Introduction: The aim of the present study was to evaluate the fiber post surface after plasma an... more Introduction: The aim of the present study was to evaluate the fiber post surface after plasma and usual treatments and the adhesion between treated fiber posts and Rely X Unicem resin cement (3M ESPE, St Paul, MN). Methods: Flat fiber posts were divided into 6 groups according to surface treatment: silane, hydrofluoric acid, hydrofluoric acid plus silane, plasma polymerization with argon, ethylenediamine plasma (EDA), and the control group. A goniometer was used to measure the contact angle between the groups with water or resin cement. Scanning electron microscopy and electron dispersive spectroscopy were used to examine the topography and chemical changes in the post surfaces after treatment. Push-out tests were performed using a universal testing machine to evaluate the adhesion strength between treated fiber posts and resin cement. Results: In the contact angle with water, the most hydrophilic surface was observed in samples treated with argon plasma, followed by treatments with silane and hydrofluoric acid plus silane. The hydrophobic characteristic was observed with EDA and hydrofluoric acid. The contact angle with dual resin cement showed lower values with argon and EDA, followed by silane and hydrofluoric acid plus silane. Electron dispersive spectroscopy analyses showed chemical modifications in the surface after different treatments although topographic changes were verified only with EDA plasma compared with the control. Push-out results did not show differences between groups compared with the control, except for EDA plasma treatment. Conclusions: Plasma treatment favored the wettability of the post surface by modifying it chemically. Adhesion improvement was only observed after EDA treatment.
Stability upon heat treatment of magnetron sputtered Ti-SiO 2 solar-absorbing cermet thin films w... more Stability upon heat treatment of magnetron sputtered Ti-SiO 2 solar-absorbing cermet thin films was studied via TEM and XPS. The films, produced using Ti and SiO 2 targets, consists of an infrared-reflective metallic base layer (or metallic substrate), two cermet solar-absorbing layersone with a high metal volume fraction (HMVF) and another with low metal volume fraction (LMVF)and a SiO 2 anti-reflective layer. The HMVF layer was composed of nanometric Ti crystals embedded on an amorphous Ti-Si-O matrix, whereas the LMVF layer consisted only of an amorphous Ti-Si-O matrix. The influence of the base layer metal and both cermet layer thicknesses on the solar absorbance (α) and thermal emittance (ε) was studied. Films reached a α/ε ratio of 43.0. HMVF layer thickness had a strong influence over thermal emittance, while LMVF layer had more influence over solar absorbance. Thermal stability was tested for selected samples, indicating that films exhibit resistance up to at least 300°C on air. Reasons for this stability are related either to the formation of a Ti-Si barrier layer for vacuum treated samples or to the further oxidation of the film for the samples treated on air.
In this study, it was possible to evidence the efficiency of the use of carbon fiber coating in c... more In this study, it was possible to evidence the efficiency of the use of carbon fiber coating in concrete structures and its application to promote the protection and maintenance of these materials, seeking to prolong the useful life of this type of structure. From mechanical tests, such as compressive strength, it was possible to observe an increase of 37% in the breaking load, as well as an increase of about 40% in compressive strength, when compared to tests with pure concrete. Therefore, the results pointed to the optimization of the mechanical properties of the structure, coated with carbon fiber and cured with epoxy resin. In other words, the use of this external load combined with epoxy resin was an important element in concrete reconstruction and reinforcement. Another interesting point was the issue of the high fiber rigidity observed in the AFM, allowing an excellent interaction with the resin in the coating of the specimen. The study showed that this type of coating can be used for the recovery of structures, as well as a reinforcement element, since many projects have difficulties with the high maintenance cost, as well as the daily monitoring of concrete structures.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Efeito do plasma de oxigênio na dentina previamente exposta ao NaOCl Effect of oxygen plasma on d... more Efeito do plasma de oxigênio na dentina previamente exposta ao NaOCl Effect of oxygen plasma on dentin exposed to NaOCl
RESUMO O microscópio de força atômica (AFM) tem sido usado para a caracterização microestrutural ... more RESUMO O microscópio de força atômica (AFM) tem sido usado para a caracterização microestrutural de ligantes asfál"cos, a par"r da iden"ficação das suas frações cons"tuintes. Adicionalmente, estudos mais recentes têm determinado propriedades mecânicas dos componentes dos ligantes, tais como fluência e módulo de relaxação, a par"r de ensaios de indentação no AFM. No entanto, o processo de preparação das amostras usadas nestes ensaios geralmente não é descrito detalhadamente na literatura. Este trabalho tem o obje"vo de avaliar diferentes métodos de preparação de amostras, empregando imagens topográficas usadas para caracterizações microestruturais. Para tal, microestruturas de um ligante ob"das de amostras preparadas usando diferentes métodos foram avaliadas e os resultados contribuíram para iden"ficar o processo de preparação mais o"mizado.
