regeneration and functional restoration, and prevascularization and biotransportation within 3D fascicle structures are critical. Unfortunately, an ideal internal fascicle and microvascular model of human peripheral nerves is lacking. In this study, we used microcomputed tomography (microCT) to acquire high-resolution images of the human sciatic nerve. We propose a novel deep-learning network technique, called ResNetH3D-Unet, to segment fascicles and microvascular structures. We reconstructed 3D intraneural fascicles and microvascular topography to quantify the fascicle volume ratio (FVR), microvascular volume ratio (MVR), microvascular to fascicle volume ratio (MFVR), fascicle surface area to volume ratio (FSAVR), and microvascular surface area to volume ratio (MSAVR) of human s les. The frequency distributions of the fascicle diameter, microvascular diameter, and fascicle-to-microvasculature distance were analyzed. The obtained microCT analysis and reconstruction provided high-resolution microstructures of human peripheral nerves. Our proposed ResNetH3D-Unet method for fascicle and microvasculature segmentation yielded a mean intersection over union (IOU) of 92.1% (approximately 5% higher than the U-net IOU). The 3D reconstructed model showed that the internal microvasculature runs longitudinally within the internal epineurium and connects to the external vasculature at some points. Analysis of the 3D data indicated a 48.2 ± 3% FVR, 23.7 ± 1.8% MVR, 4.9 ± 0.5% MFVR, 7.26 ± 2.58 mm
Publisher: Elsevier BV
Date: 12-2015
DOI: 10.1016/J.JBIOMECH.2015.10.019
Abstract: Despite the importance of dynamic behaviors of dental and periodontal structures to clinics, the biomechanical roles of anatomic sophistication and material properties in quantification of vibratory characteristics remain under-studied. This paper aimed to generate an anatomically accurate and structurally detailed 3D finite element (FE) maxilla model and explore the dynamic behaviors of human teeth through characterizing the natural frequencies (NFs) and mode shapes. The FE models with different levels of structural integrities and material properties were established to quantify the effects of modeling techniques on the computation of vibratory characteristics. The results showed that the integrity of computational model considerably influences the characterization of vibratory behaviors, as evidenced by declined NFs and perceptibly altered mode shapes resulting from the models with higher degrees of completeness and accuracy. A primary NF of 889Hz and the corresponding mode shape featuring linguo-buccal vibration of maxillary right 2nd molar were obtained based on the complete maxilla model. It was found that the periodontal ligament (PDL), a connective soft tissue, plays an important role in quantifying NFs. It was also revealed that d ing and heterogeneity of materials contribute to the quantification of vibratory characteristics. The study provided important biomechanical insights and clinical references for future studies on dynamic behaviors of dental and periodontal structures.
Publisher: Elsevier BV
Date: 12-2016
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.JMBBM.2019.103490
Abstract: Mechanical failure of zirconia-based full-arch implant-supported fixed dental prostheses (FAFDPs) remains a critical issue in prosthetic dentistry. The option of full-arch implant treatment and the biomechanical behaviour within a sophisticated screw-retained prosthetic structure have stimulated considerable interest in fundamental and clinical research. This study aimed to analyse the biomechanical responses of zirconia-based FAFDPs with different implant configurations (numbers and distributions), thereby predicting the possible failure sites and the optimum configuration from biomechanical aspect by using finite element method (FEM). Five 3D finite element (FE) models were constructed with patient-specific heterogeneous material properties of mandibular bone. The results were reported using volume-averaged von-Mises stresses (σ
Publisher: Springer Science and Business Media LLC
Date: 18-03-2019
DOI: 10.1038/S41598-019-41304-Z
Abstract: The aim of this study was to investigate the fracture behaviour of fissural dental enamel under simulated occlusal load in relation to various interacting factors including fissure morphology, cuspal angle and the underlying material properties of enamel. Extended finite element method (XFEM) was adopted here to analyse the fracture load and crack length in tooth models with different cusp angles (ranging from 50° to 70° in 2.5° intervals), fissural morphologies (namely U shape, V shape, IK shape, I shape and Inverted-Y shape) and enamel material properties (constant versus graded). The analysis results showed that fissures with larger curved morphology, such as U shape and IK shape, exhibit higher resistance to fracture under simulated occlusal load irrespective of cusp angle and enamel properties. Increased cusp angle (i.e. lower cusp steepness), also significantly enhanced the fracture resistance of fissural enamel, particularly for the IK and Inverted-Y shape fissures. Overall, the outcomes of this study explain how the interplay of compositional and structural features of enamel in the fissural area contribute to the resistance of the human tooth against masticatory forces. These findings may provide significant indicators for clinicians and technicians in designing/fabricating extra-coronal dental restorations and correcting the cuspal inclinations and contacts during clinical occlusal adjustment.
