Pub Date : 2025-01-20DOI: 10.1016/j.jmbbm.2025.106902
Yueyue Wang, Hongxia Zhang, Huaizhu Li, Xiaohong Yao, Ruiqiang Hang
Mesoporous silica particles are of great interest in the field of dental composites as functional inorganic fillers due to their unique interconnected pores which can form micromechanical interlocking at the filler-resin interfaces. However, the degradation of mesoporous silica is fast in wet environments, leading to the poor mechanical stability of dental composites. Here, we synthesized Zr-doped mesoporous silica spheres (Zr-MSS) to increase the chemical stability of the particles. The particles were formulated with dental resins (Bisphenol A glycerolate dimethacrylate/triethylene glycol dimethacrylate, 50/50, wt%) to evaluate the performance of dental composites. Dental composites filled with different amount of Zr-MSS (15, 20, 25 and 30 wt%) and their bimodal fillers with nonporous silica spheres (NSS) at a total filler loading of 60 wt% (mass ratios of Zr-MSS: NSS = 10:50) were prepared. Neat resin matrix and samples filled with mesoporous silica spheres (MSS) were used as control. The results showed that the decrease percentage of flexural strength of dental resins with Zr-MSS was the lowest, which was between 3.4 and 6.8%. It was between 20.8 and 35.5% for those with MSS. Further studies revealed that the incorporation of Zr into mesoporous fillers did not affect their light curing ability of dental composites. Not only that, cell proliferation on the dental composites with Zr-MSS was promoted, suggesting improved biocompatibility of the restorations. These indicated that the prepared Zr-MSS would be promising functional fillers for dental composite resins.
{"title":"Zr-doped mesoporous silica (Zr-MSS) for improved mechanical stability and biocompatibility of dental composite resins","authors":"Yueyue Wang, Hongxia Zhang, Huaizhu Li, Xiaohong Yao, Ruiqiang Hang","doi":"10.1016/j.jmbbm.2025.106902","DOIUrl":"10.1016/j.jmbbm.2025.106902","url":null,"abstract":"<div><div>Mesoporous silica particles are of great interest in the field of dental composites as functional inorganic fillers due to their unique interconnected pores which can form micromechanical interlocking at the filler-resin interfaces. However, the degradation of mesoporous silica is fast in wet environments, leading to the poor mechanical stability of dental composites. Here, we synthesized Zr-doped mesoporous silica spheres (Zr-MSS) to increase the chemical stability of the particles. The particles were formulated with dental resins (Bisphenol A glycerolate dimethacrylate/triethylene glycol dimethacrylate, 50/50, wt%) to evaluate the performance of dental composites. Dental composites filled with different amount of Zr-MSS (15, 20, 25 and 30 wt%) and their bimodal fillers with nonporous silica spheres (NSS) at a total filler loading of 60 wt% (mass ratios of Zr-MSS: NSS = 10:50) were prepared. Neat resin matrix and samples filled with mesoporous silica spheres (MSS) were used as control. The results showed that the decrease percentage of flexural strength of dental resins with Zr-MSS was the lowest, which was between 3.4 and 6.8%. It was between 20.8 and 35.5% for those with MSS. Further studies revealed that the incorporation of Zr into mesoporous fillers did not affect their light curing ability of dental composites. Not only that, cell proliferation on the dental composites with Zr-MSS was promoted, suggesting improved biocompatibility of the restorations. These indicated that the prepared Zr-MSS would be promising functional fillers for dental composite resins.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"164 ","pages":"Article 106902"},"PeriodicalIF":3.3,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143043961","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}
Pub Date : 2025-01-18DOI: 10.1016/j.jmbbm.2025.106896
Mostafa Aldesoki , Ludger Keilig , Abdulaziz Alhotan , Al-Hassan Diab , Tarek M. Elshazly , Christoph Bourauel
Objectives
To create a validated 3D finite element model and employ it to examine the biomechanical behaviour of multirooted root analogue implants (RAIs).
Methods
A validated finite element model comprising either an RAI or a threaded implant (TI) and an idealised bone block was developed based on a previously conducted in vitro study. All the experimental boundary conditions and material properties were reproduced. Force/displacement curves were plotted to ensure complete alignment with the in vitro findings. Following the validation of the FE model, the material properties were adjusted to align with those reported in the literature. Two contact scenarios were then examined: immediate placement with touching contact and osseointegration with glued contact. The bone block was constrained in all directions, and a 300 N point load was applied along the long axis of the implant, and with an angulation of 30°. The resulting values for equivalent stress, maximum principal stress, microstrain, and displacement were evaluated.
