Othniel J. Aryeetey, Martin Frank, A. Lorenz, D. Pahr
The ability of soft collagenous tissue (SCT) to withstand propagation of a defect in the presence of a macroscopic crack is termed the 'fracture toughness parameter'. In soft tissues not undergoing significant plastic deformation, it is purported that a considerable amount of additional energy is dissipated during failure processes, due to viscoelasticity. Hence the total work, measured experimentally during failure, is the sum of fracture and viscoelastic energies. Previous authors have aimed to apply constitutive modeling to describe viscoelastic hysteresis for fracture toughness determination with a tendency of models to either over or underestimate the viscous energy. In this study, the fracture toughness of porcine muscle tissue is determined using two strategies. Firstly, it was determined experimentally by calculation of the difference in dissipated energy of notched and unnotched tissue specimens undergoing cyclic 'triangular wave' excitation with increasing strain levels in uniaxial tension. The second strategy involved the extension and use of the adaptive quasi-linear viscoelastic model (AQLV) to model cyclic loading (model parameters were obtained from a previous study) and sequentially the dissipated energy was calculated. The mean value of the dissipated energy based on the AQLV approach was then subtracted from the total dissipated energy of notched porcine muscle tissue samples to determine the fracture toughness. The mean experimental viscous dissipated energy ratio was 0.24 ± 0.04 in the experimental approach, compared to 0.28 ± 0.03 for the AQLV model. Fracture toughness determined experimentally yielded 0.84 ± 0.80 kJ/m2, and 0.71 ± 0.76 kJ/m2 for the AQLV model, without a significant difference (p = 0.87). Hence, the AQLV model enables a reasonable estimation of viscous dissipated energy in porcine muscle tissue with the advantage to perform tests only on notched specimens, instead of testing additional unnotched samples. Moreover, the AQLV model will help to better understand the constitutive viscoelastic behaviour of SCTs and might also serve as a basis for future fracture toughness determination with constitutive model simulations.
{"title":"Fracture toughness determination of porcine muscle tissue based on AQLV model derived viscous dissipated energy.","authors":"Othniel J. Aryeetey, Martin Frank, A. Lorenz, D. Pahr","doi":"10.2139/ssrn.4061495","DOIUrl":"https://doi.org/10.2139/ssrn.4061495","url":null,"abstract":"The ability of soft collagenous tissue (SCT) to withstand propagation of a defect in the presence of a macroscopic crack is termed the 'fracture toughness parameter'. In soft tissues not undergoing significant plastic deformation, it is purported that a considerable amount of additional energy is dissipated during failure processes, due to viscoelasticity. Hence the total work, measured experimentally during failure, is the sum of fracture and viscoelastic energies. Previous authors have aimed to apply constitutive modeling to describe viscoelastic hysteresis for fracture toughness determination with a tendency of models to either over or underestimate the viscous energy. In this study, the fracture toughness of porcine muscle tissue is determined using two strategies. Firstly, it was determined experimentally by calculation of the difference in dissipated energy of notched and unnotched tissue specimens undergoing cyclic 'triangular wave' excitation with increasing strain levels in uniaxial tension. The second strategy involved the extension and use of the adaptive quasi-linear viscoelastic model (AQLV) to model cyclic loading (model parameters were obtained from a previous study) and sequentially the dissipated energy was calculated. The mean value of the dissipated energy based on the AQLV approach was then subtracted from the total dissipated energy of notched porcine muscle tissue samples to determine the fracture toughness. The mean experimental viscous dissipated energy ratio was 0.24 ± 0.04 in the experimental approach, compared to 0.28 ± 0.03 for the AQLV model. Fracture toughness determined experimentally yielded 0.84 ± 0.80 kJ/m2, and 0.71 ± 0.76 kJ/m2 for the AQLV model, without a significant difference (p = 0.87). Hence, the AQLV model enables a reasonable estimation of viscous dissipated energy in porcine muscle tissue with the advantage to perform tests only on notched specimens, instead of testing additional unnotched samples. Moreover, the AQLV model will help to better understand the constitutive viscoelastic behaviour of SCTs and might also serve as a basis for future fracture toughness determination with constitutive model simulations.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"135 1","pages":"105429"},"PeriodicalIF":0.0,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48844356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
David E. Myers, A. Abdel-Wahab, F. Hafeez, K. Essa, Nikolina Kovacev
