Bionic mechanical design and 3D printing of novel porous Ti6Al4V implants for biomedical applications / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

In maxillofacial surgery, there is a significant need for the design and fabrication of porous scaffolds with customizable bionic structures and mechanical properties suitable for bone tissue engineering. In this paper, we characterize the porous Ti6Al4V implant, which is one of the most promising and attractive biomedical applications due to the similarity of its modulus to human bones. We describe the mechanical properties of this implant, which we suggest is capable of providing important biological functions for bone tissue regeneration. We characterize a novel bionic design and fabrication process for porous implants. A design concept of "reducing dimensions and designing layer by layer" was used to construct layered slice and rod-connected mesh structure (LSRCMS) implants. Porous LSRCMS implants with different parameters and porosities were fabricated by selective laser melting (SLM). Printed samples were evaluated by microstructure characterization, specific mechanical properties were analyzed by mechanical tests, and finite element analysis was used to digitally calculate the stress characteristics of the LSRCMS under loading forces. Our results show that the samples fabricated by SLM had good structure printing quality with reasonable pore sizes. The porosity, pore size, and strut thickness of manufactured samples ranged from (60.95± 0.27)% to (81.23±0.32)%, (480±28) to (685±31) μm, and (263±28) to (265±28) μm, respectively. The compression results show that the Young's modulus and the yield strength ranged from (2.23±0.03) to (6.36±0.06) GPa and (21.36±0.42) to (122.85±3.85) MPa, respectively. We also show that the Young's modulus and yield strength of the LSRCMS samples can be predicted by the Gibson-Ashby model. Further, we prove the structural stability of our novel design by finite element analysis. Our results illustrate that our novel SLM-fabricated porous Ti6Al4V scaffolds based on an LSRCMS are a promising material for bone implants, and are potentially applicable to the field of bone defect repair.

Bionic mechanical design and 3D printing of novel porous Ti6Al4V implants for biomedical applications / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

In maxillofacial surgery, there is a significant need for the design and fabrication of porous scaffolds with customizable bionic structures and mechanical properties suitable for bone tissue engineering. In this paper, we characterize the porous Ti6Al4V implant, which is one of the most promising and attractive biomedical applications due to the similarity of its modulus to human bones. We describe the mechanical properties of this implant, which we suggest is capable of providing important biological functions for bone tissue regeneration. We characterize a novel bionic design and fabrication process for porous implants. A design concept of “reducing dimensions and designing layer by layer” was used to construct layered slice and rod-connected mesh structure (LSRCMS) implants. Porous LSRCMS implants with different parameters and porosities were fabricated by selective laser melting (SLM). Printed samples were evaluated by microstructure characterization, specific mechanical properties were analyzed by mechanical tests, and finite element analysis was used to digitally calculate the stress characteristics of the LSRCMS under loading forces. Our results show that the samples fabricated by SLM had good structure printing quality with reasonable pore sizes. The porosity, pore size, and strut thickness of manufactured samples ranged from (60.95± 0.27)% to (81.23±0.32)%, (480±28) to (685±31) µm, and (263±28) to (265±28) µm, respectively. The compression results show that the Young’s modulus and the yield strength ranged from (2.23±0.03) to (6.36±0.06) GPa and (21.36±0.42) to (122.85±3.85) MPa, respectively. We also show that the Young’s modulus and yield strength of the LSRCMS samples can be predicted by the Gibson-Ashby model. Further, we prove the structural stability of our novel design by finite element analysis. Our results illustrate that our novel SLM-fabricated porous Ti6Al4V scaffolds based on an LSRCMS are a promising material for bone implants, and are potentially applicable to the field of bone defect repair.