Results
The numerical model demonstrated a high degree of agreement with the experimental results, particularly regarding displacement in the loading direction (Z). The findings of the applied FEA indicated that RAIs generally outperformed TIs. The RAI exhibited lower equivalent stress, with values of 3.3 MPa for axial loading and 13.1 MPa for oblique loading, compared to 5.4 MPa and 29.5 MPa for the TI, respectively. Furthermore, microstrain was observed to be lower in the RAI, with a value of 4,000 με compared to 13,000 με in the TI under oblique loading. Additionally, the RAI exhibited superior primary and secondary stability, with lower micromotion values compared to the TI.
Conclusions
The root analogue implant showed superior biomechanical performance, with more uniform stress distribution and greater stability compared to the conventional threaded implant, positioning it as a promising alternative.
{"title":"From model validation to biomechanical analysis: In silico study of multirooted root analogue implants using 3D finite element analysis","authors":"Mostafa Aldesoki , Ludger Keilig , Abdulaziz Alhotan , Al-Hassan Diab , Tarek M. Elshazly , Christoph Bourauel","doi":"10.1016/j.jmbbm.2025.106896","DOIUrl":"10.1016/j.jmbbm.2025.106896","url":null,"abstract":"<div><h3>Objectives</h3><div>To create a validated 3D finite element model and employ it to examine the biomechanical behaviour of multirooted root analogue implants (RAIs).</div></div><div><h3>Methods</h3><div>A validated finite element model comprising either an RAI or a threaded implant (TI) and an idealised bone block was developed based on a previously conducted <em>in vitro</em> study. All the experimental boundary conditions and material properties were reproduced. Force/displacement curves were plotted to ensure complete alignment with the <em>in vitro</em> findings. Following the validation of the FE model, the material properties were adjusted to align with those reported in the literature. Two contact scenarios were then examined: immediate placement with touching contact and osseointegration with glued contact. The bone block was constrained in all directions, and a 300 N point load was applied along the long axis of the implant, and with an angulation of 30°. The resulting values for equivalent stress, maximum principal stress, microstrain, and displacement were evaluated.</div></div><div><h3>Results</h3><div>The numerical model demonstrated a high degree of agreement with the experimental results, particularly regarding displacement in the loading direction (Z). The findings of the applied FEA indicated that RAIs generally outperformed TIs. The RAI exhibited lower equivalent stress, with values of 3.3 MPa for axial loading and 13.1 MPa for oblique loading, compared to 5.4 MPa and 29.5 MPa for the TI, respectively. Furthermore, microstrain was observed to be lower in the RAI, with a value of 4,000 με compared to 13,000 με in the TI under oblique loading. Additionally, the RAI exhibited superior primary and secondary stability, with lower micromotion values compared to the TI.</div></div><div><h3>Conclusions</h3><div>The root analogue implant showed superior biomechanical performance, with more uniform stress distribution and greater stability compared to the conventional threaded implant, positioning it as a promising alternative.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"164 ","pages":"Article 106896"},"PeriodicalIF":3.3,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143025413","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}
Pub Date : 2025-01-17DOI: 10.1016/j.jmbbm.2025.106895
Rupesh Shrestha , Steven Fredeen , Niyati Reddy , Larissa M.M. Alves , Yu Zhang , Jeongho Kim
This study aims to investigate the effects of material compatibility, variable cooling rates, and crown geometry on thermal stress development in porcelain-veneered lithium disilicate (PVLD) and porcelain-veneered zirconia (PVZ) dental crown systems, and subsequently anticipate parameters for their optimum performance. An anatomically correct 3D crown model was developed from STL files generated using 3D scans of the experimental crown sample. Next, the viscoelastic finite element model (VFEM) based on the 3D crown model was developed and validated for anatomically correct bilayer PVLD and PVZ crown systems. The Vicker's indentation method was used on experimental PVLD and PVZ crown samples to validate the simulated thermal stress results from the VFEM. The validated VFEM was then used to predict thermal transient and residual stresses within the dental crown systems. The comparison between thermal residual stress profiles in PVLD and PVZ crowns showed that the interfacial stress concentrations were comparatively lower for PVLD crowns. However, the PVLD crowns also experienced prominent tensile stresses in the veneer layer. Furthermore, the rapid cooling protocol was seen to cause intensification of compressive stresses on the exterior veneer surface for both PVLD and PVZ crowns which can enhance resistance against crack growth. But faster cooling rates also caused rapid stress evolution which may cause material defects within the crown. This study highlights the importance of material compatibility by comparing stress distribution within the PVLD and PVZ crowns. Moreover, the post-firing cooling protocols showed significant effects on overall thermal stress distribution and consequently, the long-term dental crown performance.
