Comparison of the microstructure and phase stability of as-cast, CAD/CAM and powder metallurgy manufactured Co–Cr dental alloys

Li, Kai Chun; Prior, David J.; Waddell, John Neil; Swain, Michael V.

doi:10.1016/j.dental.2015.10.010

Cited by 40 publications

(29 citation statements)

References 30 publications

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“…Techniques such as stereolithography were implemented to manufacture resin models for posterior manufacture of dental prostheses (crowns and bridges) by conventional process of lost wax castings. Mechanical, chemical, and microstructural properties are evaluated in comparison to new AM technologies, for example, the selective laser melting (SLM) in relation to conventional techniques as lost wax casting [21][22][23]. In this way, the preparation of medical and dental components provides customized final components with high mechanical properties, compared to conventional techniques (see Figure 1) [24].…”

Section: Introductionmentioning

confidence: 99%

Perspective of Additive Manufacturing Selective Laser Melting in Co-Cr-Mo Alloy in the Consolidation of Dental Prosthesis

Mergulhão¹,

Podestá²,

Neves³

2018

Biomaterials in Regenerative Medicine

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This chapter seeks to compare the properties of samples manufactured by additive manufacturing (AM) by the selective laser melting (SLM) technology and compare with the precision casting (PC) processes using the Co-Cr-Mo (ASTM F75) alloy to manufacture of dental prosthesis. This AM process can be manufactured three-dimensional models by means of a laser beam that completely melts particles of powder deposited layer by layer. However, it is still relevant to know the properties of: performance, dimensional, mechanical and microstructural of this laser melting process and compare with a convencional process. The results of mechanical evaluation showed that the SLM technique provides superior mechanical properties compared to those obtained by the PC technique. It is possible to verify that the consolidation by SLM technique results in lower presence of porosity than PC technique. In addition, PC samples presented a gross dendritic microstructure of casting process. Microstructural analysis of SLM samples results in a characteristic morphology of layer manufacturing with ultrafine grains and a high chemical homogeneity. In this way, the development of the present study evidenced to improve the manufacture of customized components (copings) using the SLM technology.

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Section: Introductionmentioning

confidence: 99%

Perspective of Additive Manufacturing Selective Laser Melting in Co-Cr-Mo Alloy in the Consolidation of Dental Prosthesis

Mergulhão¹,

Podestá²,

Neves³

2018

Biomaterials in Regenerative Medicine

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“…18 To widen access to this technology, a Co-Cr alloy for CAD/CAM has been developed (Ceramill Sintron) and presented in the form of metal blocks composed of pressed powder and binding polymers to increase stability. 19 The manufacturing method using agglutinated Co-Cr allows machining of dry material with subtractive techniques using less robust equipment. 18 The processing steps involved in Co-Cr alloy preparation are comparable to those of zirconia because the material needs to be machined into relatively high dimensions then immediately sintered in a special furnace in the presence of argon to achieve its chemical and mechanical properties, which are comparable to those of cast Co-Cr alloys.…”

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confidence: 99%

Scanning Electron Microscopy Analysis of the Adaptation of Single-Unit Screw-Retained Computer-Aided Design/Computer-Aided Manufacture Abutments After Mechanical Cycling

