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Objective: The selective laser melting (SLM) technique used in manufacturing results in a rougher surface that requires more satisfying processing than conventional hand-finishing operations. The electro discharge machine (EDM) has various possibilities in the adjustment of surfaces. The present study assesses whether the participation of the EDM technique with the conventional finishing and polishing methods enables surface improvement for the Cobalt-Chromium alloy fabricated by SLM. Material and Methods: Twenty discs of cobalt chromium alloy were fabricated by SLM, divided equally into two groups: (TF) control group for finishing and polishing in the conventional method in accordance with the manufacturer's recommendations; and (EF) group for conducting polishing incorporating the EDM method. Results: The EF group recorded the lowest mean value of surface roughness and the highest mean value of micro hardness compared to the TF group. Furthermore, statistically significant differences (P < 0.05) were found for surface roughness as well as micro hardness. Conclusion: Reliance of the electric discharge machine proactively within finishing and polishing procedures promotes competence in the conventional polishing method and improves the surface properties of cobalt chromium alloy printed by SLM technology (AU)
Objetivo: A técnica de fusão a laser seletiva (SLM) usada na fabricação resulta em uma superfície mais rugosa a qual requer um processamento mais satisfatório do que o acabamento manual. A máquina de eletro descarga (EDM) possui várias possibilidades no ajuste de superfícies. O presente estudo avalia se a participação da técnica EDM associada aos métodos convencionais de acabamento e polimento possibilita a melhora da superfície da liga Cobalto-Cromo fabricada através da SLM. Material e Métodos: Vinte discos de liga de cromo-cobalto foram confeccionados por SLM, e divididos igualmente em dois grupos: (TF) grupo controle, realizado acabamento e polimento pelo método convencional de acordo com as recomendações do fabricante; e (EF) grupo do polimento associado ao método EDM. Resultados: O grupo EF registrou o menor valor médio de rugosidade superficial e o maior valor médio de microdureza em relação ao grupo TF. Além disso, diferenças estatisticamente significativas (P < 0,05) foram encontradas para rugosidade superficial, assim como para a microdureza. Conclusão: A confiança na máquina de descarga elétrica proativamente nos procedimentos de acabamento e polimento promove a competência no método de polimento convencional e melhora as propriedades de superfície da liga de cromo-cobalto impressa pela tecnologia SLM(AU)
Subject(s)
Chromium Alloys , Dental PolishingABSTRACT
Objective@# To evaluate the effect of heat treatment on the bonding strength of pure titanium formed by selective laser melting (SLM) and porcelain.@*Methods@#Ninety-six pure titanium specimens were laser machined to meet ISO 9693 standards. The specimens were divided into a heat treated group (A) and a nonheat treated group (B). According to the porcelain type, the specimens in groups A and B were divided into Super Ti22 (a), Titankeramik (b), and Triceram (c) groups. Then, according to sandblasting pressures of 0.25 MPa (1) and 0.45 MPa (2), they were further divided into Aa1, Aa2, Ab1, Ab2, Ac1, Ac2, Ba1, Ba2, Bb1, Bb2, Bc1, and Bc2 groups. The surface morphology and roughness of the sandblasted specimens were assessed using a laser scanning confocal microscope. After the porcelain was fused, the three-point bending titanium-porcelain bonding strength was tested. A stereomicroscope was used to characterize the titanium-porcelain interfaces and determine the mode of failure.@* Results@# The Vickers hardness of group A specimens (188.21 ± 11.94) was significantly lower than that of group B specimens (204.48 ± 6.32) HV (P<0.05). The roughness value in group A1 (2.90 ± 0.32) μm was significantly lower than that in group A2 (3.43 ± 0.43) μm (P<0.05). Specimens in group B1 (2.62 ± 0.08) μm were significantly smaller than those in group B2 (3.01 ± 0.06) μm (P<0.05). The bonding strength in group Aa1 was (33.75 ± 2.31) MPa, group Aa2 was (36.32 ± 1.44) MPa, group Ab1 was (39.82 ± 2.28) MPa, group Ab2 was (33.74 ± 1.53) MPa and group Ac2 was (38.63 ± 1.36) MPa, which was significantly higher than that in the corresponding groups Ba1 (29.65 ± 1.10) MPa, Ba2 (27.17 ± 2.24) MPa, Bb1 (27.29 ± 1.61) MPa, Bb2 (23.85 ± 0.97) MPa, and Bc2 (35.75 ± 1.93) MPa (P<0.05). With increasing sandblasting pressure, the bonding strength of the titanium ceramic in group Aa2 was significantly higher than in group Aa1, while that in group Ab2 was significantly lower than that in group Ab1 (P<0.05). In groups A, Bc1 and Bc2, the fracture model showed mixed failure, while in groups Ba1, Ba2, Bb1, and Bb2, the model showed interfacial failure.@* Conclusion @# The Vickers hardness of SLM titanium can be significantly reduced by heat treatment. SLM pure titanium after heat treatment is beneficial to combination of the three porcelain types and titanium. The titanium-porcelain bonding strength may be affected by sandblasting pressure.