Fused deposition modelling (FDM) is an additive manufacturing technology used to create functional and complex geometries directly from computer-generated models. This technique can be utilised to generate cellular structures with controllable pore size, pore shape, and porosity. Cellular structures are fundamental in orthopaedics scaffolds because of its low elastic modulus, high compressive strength, and adequate cell accommodation spaces. This paper aims at investigating and optimising the FDM additive manufacturing process parameters of polylactic Acid (PLA) for two lattice structures namely Schoen Gyroid and Schwarz Primitive. The effect of additive manufacturing critical process parameters including layer height, flow rate, and print speed on the geometrical accuracy and compressive strength of the specimens were analysed. In addition, other parameters that have minimal effect on the geometrical accuracy of the printed parts were discussed. A Full Factorial Analysis (FFA) using Minitab software was undertaken to identify the perfect combination of printing parameters to provide the most geometrically accurate structure. In this study, samples of the Schoen Gyroid and the Schwarz Primitive lattices and a solid control cylinder were 3D printed using the ideal printing combination to assess the manufacturability, the geometrical accuracy, and the mechanical behaviour of both designs. It was found that the optimised FDM process parameters for the studied cellular structures were a layer height of 0.16 mm, a printing speed of 50 mm/s and a flow rate of 90%. As a result of using these parameters, the solid, Schoen Gyroid and Schwarz Primitive specimens demonstrated elastic moduli values of 951 MPa, 264 MPa, and 221 MPa, respectively. In addition, the Schoen Gyroid and the Schwarz Primitive have reached their stress limits at around 8.68 MPa and 7.06 MPa, respectively. It was noticed that the Schoen Gyroid structure exhibited ∼ 18% higher compressive strength and ∼ 16% higher elastic modulus compared to the Schwarz Primitive structure for the same volume fraction of porosity, overall dimensions, and the manufacturing process parameters. Although both structures revealed mechanical properties that fall within the range of the human trabecular bone, but Schoen Gyroid exhibited improved structural integrity performance that is evident by its post-yield behaviour.
{"title":"Optimisation of the additive manufacturing parameters of polylactic acid (PLA) cellular structures for biomedical applications.","authors":"David E. Myers, A. Abdel-Wahab, F. Hafeez, K. Essa, Nikolina Kovacev","doi":"10.2139/ssrn.4115315","DOIUrl":"https://doi.org/10.2139/ssrn.4115315","url":null,"abstract":"Fused deposition modelling (FDM) is an additive manufacturing technology used to create functional and complex geometries directly from computer-generated models. This technique can be utilised to generate cellular structures with controllable pore size, pore shape, and porosity. Cellular structures are fundamental in orthopaedics scaffolds because of its low elastic modulus, high compressive strength, and adequate cell accommodation spaces. This paper aims at investigating and optimising the FDM additive manufacturing process parameters of polylactic Acid (PLA) for two lattice structures namely Schoen Gyroid and Schwarz Primitive. The effect of additive manufacturing critical process parameters including layer height, flow rate, and print speed on the geometrical accuracy and compressive strength of the specimens were analysed. In addition, other parameters that have minimal effect on the geometrical accuracy of the printed parts were discussed. A Full Factorial Analysis (FFA) using Minitab software was undertaken to identify the perfect combination of printing parameters to provide the most geometrically accurate structure. In this study, samples of the Schoen Gyroid and the Schwarz Primitive lattices and a solid control cylinder were 3D printed using the ideal printing combination to assess the manufacturability, the geometrical accuracy, and the mechanical behaviour of both designs. It was found that the optimised FDM process parameters for the studied cellular structures were a layer height of 0.16 mm, a printing speed of 50 mm/s and a flow rate of 90%. As a result of using these parameters, the solid, Schoen Gyroid and Schwarz Primitive specimens demonstrated elastic moduli values of 951 MPa, 264 MPa, and 221 MPa, respectively. In addition, the Schoen Gyroid and the Schwarz Primitive have reached their stress limits at around 8.68 MPa and 7.06 MPa, respectively. It was noticed that the Schoen Gyroid structure exhibited ∼ 18% higher compressive strength and ∼ 16% higher elastic modulus compared to the Schwarz Primitive structure for the same volume fraction of porosity, overall dimensions, and the manufacturing process parameters. Although both structures revealed mechanical properties that fall within the range of the human trabecular bone, but Schoen Gyroid exhibited improved structural integrity performance that is evident by its post-yield behaviour.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"136 1","pages":"105447"},"PeriodicalIF":0.0,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46084998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Haneef, Y. Buys, N. Shaffiar, A. A. Abdul Hamid, S. I. S. Shaharuddin, Fitriani
The need to overcome the secondary surgery to remove implanted metal fixation plate leads to the idea of replacing the material with degradable bionanocomposite. In this research, polylactic acid/polypropylene (PLA/PPC) blends incorporated with halloysite nanotubes (HNT) (0-6 wt %) were considered as the candidate material for mandibular fixation plate. A single-factor design using Design Expert software was used to determine 20 different compositions of PLA/PPC/HNT nanocomposites and their mechanical properties were then measured. The optimization of the PLA/PPC/HNT nanocomposite composition was performed based on the nanocomposite's response to Young's modulus, tensile strength, and elongation at break. Further analysis suggested an optimum composition of 92.5/7.5 PLA/PPC with 6 wt % of HNT. The statistical results predicted that there was a 71.7% possibility that the proposed nanocomposite would have the following mechanical properties: Young's modulus of 2.18 GPa, a tensile strength of 64.16 MPa, and an elongation at break of 106.53%.
