Journal of the Mechanical Behavior of Biomedical Materials最新文献

{"title":"Linking morphometric variations in human cranial bone to mechanical behavior using machine learning","authors":"Weihao Guo ,&nbsp;Kapil Bharadwaj Bhagavathula ,&nbsp;Kevin Adanty ,&nbsp;Karyne N. Rabey ,&nbsp;Simon Ouellet ,&nbsp;Dan L. Romanyk ,&nbsp;Lindsey Westover ,&nbsp;James David Hogan","doi":"10.1016/j.jmbbm.2025.107165","DOIUrl":"10.1016/j.jmbbm.2025.107165","url":null,"abstract":"<div><div>With the development of increasingly detailed imaging techniques, there is a need to update the methodology and evaluation criteria for bone analysis to understand the influence of bone microarchitecture on mechanical response. The present study aims to develop a machine learning-based approach to investigate the link between morphology of the human calvarium and its mechanical response under quasi-static uniaxial compression. Micro-computed tomography is used to capture the microstructure at a resolution of <span><math><mrow><mn>18</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> of male (n=5) and female (n=5) formalin-fixed calvarium specimens of the frontal and parietal regions. Image processing-based machine learning methods using convolutional neural networks are developed to isolate and calculate specific morphometric properties, such as porosity, trabecular thickness and trabecular spacing. Then, an ensemble method using a gradient boosted decision tree (XGBoost) is used to predict the mechanical strength based on the morphological results, and found that mean and minimum porosity at <span><math><mrow><mi>d</mi><mi>i</mi><mi>p</mi><mi>l</mi><mi>o</mi><mi>ë</mi></mrow></math></span> are the most relevant factors for the mechanical strength of cranial bones under the studied conditions. Overall, this study provides new tools that can predict the mechanical response of human calvarium a priori. Besides, the quantitative morphology of the human calvarium can be used as input data in finite element models, as well as contributing to efforts in the development of cranial simulant materials.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"172 ","pages":"Article 107165"},"PeriodicalIF":3.5,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894770","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":"Evaluation of statistical methods to study flexural strength of dental CAD-CAM composites","authors":"Yousef Karevan ,&nbsp;Christelle Sanchez ,&nbsp;Adelin Albert ,&nbsp;Amélie Mainjot","doi":"10.1016/j.jmbbm.2025.107171","DOIUrl":"10.1016/j.jmbbm.2025.107171","url":null,"abstract":"<div><div>Determining the optimal statistical method is key for reliable interpretation of the flexural strength test. To date, statistical recommendations regarding the best approach and sample size are based on theoretical assumptions that may not hold in practice. Therefore, this study identified the optimal statistical approach for analyzing the flexural strength of computer-aided design/computer-aided manufacturing (CAD-CAM) composites using a real dataset. In this perspective, the flexural strength dataset of commercial CAD-CAM composites, Cerasmart 270 (CER), Katana Avencia (KAT), Grandio (GRN), and polymer-infiltrated ceramic network Vita Enamic (ENA) were used (10 blocks/material; 15 samples/block). Leave-K-out cross-validation was performed on this dataset with K = 3 to 9 blocks (a total of 967 scenarios per material). The goal was to compare seven common statistical methods: Normal distribution (1), Lognormal distribution (2), the 2-parameter Weibull distribution calculated by maximum likelihood estimation (MLE) (3) and least squares (LSQ) estimation (LSQ; with three different estimators 4-5-6); (4) 3-parameters Weibull distribution. These methods were assessed based on comparative performance, standalone performance, and lower tail prediction.</div><div>The results highlight that all statistical approaches have limited reliability with small sample sizes (e.g., n = 30) employed in dental materials research. Factors such as inter-block heterogeneity and physical characteristics of CAD-CAM composites could affect the efficacy of the statistical methods. The 2P-Weibull distribution was less prone to overestimating strength at low failure probability. LSQ with the mean estimator <span><math><mrow><mo>(</mo><mrow><mi>i</mi><mo>/</mo><mrow><mo>(</mo><mrow><mi>n</mi><mo>+</mo><mn>1</mn></mrow><mo>)</mo></mrow></mrow><mo>)</mo></mrow></math></span> comparatively outperformed others, particularly with small sample sizes. Weibull analysis would be more reliable with over 60 samples, but ideally more than 100 is recommended.