Dimensional accuracy and internal and marginal fit evaluation of Co-Cr crowns prepared by SLM / 实用口腔医学杂志

Objective: To study the dimensional accuracy of the Co-Cr crowns prepared by selective laser melting(SLM) technology and to evaluate their internal and marginal fit by "Virtual seating". Methods: The Co-Cr metal crowns were fabricated with 2 different methods(n = 10): milling wax with lost-wax method in the control group and SLM in the test group. After collecting the data of the die and crowns, "virtual seating" was completed by the software of reverse engineering. The gaps between the die and crowns on the 2D cross-sectional were measured by the same software. At last, crowns were cemented on the dies. And the thickness of the crowns and the cement films were measured under a scanning electron microscope. Data were statistically analyzed. Results: The most appropriate pre-set die spacer thickness was 50 μm. The relative errors of the crown thickness of SLM group and the control group were 1. 80％ and 2. 20％ respectively(P＞ 0. 05). No statistically significant difference was found in both internal and marginal fit between the 2 groups (P＞ 0. 05). And there was no statistical difference between the 2 measuring methods (P＞ 0. 05). Conclusion: SLM technique achieves clinically values for internal and marginal fit. "Virtual seating" can be used for evaluate crown dimensional accuracy.

Micro-pore structure and mechanical properties of porous titanium scaffold using 3D print technology / 医用生物力学

Objective To study the micro-pore architecture and mechanical properties of porous titanium scaffolds with diamond molecule structure produced by 3D print technology,so as to guide the development of 3D-prinited porous titanium orthopedic implants.Methods Selective laser melting (SLM) and electron beam melting (EBM) were used to fabricate porous Ti6Al4V scaffolds with diamond molecule structure.The micro-pore architectures of those scaffolds were observed using optical microscope and scanning electron microscope (SEM),and universal material testing machine was used to conduct compressive test on the scaffolds.Results Both SLM and EBM techniques had machining error and half-melted metal particles were found on the strut surface.The relative error of strut size produced by SLM and EMB was 20.9％-35.8％ and-9.1％-46.8％,respectively.The scaffold with strut width of 0.2 mm could not be produced by EBM.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 99.7-192.6 MPa and 2.43-4.23 GPa,respectively.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 39.5-96.9 MPa and 1.44-2.83 GPa,respectively.Conclusions The manufacturing precision of SLM is higher than that of EBM.Porosity is the main factor that affects the compressive strength and elastic modulus of the scaffolds.In the same process,with the increase of porosity,both the compressive strength and elastic modulus decrease.When the porosities are similar,the scaffolds fabricated by SLM possess higher compressive strength and elastic modulus than those by SLM.

Study on the fit of titanium alloy removable partial denture framework fabricated by selective laser melting / 实用口腔医学杂志

Objective:To evaluate the fit of titanium alloy removable partial denture framework fabricated by selective laser melting(SLM) technique.Methods:7 Kennedy Ⅲ Ti-6Al-4V removable titanium alloy partial denture frameworks were fabricated by SLM technology.An optical scanner was used to scan the gypsum model adhered with the silicone rubber film obtained by the impression method before and after removal of the film.Geomagic Qualify 2013 software was used to analyze the gap between the model and the tissue surface of the major connector of the framework,the fit of the frame work was evaluated.Results:The overall 3D deviation between the titanium alloy frameworks and the gypsum model was (0.221 9±0.07) mm.Conclusion:The fit of the titanium alloy removable partial denture framework made by SLM technology can basically met the clinical requirements.

Micro-pore structure and mechanical properties of porous titanium scaffold using 3D print technology / 医用生物力学

Objective To study the micro-pore architecture and mechanical properties of porous titanium scaffolds with diamond molecule structure produced by 3D print technology,so as to guide the development of 3D-prinited porous titanium orthopedic implants.Methods Selective laser melting (SLM) and electron beam melting (EBM) were used to fabricate porous Ti6Al4V scaffolds with diamond molecule structure.The micro-pore architectures of those scaffolds were observed using optical microscope and scanning electron microscope (SEM),and universal material testing machine was used to conduct compressive test on the scaffolds.Results Both SLM and EBM techniques had machining error and half-melted metal particles were found on the strut surface.The relative error of strut size produced by SLM and EMB was 20.9％-35.8％ and-9.1％-46.8％,respectively.The scaffold with strut width of 0.2 mm could not be produced by EBM.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 99.7-192.6 MPa and 2.43-4.23 GPa,respectively.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 39.5-96.9 MPa and 1.44-2.83 GPa,respectively.Conclusions The manufacturing precision of SLM is higher than that of EBM.Porosity is the main factor that affects the compressive strength and elastic modulus of the scaffolds.In the same process,with the increase of porosity,both the compressive strength and elastic modulus decrease.When the porosities are similar,the scaffolds fabricated by SLM possess higher compressive strength and elastic modulus than those by SLM.