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OBJECTIVE@#To compare the retentions of different designs of cobalt-chromium (Co-Cr), pure titanium (CP Ti), and titanium alloy (Ti-6Al-4V) removable partial denture (RPD) circumferential clasps manufactured by selective laser melting (SLM) and to analyze the stress distribution of these clasps during the removal from abutment teeth.@*METHODS@#Clasps with clasp arm size A (1.9 mm width/1.1 mm thickness at the body and 0.8-taper) or B (1.2 times A) and 0.25 mm or 0.50 mm undercut engagement were modeled on a prepared first premolar die, named as designs A1, A2, A3, and A4, respectively. The density and elastic modulus of SLM-built Co-Cr, CP Ti, and Ti-6Al-4V were measured and given to different groups of clasps. The density, elastic modulus, and Poisson ' s ratio of enamel were given to the die. The control group was the cast Co-Cr clasp with design A1, to which the density and elastic modulus of cast Co-Cr alloy were given. The Poisson's ratio of all metals was 0.33. The initial 5 N dislodging force was applied, and the maximum displacement of the clasp along the insertion path was computed. The load was reapplied with an increment of 5 N than in the last simulation until the clasp was completely dislodged. The retentive force range of different groups of clasps was obtained. The retentive forces of the SLM-built Co-Cr, CP Ti, and Ti-6Al-4V clasps with equivalent computed retentive force range to the control group were validated through the insertion/removal experiment. The von Mises stress distributions of these three groups of SLM-built clasps under 15 N loads were analyzed.@*RESULTS@#SLM-built Co-Cr, CP Ti, and Ti-6Al-4V clasps with designs B1 or B2, and Co-Cr clasps with design A2 had higher retentive forces than those of the control group. SLM-built CP Ti and Ti-6Al-4V clasps with design A1 had lower retentive forces than those of the control group. SLM-built Co-Cr clasp with design A1 and SLM-built CP Ti and Ti-6Al-4V clasps with design A2 had equivalent retentive forces to those of the control group. The insertion/removal experiment showed that the measured retentive forces of these three groups of SLM-built clasps were (21.57±5.41) N, (19.75±4.47) N, and (19.32±2.04) N, respectively. No statistically significant measured retentive force difference was found among these three groups of SLM-built clasps (P>0.05). The maximum von Mises stress of these three groups of SLM-built clasps exceeded their responding yield strength except for the Ti-6Al-4V one.@*CONCLUSION@#SLM-built Co-Cr circumferential clasps had higher retention than CP Ti and Ti-6Al-4V ones with the same clasp arm size and undercut engagement. The retention of SLM-built circumferential clasps could be adjusted by changing the undercut engagement and clasp arm size. If SLM-built circumferential clasps are used in clinical practice, the Ti-6Al-4V clasp with clasp arm size A and 0.50 mm undercut engagement is recommended considering the long-term use of RPD in the patient's mouth.