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"172 ","pages":"Article 107171"},"PeriodicalIF":3.5,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144892835","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":"A review of ventral hernia biomechanics","authors":"Victoria Joppin ,&nbsp;Catherine Masson ,&nbsp;David Bendahan ,&nbsp;Thierry Bege","doi":"10.1016/j.jmbbm.2025.107159","DOIUrl":"10.1016/j.jmbbm.2025.107159","url":null,"abstract":"<div><div>Despite advancements in surgical techniques, hernia recurrence rates remain high, underscoring the need for improved understanding of abdominal wall behaviour. While surgeons are aware of many factors contributing to hernia occurrence (e.g obesity, smoking, surgical technique or site infection), it would be of interest to consider it as a biomechanical pathology. Indeed, an abdominal hernia arises from an imbalance between abdominal wall deformability and applied forces. This review article discusses how biomechanics offer a quantitative framework for assessing healthy and damaged tissue behaviour, guiding personalised surgical strategies throughout the pre-, intra-, and post-operative periods.</div><div>The abdominal wall is a dynamic, load-bearing structure, continuously subjected to intra-abdominal pressure and mechanical stress. Its biomechanical properties, including elasticity and resistance to loading forces, dictate its function and response to surgical intervention. The linea alba is the stiffest component experiencing the highest stress, while the abdominal wall's anisotropic nature influences deformation patterns. Various experimental and computational methods enable biomechanical characterisation.</div><div>Hernias represent mechanical failures at anatomical weak points. While surgeons qualitatively evaluate abdominal wall's biomechanics by estimating deformation and closure forces, functional imaging (elastography, dynamic acquisitions) could provide objective biomechanical insights. Hernia formation alters abdominal wall biomechanics, inducing greater mobility and elasticity.</div><div>Surgical repair fundamentally alters the biomechanics of the abdominal wall. The choice of defect's suturing technique, mesh properties, placement, overlap and fixation methods (e.g. suture, tacks) significantly influence mechanical outcomes. Surgical repair tends to restore physiological biomechanics by re-establishing force transmission and hernia-induced excessive mobility. Suturing techniques, mesh selection and placement influence mechanical outcomes. However, optimal results require implants with mechanical properties mimicking native tissue. Lightweight meshes (&lt;70 g/m²) placed in a retrorectus position, combined with a small-bite suture technique, have been associated with lower recurrence rates and improved post-operative function.</div><div>By bridging biomechanics with surgical practice, this review highlights how mechanical principles shape hernia formation, diagnosis, and repair. A deeper integration of biomechanical principles into surgical decision-making could refine hernia management and lead to patient-specific, mechanics-informed strategies. For surgeons, this knowledge is not just academic - it is practical and can make a difference to patient outcomes.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"173 ","pages":"Article 107159"},"PeriodicalIF":3.5,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145047220","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":"Study of nanohydroxyapatite composites loaded with gentamicin sulfate and silver nanoparticles","authors":"Klaudia Malisz ,&nbsp;Beata Świeczko – Żurek ,&nbsp;Jakub Karczewski ,&nbsp;Aleksandra Mirowska ,&nbsp;Anna Pałubicka","doi":"10.1016/j.jmbbm.2025.107172","DOIUrl":"10.1016/j.jmbbm.2025.107172","url":null,"abstract":"<div><div>The aim of the work is to compare the properties of nanohydroxyapatite coatings containing antibiotic - gentamicin or silver nanoparticles. The coatings were obtained using the electrophoretic deposition method (EDP). The additives were introduced by the immersion method. Evaluation of the coating was performed by using a Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectrometer (EDX), and a drop shape analyzer. Antibacterial properties were examined by assessing the surface after incubation in a bacterial solution for 30 days. The corrosion properties of the materials were also assessed. Silver nanoparticles and the antibiotic were successfully incorporated into the nanohydroxyapatite coating. The wettability test shows the hydrophilic behavior of the coatings that contains an antibiotic. Furthermore, the average contact angle (CA) value for nanohydroxyapatite doped with silver nanoparticles increased to 120°. The highest surface roughness was observed for the coating containing silver. All nanohydroxapatite modifications improved the corrosion resistance of the titanium alloy, but the best results were obtained by nanohydroxapatite with AgNPs, where the Icorr parameter was 15.5 ± 3.9 μA/cm², Ecorr showed the most positive value of 25.6 ± 1.7 mV, and Rpol was 8.1 ± 0.2 kΩ cm². For comparison, the corresponding values for the nHAp coating are: 41.7 ± 1.9 μA/cm², -56.1 ± 1.6 mV, 3.6 ± 0.4 kΩ cm². It was found that both the coating with added AgNPs and the one with a higher concentration of gentamicin exhibited antibacterial properties. It can be stated that the silver-containing coating shows greater potential for combating perioperative infections due to the combination of good corrosion resistance and broad-spectrum antibacterial properties.