ABSTRACT
Abstract This study verified the effect of surface treatments of the zirconia-reinforced lithium disilicate ceramic bonded to resin cement. Ceramic blocks were divided according to treatments (n=10): FA+SRX (Fluoric acid + silane RX), FA+MDP (Fluoric acid + MDP), FA+SCF+MDP (Fluoric acid + silane CF + MDP), FA+MEP (Fluoric acid + MEP), and MEP (Self-etch primer). Resin cement cylinders were made in the ceramic blocks, photoactivated with 1,200 mW/cm² for 40s, stored in water at 37°C for 24h, and evaluated by the microshear strength test, optical failure descriptive analysis (%), surface characterization (SEM) and contact angle (Goniometer). Other samples were submitted to 10,000 thermocycles between 5°C and 55°C. Bond strength data were submitted to two-way ANOVA and Tukey's test. Contact angle to one-way ANOVA and Games-Howell's test (5%). At 24h, MEP showed higher bond strength, and FA+SRX the lower. FA+MDP and FA+SCF+MDP showed similar values and FA+MEP was intermediate. After thermocycling, FA+SCF+MDP, FA+MEP, and MEP showed higher values, and FA+SRX the lower while FA+MDP was intermediate. When the periods were compared, FA+MDP, FA+SCF+MDP, FA+MEP, and MEP showed higher values for 24h while FA+SRX was similar. SEM showed retentive surface and crystal exposure when treated with FA+SCF+MDP. The less retentive surface was obtained with MEP, and the other treatments promoted intermediate irregularities. In conclusion, surface treatment and thermocycling promoted different values of adhesive strength and contact angle in a zirconia-reinforced lithium silicate ceramic. Failures were predominantly adhesive, and the ceramic surface was characterized by different levels of roughness and selective exposure of crystals.
Resumo O objetivo neste estudo foi verificar o efeito de tratamentos de superfície da cerâmica de dissilicato de lítio reforçada com zircônia fixada ao cimento resinoso. Os blocos cerâmicos foram separados de acordo com os tratamentos (n=10): AF+SRX (ácido fluorídrico + silano), AF+MDP (ácido fluorídrico + MDP), AF+SCF+MDP (ácido fluorídrico + silano + MDP), AF+MEP (Ácido fluorídrico + MEP) e MEP (Primer auto condicionante). Cilindros de cimento resinoso foram confeccionados em cada bloco cerâmico, foto ativados com 1.200 mW/cm² por 40 segundos, armazenados em água a 37°C por 24 horas e avaliados pelo teste de resistência ao micro cisalhamento, falha por análise descritiva em microscopia óptica (%), caracterização da superfície por imagens MEV e ângulo de contato (Goniômetro). Outras amostras foram submetidas a 10.000 ciclos térmicos (5° e 55°C). Os dados de resistência de união foram submetidos a ANOVA dois fatores e teste de Tukey (5%). Ângulo de contato com ANOVA um fator e teste de Games-Howell (5%). Em 24 horas, MEP apresentou maior resistência de união e AF+S a menor. AF+MDP e AF+SCF+MDP apresentaram valores similares e AF+MEP foi intermediário. Após a ciclagem térmica, AF+SCF+MDP, AF+MEP e MEP apresentaram valores maiores e AF+SRX o menor enquanto AF+MDP foi intermediário. Quando comparados os períodos, AF+MDP, AF+SCF+MDP, AF+MEP e MEP apresentaram valores maiores em 24 horas enquanto AF+SRX foi similar. MEV mostrou superfície mais retentiva e exposição de cristais quando tratada com AF+SCF+MDP. A superfície menos retentiva foi obtida com MEP, e os demais tratamentos promoveram irregularidades de superfície intermediárias. Conclui-se que o tratamento superficial e a termociclagem promoveram diferentes valores de resistência adesiva e ângulo de contato em cerâmica de silicato de lítio reforçada com zircônia. As falhas foram predominantemente adesivas, e a superfície cerâmica foi caracterizada com diferentes níveis de rugosidade e exposição seletiva de cristais.