{"title":"Composition optimization of PLA/PPC/HNT nanocomposites for mandibular fixation plate using single-factor experimental design.","authors":"I. Haneef, Y. Buys, N. Shaffiar, A. A. Abdul Hamid, S. I. S. Shaharuddin, Fitriani","doi":"10.2139/ssrn.4148312","DOIUrl":"https://doi.org/10.2139/ssrn.4148312","url":null,"abstract":"The need to overcome the secondary surgery to remove implanted metal fixation plate leads to the idea of replacing the material with degradable bionanocomposite. In this research, polylactic acid/polypropylene (PLA/PPC) blends incorporated with halloysite nanotubes (HNT) (0-6 wt %) were considered as the candidate material for mandibular fixation plate. A single-factor design using Design Expert software was used to determine 20 different compositions of PLA/PPC/HNT nanocomposites and their mechanical properties were then measured. The optimization of the PLA/PPC/HNT nanocomposite composition was performed based on the nanocomposite's response to Young's modulus, tensile strength, and elongation at break. Further analysis suggested an optimum composition of 92.5/7.5 PLA/PPC with 6 wt % of HNT. The statistical results predicted that there was a 71.7% possibility that the proposed nanocomposite would have the following mechanical properties: Young's modulus of 2.18 GPa, a tensile strength of 64.16 MPa, and an elongation at break of 106.53%.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"135 1","pages":"105423"},"PeriodicalIF":0.0,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48368000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Explant analyses are key to better understanding the effectiveness of medical implants in replacing natural joints. For the first time, an explanted Discocerv cervical disc was examined. The implant utilised the articulation of a caudal zirconia cup (inferior component) and a cephalic alumina head (superior component). The articulating surface of the superior alumina head had an average surface roughness of 0.016 ± 0.003 μm (Sa) and the articulating surface of the inferior zirconia cup had an average surface roughness of 0.015 ± 0.002 μm (Sa). Both articulating surfaces had negative skewness, indicating the removal of local peaks. The difference between the average surface roughness of the components was not significant (p-value: 0.741). Dark grey marks were observed on both of the articulating surfaces, which were found to be adhered titanium debris that was generated due to component impingement. This titanium debris may explain the small amount of metallosis that was reported at explantation. Some transfer of zirconium to the alumina articulating surface was also seen.
{"title":"Explant analysis of a Discocerv cervical disc: A case study for a ceramic-on-ceramic cervical disc.","authors":"Göksu Kandemir, A. Bowey, C. Jensen, T. Joyce","doi":"10.2139/ssrn.4101074","DOIUrl":"https://doi.org/10.2139/ssrn.4101074","url":null,"abstract":"Explant analyses are key to better understanding the effectiveness of medical implants in replacing natural joints. For the first time, an explanted Discocerv cervical disc was examined. The implant utilised the articulation of a caudal zirconia cup (inferior component) and a cephalic alumina head (superior component). The articulating surface of the superior alumina head had an average surface roughness of 0.016 ± 0.003 μm (Sa) and the articulating surface of the inferior zirconia cup had an average surface roughness of 0.015 ± 0.002 μm (Sa). Both articulating surfaces had negative skewness, indicating the removal of local peaks. The difference between the average surface roughness of the components was not significant (p-value: 0.741). Dark grey marks were observed on both of the articulating surfaces, which were found to be adhered titanium debris that was generated due to component impingement. This titanium debris may explain the small amount of metallosis that was reported at explantation. Some transfer of zirconium to the alumina articulating surface was also seen.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"135 1","pages":"105473"},"PeriodicalIF":0.0,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48037162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zn is a promising biodegradable metal that shows huge potential as bioresorbable implant material as it possesses outstanding biocompatibility and high corrosion resistance than Mg. However, the low value of mechanical strength and hardness has hugely restricted its application. Moreover, incorporating alloying elements have typically magnified its mechanical properties. In the current study, the effect of the alloying component Mn and HA on the Zn-Mg composite and also the effect of polymer-ceramics nanofiber coating on the composite sample was studied. The result shows that the current studied samples were mainly comprised of a primary Zn matrix and a secondary phase of Mg2Zn11. The prepared sample shows very high compressive yield strength (CYS 228 MPa) and hardness (83 HV). The value of corrosion rates of the as-cast Zn-1Mg-1Mn-1HA sample was higher in comparison to that of the as-cast Zn-1Mg-1Mn sample, but after the polymer-ceramics nanofiber coating formation of PLA/HA/TiO2, the values were reduced to a more significant extent and achieved values of 0.01484 mm/year from 0.01892 mm/year in electrochemical tests. Moreover, the coated and uncoated sample shows outstanding hemocompatibility for both samples, but the minimum value is obtained for coated Zn-1Mg-1Mn-1HA sample (2.251%). The viability of MG63 cells cultured in different diluted extracts (25% and 50% extract) of the coated Zn-1Mg-1Mn-1HA sample reached a value greater than 90%, which displayed no possible cytotoxicity for biomedical applications.