Markarian¹,

Galles²,

França³

2018

Int J Oral Maxillofac Implants

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Purpose: To measure the microgap between dental implants and custom abutments fabricated using different computer-aided design/computer-aided manufacture (CAD/CAM) methods before and after mechanical cycling. Materials and Methods: CAD software (Dental System, 3Shape) was used to design a custom abutment for a single-unit, screw-retained crown compatible with a 4.1-mm external hexagon dental implant. The resulting stereolithography file was sent for manufacturing using four CAD/CAM methods (n = 40): milling and sintering of zirconium dioxide (ZO group), cobalt-chromium (Co-Cr) sintered via selective laser melting (SLM group), fully sintered machined Co-Cr alloy (MM group), and machined and sintered agglutinated Co-Cr alloy powder (AM group). Prefabricated titanium abutments (TI group) were used as controls. Each abutment was placed on a dental implant measuring 4.1 × 11 mm (SA411, SIN) inserted into an aluminum block. Measurements were taken using scanning electron microscopy (SEM) (×4,000) on four regions of the implant-abutment interface (IAI) and at a relative distance of 90 degrees from each other. The specimens were mechanically aged (1 million cycles, 2 Hz, 100 N, 37°C) and the IAI width was measured again using the same approach. Data were analyzed using two-way analysis of variance, followed by the Tukey test. Results: After mechanical cycling, the best adaptation results were obtained from the TI (2.29 ± 1.13 µm), AM (3.58 ± 1.80 µm), and MM (1.89 ± 0.98 µm) groups. A significantly worse adaptation outcome was observed for the SLM (18.40 ± 20.78 µm) and ZO (10.42 ± 0.80 µm) groups. Mechanical cycling had a marked effect only on the AM specimens, which significantly increased the microgap at the IAI. Conclusion: Custom abutments fabricated using fully sintered machined Co-Cr alloy and machined and sintered agglutinated Co-Cr alloy powder demonstrated the best adaptation results at the IAI, similar to those obtained with commercial prefabricated titanium abutments after mechanical cycling. The adaptation of custom abutments made by means of SLM or milling and sintering of zirconium dioxide were worse both before and after mechanical cycling.

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“…The XRD and SEM/EBSD analysis results (Figures 1 and 2) indicated that all the three alloys consisted of γ and ε phases. In the 1350 • C and 1450 • C groups, the formation of the γ phase was more predominant than that of the ε phase, probably because a majority of the γ phase was retained due to more rapid cooling [19][20][21]. In addition, the 1450 • C group showed a higher peak intensity of the γ phase than the 1350 • C group, indicating greater grain growth and enhanced crystallographic orientation [22].…”

Section: Discussionmentioning

confidence: 97%

Effect of Different Post-Sintering Temperatures on the Microstructures and Mechanical Properties of a Pre-Sintered Co–Cr Alloy

Jang

Min

Hong

et al. 2018

Metals

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Although a cobalt–chromium (Co–Cr) blank in a pre-sintered state has been developed, there are few data on the optimal temperature for the alloy in terms of the desired mechanical properties. A metal block (Soft Metal, LHK, Chilgok, Korea) was milled to produce either disc-shaped or dumbbell-shaped specimens. All the milled specimens were post-sintered in a furnace at 1250, 1350 or 1450 °C. The microstructures, shrinkage and density of the three different alloys were investigated using the disc-shaped specimens. The mechanical properties were investigated with a tensile test according to ISO 22674 (n = 6). The number and size of the pores in the alloys decreased with increased temperature. The shrinkage and density of the alloys increased with temperature. In the 1250 °C alloy, the formation of the ε (hexagonal close-packed) phase was more predominant than that of the γ (face-centered cubic) phase. The 1350 °C and 1450 °C alloys showed γ phase formation more predominantly. Carbide formation was increased along with temperature. The 1450 °C group showed the largest grain size among the three groups. In general, the 1350 °C group exhibited mechanical properties superior to the 1250 °C and 1450 °C groups. These findings suggest that 1350 °C was the most optimal post-sintering temperature for the pre-sintered blank.

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Comparison of the microstructure and phase stability of as-cast, CAD/CAM and powder metallurgy manufactured Co–Cr dental alloys

Cited by 40 publications

References 30 publications

Perspective of Additive Manufacturing Selective Laser Melting in Co-Cr-Mo Alloy in the Consolidation of Dental Prosthesis

Perspective of Additive Manufacturing Selective Laser Melting in Co-Cr-Mo Alloy in the Consolidation of Dental Prosthesis

Scanning Electron Microscopy Analysis of the Adaptation of Single-Unit Screw-Retained Computer-Aided Design/Computer-Aided Manufacture Abutments After Mechanical Cycling

Effect of Different Post-Sintering Temperatures on the Microstructures and Mechanical Properties of a Pre-Sintered Co–Cr Alloy

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