Journal of the Mechanical Behavior of Biomedical Materials最新文献

{"title":"Topological optimization of hip spacer reinforcement","authors":"Abdelhafid Mallek ,&nbsp;Abdulmohsen Albedah ,&nbsp;Mohammed Mokhtar Bouziane ,&nbsp;Bel Abbes Bachir Bouiadjra ,&nbsp;Sohail M.A.K. Mohammed ,&nbsp;Richie H.S. Gill","doi":"10.1016/j.jmbbm.2024.106763","DOIUrl":"10.1016/j.jmbbm.2024.106763","url":null,"abstract":"<div><div>The use of an antibiotic-enriched hip spacer represents the optimal treatment for periprosthetic joint infections (PJI). The addition of reinforcement significantly enhances its mechanical properties. Employing the explicit method enables accurate prediction of the mechanical behavior of both the spacer and its reinforcement. Topological optimization of the reinforcement emerges as the most effective strategy to prevent bone demineralization, enhance antibiotic diffusion, and improve spacer resistance. The objective of this study is to conduct topological optimization of a validated numerical model of a reinforced hip spacer and to select, from the obtained topologies, the one that best improves mechanical properties and prevents stress shielding while minimizing volume. The results indicate that an 8 mm thick titanium reinforcement, optimized to 70% of its original volume, proves to be the most effective choice.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"160 ","pages":"Article 106763"},"PeriodicalIF":3.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142383036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"One-step synthesis of a piezoelectric hybrid BNNT/BaTiO3 composite and its application in bone tissue engineering","authors":"Zehra Çobandede ,&nbsp;Mustafa Çulha","doi":"10.1016/j.jmbbm.2024.106758","DOIUrl":"10.1016/j.jmbbm.2024.106758","url":null,"abstract":"<div><div>Nanomaterials with piezoelectric properties can significantly improve the applicability of polymers used in tissue engineering applications. In this study, we report the one-step synthesis of a novel hybrid piezoelectric composite comprising barium titanates and boron nitride nanotubes. This composite is distinguished by its unique microstructures, including nanoflakes, triangular boron nitride structures, and fiber-like boron nitride nanotube configurations, which contribute to its enhanced piezoelectric properties. The composite was incorporated into a chitosan-based tissue scaffold and evaluated in vitro. Electric-responsive Human Osteoblast cells cultured on the scaffolds are exposed to low-frequency ultrasound stimulation during cell growth. The biocompatibility, cell adhesion, alkaline phosphatase activities, and mineralization of osteoblast cells on the piezo-composite scaffolds were evaluated. The results show that the hybrid piezoelectric composite significantly enhances the properties of chitosan-based scaffold.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"160 ","pages":"Article 106758"},"PeriodicalIF":3.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142356993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computationally derived endosteal strain and strain gradients correlate with increased bone formation in an axially loaded murine tibia model","authors":"Murat Horasan ,&nbsp;Kari A. Verner ,&nbsp;Haisheng Yang ,&nbsp;Russell P. Main ,&nbsp;Eric A. Nauman","doi":"10.1016/j.jmbbm.2024.106761","DOIUrl":"10.1016/j.jmbbm.2024.106761","url":null,"abstract":"<div><div>Osteoporosis is a common metabolic bone disorder characterized by low bone mass and microstructural degradation of bone tissue due to a derailed bone remodeling process. A deeper understanding of the mechanobiological phenomena that modulate the bone remodeling response to mechanical loading in a healthy bone is crucial to develop treatments. Rodent models have provided invaluable insight into the mechanobiological mechanisms regulating bone adaptation in response to dynamic mechanic stimuli. This study sheds light on these aspects by means of assessing the mechanical environment of the cortical and cancellous tissue to <em>in vivo</em> dynamic compressive loading within the mouse tibia using microCT-based finite element model in combination with diaphyseal strain gauge measures. Additionally, this work describes the relation between the mid-diaphyseal strains and strain gradients from the finite element analysis and bone formation measures from time-lapse <em>in vivo</em> tibial loading with a fluorochrome-derived histomorphometry analysis. The mouse tibial loading model demonstrated that cancellous strains were lower than those in the midshaft cortical bone. Sensitivity analyses demonstrated that the material property of cortical bone was the most significant model parameter. The computationally-modeled strains and strain gradients correlated significantly to the histologically-measured bone formation thickness at the mid-diaphyseal cross-section of the mouse tibia.