{"title":"Evaluation of biodegradable Zn-1Mg-1Mn and Zn-1Mg-1Mn-1HA composites with a polymer-ceramics coating of PLA/HA/TiO2 for orthopaedic applications.","authors":"N. Anand, K. Pal","doi":"10.2139/ssrn.4039434","DOIUrl":"https://doi.org/10.2139/ssrn.4039434","url":null,"abstract":"Zn is a promising biodegradable metal that shows huge potential as bioresorbable implant material as it possesses outstanding biocompatibility and high corrosion resistance than Mg. However, the low value of mechanical strength and hardness has hugely restricted its application. Moreover, incorporating alloying elements have typically magnified its mechanical properties. In the current study, the effect of the alloying component Mn and HA on the Zn-Mg composite and also the effect of polymer-ceramics nanofiber coating on the composite sample was studied. The result shows that the current studied samples were mainly comprised of a primary Zn matrix and a secondary phase of Mg2Zn11. The prepared sample shows very high compressive yield strength (CYS 228 MPa) and hardness (83 HV). The value of corrosion rates of the as-cast Zn-1Mg-1Mn-1HA sample was higher in comparison to that of the as-cast Zn-1Mg-1Mn sample, but after the polymer-ceramics nanofiber coating formation of PLA/HA/TiO2, the values were reduced to a more significant extent and achieved values of 0.01484 mm/year from 0.01892 mm/year in electrochemical tests. Moreover, the coated and uncoated sample shows outstanding hemocompatibility for both samples, but the minimum value is obtained for coated Zn-1Mg-1Mn-1HA sample (2.251%). The viability of MG63 cells cultured in different diluted extracts (25% and 50% extract) of the coated Zn-1Mg-1Mn-1HA sample reached a value greater than 90%, which displayed no possible cytotoxicity for biomedical applications.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"136 1","pages":"105470"},"PeriodicalIF":0.0,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49430558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. F. de Castro, G. Nima, F. Rueggeberg, M. Giannini
PURPOSE This study evaluated the effects of 3D-printing build orientation on accuracy, flexural modulus (FM), flexural strength (FS), and microhardness of selected, commercial 3D-printed provisional resins (3DRs). MATERIAL AND METHODS PMMA CAD/CAM provisional material (Vita Temp/Vita) served as Control. Four 3DRs (Cosmos-SLA/Yller, Cosmos-DLP/Yller, PriZma-Bioprov/Makertech, Nanolab/Wilcos) were used in three printing orientations (0°, 45°, and 90°). Printed samples were cleaned with isopropyl alcohol prior to post-curing in specific post-curing units. For each group, 20 bar-shaped samples (25 × 2x2 mm) and ten disc-shaped samples (15-mm diameter, 2.5-mm thick) were obtained. The dimensions of bar samples were measured and the mean percent errors were compared to the reference (digital) values to obtain "accuracy" (n = 20). Samples were then aged in distilled water at 37 °C and half were submitted to a three-point bend test in a universal testing machine after 24 h and the other half after 1 year (n = 10). Disc samples were polished prior to microhardness evaluation (n = 10). Microstructure and elemental composition of filler particles in the 3DRs were analyzed using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) (n = 3). Accuracy and microhardness were submitted to two way-, and FM and FS to three way-ANOVA, followed by Tukey's tests. Results of experimental groups were compared to a milled PMMA Control using Dunnett's tests, and Student's t-tests compared FM and FS to Control at different aging periods (α = 0.05). RESULTS Except for Cosmos-DLP, the 90° orientation demonstrated the best overall accuracy in all dimensions evaluated. The overall accuracy of Cosmos-SLA was not significantly different from Control and higher than other 3DRs. The FM of all 3DRs was lower than Control, regardless of orientation and aging period. After 1 year of aging, FS of 45°-Cosmos-SLA and all orientations of PriZma were not different from Control, while 90°-Cosmos-SLA was higher. Build orientation had no influence on microhardness of the 3DRs: Nanolab was the only resin harder than Control. Very few nanometric spherical filler particles were found in Cosmos-SLA, Cosmos-DLP, and PriZma, while Nanolab presented higher number of particles having irregular shapes and sizes. CONCLUSIONS In general, although build orientation did not influence microhardness results, the 90° -orientation resulted in the best overall accuracy for most 3DRs. After 1-year water storage, Cosmos-SLA printed vertically showed the highest FS, while the PMMA Control obtained the highest FM for both aging periods.
