Browsing by Author "Polido, M."
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- Depth of cure of bulk-fill light cured composite resins with different initiatorsPublication . Santos, A.; Proença, L.; Polido, M.; Azul, A. C.
- Efeito do envelhecimento na susceptibilidade para pigmentação de resinas compostasPublication . Costa, C. I. G.; Monteiro, P.; Mendes, José João; Polido, M.; Azul, A. C.
- Effect of bleaching teeth with hydrogen peroxide on the morphology, hydrophilicity, and mechanical and tribological properties of the enamelPublication . Rodrigues, F. T.; Serro, A. P.; Polido, M.; Ramalho, A.; Figueiredo-Pina, C. G.The tooth whitening process is intended to restore the original color of teeth. It consists of the application of oxidizing agents, including hydrogen peroxide. Although these products considerably improve the color of teeth, their effects on other properties of enamel are not fully understood. This work aimed to study the effects of hydrogen peroxide concentration on hydrophilicity, roughness, morphology, and mechanical and tribological properties of human tooth enamel. Human teeth were subjected to bleaching sessions with 6%, 15%, and 35% hydrogen peroxide to achieve a similar level of whitening. The enamel roughness and morphology were characterized by atomic force microscopy and scanning electron microscopy. Vickers microindentation hardness data were obtained. The hydrophilicity was determined using the captive bubble method. Reciprocating, ball-on-flat friction, and wear tests were conducted in artificial saliva using zirconia as the ball and polished enamel as the flat specimens. Although all three test solutions improved tooth color, they also changed the properties of the enamel. Morphological and roughness changes were observed, and there was a decrease in hardness and wear resistance. The wettability was nearly unaffected. It was found that the 15% hydrogen peroxide solution damaged the enamel the least. It was concluded that there is an ideal concentration of hydrogen peroxide for whitening treatments.
- Effect of H2O2 solution’s pH on the human enamel micro and nanowearPublication . Branco, A. C; Rodrigues, I.; Paradiso, P.; Polido, M.; Colaço, R.; Figueiredo-Pina, C. G.; Serro, A. P."The effect of 30% H2O2 solutions with different pH (2, 4 and 6) on the wear of human dental enamel was studied. Additionally, the whitening efficiency and changes in hardness and morphology were evaluated. The enamel tribological response was accessed through two different approaches: ball-on-plate and atomic force microscopy (AFM), the later following a tribological model based on a single asperity contact. The results showed differences in the specific wear rate and wear mechanisms between the two used approaches. Regardless of the tribological approach used, the wear resistance of enamel was lower for pH = 2. It was observed that pH = 6 leads to a safe and efficient whitening treatment."
- Effect of pH of H2O2 solutions on the morphology and wear resistance of human dental enamel: an AFM studyPublication . Branco, A. C.; Polido, M.; Colaço, R.; Figueiredo-Pina, C. G.; Serro, A. P.
- Estudo das propriedades mecânicas do material de restauração de Ormocer® – Admira Fusion®Publication . Marques, A. F.; Polido, M.; Brito, J.; Azul, A. C.
- Immediate microleakage in direct and indirect restorative proceduresPublication . Cruz, J. Nunes da; Azul, A. C.; Moura, P.; Polido, M.
- Influência de adesivos universais na reparação de cerâmica de Dissilicato de lítioPublication . Martins, B.; Proença, L.; Polido, M.; Azul, A. C.; Moura, P. Melo e
- Suitability of 3D printed pieces of nanocrystalline zirconia for dental applicationsPublication . 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.
- The effect of aluminum oxide sandblasting on immediate dentin sealingPublication . Belbut, M.; Mendes, José João; Polido, M.; Rua, J.; Azul, A. M.; Proença, L.