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Evaluation of the differentiation of structural and physicochemical properties of orthodontic wires of AISI 304 stainless steel

Grygier D., Hoppe V., Zięty A., Rutkowska-Gorczyca M.

Engineering of Biomaterials

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2018

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Vol. 21, no. 146

8--13

EN

Wires used for orthodontic arches play a very important role in the process of orthodontic treatment. In combination with the lock attached to the tooth, they move and align the teeth along the set trajectories. Wires of stainless steel are commonly used in orthodontics for several reasons: they are characterised by high resistance to corrosion, high strength and elasticity, formability and a possibility of obtaining defined properties through cold working and annealing during production process. The purpose of the research presented in the work is the analysis of differences of the selected structural properties in the context of corrosion resistance of the orthodontic wire material. The object of the research was edge arches of the 0.016”x0.022” size made of the stainless steel type AISI 304, provided by two different producers: G&H Orthodontics and Adenta. The research methodology involved analysis of chemical and phase composition of the tested alloy, microscopic tests with application of the light and electron microscopy methods, as well as electrochemical direct current measurements. The research presented in the work has shown significant differences in structural and physical-chemical properties of the orthodontic wires made of AISI 304 type stainless steel. Despite the fact, that the tested arches were manufactured of the theoretically the same materials, but by different producers, they significantly differ in chemical composition, metallurgical purity, phase composition and corrosion resistance. In addition, it is worth noticing that the tested materials, in terms of structure, do not meet the normative requirements obligatory for biomaterials.

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Evaluation of the differentiation of structural and physicochemical properties of orthodontic wires of AlSl 304 stainless steel

Grygier D., Hoppe V., Zięty A., Rutkowska-Gorczyca M.

Engineering of Biomaterials

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2018

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Vol. 21, no. 148

14

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Microstructure, hardness measurements and cytotoxicity of medical titanium alloys manufactured using additive manufacturing

Czach J., Hoppe V., Szymczyk P., Junka A.

Aktualne Problemy Biomechaniki

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2018

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z. 15

5--12

EN

Additive Manufacturing (AM) is a rapidly developing technology that has many applications in the industry nowadays, as well as in medicine. That group of technologies have a significant advantage over traditional manufacturing processes as they enable fabrication of parts of almost any conceivable geometric shape and complex internal architecture. Electron Beam Melting (EBM) and Selective Laser Melting (SLM) are examples of Additive Manufacturing. Both use metallic powder as their building material, however energy sources used during the manufacturing process are different. First technology uses a concentrated electron beam and the second a high-energy laser. In this paper, cubic samples manufactured using EBM and SLM technologies from medical titanium alloys (Ti6Al4V and Ti6Al7Nb) were tested. Microstructure, hardness of samples and their cytotoxicity was determined. Due to very high gradients of temperature, during the AM processes, obtained microstructures are similar to multistage heat treatment of a conventionally manufactured titanium alloys. Hardness measurements show a great repeatability of results, with similar values regardless of building direction. They maintain at the level of 372 - 392 HV, which also suggests that heat treatment occurs during the process. For medical application, it is necessary that the used materials were characterized by low cytotoxicity. Due to their contact with human body, the possibility of harming cells must be eliminated. For this purpose, a biological analysis was performed under controlled conditions (37 ° C / 5% CO2) at 100% humidity, which confirmed the high purity of the materials.

PL

Wytwarzanie przyrostowe to szybko rozwijające się technologie mająca wiele zastosowań, zarówno w przemyśle, jak i medycynie. Charakteryzują się one wyraźną przewagą nad tradycyjnymi sposobami produkcji, gdyż pozwalają na wytwarzanie każdego geometrycznego kształtu, a także skomplikowaną architekturę wewnętrzną. Przetapianie Wiązką Elektronów (EBM, ang. Electron Beam Melting) oraz Selektywne Przetapianie Laserowe (SLM, ang. Selective Laser Sintering) są przykładami wytwarzania przyrostowego. Oba używają proszku metalowego jako materiału, jednakże źródła energii wykorzystywane w czasie produkcji są różne. Pierwszy używa skoncentrowanej wiązki elektronów, a drugi wysokoenergetycznego lasera. Podczas badania wyznaczono mikrostrukturę, twardość i cytotoksyczność próbek wykonanych metodami EBM i SLM z medycznych stopów tytanu (Ti6Al4V i Ti6Al7Nb).W związku z wysokimi gradientami temperaturowymi, mikrostruktury otrzymane podczas wytwarzania przyrostowego przypominają te, które daje konwencjonalna, wieloetapowa obróbka cieplna. Pomiary twardości wykazały powtarzalność wyników, z podobnymi wartościami niezależnie od kierunku budowy próbki. Znajdują się one w zakresie 372 - 392 HV, co sugeruje zachodzenie obróbki cieplnej podczas samego procesu. Użytkowanie materiału w medycynie wymaga niskiej cytotoksyczności, ze względu na kontakt z ludzkim ciałem. Próbki poddano biologicznej analizie w kontrolowanych warunkach (37 ° C / 5% CO2) w wilgotności równej 100%, co potwierdziło wysoką czystość materiałów.