{"title":"Effect of build orientation in accuracy, flexural modulus, flexural strength, and microhardness of 3D-Printed resins for provisional restorations.","authors":"E. F. de Castro, G. Nima, F. Rueggeberg, M. Giannini","doi":"10.2139/ssrn.4153617","DOIUrl":"https://doi.org/10.2139/ssrn.4153617","url":null,"abstract":"PURPOSE\u0000This study evaluated the effects of 3D-printing build orientation on accuracy, flexural modulus (FM), flexural strength (FS), and microhardness of selected, commercial 3D-printed provisional resins (3DRs).\u0000\u0000\u0000MATERIAL AND METHODS\u0000PMMA CAD/CAM provisional material (Vita Temp/Vita) served as Control. Four 3DRs (Cosmos-SLA/Yller, Cosmos-DLP/Yller, PriZma-Bioprov/Makertech, Nanolab/Wilcos) were used in three printing orientations (0°, 45°, and 90°). Printed samples were cleaned with isopropyl alcohol prior to post-curing in specific post-curing units. For each group, 20 bar-shaped samples (25 × 2x2 mm) and ten disc-shaped samples (15-mm diameter, 2.5-mm thick) were obtained. The dimensions of bar samples were measured and the mean percent errors were compared to the reference (digital) values to obtain \"accuracy\" (n = 20). Samples were then aged in distilled water at 37 °C and half were submitted to a three-point bend test in a universal testing machine after 24 h and the other half after 1 year (n = 10). Disc samples were polished prior to microhardness evaluation (n = 10). Microstructure and elemental composition of filler particles in the 3DRs were analyzed using scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) (n = 3). Accuracy and microhardness were submitted to two way-, and FM and FS to three way-ANOVA, followed by Tukey's tests. Results of experimental groups were compared to a milled PMMA Control using Dunnett's tests, and Student's t-tests compared FM and FS to Control at different aging periods (α = 0.05).\u0000\u0000\u0000RESULTS\u0000Except for Cosmos-DLP, the 90° orientation demonstrated the best overall accuracy in all dimensions evaluated. The overall accuracy of Cosmos-SLA was not significantly different from Control and higher than other 3DRs. The FM of all 3DRs was lower than Control, regardless of orientation and aging period. After 1 year of aging, FS of 45°-Cosmos-SLA and all orientations of PriZma were not different from Control, while 90°-Cosmos-SLA was higher. Build orientation had no influence on microhardness of the 3DRs: Nanolab was the only resin harder than Control. Very few nanometric spherical filler particles were found in Cosmos-SLA, Cosmos-DLP, and PriZma, while Nanolab presented higher number of particles having irregular shapes and sizes.\u0000\u0000\u0000CONCLUSIONS\u0000In general, although build orientation did not influence microhardness results, the 90° -orientation resulted in the best overall accuracy for most 3DRs. After 1-year water storage, Cosmos-SLA printed vertically showed the highest FS, while the PMMA Control obtained the highest FM for both aging periods.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"136 1","pages":"105479"},"PeriodicalIF":0.0,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48771715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sultan Aati, Seerat Aneja, Michael Kassar, Ryan Leung, A. Nguyen, Susan Tran, Barsha Shrestha, A. Fawzy
The aim of this study is to develop a novel 3D printed denture base resin material modified with mesoporous silica nanocarrier loaded with silver (Ag/MSN) to enhance mechanical and antimicrobial properties. Acrylate resin-based was incorporated with various proportion of Ag/MSN (0.0-2.0 wt%). Specimens with different geometry were printed and characterized accordingly for the effect of modification on properties such as: mechanical and physical properties, chemical composition and degree of conversion, as well as biological response in term of biocompatibility and antimicrobial against oral fibroblast and candida biofilm (C. albicans), respectively. The consecutive addition of Ag/MSN improved significantly surface hardness and crack propagation resistance, while flexural strength remained similar to control; however, a negligible decrease was observed with higher concentrations ≥1 wt%. No significant difference was noticed with water sorption, while water solubility had a remarkable trend of reduction associated with filler content. The surface roughness significantly increased when concentration of Ag/MSN was ≥1.0 wt%. A significant reduction in C. albicans biofilm mass, as the inhibition proficiency was correlated with the proportion of the filler. With respect to the amount of Ag/MSN, the modification was compatible toward fibroblast cells. The sequential addition of Ag/MSN enhanced significantly the mechanical and antimicrobial properties of the 3D printed resin-based material without affecting adversely compatibility. The acrylic resin denture base material has susceptibility of microbial adhesion which limits its application. Silver loaded MSN showed a significant performance to enhance antimicrobial activity against C. albicans which is the main cause of denture stomatitis. The proposed invention is a promise technique for clinical application to provide an advanced prosthesis fabrication and serve as long-term drug delivery.