Objective: to evaluate the bond strength of composite resin to bovine enamel after bleached surfa... more Objective: to evaluate the bond strength of composite resin to bovine enamel after bleached surfaces were treated with two different reducing substances. Material and Methods: bovine teeth were embedded, had their buccal face planed and were divided into 4 groups (n=10). Group 1 (control) was not subjected to bleaching, acid etched and restored with adhesive and composite resin. Groups 2 to 4 were bleached with 35% hydrogen peroxide during 4 consecutive days for 40 min/session and subjected or not to the proposed surface treatments before being restored. Group 2 was bleached and restored, while Groups 3 and 4 were bleached and immersed in sodium thiosulfate or sodium ascorbate solution, respectively, before being restored. Samples were stored for 24 hours and then submitted to a microshear strength test. Results: according to the statistical tests, the bond strength results using reducing agents were similar to those of the control group and statistically different from those of the only-bleached group. Conclusion: the reducing solutions were capable of recovering the bond strength of freshly bleached teeth without statistically significant difference between them.
Avaliar os efeitos das soluções de hipoclorito de sódio 5,25% (NaOCl) e clorexidina 2% (CHX) na t... more Avaliar os efeitos das soluções de hipoclorito de sódio 5,25% (NaOCl) e clorexidina 2% (CHX) na topografia e rugosidade de superfícies de guta-percha (GP) e Resilon (RE). Materiais e método: Superfícies planas de guta-percha e Resilon foram utilizadas. Seis grupos foram avaliados: Controle GP (CGP)-guta-percha imersa em água destilada (AD) por 1 minuto; CHX GP (CHXGP)-guta-percha imersa em CHX por 1 minuto e em seguida lavada com AD; NaOCl GP (NGP)-guta-percha imersa em NaOCl por 1 minuto e em seguida lavada com AD; Controle RE (CR)-Resilon imerso em AD por 1 minuto; CHX RE (CHXR)-Resilon imerso em CHX por 1 minuto e em seguida lavado com AD; NaO-Cl RE (NR)-Resilon imerso em NaOCl por 1 minuto e em seguida lavado com AD. Microscopia eletrônica de varredura (MEV), Espectroscopia de energia dispersiva (EDS) e Perfilometria foram utilizadas para análise das amostras antes e após os tratamentos. Os valores de rugosidade obtidos por perfilomentria foram avaliados estatisticamente utilizando-se os testes de Kruskal-Wallis e Mann-Whitney (p < 0,05). MEV e EDS foram avaliados qualitativamente. Resultados: Os valores inicial e final de rugosidade foram respectivamente: CGP
Efeito de diferentes soluções utilizadas como irrigante final na superfície dentinária: análise d... more Efeito de diferentes soluções utilizadas como irrigante final na superfície dentinária: análise de rugosidade Effect of different solutions used as final irrigant on dentin surface: roughness analysis Maíra do PRADO a , Danielle Ferreira de ASSIS a , Renata Antoun SIMÃO a
Abstract Amorphous aluminum alloys have been evaluated as suitable thin films for protective coat... more Abstract Amorphous aluminum alloys have been evaluated as suitable thin films for protective coatings. Magnetron sputtering deposition may provide the necessary conditions for preparing such alloys due to its far-from-equilibrium deposition conditions. In this work, Al-Ti-C nanocomposite films were deposited by magnetron sputtering technique using TiC and Al targets. The produced films are mainly composed of Al nanocrystallites embedded into an amorphous matrix. Films effective hardness varied in the 6.4–8.2 GPa range, while their elastic modulus ranged from 109 up to 134 GPa. The higher the TiC/Al target power ratio, the harder the film. Topographic atomic force microscopy (AFM) images showed that films are mainly constituted by unevenly dispersed grains. Also, the dark phase angle fraction calculation derived from the phase angle contrast AFM images could be correlated with the deposited Al–Ti–C films hardness measured by nanoindentation tests; the higher the surface dark phase angle fraction, the harder the Al–Ti–C films.