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"172 ","pages":"Article 107172"},"PeriodicalIF":3.5,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894771","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":"Regional quantification of glycosaminoglycans and their association with collagen fibril ultrastructure in the sclera following enzymatic degradation","authors":"Ahmed Kazaili ,&nbsp;Zhuola ,&nbsp;Noor Ali Sadek ,&nbsp;Hayder Abdul-Amir Maki Al-Hindy ,&nbsp;Brendan Geraghty ,&nbsp;Yalda Ashraf Kharaz ,&nbsp;Eithne Comerford ,&nbsp;Edwin Yates ,&nbsp;Lu-Ning Liu ,&nbsp;Riaz Akhtar","doi":"10.1016/j.jmbbm.2025.107169","DOIUrl":"10.1016/j.jmbbm.2025.107169","url":null,"abstract":"<div><div>Sclera biomechanics play an important role in clear vision. Understanding the biomechanical, composition and ultrastructural topography of the sclera may help provide better insight into eye health. Some prior research has investigated the ultrastructural and biomechanical properties of the sclera in relation to regional variations. However, the complex association between regional variations in collagen fibril morphology and elasticity with proteoglycan types and quantities has not been investigated. This study aimed to explore regional variations in scleral collagen fibril topography and proteoglycan quantities and to investigate their role in the mechanical properties of the sclera. Atomic force microscopy (AFM), collagen autofluorescence, glycosaminoglycans (GAGs) quantification, and Coomassie blue staining techniques were used to assess alterations of the porcine sclera following treatment with amylase (Amy) and chondroitinase ABC (ChABC). Collagen fibril diameters were found to vary among the regions of the scleral stroma, with the largest diameters (268 ± 23 nm) in the anterior region and smallest diameters (148 ± 14 nm) in the posterior region. Collagen fibril stiffness and diameters were reduced following incubation with these enzymes. GAGs were depleted from the enzymatically treated tissues with the greater depletion in the posterior region. GAG depletion was inversely correlated (Pearson's r = −0.75 and −0.85 for the amylase and ChABC treated groups) with collagen fibril diameter and elastic modulus. In summary, we show the direct link between GAGs and collagen fibril properties at the nano-scale from the anterior to the posterior region of the porcine sclera.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"172 ","pages":"Article 107169"},"PeriodicalIF":3.5,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903808","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":"The impact of conical design of dental implant and osteotomy shape on the insertion process and primary stability","authors":"Armin Shanazari,&nbsp;Pedram Akhlaghi,&nbsp;Gholamreza Rouhi","doi":"10.1016/j.jmbbm.2025.107170","DOIUrl":"10.1016/j.jmbbm.2025.107170","url":null,"abstract":"<div><div>This study investigated the impact of dental implant shape (conical vs. cylindrical) and pilot-hole geometry (conical vs. cylindrical) on primary stability. Finite element analysis was employed to simulate the insertion process and push-in test. Three implantation scenarios were examined: a cylindrical implant in a cylindrical pilot-hole (cy-cy model), a conical implant in a cylindrical pilot-hole (co-cy model), and a conical implant in a conical pilot-hole (co-co model). These configurations were evaluated based on the maximum insertion torque, insertion energy, stiffness, and holding power of the implant-bone construct. Given peri-implant damage during the insertion process and push-in test, elastic-plastic-damage properties were used to model bone material behavior. Results showed that despite lower implant-bone engagement in the co-cy scenario, its maximum insertion torque was 81 % higher than the cy-cy model. However, the stiffness and the holding power were 31 % and 44 % lower, respectively. Additionally, the co-co scenario demonstrated a significant increase in maximum insertion torque compared to other models while maintaining stiffness and holding power comparable to the cy-cy configuration, making it the most favorable model. This study also highlighted the importance of insertion energy as a potential indicator of implant-bone construct engagement, suggesting its consideration alongside other traditional stability factors. Further research, including in-vitro experiments, is necessary to refine pilot-hole geometry based on implant body design, ultimately enhancing primary stability and improving clinical outcomes in dental implantation.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"172 ","pages":"Article 107170"},"PeriodicalIF":3.5,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144890272","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":"Strain rate-dependent non-linear constitutive model of bone: From quasi-static to low-impact loading scenarios","authors":"Gabriela Gerber ,&nbsp;Peter Varga ,&nbsp;Jakob Schwiedrzik ,&nbsp;Philippe Zysset","doi":"10.1016/j.jmbbm.2025.107157","DOIUrl":"10.1016/j.jmbbm.2025.107157","url":null,"abstract":"<div><div>Osteoporotic fractures at the upper and lower extremity are typically caused by falls from standing height involving relatively high strain rates. Finite element models of bone used for fracture risk prediction often underestimate both stiffness and strength in such low-impact fall scenarios due to the absence of strain rate dependency in constitutive models of bone.