{"title":"Silver-loaded mesoporous silica nanoparticles enhanced the mechanical and antimicrobial properties of 3D printed denture base resin.","authors":"Sultan Aati, Seerat Aneja, Michael Kassar, Ryan Leung, A. Nguyen, Susan Tran, Barsha Shrestha, A. Fawzy","doi":"10.2139/ssrn.4166940","DOIUrl":"https://doi.org/10.2139/ssrn.4166940","url":null,"abstract":"The aim of this study is to develop a novel 3D printed denture base resin material modified with mesoporous silica nanocarrier loaded with silver (Ag/MSN) to enhance mechanical and antimicrobial properties. Acrylate resin-based was incorporated with various proportion of Ag/MSN (0.0-2.0 wt%). Specimens with different geometry were printed and characterized accordingly for the effect of modification on properties such as: mechanical and physical properties, chemical composition and degree of conversion, as well as biological response in term of biocompatibility and antimicrobial against oral fibroblast and candida biofilm (C. albicans), respectively. The consecutive addition of Ag/MSN improved significantly surface hardness and crack propagation resistance, while flexural strength remained similar to control; however, a negligible decrease was observed with higher concentrations ≥1 wt%. No significant difference was noticed with water sorption, while water solubility had a remarkable trend of reduction associated with filler content. The surface roughness significantly increased when concentration of Ag/MSN was ≥1.0 wt%. A significant reduction in C. albicans biofilm mass, as the inhibition proficiency was correlated with the proportion of the filler. With respect to the amount of Ag/MSN, the modification was compatible toward fibroblast cells. The sequential addition of Ag/MSN enhanced significantly the mechanical and antimicrobial properties of the 3D printed resin-based material without affecting adversely compatibility. The acrylic resin denture base material has susceptibility of microbial adhesion which limits its application. Silver loaded MSN showed a significant performance to enhance antimicrobial activity against C. albicans which is the main cause of denture stomatitis. The proposed invention is a promise technique for clinical application to provide an advanced prosthesis fabrication and serve as long-term drug delivery.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"134 1","pages":"105421"},"PeriodicalIF":0.0,"publicationDate":"2022-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46143750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Fitzpatrick, Kevin Pham, Colton J. Ross, Luke T. Hudson, Devin W. Laurence, Yue Yu, Chung-Hao Lee
Unidirectional blood flow in the left side of the heart is regulated by the mitral valve. To better understand the mitral valve function, researchers have examined the structural and mechanical properties of the mitral valve leaflets; however, limitations of the previous studies include the use of mechanics- and structure-altering tissue modifications (e.g., optical clearing) that limit the ability to quantify the unique load-dependent reorientation and realignment of the collagen fibers as well as their interrelation with the valve tissue mechanics. Herein, we aimed to circumvent these limitations by utilizing an integrated polarized-light imaging and biaxial testing system for understanding the mechanics-microstructure interrelationship for porcine mitral valve leaflets. We further performed constitutive modeling and evaluated the accuracy of the affine fiber kinematics theory. From the tissue mechanics perspective, the posterior leaflet was more extensible in the radial direction than the anterior leaflet (14.2% difference in radial tissue stretch), while exhibiting smaller collagen and elastin moduli based on the determined constitutive model parameters. From the collagen microstructure's standpoint, the posterior leaflet had smaller increases in optical anisotropy (closely related to the degree of fiber alignment) than the anterior leaflet (32.8±7.7% vs. 50.0±19.7%). Further, the leaflets were found to possess two distinct fiber families - one family oriented along the circumferential tissue direction, and another more disperse family with a 30°-40° offset from the first fiber family. Finally, affine fiber kinematics consistently underpredicted the collagen fiber reorientations Overall, this study improved our understanding of the mitral valve leaflets that is essential for facilitating tissue-emulated valve replacement and cardiac valve modeling frameworks.