Surface treatment of fiber-reinforced posts can increase adhesion, especially on the post/resin c... more Surface treatment of fiber-reinforced posts can increase adhesion, especially on the post/resin cement interface. The purpose of this in vitro study was to evaluate the effect of different surface treatments on fiber post cemented with a self-adhesive system. Sixty fiberglass epoxy resin posts were cleaned, dried and divided into 6 groups (n = 10): Control (no surface treatment), silane (silane coupling agent was applied homogeneously on surface), 24% hydrogen peroxide (H 2 O 2) (immersion during 1 min), blasting (blasting with aluminum oxide for 30 sec), NH 3 plasma (plasma treatment for 3 min) and HMDSO plasma (plasma treatment for 15 min). After the treatments, posts were inserted into a silicon matrix that was filled with the resin cement RelyX U200. Afterwards, the post/cement specimens were cut perpendicularly to the long axis of the posts into six 1.0 mm thick discs and submitted to a push-out bond strength (POBS) test. Failure pattern was classified in 5 types: Type I: Cohesive in post; Type II: Cohesive in cement; Type III: Cohesive post and cement; Type IV: Adhesive post/cement; and Type V: Mixed (association between cohesive and adhesive). Data were analyzed by one-way ANOVA and Tukey HSD' post hoc test ( = 0.05). Silane (15.94 ± 6.5), blasting (13.13 ± 3.6), NH 3 plasma (14.44 ± 4.0) and HMDSO plasma (13.23± 5.3) showed higher POBS when compared to control (p < 0.05) and similar among them. H 2 O 2 (9.40 ± 4.0) treatment showed POBS values statistically similar to control (9.65 ± 3.6). Failures were predominantly cohesive post and cement, type III, in all groups. In conclusion, surface treatments influenced in the adhesion of fiberglass post with the self-adhesive cement RelyX U200. Silane, blasting with aluminum oxide and plasmas (NH 3 and HMDSO) showed results superior to 24% hydrogen peroxide.
Introduction: The aim of the present study was to evaluate the fiber post surface after plasma an... more Introduction: The aim of the present study was to evaluate the fiber post surface after plasma and usual treatments and the adhesion between treated fiber posts and Rely X Unicem resin cement (3M ESPE, St Paul, MN). Methods: Flat fiber posts were divided into 6 groups according to surface treatment: silane, hydrofluoric acid, hydrofluoric acid plus silane, plasma polymerization with argon, ethylenediamine plasma (EDA), and the control group. A goniometer was used to measure the contact angle between the groups with water or resin cement. Scanning electron microscopy and electron dispersive spectroscopy were used to examine the topography and chemical changes in the post surfaces after treatment. Push-out tests were performed using a universal testing machine to evaluate the adhesion strength between treated fiber posts and resin cement. Results: In the contact angle with water, the most hydrophilic surface was observed in samples treated with argon plasma, followed by treatments with silane and hydrofluoric acid plus silane. The hydrophobic characteristic was observed with EDA and hydrofluoric acid. The contact angle with dual resin cement showed lower values with argon and EDA, followed by silane and hydrofluoric acid plus silane. Electron dispersive spectroscopy analyses showed chemical modifications in the surface after different treatments although topographic changes were verified only with EDA plasma compared with the control. Push-out results did not show differences between groups compared with the control, except for EDA plasma treatment. Conclusions: Plasma treatment favored the wettability of the post surface by modifying it chemically. Adhesion improvement was only observed after EDA treatment.
Stability upon heat treatment of magnetron sputtered Ti-SiO 2 solar-absorbing cermet thin films w... more Stability upon heat treatment of magnetron sputtered Ti-SiO 2 solar-absorbing cermet thin films was studied via TEM and XPS. The films, produced using Ti and SiO 2 targets, consists of an infrared-reflective metallic base layer (or metallic substrate), two cermet solar-absorbing layersone with a high metal volume fraction (HMVF) and another with low metal volume fraction (LMVF)and a SiO 2 anti-reflective layer. The HMVF layer was composed of nanometric Ti crystals embedded on an amorphous Ti-Si-O matrix, whereas the LMVF layer consisted only of an amorphous Ti-Si-O matrix. The influence of the base layer metal and both cermet layer thicknesses on the solar absorbance (α) and thermal emittance (ε) was studied. Films reached a α/ε ratio of 43.0. HMVF layer thickness had a strong influence over thermal emittance, while LMVF layer had more influence over solar absorbance. Thermal stability was tested for selected samples, indicating that films exhibit resistance up to at least 300°C on air. Reasons for this stability are related either to the formation of a Ti-Si barrier layer for vacuum treated samples or to the further oxidation of the film for the samples treated on air.