Publisher: Trans Tech Publications, Ltd.
Date: 07-2016
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.846.488
Abstract: The dental implants have been increasingly used for replacing missing teeth over the past three decades. However, its mechanical strength remains a major concern to dental clinicians and patients. To investigate failure modes and fracture loads of implant-supported fixed partial bridge, eXtended Finite Element Method (XFEM) was employed in this study. The 3D finite element (FE) models simulating full mandibular teeth and implant-supported three-unit fixed partial denture (FPD) were developed to determine the crack initiation and propagation in the dental prostheses. The failure modes and fracture loads are compared for three typical treatment scenarios: namely three-unit FPD supported by two implants at left second premolar and first molar (named as cantilever Model-IIP), second premolar and second molar (bridge Model-IPI), and first and second molars (cantilever Model-PII). The XFEM analyses show that the bridge Model-IPI exhibited considerably high fracture resistance than the other two configurations. Model-IIP displays the worst fracture strength of these three case scenarios. The results provide a basis for clinical assessment of mechanical strength for implant-supported FPD or other restorative devices.
Publisher: Wiley
Date: 09-06-2017
DOI: 10.1002/CNM.2889
Abstract: Dynamic load exists in numerous biomechanical systems, and its identification signifies a critical issue for characterizing dynamic behaviors and studying biomechanical consequence of the systems. This study aims to identify dynamic load in the dental prosthetic structures, namely, 3-unit implant-supported fixed partial denture (I-FPD) and teeth-supported fixed partial denture. The 3-dimensional finite element models were constructed through specific patient's computerized tomography images. A forward algorithm and regularization technique were developed for identifying dynamic load. To verify the effectiveness of the identification method proposed, the I-FPD and teeth-supported fixed partial denture structures were investigated to determine the dynamic loads. For validating the results of inverse identification, an experimental force-measuring system was developed by using a 3-dimensional piezoelectric transducer to measure the dynamic load in the I-FPD structure in vivo. The computationally identified loads were presented with different noise levels to determine their influence on the identification accuracy. The errors between the measured load and identified counterpart were calculated for evaluating the practical applicability of the proposed procedure in biomechanical engineering. This study is expected to serve as a demonstrative role in identifying dynamic loading in biomedical systems, where a direct in vivo measurement may be rather demanding in some areas of interest clinically.
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.JBIOMECH.2019.04.007
Abstract: The human masticatory system has received significant attention in the areas of biomechanics due to its sophisticated co-activation of a group of masticatory muscles which contribute to the fundamental oral functions. However, determination of each muscular force remains fairly challenging in vivo the conventional data available may be inapplicable to patients who experience major oral interventions such as maxillofacial reconstruction, in which the resultant unsymmetrical anatomical structure invokes a more complex stomatognathic functioning system. Therefore, this study aimed to (1) establish an inverse identification procedure by incorporating the sequential Kriging optimization (SKO) algorithm, coupled with the patient-specific finite element analysis (FEA) in silico and occlusal force measurements at different time points over a course of rehabilitation in vivo and (2) evaluate muscular functionality for a patient with mandibular reconstruction using a fibula free flap (FFF) procedure. The results from this study proved the hypothesis that the proposed method is of certain statistical advantage of utilizing occlusal force measurements, compared to the traditionally adopted optimality criteria approaches that are basically driven by minimizing the energy consumption of muscle systems engaged. Therefore, it is speculated that mastication may not be optimally controlled, in particular for maxillofacially reconstructed patients. For the abnormal muscular system in the patient with orofacial reconstruction, the study shows that in general, the magnitude of muscle forces fluctuates over the 28-month rehabilitation period regardless of the decreasing trend of the maximum muscular capacity. Such finding implies that the reduction of the masticatory muscle activities on the resection side might lead to non-physiological oral biomechanical responses, which can change the muscular activities for stabilizing the reconstructed mandible.