{"title":"Ex vivo experimental characterizations for understanding the interrelationship between tissue mechanics and collagen microstructure of porcine mitral valve leaflets.","authors":"D. Fitzpatrick, Kevin Pham, Colton J. Ross, Luke T. Hudson, Devin W. Laurence, Yue Yu, Chung-Hao Lee","doi":"10.2139/ssrn.4142055","DOIUrl":"https://doi.org/10.2139/ssrn.4142055","url":null,"abstract":"Unidirectional blood flow in the left side of the heart is regulated by the mitral valve. To better understand the mitral valve function, researchers have examined the structural and mechanical properties of the mitral valve leaflets; however, limitations of the previous studies include the use of mechanics- and structure-altering tissue modifications (e.g., optical clearing) that limit the ability to quantify the unique load-dependent reorientation and realignment of the collagen fibers as well as their interrelation with the valve tissue mechanics. Herein, we aimed to circumvent these limitations by utilizing an integrated polarized-light imaging and biaxial testing system for understanding the mechanics-microstructure interrelationship for porcine mitral valve leaflets. We further performed constitutive modeling and evaluated the accuracy of the affine fiber kinematics theory. From the tissue mechanics perspective, the posterior leaflet was more extensible in the radial direction than the anterior leaflet (14.2% difference in radial tissue stretch), while exhibiting smaller collagen and elastin moduli based on the determined constitutive model parameters. From the collagen microstructure's standpoint, the posterior leaflet had smaller increases in optical anisotropy (closely related to the degree of fiber alignment) than the anterior leaflet (32.8±7.7% vs. 50.0±19.7%). Further, the leaflets were found to possess two distinct fiber families - one family oriented along the circumferential tissue direction, and another more disperse family with a 30°-40° offset from the first fiber family. Finally, affine fiber kinematics consistently underpredicted the collagen fiber reorientations Overall, this study improved our understanding of the mitral valve leaflets that is essential for facilitating tissue-emulated valve replacement and cardiac valve modeling frameworks.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"134 1","pages":"105401"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43858837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Jana, P. Datta, Himanka Das, S. Jaiswal, P. R. Ghosh, D. Lahiri, B. Kundu, S. Nandi
The wounds arising out of underlying hyperglycemic conditions such as diabetic foot ulcers demand a multifunctional tissue regeneration approach owing to several deficiencies in the healing mechanisms. Herein, four different types of electrospun microfibers by combining Rohu fish skin-derived collagen (Fcol) with a bioactive glass (BAG)/ion-doped bioactive glass, namely, Fcol/BAG, Fcol/CuBAG, Fcol/CoBAG, and Fcol/CuCoBAG was developed to accelerate wound healing through stimulation of key events such as angiogenesis and ECM re-construction under diabetic conditions. SEM analysis shows the porous and microfibrous architecture, while the EDX mapping provides evidence of the incorporation of dopants inside various inorganic-organic composite mats. The viscoelastic properties of the microfibrous mats as measured by a nano-DMA test show a higher damping factor non-uniform tan-delta value. The maximum ultimate tensile strength and toughness are recorded for fish collagen with copper doped bioactive glass microfibers while the least values are demonstrated by microfibers with cobalt dopant. In vitro results demonstrate excellent cell-cell and cell-material interactions when human dermal fibroblasts (HDFs) were cultured over the microfibers for 48 h. When these mats were applied over full-thickness diabetic wounds in the rabbit model, early wound healing is attained with Fcol/CuBAG, Fcol/CoBAG, and Fcol/CuCoBAG microfibers. Notably, these microfibers-treated wounds demonstrate a significantly (p < 0.01) higher density of blood vessels by CD-31 immunostaining than control, Duoderm, and Fcol/BAG treated wounds. Mature collagen deposition and excellent ECM remodeling are also evident in wounds treated with fish collagen/ion-doped bioactive glass microfibers suggesting their positive role in diabetic wound healing.