In this study, it was possible to evidence the efficiency of the use of carbon fiber coating in c... more In this study, it was possible to evidence the efficiency of the use of carbon fiber coating in concrete structures and its application to promote the protection and maintenance of these materials, seeking to prolong the useful life of this type of structure. From mechanical tests, such as compressive strength, it was possible to observe an increase of 37% in the breaking load, as well as an increase of about 40% in compressive strength, when compared to tests with pure concrete. Therefore, the results pointed to the optimization of the mechanical properties of the structure, coated with carbon fiber and cured with epoxy resin. In other words, the use of this external load combined with epoxy resin was an important element in concrete reconstruction and reinforcement. Another interesting point was the issue of the high fiber rigidity observed in the AFM, allowing an excellent interaction with the resin in the coating of the specimen. The study showed that this type of coating can be used for the recovery of structures, as well as a reinforcement element, since many projects have difficulties with the high maintenance cost, as well as the daily monitoring of concrete structures.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Efeito do plasma de oxigênio na dentina previamente exposta ao NaOCl Effect of oxygen plasma on d... more Efeito do plasma de oxigênio na dentina previamente exposta ao NaOCl Effect of oxygen plasma on dentin exposed to NaOCl
RESUMO O microscópio de força atômica (AFM) tem sido usado para a caracterização microestrutural ... more RESUMO O microscópio de força atômica (AFM) tem sido usado para a caracterização microestrutural de ligantes asfál"cos, a par"r da iden"ficação das suas frações cons"tuintes. Adicionalmente, estudos mais recentes têm determinado propriedades mecânicas dos componentes dos ligantes, tais como fluência e módulo de relaxação, a par"r de ensaios de indentação no AFM. No entanto, o processo de preparação das amostras usadas nestes ensaios geralmente não é descrito detalhadamente na literatura. Este trabalho tem o obje"vo de avaliar diferentes métodos de preparação de amostras, empregando imagens topográficas usadas para caracterizações microestruturais. Para tal, microestruturas de um ligante ob"das de amostras preparadas usando diferentes métodos foram avaliadas e os resultados contribuíram para iden"ficar o processo de preparação mais o"mizado.
Objective: to evaluate the bond strength of composite resin to bovine enamel after bleached surfa... more Objective: to evaluate the bond strength of composite resin to bovine enamel after bleached surfaces were treated with two different reducing substances. Material and Methods: bovine teeth were embedded, had their buccal face planed and were divided into 4 groups (n=10). Group 1 (control) was not subjected to bleaching, acid etched and restored with adhesive and composite resin. Groups 2 to 4 were bleached with 35% hydrogen peroxide during 4 consecutive days for 40 min/session and subjected or not to the proposed surface treatments before being restored. Group 2 was bleached and restored, while Groups 3 and 4 were bleached and immersed in sodium thiosulfate or sodium ascorbate solution, respectively, before being restored. Samples were stored for 24 hours and then submitted to a microshear strength test. Results: according to the statistical tests, the bond strength results using reducing agents were similar to those of the control group and statistically different from those of the only-bleached group. Conclusion: the reducing solutions were capable of recovering the bond strength of freshly bleached teeth without statistically significant difference between them.