Subject(s)
Humans , Chromium Alloys , Dental Clasps , Denture Retention , Denture, Partial, Removable , Finite Element Analysis , Lasers , TitaniumABSTRACT
Objective@# To explore the application of digital technology in the restoration of partial edentulous patients with microstomia. @*Methods@# A patient with microstomia was presented and seeking for the restoration of her full edentulous in the upper jaw and partial edentulous in the lower jaw (Kennedy Ⅲ). A digital intraoral scanning was used to obtain digital impressions of soft and hard tissues in the oral cavity. Computer aided design and 3D printing technology were used to design and fabricate the metal framework. @* Results @#The patient had no difficulty to wear or take off the dentures. The maxillary and mandibular dentures showed good retention, stability, mastication function and articulation. There was no tenderness in the one week and one month′s follow-up. And the chewing efficiency was satisfactory@*Conclusion@#This case report successfully designed and fabricated mandibular removable partial dentures for patients with microstomia through intraoral scanning and 3D printing technology. Thus, this work provides a new method and idea for treating partial edentulous dentition with microstomia
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BACKGROUND: In the case of tooth defect or missing, the treatment should be achieved by making a personalized prosthesis. Traditional manufacturing process is time-consuming, costly and accurate. After the introduction of 3D printing technology into dental manufacture, the manufacturing efficiency and quality can be improved to a certain extent. OBJECTIVE: To introduce the application of 3D printing technology in dental manufacture, discuss the bottleneck in recent application, and guide the development of 3D printing technology in dental manufacture. METHODS: The authors used the search times "3D printing, metal implant, dental manufacturing, dental restorations” to search Web of Science, Wanfang, CNKI databases in English and Chinese separately to search papers published during 1980-2019. 261 papers were preliminarily retrieved and 60 of them were included in the final analysis. RESULTS AND CONCLUSION: 3D printing dental mold, digital implant guide plate and wax pattern have been widely used in dental manufacture. 3D printing technology has been widely used in dental manufacture. The most widely used six processes are stereo lithography appearance, laminated object manufacturing, fused deposition modeling, selective laser sintering, selective laser melting, and inkjet printing. There are some technical bottlenecks in the application of 3D printing technology in the field of dental manufacturing. After breaking through technology bottlenecks, 3D printing will be more useful in the field of dental manufacturing in the future.
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Objective@#To investigate the effect of denture stomatitis of selective laser melting (SLM) titanium alloy for removable partial denture frameworks.@*Methods @#Twenty patients with dentition defects in our hospital were divided into two groups according to the different methods of creating a removable partial denture framework: the SLM group and casting group. The success rate, placement rate, masticatory efficiency and incidence of denture stomatitis were compared. Experimental data were analyzed with SPSS20.0.@*Results @# The success rate of the SLM framework group was 100.00%, which was higher than that of the casting group (90.00%) (P ＜ 0.01). The rate of framework placement in the SLM group was slightly lower than that in the casting group (P ＜ 0.05). The masticatory efficiency of the SLM group was higher than that of the casting group (0.783 ± 0.030 vs. 0.699 ± 0.037, P ＜ 0.001). The incidence of denture stomatitis (10.00%) in the SLM group was significantly lower than that in the casting group (30.00%) (P ＜ 0.001). @*Conclusion @#SLM is superior to the traditional casting method in mastication efficiency and reducing the incidence of denture stomatitis. This method can meet the clinical requirements, but the accuracy of the long-term stent needs to be improved.
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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.