{"title":"Thermal stresses in porcelain veneered lithium disilicate and zirconia dental crowns: Comparative analysis using a validated viscoelastic finite element model","authors":"Rupesh Shrestha , Steven Fredeen , Niyati Reddy , Larissa M.M. Alves , Yu Zhang , Jeongho Kim","doi":"10.1016/j.jmbbm.2025.106895","DOIUrl":"10.1016/j.jmbbm.2025.106895","url":null,"abstract":"<div><div>This study aims to investigate the effects of material compatibility, variable cooling rates, and crown geometry on thermal stress development in porcelain-veneered lithium disilicate (PVLD) and porcelain-veneered zirconia (PVZ) dental crown systems, and subsequently anticipate parameters for their optimum performance. An anatomically correct 3D crown model was developed from STL files generated using 3D scans of the experimental crown sample. Next, the viscoelastic finite element model (VFEM) based on the 3D crown model was developed and validated for anatomically correct bilayer PVLD and PVZ crown systems. The Vicker's indentation method was used on experimental PVLD and PVZ crown samples to validate the simulated thermal stress results from the VFEM. The validated VFEM was then used to predict thermal transient and residual stresses within the dental crown systems. The comparison between thermal residual stress profiles in PVLD and PVZ crowns showed that the interfacial stress concentrations were comparatively lower for PVLD crowns. However, the PVLD crowns also experienced prominent tensile stresses in the veneer layer. Furthermore, the rapid cooling protocol was seen to cause intensification of compressive stresses on the exterior veneer surface for both PVLD and PVZ crowns which can enhance resistance against crack growth. But faster cooling rates also caused rapid stress evolution which may cause material defects within the crown. This study highlights the importance of material compatibility by comparing stress distribution within the PVLD and PVZ crowns. Moreover, the post-firing cooling protocols showed significant effects on overall thermal stress distribution and consequently, the long-term dental crown performance.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106895"},"PeriodicalIF":3.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143018996","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}
Surgeons frequently use allograft bone due to its osteoconductive, osteoinductive, and osteogenic properties. Preservation processes are employed to clean the allograft, improve its conservation, and ensure its sterilization. Many current processes use the properties of supercritical CO2 to remove bone marrow.
This study aims to measure the effect of a supercritical CO2 process on the microarchitecture and the mechanical properties of trabecular bone. Eleven femoral heads were harvested from patients undergoing total hip arthroplasty. Sixty-seven cubic samples with 10 mm sides from these femoral heads were distributed in 3 groups: frozen at −20 °C, gamma irradiated and frozen at −20 °C, and treated with a supercritical CO2 process including gamma irradiation. All the samples were tested with a microcomputer tomography scanner and a compression testing machine.
The supercritical CO2 process has no significant effect on the microarchitectural parameters (BV/TV, Tb.th, Tb.sp, Tb.N, DA, and Conn.D). It has also no significant effect on the elastic modulus, yield stress, and ultimate stress. However, it has a significant effect on the densification stress.
An advanced study on the correlation between the microarchitecture and the mechanical properties shows that for a given volume fraction of 0.26 (the mean value for our study), the elastic modulus and ultimate stress of the bone treated with supercritical CO2 were lower than those from the frozen group by 19% and 24% respectively.
{"title":"Effects of a supercritical CO2 process on the mechanical properties and microarchitecture of trabecular bone using compression testing and microcomputed tomography","authors":"Théo Krieger , Virginie Taillebot , Aurélien Maurel-Pantel , Marylène Lallemand , Grégoire Edorh , Matthieu Ollivier , Martine Pithioux","doi":"10.1016/j.jmbbm.2025.106893","DOIUrl":"10.1016/j.jmbbm.2025.106893","url":null,"abstract":"<div><div>Surgeons frequently use allograft bone due to its osteoconductive, osteoinductive, and osteogenic properties. Preservation processes are employed to clean the allograft, improve its conservation, and ensure its sterilization. Many current processes use the properties of supercritical CO<sub>2</sub> to remove bone marrow.</div><div>This study aims to measure the effect of a supercritical CO<sub>2</sub> process on the microarchitecture and the mechanical properties of trabecular bone. Eleven femoral heads were harvested from patients undergoing total hip arthroplasty. Sixty-seven cubic samples with 10 mm sides from these femoral heads were distributed in 3 groups: frozen at −20 °C, gamma irradiated and frozen at −20 °C, and treated with a supercritical CO<sub>2</sub> process including gamma irradiation. All the samples were tested with a microcomputer tomography scanner and a compression testing machine.</div><div>The supercritical CO<sub>2</sub> process has no significant effect on the microarchitectural parameters (BV/TV, Tb.th, Tb.sp, Tb.N, DA, and Conn.D). It has also no significant effect on the elastic modulus, yield stress, and ultimate stress. However, it has a significant effect on the densification stress.</div><div>An advanced study on the correlation between the microarchitecture and the mechanical properties shows that for a given volume fraction of 0.26 (the mean value for our study), the elastic modulus and ultimate stress of the bone treated with supercritical CO<sub>2</sub> were lower than those from the frozen group by 19% and 24% respectively.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106893"},"PeriodicalIF":3.3,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143018980","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}
Pub Date : 2025-01-16DOI: 10.1016/j.jmbbm.2025.106894
Francesco Valente , Andrea Marrocco , Cristina Falcinelli