Publisher: Wiley
Date: 29-10-2016
DOI: 10.1002/CNM.2749
Abstract: Layered all-ceramic systems have been increasingly adopted in major dental prostheses. However, ceramics are inherently brittle, and they often subject to premature failure under high occlusion forces especially in the posterior region. This study aimed to develop mechanically sound novel topological designs for all-ceramic dental bridges by minimizing the fracture incidence under given loading conditions. A bi-directional evolutionary structural optimization (BESO) technique is implemented within the extended finite element method (XFEM) framework. Extended finite element method allows modeling crack initiation and propagation inside all-ceramic restoration systems. Following this, BESO searches the optimum distribution of two different ceramic materials, namely porcelain and zirconia, for minimizing fracture incidence. A performance index, as per a ratio of peak tensile stress to material strength, is used as a design objective. In this study, the novel XFEM based BESO topology optimization significantly improved structural strength by minimizing performance index for suppressing fracture incidence in the structures. As expected, the fracture resistance and factor of safety of fixed partial dentures structure increased upon redistributing zirconia and porcelain in the optimal topological configuration. Dental CAD/CAM systems and the emerging 3D printing technology were commercially available to facilitate implementation of such a computational design, exhibiting considerable potential for clinical application in the future. Copyright © 2015 John Wiley & Sons, Ltd.
Publisher: Elsevier BV
Date: 06-2021
Publisher: Trans Tech Publications, Ltd.
Date: 05-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.553.327
Abstract: Besides the prevention strategies against early stage dental caries, restoration is a preferable way to prevent decayed tooth from further deterioration. This study aimed to compare the mechanical strengths of carious tooth, traditionally restored tooth, and novel conservatively restored teeth under occlusal loading. The two-dimensional (2D) finite element method (FEM) was applied to quantify and compare maximum tensile stresses thereby predicting the initiation of crack. Taking into consideration of peak tensile stresses, it was found that the conservative (minimal intervention) restorations exhibited better fracture resistance than traditional restoration.
Publisher: Elsevier BV
Date: 08-2020
Publisher: Wiley
Date: 12-2013
DOI: 10.1111/ADJ.12107
Abstract: This study is the last in a series detailing an investigation into the all-ceramic, inlay supported fixed partial denture, the major concern of which has been the examination of the stress responses of the bridge via the use of finite element analysis (FEA) and its validation. The progression from a classic FEA to the current extended or enriched FEA (XFEA) will be described and the validation performed. XFEA modelling was compared and validated against the experimental model analysis (EMA) as described in a previous study. The two EMA load case fracture strengths of 160 N and 313 N compared favourably with the best two fracture predictions from the XFEA of 185 N and 213 N (maximum principal stress criterion) respectively, with the origin of fracture and overall trajectory and pattern of crack propagation agreeing very well. XFEA load prediction is within 15% of the EMA in the best case. The sensitivity of the bridges to loading position variations was accurately predicted by the XFEA, together with the change in fracture origin from the molar to premolar embrasures. With this, the authors believe that they have provided a convincing validation, both qualitatively and quantitatively, of an anatomically realistic dental bridge.
Publisher: Elsevier BV
Date: 02-2012
DOI: 10.1016/J.DENTAL.2011.11.012
Abstract: The reliability and longevity of ceramic prostheses have become a major concern. The existing studies have focused on some critical issues from clinical perspectives, but more researches are needed to address fundamental sciences and fabrication issues to ensure the longevity and durability of ceramic prostheses. The aim of this paper was to explore how "sensitive" the thermal and mechanical responses, in terms of changes in temperature and thermal residual stress of the bi-layered ceramic systems and crown models will be with respect to the perturbation of the design variables chosen (e.g. layer thickness and heat transfer coefficient) in a quantitative way. In this study, three bi-layered ceramic models with different geometries are considered: (i) a simple bi-layered plate, (ii) a simple bi-layer triangle, and (iii) an axisymmetric bi-layered crown. The layer thickness and convective heat transfer coefficient (or cooling rate) seem to be more sensitive for the porcelain fused on zirconia substrate models. The resultant sensitivities indicate a critical importance of the heat transfer coefficient and thickness ratio of core to veneer on the temperature distributions and residual stresses in each model. The findings provide a quantitative basis for assessing the effects of fabrication uncertainties and optimizing the design of ceramic prostheses.