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Objective@#To investigate the physical properties of Ti-6Al-4V clasps generated by selective laser melting (SLM) with different construction directions and to compare these clasps with cast clasps, which could provide a basis for fabricating SLM clasps with high precision and excellent mechanical properties. @*Methods@# Ti-6Al-4V clasps were fabricated by SLM at 0 degrees (SLM0 group), 45 degrees (SLM45 group) and 90 degrees (SLM90 group) (n = 12). Twelve clasps were cast by the casting method as the control group. Meanwhile, four metal abutments were cast randomly as the abutments of the four groups. X-ray was used to detect cracks in the clasps of each group. The roughness of the clasps was measured by confocal microscopy, the fitness tests between clasps and abutment were processed by stereomicroscopy, and the microstructure of clasps in each group was observed under a metallographic microscope to evaluate the physical properties.@*Results @# There were 0-8 visible cracks in the casting group but no obvious defects in the SLM groups. The maximum surface roughness was observed in the cast group (18.102 ± 3.762) μm, while the minimum roughness was observed in the SLM90 group (5.942 ± 1.486) μm (P < 0.05). There was no statistically significant difference in surface roughness between the SLM0 group [(8.711 ± 2.378) μm] and the SLM45 group [(8.513 ± 1.161) μm]. Fitness was worst in the casting group [(68.445 ± 14.876) μm] and best in the SLM90 group [(33.417 ± 5.880) μm] (P < 0.05). There was no statistically significant difference in fitness between the SLM0 group [(52.917 ± 12.102) μm] and the SLM45 group [(50.889 ± 7.011) μm]. In addition, the growth direction of the β grains was roughly parallel to the build direction, and acicular α grains were present between β grains. SLM was composed of fine grains, while the cast group had large grains.@* Conclusions@# Specimens generated by SLM had finer grains than cast specimens. In addition, SLM90 clasps had the highest fitness and the lowest surface roughness.
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@#How to obtain ideal regeneration of periodontal tissue remains a challenge in the clinical treatment of periodontitis. Three-dimensional printing technology is based on computer-aided design, which produces materials with specific 3D shapes by layer-by-layer superposition, and has been applied to periodontal tissue regeneration therapy, this method offers hope to achieve ideal periodontal regeneration. This article reviews the application of 3D printing technology in the field of periodontal tissue regeneration. The literature review results show that 3D printing technology can design three-dimensional structures using computer software in advance and produce materials with specific three-dimensional structures. 3D printing technology mainly includes selective laser sintering, selective laser melting, extrusion forming printing and 3D bioprinting. At present, the support materials prepared by 3D printing technology include ceramic materials, polymer materials and metals. Submaterials have been extensively studied given their high adjustability, and 3D-printed personalized titanium mesh has been applied in the clinic. Multiphase materials prepared by 3D-printing technology can regenerate periodontal tissue in animal experiments, but the effect is not good in patients with periodontitis. In addition, 3D printing of composite scaffolds for periodontal tissue regeneration need to be further studied.
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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.
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OBJECTIVE@#To investigate the effect of different sandblasting conditions on the metal-ceramic bonding strength of Co-Cr alloy fabricated by selective laser melting (SLM) technology.@*METHODS@#A total of 63 specimens of Co-Cr alloy fabricated by SLM were prepared and randomly divided into nine groups (n=7). Each group was treated with different powder particles (A1=50 µm, A2=100 µm, and A3=150 µm) and pressures (B1=0.2 MPa, B2=0.4 MPa, and B3=0.6 MPa) in sandblasting. One sample was randomly selected from each group for microstructure observation by scanning electron microscope (SEM). Ceramic was fired at the center of the specimens. Metal-ceramic bonding strength was measured with universal testing machine. Results were statistically analyzed with SPSS 17.0 software.@*RESULTS@#The mean bond strengths were as follows: Group A1B1: 27.22 MPa±0.95 MPa, Group A1B2: 27.58 MPa±0.47 MPa, Group A1B3: 26.80 MPa±0.71 MPa, Group A2B1: 27.54 MPa±0.78 MPa, Group A2B2: 30.75 MPa±0.43 MPa, Group A2B3: 26.93 MPa±0.88 MPa, Group A3B1: 28.18 MPa±0.93 MPa, Group A3B2: 29.55 MPa±0.57 MPa, and Group A3B3: 28.11 MPa±0.91 MPa. The particle factor of Al₂O₃ and the pressure factor of blasting showed statistical significance (P<0.05). An interaction was observed between the factors of particle and pressure (P<0.05). Mixed fracture mode of all specimens was observed after the shear strength test.@*CONCLUSIONS@#In conclusion, metal-ceramic bonding strength reaches the maximum when specimens are sandblasted with 100 µm alumina oxide at 0.4 MPa pressure.