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"160 ","pages":"Article 106761"},"PeriodicalIF":3.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142402477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear biomechanical behaviour of extracranial carotid artery aneurysms in the framework of Windkessel effect via FSI technique","authors":"Kaveh Moghadasi ,&nbsp;Mergen H. Ghayesh ,&nbsp;Jiawen Li ,&nbsp;Eric Hu ,&nbsp;Marco Amabili ,&nbsp;Krzysztof Kamil Żur ,&nbsp;Robert Fitridge","doi":"10.1016/j.jmbbm.2024.106760","DOIUrl":"10.1016/j.jmbbm.2024.106760","url":null,"abstract":"<div><div>Extracranial carotid artery aneurysms (ECCA) lead to rupture and neurologic symptoms from embolisation, with potentially fatal outcomes. Investigating the biomechanical behaviour of EECA with blood flow dynamics is crucial for identifying regions more susceptible to rupture. A coupled three-dimensional (3D) Windkessel-framework and hyperelastic fluid-structure interaction (FSI) analysis of ECCAs with patient-specific geometries, was developed in this paper with a particular focus on hemodynamic parameters and the arterial wall's biomechanical response. The blood flow has been modelled as non-Newtonian, pulsatile, and turbulent. The biomechanical characteristics of the aneurysm and artery are characterised employing a 5-parameter Mooney-Rivlin hyperelasticity model. The Windkessel effect is also considered to efficiently simulate pressure profile of the outlets and to capture the dynamic changes over the cardiac cycle. The study found the aneurysm carotid artery exhibited the high levels of pressure, wall shear stress (WSS), oscillatory shear index (OSI), and relative residence time (RRT) compared to the healthy one. The deformation of the arterial wall and the corresponding von Mises (VM) stress were found significantly increased in aneurysm cases, in comparison to that of no aneurysm cases, which strongly correlated with the hemodynamic characteristics of the blood flow and the geometric features of the aneurysms. This escalation would intensify the risk of aneurysm wall rupture. These findings have critical implications for enhancing treatment strategies for patients with extracranial aneurysms.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"160 ","pages":"Article 106760"},"PeriodicalIF":3.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142376441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The influence of radiation-induced collagen chain fragmentation, crosslinking, and sequential irradiation on the high-cycle fatigue life of human cortical bone","authors":"Dylan B. Crocker ,&nbsp;Ozan Akkus ,&nbsp;Megan E. Oest ,&nbsp;Clare M. Rimnac","doi":"10.1016/j.jmbbm.2024.106759","DOIUrl":"10.1016/j.jmbbm.2024.106759","url":null,"abstract":"<div><div>Both high-cycle fatigue life and fatigue crack propagation resistance of human cortical bone allograft are radiation dose-dependent between 0 and 25 kGy such that higher doses exhibit progressively shorter lifetimes. Recently, we have shown that collagen chain fragmentation and stable crosslink accumulation may contribute to the radiation dose-dependent loss in fatigue crack propagation resistance of human cortical bone. To our knowledge, the influence of these mechanisms on high-cycle fatigue life of cortical bone have not been established. Sequential irradiation has also been shown to mitigate the loss of fatigue life of tendons, however, whether this mitigates losses in fatigue life of cortical bone has not been explored. Our objectives were to evaluate the influence of radiation-induced collagen chain fragmentation and crosslinking on the high-cycle fatigue life of cortical bone in the dose range of 0–15 kGy, and to evaluate the capability of sequential irradiation at 15 kGy to mitigate the loss of high-cycle fatigue life and radiation-induced collagen damage. High-cycle fatigue life specimens from four male donor femoral pairs were divided into 5 treatment groups (0 kGy, 5 kGy, 10 kGy, 15 kGy, and 15 kGy sequentially irradiated) and subjected to high-cycle fatigue life testing with a custom rotating-bending apparatus at a cyclic stress of 35 MPa. Following fatigue testing, collagen was isolated from fatigue specimens, and collagen chain fragmentation and crosslink accumulation were quantified using SDS-PAGE and a fluorometric assay, respectively. Both collagen chain fragmentation (p = 0.006) and non-enzymatic crosslinking (p &lt; 0.001) influenced high-cycle fatigue life, which decreased with increasing