1. Estimation of the corrosion properties for titanium dental alloys produced by SLMTadeja Kosec, Mirjam Bajt Leban, Maja Ovsenik, Matej Kurnik, Igor Kopač, 2022, original scientific article Abstract: Titanium alloys are known for their excellent biocompatible properties. The development of additive-manufacturing technologies has increased the interest in the use of Ti-6Al-4V, produced by selective laser melting (SLM) method, also in dentistry, i.e., prosthodontics and orthodontics. In the present paper, the effect of laser printing parameters in the selective laser melting (SLM) process on the porosity and corrosion behavior of Ti-6Al-4V dental alloy was metallographically and electrochemically studied. All the tests were performed in artificial saliva at 37 °C. Different forms of Ti-6Al-4V alloy were selected: a reference sample, i.e., pre-fabricated milling disc in wrought condition and four different 3D-printed samples made from Ti-6Al-4V powder using the SLM method, one being heat treated. Electrochemical, spectroscopic and hardness measurements were employed in the study. It was shown that the SLM-produced Ti-6Al-4V samples with different printing parameters have similar microstructural and electrochemical properties, while the electrochemical properties of a reference and thermally treated 3D-printed sample were different, most probably due to the change in the microstructure of the alloys. The corrosion properties were related to the microstructural properties as well as to the pore density.
Keywords: Ti-6Al-4V, dental alloys, artificial saliva, selective laser melting, corrosion
Published in DiRROS: 31.05.2023; Views: 252; Downloads: 113
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2. Differences between 3-D printed and traditionally milled CoCr dental alloy from casted block in oral environmentMirjam Bajt Leban, Matej Kurnik, Igor Kopač, Matic Klug Jovičević, Bojan Podgornik, Tadeja Kosec, 2023, original scientific article Abstract: The aim of this study was to compare corrosion resistance and ion release in CoCr dental alloys with identical chemical compositions produced using different technologies (SLM – selective laser melting and milling from cast blocks) and heat treatment (SLM parts only). The corrosion properties were tested in artificial saliva, artificial saliva with fluoride ions, and artificial saliva with added lactic acid to simulate inflammations. The study included electrochemical tests, microstructural investigation and ion release tests in the three different environments for a total of 42 days. The best performance of CoCr as a result of potentiodynamic polarization was observed in the artificial saliva with added lactic acid, which is in contradiction with the highest ion release measured from all the materials tested and electrochemical impedance spectroscopy that showed a deterioration of the passive layer in an acidic environment. Microstructural investigation revealed that different phases precipitated by heat treatment trigger increased release of Mo and W ions. The printing method does not raise critically ion release from CoCr alloy, while the state of the surface greatly impacts the extent of the ion release. This study demonstrates the importance of an interdisciplinary approach to the study of corrosion and biocompatibility in dental alloys.
Keywords: CoCr dental alloy, selective laser melting, corrosion, ion release, artificial saliva
Published in DiRROS: 29.05.2023; Views: 335; Downloads: 281
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3. Robust saliva-based RNA extraction-free one-step nucleic acid amplification test for mass SARS-CoV-2 monitoringEva Rajh, Tina Šket, Arne Praznik, Petra Sušjan, Alenka Šmid, Dunja Urbančič, Irena Mlinarič-Raščan, Polona Kogovšek, Tina Demšar, Mojca Milavec, Katarina Prosenc, Žiga Jensterle, Mihaela Zidarn, Viktorija Tomič, Gabriele Turel, Tatjana Lejko-Zupanc, Roman Jerala, Mojca Benčina, 2021, original scientific article Abstract: Early diagnosis with rapid detection of the virus plays a key role in preventing the spread of infection and in treating patients effectively. In order to address the need for a straightforward detection of SARS-CoV-2 infection and assessment of viral spread, we developed rapid, sensitive, extraction-free one-step reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and reverse transcription loop-mediated isothermal amplification (RT-LAMP) tests for detecting SARS-CoV-2 in saliva. We analyzed over 700 matched pairs of saliva and nasopharyngeal swab (NSB) specimens from asymptomatic and symptomatic individuals. Saliva, as either an oral cavity swab or passive drool, was collected in an RNA stabilization buffer. The stabilized saliva specimens were heat-treated and directly analyzed without RNA extraction. The diagnostic sensitivity of saliva-based RT-qPCR was at least 95% in individuals with subclinical infection and outperformed RT-LAMP, which had at least 70% sensitivity when compared to NSBs analyzed with a clinical RT-qPCR test. The diagnostic sensitivity for passive drool saliva was higher than that of oral cavity swab specimens (95% and 87%, respectively). A rapid, sensitive one-step extraction-free RT-qPCR test for detecting SARS-CoV-2 in passive drool saliva is operationally simple and can be easily implemented using existing testing sites, thus allowing high-throughput, rapid, and repeated testing of large populations. Furthermore, saliva testing is adequate to detect individuals in an asymptomatic screening program and can help improve voluntary screening compliance for those individuals averse to various forms of nasal collections.
Keywords: SARS-CoV-2, COVID-19, COVID-19 serological testing, real-time polymerase chain reaction, saliva, oral cavity swab, passive drool, pooling
Published in DiRROS: 09.11.2021; Views: 1076; Downloads: 541
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