</div><div>In this study, an anisotropic viscoelastoplastic damage model for bone applicable for quasi-static experimental tests, physiological loading and low-impact fall scenarios covering eight orders of magnitude strain rate was developed. Single element tests, as well as homogenised finite element simulations of human distal tibiae (<span><math><mi>n</mi></math></span>=25) and proximal femora (<span><math><mi>n</mi></math></span>=14), were performed and validated against literature values and experimental tests performed under quasi-static and high strain rate conditions.</div><div>The model reproduces the experimentally observed increase in stiffness and yield stress at higher strain rates both qualitatively and quantitatively. Under quasi-static conditions, high concordance correlation coefficients (<span><math><mrow><mi>C</mi><mi>C</mi><mi>C</mi></mrow></math></span>) confirmed excellent agreement between experimental and simulated apparent stiffness (<span><math><mrow><mi>C</mi><mi>C</mi><mi>C</mi></mrow></math></span>=0.98) and yield force (<span><math><mrow><mi>C</mi><mi>C</mi><mi>C</mi></mrow></math></span>=0.98). For simulations involving high strain rates, both stiffness (<span><math><mrow><mi>C</mi><mi>C</mi><mi>C</mi></mrow></math></span>=0.33) and yield force (<span><math><mrow><mi>C</mi><mi>C</mi><mi>C</mi></mrow></math></span>=0.31) were underestimated when using a rate-insensitive constitutive model. With the viscoelastoplastic model, the apparent stiffness was overestimated (<span><math><mrow><mi>C</mi><mi>C</mi><mi>C</mi></mrow></math></span>=0.53), while the yield force was in fair agreement with the experimental data (<span><math><mrow><mi>C</mi><mi>C</mi><mi>C</mi></mrow></math></span>=0.76).</div><div>To conclude, the viscoelastoplastic constitutive model is applicable for finite element analysis involving bone at strain rates ranging from quasi-static experimental tests up to low-impact fall scenarios and substantially improves the prediction of biomechanical outcome parameters relevant for fracture risk prediction.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"172 ","pages":"Article 107157"},"PeriodicalIF":3.5,"publicationDate":"2025-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144918920","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":"Comparative analysis of micro- and homogenized finite element simulations to predict the load-bearing capacity of trabecular bone screws","authors":"Antoine Vautrin ,&nbsp;Patrik Wili ,&nbsp;Simone Poncioni ,&nbsp;Philippe Zysset ,&nbsp;Peter Varga","doi":"10.1016/j.jmbbm.2025.107168","DOIUrl":"10.1016/j.jmbbm.2025.107168","url":null,"abstract":"<div><div>The main function of fracture fixation implants is to ensure sufficient fracture stability that is a prerequisite for successful osteosynthesis. The failure of bone-screw constructs can occur when the biomechanical stability of their interface is insufficient. In complement to <em>in vitro</em> mechanical testing, these failure mechanisms can be investigated with finite element (FE) simulations. Two modeling approaches have been developed: micro-FE (μFE) discretizes trabecular bone at the microstructural scale while homogenized FE (hFE) assigns bone properties based on the local average bone density. μFE is presumably more accurate while hFE has lower computational costs and thus a higher potential for clinical translation. The elastic response of these approaches has previously been investigated and compared, but not their post-yield behavior. The present study aimed to assess and compare the ability of μFE and hFE to replicate the load-bearing capacity of bone-screw constructs determined experimentally.</div><div>Twelve stainless steel screws were inserted in trabecular bone biopsies extracted from bovine proximal tibiae and scanned with μCT after pilot hole drilling. The samples were subsequently loaded monotonically at an inclination of 30° until failure. Previously developed methodologies were followed to build sample-specific μFE and hFE models based on μCT data. The elasto-plastic behavior of the bone and all features of the FE models, with the exception of meshing and material property assignment, were identical and aimed to replicate the experimental conditions.</div><div>The experimental ultimate load correlated well with the ultimate load predicted by μFE (R² = 0.89) and hFE (R² = 0.95), although both simulations overestimated it systematically. The hFE ultimate load correlated well with the one of μFE (R² = 0.84), while being closely 75 times faster to solve. These findings indicate that hFE is a suitable modeling approach for predicting the primary stability of bone screws in trabecular bone. In conjunction with its computational efficiency and its ability to use lower-resolution CT images, these results support the potential of hFE to be translated towards clinical applications.