This study numerically investigates the impact of different loading modes on the biomechanical response of an osseointegrated dental implant. While finite element modeling is commonly employed to investigate the mechanical behavior of dental implants, several models lack physiological accuracy in their loading conditions, omitting occlusal contact points that influence stress distribution in periimplant bone. Using 3D finite element modeling and analysis, stress distributions at the bone-implant interface are evaluated under both physiological loading, incorporating natural occlusal contact points, and non-physiological loading conditions, with a focus on load transmission mechanisms and the potential risk of bone overloading. Two crown materials, zirconia and lithium disilicate, are analyzed under load values of 150 N and 300 N. The physiological loading mode leads to significantly higher Von Mises stress concentrations in both cortical and trabecular periimplant regions compared to non-physiological loading. This results in different load transfer mechanisms underlining the importance of accurately modeling load application points. Crown material seems to have a minimal impact, whereas increasing the load intensity markedly increases stress levels. Notably, physiological loading reveals stress distribution at the implant apex, unlike non-physiological models. Additionally, peak values of tensile and compressive stresses at the periimplant interfaces increase under physiological conditions, with cortical bone stress rising by up to 210%. This highlights that relying on non-physiological loading modes may inadequately capture the risk of implant failure. Overall, these results emphasize the need to consider physiological loading scenarios, particularly for assessing failure risk to better guide implant design modifications, enhancing clinical outcomes and implant longevity.
{"title":"Impact of physiological and non-physiological loading scenarios and crown material on periimplant bone stress distribution: A 3D finite element study","authors":"Francesco Valente , Andrea Marrocco , Cristina Falcinelli","doi":"10.1016/j.jmbbm.2025.106894","DOIUrl":"10.1016/j.jmbbm.2025.106894","url":null,"abstract":"<div><div>This study numerically investigates the impact of different loading modes on the biomechanical response of an osseointegrated dental implant. While finite element modeling is commonly employed to investigate the mechanical behavior of dental implants, several models lack physiological accuracy in their loading conditions, omitting occlusal contact points that influence stress distribution in periimplant bone. Using 3D finite element modeling and analysis, stress distributions at the bone-implant interface are evaluated under both physiological loading, incorporating natural occlusal contact points, and non-physiological loading conditions, with a focus on load transmission mechanisms and the potential risk of bone overloading. Two crown materials, zirconia and lithium disilicate, are analyzed under load values of 150 N and 300 N. The physiological loading mode leads to significantly higher Von Mises stress concentrations in both cortical and trabecular periimplant regions compared to non-physiological loading. This results in different load transfer mechanisms underlining the importance of accurately modeling load application points. Crown material seems to have a minimal impact, whereas increasing the load intensity markedly increases stress levels. Notably, physiological loading reveals stress distribution at the implant apex, unlike non-physiological models. Additionally, peak values of tensile and compressive stresses at the periimplant interfaces increase under physiological conditions, with cortical bone stress rising by up to 210%. This highlights that relying on non-physiological loading modes may inadequately capture the risk of implant failure. Overall, these results emphasize the need to consider physiological loading scenarios, particularly for assessing failure risk to better guide implant design modifications, enhancing clinical outcomes and implant longevity.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106894"},"PeriodicalIF":3.3,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143018982","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}
Pub Date : 2025-01-13DOI: 10.1016/j.jmbbm.2025.106897
Hongyu Xing , Hao Luo , Lei Lai , Hongyu Zhao , Runqi Xue , Qingguo Lai
A method is proposed for 3D printing and enhancing the surface bioactivity of zirconia ceramic anchor screws, specifically tailored for temporomandibular joint disc reduction surgery. Initially, the challenge posed by the brittleness and processing difficulties of fine ceramic anchor screws was addressed through the application of SLA-3D printing technology. This allowed for an exploration of the forming accuracy and biomechanical properties of the printed anchor screws. According to research findings, the dimensional deviation in the thread processing of 3D printed zirconia screws is approximately 100 μm. When the threaded segment measures 7.0 mm in length, the 3D printed zirconia anchor screw, with a diameter of 2.7 mm, demonstrates comparable maximum axial tensile forces 102.91 N to a titanium screw of 2.0 mm diameter. The maximum vertical tensile force of the zirconia anchor screws exceeds the breaking force of the anchor suture by 21.03 N, fulfilling the requirements for clinical application. Additionally, the application of a ZrO2-PDA-La3+ composite biological coating enhances the surface bioactivity of the 3D printed zirconia anchor screws. PDA ensures reliable adhesion of the biological coating during the implantation process, while La3+ significantly boosts the osteogenic capacity of the zirconia ceramic surface, thereby contributing to the long-term stability of the implant. Ultimately, zirconia anchor screws satisfying basic clinical requirements in terms of mechanical properties and biological activity were successfully developed, offering a novel treatment option for ADDwoR patients, particularly those with metal allergies.