radiation dose from 0 to 15 kGy (p = 0.016). Sequential irradiation at 15 kGy did not offer any mitigation in high-cycle fatigue life (p = 0.93), collagen chain fragmentation (p = 0.99), or non-enzymatic crosslinking (p ≥ 0.10) compared to a single radiation dose of 15 kGy. Taken together with our previous findings on the influence of collagen damage on fatigue crack propagation resistance, collagen chain fragmentation and crosslink accumulation both contribute to radiation-induced losses in notched and unnotched fatigue life of cortical bone. To maximize the functional lifetime of radiation sterilized structural cortical bone allografts, pathways other than sequential radiation should be explored to mitigate collagen matrix damage.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"160 ","pages":"Article 106759"},"PeriodicalIF":3.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142376442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring the optimal mechanical properties of triply periodic minimal surface structures for biomedical applications: A Numerical analysis","authors":"Babak Ziaie ,&nbsp;Xavier Velay ,&nbsp;Waqas Saleem","doi":"10.1016/j.jmbbm.2024.106757","DOIUrl":"10.1016/j.jmbbm.2024.106757","url":null,"abstract":"<div><div>Currently, cutting-edge Additive Manufacturing techniques, such as Selective Laser Melting (SLM) and Electron Beam Melting (EBM), offer manufacturers a valuable avenue, especially in biomedical devices. These techniques produce intricate porous structures that draw inspiration from nature, boast biocompatibility, and effectively counter the adverse issues tied to solid implants, including stress shielding, cortical hypertrophy, and micromotions. Within the domain of such porous structures, Triply Periodic Minimal Surface (TPMS) configurations, specifically the Gyroid, Diamond, and Primitive designs, exhibit exceptional performance due to their bioinspired forms and remarkable mechanical and fatigue properties, outshining other porous counterparts. Consequently, they emerge as strong contenders for biomedical implants. However, assessing the mechanical properties and manufacturability of TPMS structures within the appropriate ranges of pore size, unit cell size, and porosity tailored for biomedical applications remains paramount. This study aims to scrutinize the mechanical behavior of Gyroid, Diamond, and Primitive structures in solid and sheet network iterations within the morphological parameter ranges suitable for tasks like cell seeding, vascularization, and osseointegration. A comparison with the mechanical characteristics of host bones is also undertaken. The methodology revolves around Finite Element Method (FEM) analysis. The six structures are originally modeled with unit cell sizes of 1, 1.5, 2, and 2.5 mm, and porosity levels ranging from 50% to 85%. Subsequently, mechanical properties, such as elasticity modulus and yield strength, are quantified through numerical analysis. The results underscore that implementing TPMS designs enables unit cell sizes between 1 and 2.5 mm, facilitating pore sizes within the suitable range of approximately 300–1500 μm for biomedical implants. Elasticity modulus spans from 1.5 to 33.8 GPa, while yield strength ranges around 20–304.5 MPa across the 50%–85% porosity spectrum. Generally, altering the unit cell size exhibits minimal impact on mechanical properties within the range above; however, it's noteworthy that smaller porosities correspond to heightened defects in additively manufactured structures. Thus, for an acceptable pore size range of 500–1000 μm and a minimum wall thickness of 150 μm, a prudent choice would involve adopting a 2.5 mm unit cell size.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"160 ","pages":"Article 106757"},"PeriodicalIF":3.3,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142376429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of muscle packing on the three-dimensional architecture of rabbit M. plantaris","authors":"Mischa Borsdorf ,&nbsp;Stefan Papenkort ,&nbsp;Markus Böl ,&nbsp;Tobias Siebert","doi":"10.1016/j.jmbbm.2024.106762","DOIUrl":"10.1016/j.jmbbm.2024.106762","url":null,"abstract":"<div><div>In their physiological condition, muscles are surrounded by connective tissue, other muscles and bone. These tissues exert transverse forces that change the three-dimensional shape of the muscle compared to its isolated condition, in which all surrounding tissues are removed. A change in shape affects the architecture of a muscle and therefore its mechanical properties. The rabbit <em>M. plantaris</em> is a multi-pennate calf muscle consisting of two compartments. A smaller, bi-pennate inner muscle compartment is embedded in a