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"172 ","pages":"Article 107168"},"PeriodicalIF":3.5,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144866457","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":"Experimental and micro-finite element analysis of the toggling behaviour of a carbon fibre-reinforced PEEK pedicle screw","authors":"Matteo Frigelli ,&nbsp;Dominic Mischler ,&nbsp;Michael Indermaur ,&nbsp;Patrik Wili ,&nbsp;Amin Dolati ,&nbsp;Florian Kessler ,&nbsp;Lara Tenisch ,&nbsp;Laura Hüsken ,&nbsp;Maarten Spruit ,&nbsp;Peter Varga ,&nbsp;Philippe Zysset","doi":"10.1016/j.jmbbm.2025.107167","DOIUrl":"10.1016/j.jmbbm.2025.107167","url":null,"abstract":"<div><div>Primary stability of pedicle screws is critical for successful spinal fixation, particularly in osteoporotic patients, where screw loosening occurs in over 50 % of cases. This study combined experimental and numerical approaches to evaluate the primary stability of carbon fibre-reinforced polyether-ether-ketone (CF/PEEK) screws under toggling loading conditions.</div><div>Fifteen human cadaveric vertebrae with low bone mineral density were tested using a multidirectional loading setup with custom-designed, 3D-printed guides for accurate screw placement. Toggling tests were conducted under displacement-controlled linear loading–unloading ramps with increasing displacements (1, 2, and 4 mm). To complement the experiments, a sample-specific, explicit non-linear micro-finite element (μFE) model was developed to simulate the toggling tests. Experimental and numerical peak forces and tangential stiffnesses were compared at different displacement levels.</div><div>Experimentally, no significant correlation was found between mean bone volume fraction in the vicinity of the screw and peak forces. Similarly, volumetric bone mineral density did not show significant correlation with the experimental biomechanical variables. However, μFE-derived peak forces showed significant correlation with experimental measurements at all displacement levels (R² = 0.67, R² = 0.60, R² = 0.59 at 1 mm, 2 mm and 4 mm displacement, respectively), with the model slightly overestimating the experimental values at higher displacements (e.g., 4 mm). Across all data points, μFE and experimental peak forces strongly correlated (R² = 0.92), following a power-law relationship.</div><div>This study demonstrates that non-linear μFE models can reliably predict the primary stability of pedicle screws, offering potential for optimizing screw designs and reducing clinical failure rates associated with loosening.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"172 ","pages":"Article 107167"},"PeriodicalIF":3.5,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144878794","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":"Comparative evaluation of mechanical and thermal properties of 3D-printed restorative polymers: Effects of resin type, printer technology, and post-curing time","authors":"Nathalia S. Finck ,&nbsp;May Anny A. Fraga ,&nbsp;Américo B. Correr ,&nbsp;Tonny A. Moreira ,&nbsp;Cleocir J. Dalmaschio ,&nbsp;Vitor O. Ramagem ,&nbsp;Rafael R. Moraes","doi":"10.1016/j.jmbbm.2025.107166","DOIUrl":"10.1016/j.jmbbm.2025.107166","url":null,"abstract":"<div><div>This study evaluated how resin type, printer technology, and post-curing time influence the mechanical and thermal properties of 3D-printed polymers for dental restorations. Bar-shaped specimens were printed with digital light processing (DLP) and liquid crystal display (LCD) printers using provisional and long-term resins. The post-curing times tested were 5 and 30 min. Response variables (n = 10) included fracture toughness (K_IC, MPa√m), Knoop microhardness (kgf/mm²), and degree of C=C conversion (%DC). Thermal analyses were carried out via differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Data were analyzed via three-way ANOVA (α = 0.05). Compared with the long-term resin, the provisional resin generally presented a superior K_IC. The 30-min the post-curing time was linked to an increase in K_IC in most conditions. No differences in microhardness were detected across any group. The long-term resin generally had a greater DC, and the DC was greater for the 30-min post-curing time than for the 5-min time for the provisional resin printed by the DLP printer. Longer post-curing times resulted in more complete curing of the resins. DSC and DMA analyses revealed that the 30 min post-curing time enhanced the thermal stability of both provisional and long-term resins, indicating more homogeneous polymer network formation with reduced residual monomers. The printer type had a minor effect on the performance of the restorative polymers. In conclusion, the resin material is key for 3D-printed dental restoratives, and longer curing times improved their mechanical and thermal properties.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"172 ","pages":"Article 107166"},"PeriodicalIF":3.5,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144852513","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}