{"title":"SLA-3D printing and bioactivity enhancement of zirconia anchor screws for temporomandibular joint disc reduction surgery","authors":"Hongyu Xing , Hao Luo , Lei Lai , Hongyu Zhao , Runqi Xue , Qingguo Lai","doi":"10.1016/j.jmbbm.2025.106897","DOIUrl":"10.1016/j.jmbbm.2025.106897","url":null,"abstract":"<div><div>A method is proposed for 3D printing and enhancing the surface bioactivity of zirconia ceramic anchor screws, specifically tailored for temporomandibular joint disc reduction surgery. Initially, the challenge posed by the brittleness and processing difficulties of fine ceramic anchor screws was addressed through the application of SLA-3D printing technology. This allowed for an exploration of the forming accuracy and biomechanical properties of the printed anchor screws. According to research findings, the dimensional deviation in the thread processing of 3D printed zirconia screws is approximately 100 μm. When the threaded segment measures 7.0 mm in length, the 3D printed zirconia anchor screw, with a diameter of 2.7 mm, demonstrates comparable maximum axial tensile forces 102.91 N to a titanium screw of 2.0 mm diameter. The maximum vertical tensile force of the zirconia anchor screws exceeds the breaking force of the anchor suture by 21.03 N, fulfilling the requirements for clinical application. Additionally, the application of a ZrO<sub>2</sub>-PDA-La<sup>3+</sup> composite biological coating enhances the surface bioactivity of the 3D printed zirconia anchor screws. PDA ensures reliable adhesion of the biological coating during the implantation process, while La<sup>3+</sup> significantly boosts the osteogenic capacity of the zirconia ceramic surface, thereby contributing to the long-term stability of the implant. Ultimately, zirconia anchor screws satisfying basic clinical requirements in terms of mechanical properties and biological activity were successfully developed, offering a novel treatment option for ADDwoR patients, particularly those with metal allergies.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106897"},"PeriodicalIF":3.3,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143018993","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}
Pub Date : 2025-01-13DOI: 10.1016/j.jmbbm.2025.106898
Nicolas Bailly , Eric Wagnac , Yvan Petit
Understanding spinal cord injury requires a comprehensive knowledge of its mechanical properties, which remains debated due to the variability reported. This study aims to characterize the regional mechanical properties of the spinal cord in transverse sections using micro-indentation. Quasi-static indentations were performed on the entire surface of transverse slices obtained from 10 freshly harvested porcine thoracic spinal cords using a 0.5 mm diameter flat punch. No significant difference in average longitudinal elastic modulus was found between white matter (n = 183, E = 0.51 ± 0.21 kPa) and gray matter (n = 51, E = 0.53 ± 0.25 kPa). In the gray matter, the elastic modulus in the dorsal horn (0.48 ± 0.18 kPa) was significantly smaller than in the ventral horn (0.57 ± 0.24 kPa) (GLMM, p < 0.05). The elastic modulus in the dorsal horn was also significantly smaller than in the lateral (0.52 ± 0.22 kPa) and ventral funiculi (0.53 ± 0.18 kPa) of the white matter (GLMM, p < 0.05). However, there was no significant difference in the elastic modulus among the ventral, lateral and dorsal funiculi of the white matter (GLMM, p > 0.05). The average elastic modulus strongly varies between samples, ranging from 0.23 (±0.06) kPa to 0.79 (±0.18) kPa and the testing time postmortem was significantly associated with a decrease in elastic modulus (t = −5.2, p < 0.001). The spinal cord's white matter demonstrated significantly lower elastic modulus compared to published data on brain tissue tested under similar conditions. These findings enhance our comprehension of the mechanical properties of spinal cord white and gray matter, challenging the homogeneity assumption of current models.