Subject(s)
Ceramics , Dental Bonding , Materials Testing , Microscopy, Electron, Scanning , Shear Strength , Surface PropertiesABSTRACT
Objective: To explore the influence of different manufacturing techniques and different scanning objects in the marginal and internal fits of the Co-Cr porcelain crowns after procelain firing, and to provide the basis for judging the influencing factors of longevity of restorations. Methods: Five extracted maxillary premolar were selected. According to the prepared tooth, silicone rubber and stone die restoration models, which were fabricated by CAD/CAM and selective laser melting (SLM), the restorations were divided into control group (traditinal casting), tooth-SLM group, silicone rubber-SLM group, stone die-SLM group, tooth-CAD/CAM group, silicone rubber-CAD/CAM group, and stone die-CAD/CAM group. Then all the restorations were fired with the porcelain. The marginal and internal fits of the specinens were measured by micro-compated tomography (Micro-CT). Results: Compared with control group, the AMD of restorations in tooth-SLM and CAD/CAM groups were decresed (P<0. 05), and the MG of restorations in silicone rubber-SLM group was decresed (P<0. 05). Compared with control group, the CA and AW of restorations in silicone rubber-SLM group were decresed (P< 0. 05), the AW of restorations in tooth-CAD/CAM group was the least; compared with control group, the AOT and OA of restorations in stone die-SLM group and CAD/CAM group were decresed (P<0. 05), and the AOT and OA of restorations in silicone rubber-CAD/CAM were the least. Compared with before porcelain firing, the marginal fit and internal fit of restorations after porcelain firing were incresed (P<0. 05). There was positive corrlation between the MG of restorations and fabricated techniques and scanning objects (P<0. 05). There was positive corrlation between the average of internal fit of restorations and fabricated techniques and scanning objects (P<0. 05). Conclusion: The porcelain firing can affect the marginal and internal fits of Co-Cr porcelain crowns. The restorations fabricated by SLM had a better marginal fit and the restorations fabricated by CAD/CAM has a better internal fit.
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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.
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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.
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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.
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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.
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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.
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Objective @# A titanium personalized orthodontic bracket is designed and manufactured using the technology of computed tomography (CT), computer aided design (CAD), finite element analysis (FEA), and selective laser melting (SLM) to well match the patient tooth so as to realize mold-free manufacturing. @*Methods@#A model of a titanium personalized orthodontic bracket which is built by CT scanning machine and Pro/E software, is imported into Ansys software to carry out finite element simulation analysis with nonlinear contact method. Then, the titanium personalized orthodontic bracket is proposed after the model data above is imported to SLM molding equipment via titanium powder melted with layer by layer using a high-speed scanning galvanometer. @*Results @#The maximum equivalent stress of the titanium personalized orthodontic bracket is distributed uniformly and reasonably, the titanium personalized orthodontic bracket formed by SLM molding equipment can provide high accuracy and there is a high similarity between the bottom of the orthodontic bracket and the tooth surface shape.@*Conclusion @#The combination of CT, CAD, FEA, SLM technology can fulfill model-free manufacturing of the personalized orthodontic bracket and thus shorten the manufacturing cycle.
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PURPOSE: Considering the importance of metal-ceramic bond, the present study aimed to compare the bond strength of ceramics to cobalt-chrome (Co-Cr) alloys made by casting and selective laser melting (SLM). MATERIALS AND METHODS: In this in-vitro experimental study, two sample groups were prepared, with one group comprising of 10 Co-Cr metal frameworks fabricated by SLM method and the other of 10 Co-Cr metal frameworks fabricated by lost wax cast method with the dimensions of 0.5 × 3 × 25 mm (following ISO standard 9693). Porcelain with the thickness of 1.1 mm was applied on a 3 × 8-mm central rectangular area of each sample. Afterwards, bond strengths of the samples were assessed with a Universal Testing Machine. Statistical analysis was performed with Kolmogorov-Smirnov test and T-test. RESULTS: Bond strength in the conventionally cast group equaled 74.94 ± 16.06 MPa, while in SLM group, it equaled 69.02 ± 5.77 MPa. The difference was not statistically significant (P ≤ .05). CONCLUSION: The results indicated that the bond strengths between ceramic and Co-Cr alloys made by casting and SLM methods were not statistically different.
Subject(s)
Alloys , Ceramics , Dental Porcelain , Freezing , MethodsABSTRACT
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.