Selective laser melting and sintering technique of the cobalt-chromium dental alloy

Abstract

Introduction/Objective The objective of this paper is to describe the microstructure and mechanical properties of sintered Co-Cr alloy and to emphasize its advantages and disadvantages with respect to the microstructure and mechanical properties of cast Co-Cr alloy. Methods Base Co-Cr alloy, EOSint M EOS Co-Cr SP2 (EOS GmbH, Munch, Germany), was used for the purpose of this research as the base material for sintering metal structures of metal-ceramic restorations. Metal sintering was conducted by using EOSint M 280 device of German origin in a stream of neutral gas-argon. After that, the alloy was heated over a period of 20 minutes at the temperature of 800°C. The chemical composition of the alloy was determined by energy dispersive spectroscopy. Microstructure of the tested alloy samples was examined under an optical metallographic and scanning electron microscope. Physical and mechanical properties were measured in a universal testing machine. The samples were prepared according to the standard ISO 527-1:1993. Results Chemical composition of the sintered Co-Cr alloy, determined by applying energy dispersive spectroscopy, indicated the same qualitative but different quantitative composition compared to cast Co-Cr alloys. The microstructure of the sintered Co-Cr alloy is lamellar in nature, with two dominant phases: ξ-Co and/or ξ-Cr (fcc-face-centered cubic) and γ-Co (hcp-hexagonal close-packed). Mechanical properties of the Co-Cr alloy obtained by applying selective laser melting technology compared to the cast Co-Cr alloy are superior or approximately the same. Conclusion Selective laser melting of the Co-Cr alloy is a good example of new technologies based on digitization. Together with other digitized procedures, this technology is an introduction to a new era in dentistry popularly called Dentistry 4.0. The advantages of the selective laser melting technology with respect to the conventional technology of casting Co-Cr alloy metal structures are precise metal structure fitting and eco-friendly technology.

Investigation of CoCr Dental Alloy: Example from a Casting Workflow Standpoint

“…The instructions for working with the CoCr alloy state to use individual crucibles for preventing cross-contaminations between other materials and to clean the crucible after use [26]. In practice, the technician cleans the ceramic crucible with a knife, removing any residual material large enough for removal manually.…”

Dentistry 4.0 concept in designing and manufacturing removable partial denture frameworks

“…The Dentistry 4.0 approach requires the involvement of people of different professions and the knowledge of new generation dental materials, new technologies and application possibilities of Cyber-physical systems in Dentistry. Materials used today in printing the RPD metal framework are highly sophisticated materials 14,[18][19][20] . Today, the most precise metal framework RPDs are obtained using special Co-Cr "type 5" according to ISO 22674 (e.g., EOS Cobalt-Chrome RPD, Krailling, Germany; Mediloy S-Co, BEGO, Bremen, Germany).…”

The Fourth Industrial Revolution`s impact on dentistry

“…The framework of a removable denture is an example of the superiority of this technology over traditional methods. A digital impression of a partially edentulous patient is sent to the laboratory via the internet and serves as basis for the virtual model from which the framework is manufactured, in five steps, using SLM technology, Figures 8 and 9 [17][18][19][20]. In order to transfer the physical framework of the denture to a real model and send it to the dental office, a real working polymer model is made on a 3D printer (Dental Model Resin).…”