larger, uni-pennate outer compartment (Böl et al., 2015). As part of the calf, the plantaris is tightly packed between other muscles. It is unclear how packing affects the shape and architecture of the plantaris. Therefore, we examined the isolated and packed plantaris of the contralateral legs of three rabbits to determine the influence of the surrounding muscles on its shape and architectural properties using photogrammetric reconstruction and manual digitization, respectively. In the packed condition, the plantaris showed a 27% increase in fascicle pennation and a 54% increase in fascicle curvature compared to the isolated condition. Fascicle length was not affected by muscle packing. The change in muscle architecture occurred mainly in the outer compartment of the plantaris. Furthermore, the isolated plantaris showed a more circular shape and a reduced width of its muscle belly. It can be concluded that the packed plantaris is flattened by the forces exerted by the surrounding muscles, causing a complex architectural change. The data provided improve our understanding of muscle packages in general and can be used to develop and validate realistic three-dimensional muscle models.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"160 ","pages":"Article 106762"},"PeriodicalIF":3.3,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Articular cartilage fatigue causes frequency-dependent softening and crack extension","authors":"Dipul Chawla ,&nbsp;Alexandria K. Thao ,&nbsp;Melih Eriten ,&nbsp;Corinne R. Henak","doi":"10.1016/j.jmbbm.2024.106753","DOIUrl":"10.1016/j.jmbbm.2024.106753","url":null,"abstract":"<div><div>Soft biological polymers, such as articular cartilage, possess exceptional fracture and fatigue resistance, offering inspiration for the development of novel materials. However, we lack a detailed understanding of changes in cartilage material behavior and of crack propagation following cyclic compressive loading. We investigated the structure and mechanical behavior of cartilage as a function of loading frequency and number of cycles. Microcracks were initiated in cartilage samples using microindentation, then cracks were extended under cyclic compression. Thickness, apparent stiffness, energy dissipation, phase angle, and crack length were measured to determine the effects of cyclic loading at two frequencies (1 Hz and 5 Hz). To capture the fatigue-induced material response (thickness, stiffness, energy dissipation, and phase angle), material properties were compared between pre-and-post diagnostic tests. The findings indicate that irreversible structural damage (reduced thickness), cartilage softening (reduced apparent stiffness), and reduced energy dissipation (including phase angle) increased with an increase in the number of cycles. Higher frequency loading resulted in less reduction in energy dissipation, phase angle, and thickness change. Crack lengths, quantified through brightfield imaging, increased with number of cycles and frequency. This study sheds light on the complex response of cartilage under cyclic loading resulting in softening, structural damage, and altered dynamic behavior. The findings provide better understanding of failure mechanisms in cartilage and thus may help in diagnosis and treatment of osteoarthritis.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"160 ","pages":"Article 106753"},"PeriodicalIF":3.3,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142383035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of silver coated zeolite fillers on the chemical and mechanical properties of 3D-printed polyphenylene sulfone restorations","authors":"Felicitas Mayinger ,&nbsp;Andrea Lösch ,&nbsp;Elena Reznikova ,&nbsp;Christian Wilhelm ,&nbsp;Bogna Stawarczyk","doi":"10.1016/j.jmbbm.2024.106756","DOIUrl":"10.1016/j.jmbbm.2024.106756","url":null,"abstract":"<div><h3>Objectives</h3><div>To investigate the chemical and mechanical properties of polyphenylene sulfone (PPSU) depending on its composition and manufacturing.</div></div><div><h3>Methods</h3><div>Unfilled–PPSU1 and with antimicrobial silver coated zeolites filled–PPSU2 specimens were made of granulate–GR, filament–FI, or printed–3D. Scanning microscopy and X-ray spectroscopy were performed. Martens hardness–HM, elastic indentation modulus–E_IT and flexural strength–FS were determined initially and after aging. Shear bond strength–SBS to veneering and luting composite after conditioning with 7 adhesive systems were examined after aging. Silver leaching was tested after 1-, 3-, 7-, 14-, 21-, 28- and 42 days. Analyses of variance, Kolmogorov–Smirnov, Kruskal–Wallis, Mann–Whitney <em>U</em>, unpaired t-tests and Weibull modulus were computed (p &lt; 0.05).