Micro-pore structure and mechanical properties of porous titanium scaffold using 3D print technology / 医用生物力学

Objective To study the micro-pore architecture and mechanical properties of porous titanium scaffolds with diamond molecule structure produced by 3D print technology,so as to guide the development of 3D-prinited porous titanium orthopedic implants.Methods Selective laser melting (SLM) and electron beam melting (EBM) were used to fabricate porous Ti6Al4V scaffolds with diamond molecule structure.The micro-pore architectures of those scaffolds were observed using optical microscope and scanning electron microscope (SEM),and universal material testing machine was used to conduct compressive test on the scaffolds.Results Both SLM and EBM techniques had machining error and half-melted metal particles were found on the strut surface.The relative error of strut size produced by SLM and EMB was 20.9％-35.8％ and-9.1％-46.8％,respectively.The scaffold with strut width of 0.2 mm could not be produced by EBM.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 99.7-192.6 MPa and 2.43-4.23 GPa,respectively.The compressive strength and elastic modulus of the scaffold fabricated by SLM was 39.5-96.9 MPa and 1.44-2.83 GPa,respectively.Conclusions The manufacturing precision of SLM is higher than that of EBM.Porosity is the main factor that affects the compressive strength and elastic modulus of the scaffolds.In the same process,with the increase of porosity,both the compressive strength and elastic modulus decrease.When the porosities are similar,the scaffolds fabricated by SLM possess higher compressive strength and elastic modulus than those by SLM.

Clinical observation of the marginal and internal fit of titanium crowns fabricated by a selective laser mel-ting technology / 实用口腔医学杂志

Objective:To compare the marginal and internal fit of selective laser melting(SLM)titanium crowns with lost-wax cast (LW)titanium crowns.Methods:Titanium crowns of 10 subjects were fabricated by SLM and conventional LW respectively(n =10).The marginal and internal gaps of the crowns were recorded with silicon film using a replica technique.Each silicon film was cut into 2 parts and the thickness of silicon layer was measured at ×100 magnification using a stereomicroscope,the data of marginal gap (MG)and internal gap(IG)were statistically analysed by ANOVA and SPSS statistical package version 17.0.Results:The MG (μm)of the titanium crowns of SLMgroup and LMgroup were 90.67 ±14.7 and 94.77 ±21.9(P 0.05),respectively.Conclusion:The marginal fit of the SLMcrowns is better than that of the LW ones,and is significantly smaller than 120 μm of the clinical generally accepted standards.

Evaluation of the fit of cobalt-chromium crowns fabricated by selective laser melting / 实用口腔医学杂志

Objective:To compare the adaption of cobalt-chromium prostheses fabricated by selective laser melting(SLM)and conven-tional lost wax technique(LW)method.Methods:Cobalt-chromium crowns and three-unit fixed dental prostheses(FDPs)were fabrica-ted by selective laser melting(SLM)or by conventional lost wax technique(LW)respectively(n =5).Marginal fit and internal fit were examined using a light-body silicone.After setting,each silicon film was cut into 2 parts and the thickness of silicon layer was measured at 1 00 ×magnification using a digital microscope,the data of marginal gap(MG)and internal gap(IG)were statistically analysed by ANOVA and SPSS statistical package version 1 7.0.Results:The MG and IG(μm)of cobalt-chromium alloy crowns in EOS M270 group were 42.28 ±1 1 .58 and 1 25.75 ±47.67,in EOS M280 group 46.54 ±8.4 and 1 28.22 ±54.1 8,in LW group 48.66 ±1 2.08 and 1 35.37 ±46.89.The MG and IG(μm)of three-unit FDPs in EOS M270 group were 40.55 ±1 0.04 and 1 33.09 ±39.80,in EOS M280 group 45.36 ±1 0 and 1 38.94 ±50.61 ,in LW group 54.24 ±1 2.04 and 1 51 .87 ±61 .94(P <0.05),respectively.Conclu-sion:The marginal fit of the SLMgroup is superior to that of the LW group and significantly smaller than 1 20 μm of clinical generally accepted standards.SLMsystem can satisfy the clinical requirements.