Publisher: Elsevier BV
Date: 05-2015
Publisher: Elsevier BV
Date: 2022
Publisher: Elsevier BV
Date: 11-2014
Publisher: Informa UK Limited
Date: 06-04-2016
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.DENTAL.2018.11.005
Abstract: Tooth enamel has unsurpassed hardness and stiffness among mammalian tissue structures. Such stiff materials are usually brittle, yet mature enamel can survive for a lifetime. Understanding the nanoscale origin of enamel durability is important for developing advanced load-bearing biomaterials. Here, nanoscale exceptional contact elasticity of the human tooth enamel, based on nanoindentation tests, is reported. Spherical indenter tips with radii of 243 and 1041nm were used to determine stress-strain curves of enamel. Force-displacement curves were recorded using quasi-static loading strain rates of 0.031, 0.041, and 0.061s The elastic limits were 7-9GPa and 5-6GPa for the small and large indenters, respectively. The elastic-plastic transition point and elastic modulus value increased with substantially increased quasi-static loading strain rate. The results suggested that the increase of the elastic limit during high-loading strain was associated with exceptional contact elasticity at the nanoscale of the enamel structure and the consequent extension of the contact area (i.e., a temporary pile-up response, dependent on the enamel nanocrystals and protein glue). Structural modification at this scale effectively prevents the initiation of cracking from localized strain, thus reinforcing the bulk structure. These results may provide valuable insight for conceptualizing bio-inspired nanocomposites.
Publisher: Wiley
Date: 09-03-2020
DOI: 10.1002/NME.6340
Publisher: Trans Tech Publications, Ltd.
Date: 03-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.97-101.2241
Abstract: Fabrication of multilayered ceramics signifies an important topic in many advanced applications aerospace and prosthetic dentistry. This paper presents a numerical approach to characterising the transient thermal responses and corresponding thermal residual stresses that are developed in the bi-layered dental ceramic crowns model under a controlled cooling rate from a temperature around its glass transition temperature (typically 550°C) to room temperature (25°C). Finite element method (FEM) is adopted to model the residual stresses in normal or rapid cooling fabrication process. The demonstrative ex les take into account the effect of thickness in core veneered all-ceramic restorative prosthesis (specific porcelain bonded to an alumina or zirconia core layer), cooling rates and mismatches in temperature-dependent material properties such as thermal expansion coefficients, specific heat and Young’s modulus. The model of transient ceramic fabrication processing showed significant potential to development of optimal prosthetic devices.
Publisher: Elsevier BV
Date: 06-2016
DOI: 10.1016/J.JMBBM.2016.01.035
Abstract: This study aimed to explore the "sensitivity" of the fracture load and initiation site to loading position on the central occlusal surface of a pontic tooth for both all-ceramic inlay retained and onlay supported partial denture systems. Three dimensional (3D) finite element (FE) inlay retained and onlay supported partial denture models were established for simulating crack initiation and propagation by using the eXtended Finite Element Method (XFEM). The models were subjected to a mastication force up to 500N on the central fossa of the pontic. The loading position was varied to investigate its influence on fracture load and crack path. Small perturbation of the loading position caused the fracture load and crack pattern to vary considerably. For the inlay fixed partial dentures (FPDs), the fracture origins changed from the bucco-gingival aspect of the molar embrasure to the premolar embrasure when the indenter force location is slightly shifted from the mesial to distal side. In contrast, for onlay FPDs, cracking initiated from bucco-gingival aspect of the premolar embrasure when the indenter is slightly shifted to the buccal side and from molar embrasure when the indenter is shifted to the lingual side. The fracture load and cracking path were found to be very sensitive to loading position in the all-ceramic inlay and onlay FPDs. The study provides a basis for improved understanding on the role of localized contact loading of the cusp surface in all-ceramic FPDs.
Publisher: Elsevier BV
Date: 06-2020
Publisher: World Scientific Pub Co Pte Lt
Date: 03-2016
DOI: 10.1142/S0219876216400028
Abstract: Periodic microstructural composites have gained considerable attention in material science and engineering attributable to their excellent flexibility in tailoring various desirable physical properties. Conventionally, the finite element technique has been widely used in implementing the homogenization. However, the standard finite element method (FEM) leads to an overly stiff model which sometimes gives unsatisfactory accuracy especially using triangular elements in 2D or tetrahedral elements in 3D with coarse mesh. In this paper, different forms of smoothed finite element method (SFEM) are presented to develop new asymptotic homogenization techniques for analyzing various effective physical properties of periodic microstructural composite materials. A range of multifunctional material ex les, including elastic modulus with multiphase composites, conductivity of thermal and electrical composites, and diffusivity ermeability of 3D tissue scaffold, has exemplified herein to demonstrate that SFEM is able to provide more accurate results using the same set of mesh compared with the standard FEM. In addition, the computational efficiency of SFEM is also higher than that of the standard FEM counterpart.
Publisher: Elsevier BV
Date: 06-2021
Publisher: Scientific Research Publishing, Inc.
Date: 2014
Start Date: 2023
End Date: 12-2025
Amount: $362,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 12-2023
End Date: 12-2026
Amount: $448,354.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2021
End Date: 12-2021
Amount: $289,500.00
Funder: Australian Research Council
View Funded Activity