</div></div><div><h3>Results</h3><div>Zeolites were homogeneously distributed. PPSU1-GR and PPSU1-FI showed the highest HM/E_IT, followed by PPSU2-GR, PPSU1-3D and PPSU2-3D. PPSU2-FI presented the lowest HM/E_IT, displaying micro pits. Aging showed reduced HM/E_IT in PPSU1 and no impact on PPSU2, while FS increased (PPSU1) or decreased (PPSU2). PPSU2-3D presented lower FS than PPSU1-3D. High SBS to the luting (7.0–16.2 MPa) and veneering composite (11.8–22.2 MPa), except for adhesive system PR, were observed. PPSU2-3D showed the highest silver release (9.6%), with all compositions dispensing silver over 42 days.</div></div><div><h3>Conclusions</h3><div>For the examined period of 6 weeks, antimicrobial silver ions were released from filled PPSU. The high SBS between PPSU and veneering/luting composite confirmed the feasibility of esthetically veneering and luting filled PPSU. To achieve mechanical properties like unfilled PPSU, the processing parameters of filled PPSU require refinement.</div></div><div><h3>Clinical significance</h3><div>This investigation provides proof of principle that PPSU can be successfully doped with silver-coated zeolites. The combination of 3D-printing with an antimicrobial thermoplastic constitutes a great opportunity in the field of prosthetic dentistry. Potential applications include clasps for removable dental prostheses, provisional or permanent fixed dental prostheses and implant abutments.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"160 ","pages":"Article 106756"},"PeriodicalIF":3.3,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142368078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Validation of finite-element-simulated orthodontic forces produced by thermoplastic aligners: Effect of aligner geometry and creep","authors":"N. Ye ,&nbsp;B.E. Brown ,&nbsp;S.C. Mantell ,&nbsp;B.E. Larson ,&nbsp;T. Gruenheid ,&nbsp;A.S. Fok","doi":"10.1016/j.jmbbm.2024.106755","DOIUrl":"10.1016/j.jmbbm.2024.106755","url":null,"abstract":"<div><h3>Purpose</h3><div>Finite element (FE) models for determining the orthodontic forces delivered by clear aligners often lack validation. The aim of this study was to develop and validate accurate FE models for clear aligners, considering the small but important geometrical variations from the thermoforming process and the creep behavior of the aligner material.</div></div><div><h3>Methods and materials</h3><div>The tooth misalignment considered was a 2.4° torque aberration (rotation about the mesial-distal axis at the level of the center of resistance) of the maxillary left central incisor. FE models were created from Micro-CT scans of a model dental arch and five nominally identical aligners with the aforementioned misfit. Fitting of the aligners onto the dental arch was simulated using Abaqus's Interference Fit function, followed by surface-to-surface frictional interaction. Stress relaxation of the aligner material was measured using double-cantilever beam bending and modeled with a Prony series. The assembled FE models were validated by comparing the predicted forces and moments delivered to the maxillary left central incisor with experimental data, obtained with a custom-built but fully calibrated apparatus.</div></div><div><h3>Results</h3><div>Good agreement between prediction and measurement was obtained for both the short- and long-term forces and moments. In the short-term, i.e., after 30 s, the dominant force in the labial-lingual direction had a maximum difference of 2.9% between experiment and simulation, and the dominant moment about the mesial-distal axis had a maximum difference of 8.3%. In the long-term, i.e., after 4 h, the experimental and numerical forces had a maximum difference of 8.4%. There were statistically significant differences in the forces delivered among the nominally identical aligners, which were predicted by the geometrically accurate FE models and attributed to the variations in the points of contact between the aligners and the dental arch. The decay in force applied was affected by both the viscoelastic material behavior and friction between the aligner and arch.</div></div><div><h3>Conclusion</h3><div>For accurate prediction of the forces and moments delivered by thermoplastic aligners, FE models that can accurately capture the point contacts between the aligners and the underlying teeth are essential. Stress relaxation of the aligners could be adequately modeled using the Prony series to represent the temporal changes of their elastic modulus.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"160 ","pages":"Article 106755"},"PeriodicalIF":3.3,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142320214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}