了解脊髓损伤需要对其力学特性有全面的了解，由于报道的可变性，这一点仍然存在争议。本研究旨在利用微压痕表征脊髓横切面的区域力学特性。采用直径0.5 mm的平冲床对10条新鲜收获的猪胸脊髓横切面进行准静态压痕。白质（n = 183, E = 0.51±0.21 kPa）与灰质（n = 51, E = 0.53±0.25 kPa）的平均纵向弹性模量差异无统计学意义。在灰质中，背角的弹性模量（0.48±0.18 kPa）明显小于腹角的弹性模量（0.57±0.24 kPa） （GLMM, p 0.05）。样品间的平均弹性模量差异很大，范围为0.23（±0.06）kPa至0.79（±0.18）kPa，并且死后测试时间与弹性模量的降低显著相关(t = -5.2, p
{"title":"Regional mechanical properties of spinal cord gray and white matter in transverse section","authors":"Nicolas Bailly , Eric Wagnac , Yvan Petit","doi":"10.1016/j.jmbbm.2025.106898","DOIUrl":"10.1016/j.jmbbm.2025.106898","url":null,"abstract":"<div><div>Understanding spinal cord injury requires a comprehensive knowledge of its mechanical properties, which remains debated due to the variability reported. This study aims to characterize the regional mechanical properties of the spinal cord in transverse sections using micro-indentation. Quasi-static indentations were performed on the entire surface of transverse slices obtained from 10 freshly harvested porcine thoracic spinal cords using a 0.5 mm diameter flat punch. No significant difference in average longitudinal elastic modulus was found between white matter (n = 183, E = 0.51 ± 0.21 kPa) and gray matter (n = 51, E = 0.53 ± 0.25 kPa). In the gray matter, the elastic modulus in the dorsal horn (0.48 ± 0.18 kPa) was significantly smaller than in the ventral horn (0.57 ± 0.24 kPa) (GLMM, p < 0.05). The elastic modulus in the dorsal horn was also significantly smaller than in the lateral (0.52 ± 0.22 kPa) and ventral funiculi (0.53 ± 0.18 kPa) of the white matter (GLMM, p < 0.05). However, there was no significant difference in the elastic modulus among the ventral, lateral and dorsal funiculi of the white matter (GLMM, p > 0.05). The average elastic modulus strongly varies between samples, ranging from 0.23 (±0.06) kPa to 0.79 (±0.18) kPa and the testing time postmortem was significantly associated with a decrease in elastic modulus (t = −5.2, p < 0.001). The spinal cord's white matter demonstrated significantly lower elastic modulus compared to published data on brain tissue tested under similar conditions. These findings enhance our comprehension of the mechanical properties of spinal cord white and gray matter, challenging the homogeneity assumption of current models.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106898"},"PeriodicalIF":3.3,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143018990","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}
Pub Date : 2025-01-10DOI: 10.1016/j.jmbbm.2025.106888
Shengzhi Luan , Elise F. Morgan
Despite the broad agreement that bone stiffness is heavily dependent on the underlying bone density, there is no consensus on a unified relationship that applies to both cancellous and cortical compartments. Bone from the two compartments is generally assessed separately, and few mechanical test data are available for samples from the transitional regions between them. In this study, we present a data-driven framework integrating experimental testing and numerical modeling of the human lumbar vertebra through an energy balance criterion, to develop a unified density–modulus relationship across the entire vertebral body, without the necessity of differentiation between trabecular and cortical regions. A dataset of 25 spinal segments harvested from fresh-frozen human spines consisting of L1 vertebrae with adjacent intervertebral disks and neighboring T12 and L2 endplates was examined through a systematic process. Each specimen was subjected to axial compression using a custom-designed radiolucent device, and the deformation at multiple points during the ramp was quantified using digital volume correlation applied to the time-lapse series of microcomputed tomography images acquired during loading. A finite element model of each specimen was constructed from quantitative computed tomography images, with the experimental displacement fields imposed to replicate the observed deformation. The optimal density–modulus relationship, both in exponential and polynomial forms, was then determined by using data-driven techniques to match the numerical strain energy with the experimental external work. The resulting relationships effectively recovered bone tissue modulus at the microscale. Subsequently, the unified relationships were applied to investigate the vertebral structure–property correlations at the macroscale: as expected, compressive stiffness exhibited a moderate correlation with bone mineral density, whereas bending stiffness was revealed to correlate strongly with bone mineral content. These findings support the accuracy of the developed density–modulus relationships for the vertebral body and indicate the potential of the proposed framework to extend to other properties of interest such as vertebral strength and toughness.