Avaliar os efeitos das soluções de hipoclorito de sódio 5,25% (NaOCl) e clorexidina 2% (CHX) na t... more Avaliar os efeitos das soluções de hipoclorito de sódio 5,25% (NaOCl) e clorexidina 2% (CHX) na topografia e rugosidade de superfícies de guta-percha (GP) e Resilon (RE). Materiais e método: Superfícies planas de guta-percha e Resilon foram utilizadas. Seis grupos foram avaliados: Controle GP (CGP)-guta-percha imersa em água destilada (AD) por 1 minuto; CHX GP (CHXGP)-guta-percha imersa em CHX por 1 minuto e em seguida lavada com AD; NaOCl GP (NGP)-guta-percha imersa em NaOCl por 1 minuto e em seguida lavada com AD; Controle RE (CR)-Resilon imerso em AD por 1 minuto; CHX RE (CHXR)-Resilon imerso em CHX por 1 minuto e em seguida lavado com AD; NaO-Cl RE (NR)-Resilon imerso em NaOCl por 1 minuto e em seguida lavado com AD. Microscopia eletrônica de varredura (MEV), Espectroscopia de energia dispersiva (EDS) e Perfilometria foram utilizadas para análise das amostras antes e após os tratamentos. Os valores de rugosidade obtidos por perfilomentria foram avaliados estatisticamente utilizando-se os testes de Kruskal-Wallis e Mann-Whitney (p < 0,05). MEV e EDS foram avaliados qualitativamente. Resultados: Os valores inicial e final de rugosidade foram respectivamente: CGP
Efeito de diferentes soluções utilizadas como irrigante final na superfície dentinária: análise d... more Efeito de diferentes soluções utilizadas como irrigante final na superfície dentinária: análise de rugosidade Effect of different solutions used as final irrigant on dentin surface: roughness analysis Maíra do PRADO a , Danielle Ferreira de ASSIS a , Renata Antoun SIMÃO a
Abstract Amorphous aluminum alloys have been evaluated as suitable thin films for protective coat... more Abstract Amorphous aluminum alloys have been evaluated as suitable thin films for protective coatings. Magnetron sputtering deposition may provide the necessary conditions for preparing such alloys due to its far-from-equilibrium deposition conditions. In this work, Al-Ti-C nanocomposite films were deposited by magnetron sputtering technique using TiC and Al targets. The produced films are mainly composed of Al nanocrystallites embedded into an amorphous matrix. Films effective hardness varied in the 6.4–8.2 GPa range, while their elastic modulus ranged from 109 up to 134 GPa. The higher the TiC/Al target power ratio, the harder the film. Topographic atomic force microscopy (AFM) images showed that films are mainly constituted by unevenly dispersed grains. Also, the dark phase angle fraction calculation derived from the phase angle contrast AFM images could be correlated with the deposited Al–Ti–C films hardness measured by nanoindentation tests; the higher the surface dark phase angle fraction, the harder the Al–Ti–C films.
Surface treatment of fiber-reinforced posts can increase adhesion, especially on the post/resin c... more Surface treatment of fiber-reinforced posts can increase adhesion, especially on the post/resin cement interface. The purpose of this in vitro study was to evaluate the effect of different surface treatments on fiber post cemented with a self-adhesive system. Sixty fiberglass epoxy resin posts were cleaned, dried and divided into 6 groups (n = 10): Control (no surface treatment), silane (silane coupling agent was applied homogeneously on surface), 24% hydrogen peroxide (H 2 O 2) (immersion during 1 min), blasting (blasting with aluminum oxide for 30 sec), NH 3 plasma (plasma treatment for 3 min) and HMDSO plasma (plasma treatment for 15 min). After the treatments, posts were inserted into a silicon matrix that was filled with the resin cement RelyX U200. Afterwards, the post/cement specimens were cut perpendicularly to the long axis of the posts into six 1.0 mm thick discs and submitted to a push-out bond strength (POBS) test. Failure pattern was classified in 5 types: Type I: Cohesive in post; Type II: Cohesive in cement; Type III: Cohesive post and cement; Type IV: Adhesive post/cement; and Type V: Mixed (association between cohesive and adhesive). Data were analyzed by one-way ANOVA and Tukey HSD' post hoc test ( = 0.05). Silane (15.94 ± 6.5), blasting (13.13 ± 3.6), NH 3 plasma (14.44 ± 4.0) and HMDSO plasma (13.23± 5.3) showed higher POBS when compared to control (p < 0.05) and similar among them. H 2 O 2 (9.40 ± 4.0) treatment showed POBS values statistically similar to control (9.65 ± 3.6). Failures were predominantly cohesive post and cement, type III, in all groups. In conclusion, surface treatments influenced in the adhesion of fiberglass post with the self-adhesive cement RelyX U200. Silane, blasting with aluminum oxide and plasmas (NH 3 and HMDSO) showed results superior to 24% hydrogen peroxide.
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