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Projeto de investigação
Centro de Química Estrutural
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Publicações
Suitability of 3D printed pieces of nanocrystalline zirconia for dental applications
Publication . Branco, A. C.; Silva, R.; Santos, T.; Jorge, H.; Rodrigues, A. R.; Fernandes, R.; Bandarra, S.; Barahona, I.; Matos, A. P. A.; Lorenz, K.; Polido, M.; Colaço, R.; Serro, A. P.; Figueiredo-Pina, C. G.
Objectives:
The main goal of this work is to evaluate the suitability of nanostructured zirconia pieces obtained by robocasting additive manufacturing (AM), for dental applications.
Methods:
The density, crystalline structure, morphology/porosity, surface roughness, hardness, toughness, wettability and biocompatibility of the produced samples were compared with those of samples obtained by conventional subtractive manufacturing (SM) of a similar commercial zirconia material. Chewing simulation studies were carried out against dental human cusps in artificial saliva. The wear of the material was quantified and the wear mechanisms investigated, as well as the influence of glaze coating.
Results:
AM samples, that revealed to be biocompatible, are slightly less dense and more porous than SM samples, showing lower hardness, toughness and wettability than SM samples. After chewing tests, no wear was found both on AM and SM samples. However, the dental wear was significantly lower when AM samples were used as counterbody. Concerning the glazed samples, both coated surfaces and dental cusps suffered wear, being the cusps’ wear higher than that found for unglazed samples. More, cusps tested against AM coated samples suffered less wear comparatively to those opposed to SM coated samples.
Significance.
Overall, the results presented in this paper show that AM processed nanostructured zirconia can be used in dental restorations, with important advantages from the point of view of processing and tribological performance. Moreover, the option for glaze finishing should be carefully considered both in SM and AM processed specimens.
Tribological performance of the pair human teeth vs 3D printed zirconia : an in vitro chewing simulation study
Publication . Branco, A. C.; Silva, R.; Jorge, H.; Santos, T.; Lorenz, K.; Polido, M.; Colaço, R.; Serro, A. P.; Figueiredo-Pina, C. G.
This study aims to evaluate the tribological performance of the pair human teeth/robocasted zirconia, with a special focus on the enamel wear mechanisms. Zirconia pieces produced by robocasting (RC) and unidirectional compression (UC) were compared in terms of crystalline structure, density, porosity, hardness and toughness. Chewing simulation tests were performed against human dental cusps. The cusps wear was quantified and the wear mechanisms identified. Although most of the properties of UC and RC samples are similar, differences were observed for surface roughness and porosity. Although the samples did not suffer wear, the antagonist cusps worn in a similar way. In conclusion, robocasting seems a promising technique to produce customized zirconia dental pieces, namely in what concerns the overall tribological behaviour.
Development and validation of a simple and fast method for routine analysis of new synthetic opioids and hallucinogens in whole blood using protein precipitation and UHPLC-MS/MS
Publication . Pereira, Joana R.P.; Antunes, Mónica; Neng, N.R.; Mustra, Carla; Franco, João; Fonseca, Suzana
In forensic toxicology, the rapid and reliable detection of emerging synthetic opioids and hallucinogens is crucial for case investigations and public health monitoring. This work describes the development, optimization and validation of a simple, fast and sensitive methodology for the simultaneous analysis of 6 new synthetic opioids (carfentanil, fentanyl, isotonitazene, metonitazene, norfentanyl, and sufentanil) and 2 hallucinogens (lysergide [LSD] and mescaline), together with the main LSD metabolite 2-oxo-3-hydroxy-lysergide [LSD-OH], in whole blood samples by liquid chromatography coupled to tandem mass spectrometry. Under optimized experimental conditions, linearity was verified between 0.1 and 20 ng/mL for all analytes except mescaline (2.5-500 ng/mL), with r2 > 0.99 for 1/x weighting, and no significant carryover or matrix effects were observed. Good precision (% RSD < 13 %) and trueness (% Bias within ± 20 %) values were achieved. The estimated limit of quantification (LOQ) was 0.1 ng/mL for all compounds except mescaline (2.5 ng/mL). Authentic forensic samples were also analyzed, and positive samples for fentanyl, norfentanyl, and sufentanil were identified. The proposed methodology allows the simultaneous analysis of compounds from different families of psychoactive substances, in both postmortem and in vivo samples, using only 50 µL of whole blood. The demonstrated speed, simplicity, and effectiveness make it particularly advantageous for routine implementation in forensic toxicology laboratories.
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Descrição
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/00100/2020