{"title":"A data-driven framework for developing a unified density–modulus relationship for the human lumbar vertebral body","authors":"Shengzhi Luan , Elise F. Morgan","doi":"10.1016/j.jmbbm.2025.106888","DOIUrl":"10.1016/j.jmbbm.2025.106888","url":null,"abstract":"<div><div>Despite the broad agreement that bone stiffness is heavily dependent on the underlying bone density, there is no consensus on a unified relationship that applies to both cancellous and cortical compartments. Bone from the two compartments is generally assessed separately, and few mechanical test data are available for samples from the transitional regions between them. In this study, we present a data-driven framework integrating experimental testing and numerical modeling of the human lumbar vertebra through an energy balance criterion, to develop a unified density–modulus relationship across the entire vertebral body, without the necessity of differentiation between trabecular and cortical regions. A dataset of 25 spinal segments harvested from fresh-frozen human spines consisting of L1 vertebrae with adjacent intervertebral disks and neighboring T12 and L2 endplates was examined through a systematic process. Each specimen was subjected to axial compression using a custom-designed radiolucent device, and the deformation at multiple points during the ramp was quantified using digital volume correlation applied to the time-lapse series of microcomputed tomography images acquired during loading. A finite element model of each specimen was constructed from quantitative computed tomography images, with the experimental displacement fields imposed to replicate the observed deformation. The optimal density–modulus relationship, both in exponential and polynomial forms, was then determined by using data-driven techniques to match the numerical strain energy with the experimental external work. The resulting relationships effectively recovered bone tissue modulus at the microscale. Subsequently, the unified relationships were applied to investigate the vertebral structure–property correlations at the macroscale: as expected, compressive stiffness exhibited a moderate correlation with bone mineral density, whereas bending stiffness was revealed to correlate strongly with bone mineral content. These findings support the accuracy of the developed density–modulus relationships for the vertebral body and indicate the potential of the proposed framework to extend to other properties of interest such as vertebral strength and toughness.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106888"},"PeriodicalIF":3.3,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143018977","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}
Pub Date : 2025-01-09DOI: 10.1016/j.jmbbm.2025.106891
Maria Gabriela Packaeser , Renan Vaz Machry , Elisa Donaria Aboucauch Grassi , Guilherme de Siqueira Ferreira Anzaloni Saavedra , Cornelis Johannes Kleverlaan , Luiz Felipe Valandro , João Paulo Mendes Tribst , Gabriel Kalil Rocha Pereira
This study evaluated the effect of substrate core materials and occlusal contact patterns on the fatigue mechanical behavior and stress distribution of single-unit ceramic crowns. One hundred and twenty monolithic crowns were fabricated from zirconia (YZ – IPS e.max ZirCAD, Ivoclar), lithium disilicate (LD – IPS e.max CAD, Ivoclar) and polymer infiltrated ceramic network (PICN – Enamic, Vita Zahnfabrik). The crowns were allocated considering two factors: 'substrate' (epoxy resin or cast Ni-Cr metal core) and 'occlusal contact pattern' (contact at the cusp ridges or cusp tips). The substrate models were design, milled and scanned to plan the restorations in a digital workflow. The crowns were milled, bonded to the substrates, and subjected to an accelerated fatigue test (100 N; 10,000 cycles/step; 20 Hz step-size: 100 N up to 1600 N, and after, 200 N until failure or survival at 2,800N; immersed in water). Statistical analyses were performed using two-way ANOVA, Tukey's post-hoc test, and Kaplan-Meier survival analysis (α = 0.05) considering fatigue failure load and cycles for fatigue failure (FFL/CFF). Fractographic and finite element analysis (FEA) were carried out. The results indicate that the 'substrate' factor did not influence the mechanical behavior of YZ and LD monolithic crowns (p > 0.05). However, PICN crowns bonded to epoxy resin exhibited statistically superior results for FFL and CFF (p < 0.05) compared to Ni-Cr cores. Regarding the 'occlusal contact pattern' factor, YZ and LD exhibited higher mean FFL and CFF when associated with cusp tip contact compared to cusp ridge contact (p < 0.05), except for YZ bonded to the epoxy resin substrate (p > 0.05). No differences were detected for the 'occlusal contact' factor in PICN crowns (p > 0.05). The predominant failure was Hertzian cone cracks, regardless of the restorative material. Stress measurements showed higher stress peaks at the cusp ridges. The core material did not alter the fatigue mechanical behavior of YZ or LD crowns. However, the incidence of cusp ridge contacts in YZ or LD crown increases the risk of failure. Conversely, when using PICN crowns, a core with a more similar elastic modulus enhances mechanical behavior compared to a stiffer core, and no influence on the occlusal pattern was observed.