{"title":"Copper and cobalt doped bioactive glass-fish dermal collagen electrospun mat triggers key events of diabetic wound healing in full-thickness skin defect model.","authors":"S. Jana, P. Datta, Himanka Das, S. Jaiswal, P. R. Ghosh, D. Lahiri, B. Kundu, S. Nandi","doi":"10.2139/ssrn.4135099","DOIUrl":"https://doi.org/10.2139/ssrn.4135099","url":null,"abstract":"The wounds arising out of underlying hyperglycemic conditions such as diabetic foot ulcers demand a multifunctional tissue regeneration approach owing to several deficiencies in the healing mechanisms. Herein, four different types of electrospun microfibers by combining Rohu fish skin-derived collagen (Fcol) with a bioactive glass (BAG)/ion-doped bioactive glass, namely, Fcol/BAG, Fcol/CuBAG, Fcol/CoBAG, and Fcol/CuCoBAG was developed to accelerate wound healing through stimulation of key events such as angiogenesis and ECM re-construction under diabetic conditions. SEM analysis shows the porous and microfibrous architecture, while the EDX mapping provides evidence of the incorporation of dopants inside various inorganic-organic composite mats. The viscoelastic properties of the microfibrous mats as measured by a nano-DMA test show a higher damping factor non-uniform tan-delta value. The maximum ultimate tensile strength and toughness are recorded for fish collagen with copper doped bioactive glass microfibers while the least values are demonstrated by microfibers with cobalt dopant. In vitro results demonstrate excellent cell-cell and cell-material interactions when human dermal fibroblasts (HDFs) were cultured over the microfibers for 48 h. When these mats were applied over full-thickness diabetic wounds in the rabbit model, early wound healing is attained with Fcol/CuBAG, Fcol/CoBAG, and Fcol/CuCoBAG microfibers. Notably, these microfibers-treated wounds demonstrate a significantly (p < 0.01) higher density of blood vessels by CD-31 immunostaining than control, Duoderm, and Fcol/BAG treated wounds. Mature collagen deposition and excellent ECM remodeling are also evident in wounds treated with fish collagen/ion-doped bioactive glass microfibers suggesting their positive role in diabetic wound healing.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"134 1","pages":"105414"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45032521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The samples 8YSZ containing 70, 75, 80 mol% ZrO2 and other oxides were prepared by. a high temperature solid state reaction process. Using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and spectroscopic methods were evaluated the effect of oxide addition on the properties of yttria-doped zirconia. X-ray data shows the formation of zirconia (Y-doped), YSZ and/or tetragonal zirconia crystalline phases in all samples. IR data indicate the stretching vibrations of the Si-O bonds from tetrahedral [SiO4] units and the stretching vibrations of the Fe-O bonds from [FeO6] structural units, respectively. EPR results indicate the destroying of the local ordering of the Fe+3 ion vicinities situated in the rhombic distorted octahedral geometries by the increasing of ZrO2 content in the host ceramic. The highest values of Vickers hardness were recorded for the ceramics containing 70 and 75 mol% ZrO2. This superior performance can be explained considering the presence of a smaller amount of monoclinic ZrO2 crystalline phase in the ceramic structure. The analysis of the X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data shows the presence of Fe+2 and Fe+3 ions. In the ceramics with higher ZrO2 contents the iron atoms adopt a randomly structure due to the highly distorted [FeO6] structural units and non-equivalent Fe-O distances in the first coordination shell.
{"title":"Advanced zirconia ceramics stabilized with yttria and magnesia: Structure and Vickers microhardness.","authors":"S. Rada, J. Zhang, R. Rada, E. Culea","doi":"10.2139/ssrn.4159548","DOIUrl":"https://doi.org/10.2139/ssrn.4159548","url":null,"abstract":"The samples 8YSZ containing 70, 75, 80 mol% ZrO2 and other oxides were prepared by. a high temperature solid state reaction process. Using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and spectroscopic methods were evaluated the effect of oxide addition on the properties of yttria-doped zirconia. X-ray data shows the formation of zirconia (Y-doped), YSZ and/or tetragonal zirconia crystalline phases in all samples. IR data indicate the stretching vibrations of the Si-O bonds from tetrahedral [SiO4] units and the stretching vibrations of the Fe-O bonds from [FeO6] structural units, respectively. EPR results indicate the destroying of the local ordering of the Fe+3 ion vicinities situated in the rhombic distorted octahedral geometries by the increasing of ZrO2 content in the host ceramic. The highest values of Vickers hardness were recorded for the ceramics containing 70 and 75 mol% ZrO2. This superior performance can be explained considering the presence of a smaller amount of monoclinic ZrO2 crystalline phase in the ceramic structure. The analysis of the X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data shows the presence of Fe+2 and Fe+3 ions. In the ceramics with higher ZrO2 contents the iron atoms adopt a randomly structure due to the highly distorted [FeO6] structural units and non-equivalent Fe-O distances in the first coordination shell.","PeriodicalId":94117,"journal":{"name":"Journal of the mechanical behavior of biomedical materials","volume":"134 1","pages":"105425"},"PeriodicalIF":0.0,"publicationDate":"2022-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43731449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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