{"title":"Influence of core material and occlusal contact pattern on fatigue behavior of different monolithic ceramic crowns","authors":"Maria Gabriela Packaeser , Renan Vaz Machry , Elisa Donaria Aboucauch Grassi , Guilherme de Siqueira Ferreira Anzaloni Saavedra , Cornelis Johannes Kleverlaan , Luiz Felipe Valandro , João Paulo Mendes Tribst , Gabriel Kalil Rocha Pereira","doi":"10.1016/j.jmbbm.2025.106891","DOIUrl":"10.1016/j.jmbbm.2025.106891","url":null,"abstract":"<div><div>This study evaluated the effect of substrate core materials and occlusal contact patterns on the fatigue mechanical behavior and stress distribution of single-unit ceramic crowns. One hundred and twenty monolithic crowns were fabricated from zirconia (YZ – IPS e.max ZirCAD, Ivoclar), lithium disilicate (LD – IPS e.max CAD, Ivoclar) and polymer infiltrated ceramic network (PICN – Enamic, Vita Zahnfabrik). The crowns were allocated considering two factors: 'substrate' (epoxy resin or cast Ni-Cr metal core) and 'occlusal contact pattern' (contact at the cusp ridges or cusp tips). The substrate models were design, milled and scanned to plan the restorations in a digital workflow. The crowns were milled, bonded to the substrates, and subjected to an accelerated fatigue test (100 N; 10,000 cycles/step; 20 Hz step-size: 100 N up to 1600 N, and after, 200 N until failure or survival at 2,800N; immersed in water). Statistical analyses were performed using two-way ANOVA, Tukey's post-hoc test, and Kaplan-Meier survival analysis (α = 0.05) considering fatigue failure load and cycles for fatigue failure (FFL/CFF). Fractographic and finite element analysis (FEA) were carried out. The results indicate that the 'substrate' factor did not influence the mechanical behavior of YZ and LD monolithic crowns (p > 0.05). However, PICN crowns bonded to epoxy resin exhibited statistically superior results for FFL and CFF (p < 0.05) compared to Ni-Cr cores. Regarding the 'occlusal contact pattern' factor, YZ and LD exhibited higher mean FFL and CFF when associated with cusp tip contact compared to cusp ridge contact (p < 0.05), except for YZ bonded to the epoxy resin substrate (p > 0.05). No differences were detected for the 'occlusal contact' factor in PICN crowns (p > 0.05). The predominant failure was Hertzian cone cracks, regardless of the restorative material. Stress measurements showed higher stress peaks at the cusp ridges. The core material did not alter the fatigue mechanical behavior of YZ or LD crowns. However, the incidence of cusp ridge contacts in YZ or LD crown increases the risk of failure. Conversely, when using PICN crowns, a core with a more similar elastic modulus enhances mechanical behavior compared to a stiffer core, and no influence on the occlusal pattern was observed.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106891"},"PeriodicalIF":3.3,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143018986","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}
Pub Date : 2025-01-08DOI: 10.1016/j.jmbbm.2025.106889
Sina (Mohammadmahdi) Keshavarz , Mohammad Khoobani , Rene Gilliland-Rocque , Mohammadmahdi Tahmasebi , Andrew Dueck , M. Ali Tavallaei
The integration of self-expandable nitinol frames with cable-driven parallel mechanisms offers a promising advancement in minimally invasive cardiovascular interventions. This study presents the design, fabrication, and verification of a miniaturized self-expandable nitinol frame to enhance catheter tip steerability and navigation within complex vascular anatomies. The frame is reduced in size for delivery through 7–8 Fr sheaths while accommodating diverse vascular diameters, allowing up to a maximum expansion of 15 mm. Iterative design and parametric studies ensured robust vessel anchoring with minimal deflection to maintain catheter tip control accuracy. Extensive testing included finite element simulations and benchtop experiments. Crimping simulations confirmed that the maximum Von Mises stresses (575 MPa) did not exceed nitinol's yield stress, and deformation profiles matched experimental results. Deflection tests showed minimal deflections below 0.45 mm at the frame's anchoring points, ensuring precise tip control. Radial force studies validated balanced forces below 6 N (for target vessel diameters), preventing migration without damaging vessel walls. Friction studies demonstrated superior performance, reducing friction and enhancing force transmission efficiency. These findings indicated that the proposed miniaturized frame design is a feasible option for cardiovascular interventions.
{"title":"A self-expandable nitinol frame for cable-driven parallel mechanisms in minimally invasive cardiovascular interventions","authors":"Sina (Mohammadmahdi) Keshavarz , Mohammad Khoobani , Rene Gilliland-Rocque , Mohammadmahdi Tahmasebi , Andrew Dueck , M. Ali Tavallaei","doi":"10.1016/j.jmbbm.2025.106889","DOIUrl":"10.1016/j.jmbbm.2025.106889","url":null,"abstract":"<div><div>The integration of self-expandable nitinol frames with cable-driven parallel mechanisms offers a promising advancement in minimally invasive cardiovascular interventions. This study presents the design, fabrication, and verification of a miniaturized self-expandable nitinol frame to enhance catheter tip steerability and navigation within complex vascular anatomies. The frame is reduced in size for delivery through 7–8 Fr sheaths while accommodating diverse vascular diameters, allowing up to a maximum expansion of 15 mm. Iterative design and parametric studies ensured robust vessel anchoring with minimal deflection to maintain catheter tip control accuracy. Extensive testing included finite element simulations and benchtop experiments. Crimping simulations confirmed that the maximum Von Mises stresses (575 MPa) did not exceed nitinol's yield stress, and deformation profiles matched experimental results. Deflection tests showed minimal deflections below 0.45 mm at the frame's anchoring points, ensuring precise tip control. Radial force studies validated balanced forces below 6 N (for target vessel diameters), preventing migration without damaging vessel walls. Friction studies demonstrated superior performance, reducing friction and enhancing force transmission efficiency. These findings indicated that the proposed miniaturized frame design is a feasible option for cardiovascular interventions.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"163 ","pages":"Article 106889"},"PeriodicalIF":3.3,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142974142","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}
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