ABSTRACT
Surface enhanced Raman spectroscopy (SERS) and confocal Raman microscopy are applied to investigate the structure and the molecular arrangement of sub-micron furosemide and polyvinylpyrrolidone(furosemide/PVP) particles produced by spray flash evaporation (SFE).Morphology,size and crystallinity of furosemide/PVP particles are analyzed by scanning electron microscopy (SEM) and X-ray powder diffraction (XRPD).Far-field Raman spectra and confocal far-field Raman maps of furosemide/PVP par-ticles are interpreted based on the far-field Raman spectra of pure furosemide and PVP precursors.Confocal far-field Raman microscopy shows that furosemide/PVP particles feature an intermixture of furosemide and PVP molecules at the sub-micron scale.SERS and surface-enhanced confocal Raman microscopy (SECoRM) are performed on furosemide,PVP and furosemide/PVP composite particles sputtered with silver (40 nm).SERS and SECoRM maps reveal that furosemide/PVP particle surfaces mainly consist of PVP molecules.The combination of surface and bulk sensitive analyses reveal that furosemide/PVP sub-micron particles are formed by the agglomeration of primary furosemide nano-crystals embedded in a thin PVP matrix.Interestingly,both far-field Raman microscopy and SECoRM provide molecular information on a statistically-relevant amount of sub-micron particles in a single microscopic map;this combination is thus an effective and time-saving tool for investigating organic sub-micron composites.
ABSTRACT
ABSTRACT The purpose of this study was to evaluate the effect of the use of the combined auxiliaries of oral hygiene with whitening agents on the micro-hardness and micro-morphology of dental enamel. Materials and Methods. 40 human incisors were used and sectioned to obtain 4x4mm samples and divided into four study groups. Group 1: Electric brushing with Toothpaste (BTP); Group 2: Electric brushing with Toothpaste+mouthwash (BTP+MW); Group 3: Electric brushing with Toothpaste+whitening pen (BTP+WP); Group 4: Electric brushing with Toothpaste+mouth wash+whitening pen (BTP+MW+WP). Samples were submitted toVickers micro-hardness test and visualized using scanning electron microscopy (SEM). Results. All groups, with the exception of group 1, showed a decrease in micro- hardness values after applying the treatments (p<0.05). Likewise, when comparing the values after the treatments between the groups, significant statistical differences were found in all of comparisons except for those of groups 2 and 4. SEM images showed changes in the morphology in all the study groups with the exception of group 1. Conclusion. Significant changes such as decrease in micro-hardness as well as in the topography of the enamel surface such as elevations, craters, porosities and etching patterns were founded after the use of the combination of auxiliaries of oral hygiene with whitening agents.
RESUMEN El propósito de este estudio fue evaluar el efecto del uso de los auxiliares de higiene oral combinados con agentes blanqueadores sobre la microdureza y la micro-morfología del esmalte dental. Materiales y métodos. Se utilizaron 40 incisivos humanos y se seccionaron para obtener muestras de 4x4 mm los cuales se dividieron en cuatro grupos de estudio. Grupo 1: cepillado eléctrico con pasta de dientes (BTP); Grupo 2: cepillado eléctrico con pasta dental+enjuague bucal (BTP+MW); Grupo 3: cepillado eléctrico con pasta dental+pluma blanqueadora (BTP+WP); Grupo 4: cepillado eléctrico con pasta dental+enjuague bucal+pluma blanqueadora (BTP+MW+WP). Las muestras fueron analizadas por medio de microdurezaVickers y microscopía electronica de barrido (SEM). Resultados. Todos los grupos, con la excepción del grupo 1, mostraron una disminución en los valores de microdureza después de aplicar los tratamientos (p<0.05). Del mismo modo, al comparar los valores después de los tratamientos entre los grupos, se encontraron diferencias estadísticamente significativas en todas las comparaciones, excepto en las de los grupos 2 y 4. Las imágenes de SEM nos muestran cambios en la morfología en todos los grupos de estudio con la excepción del grupo 1 Conclusión. Cambios significativos como la disminución de la microdureza y los cambios en la topografía de la superficie del esmalte, como elevaciones, cráteres, porosidades y patrones de grabado, se encontraron después del uso de la combinación de auxiliares de la higiene oral con agentes blanqueadores.
Subject(s)
Humans , Oral Hygiene , Microscopy, Electron, Scanning , Oral and Dental Hygiene Products , Tooth Bleaching/trends , Toothbrushing , Dental Devices, Home Care , Dental Enamel/injuriesABSTRACT
The clinical success of dental implants can be improved by achieving optimum implant properties,such as their biomechanical and surface characteristics.Nano-structured coatings can play an important role in improving the implant surface.The purpose of the present study was to determine the most appropriate conditions for electrophoretic deposition (EPD) of nano-zirconia coatings on Ti-6Al-7Nb substrates and to evaluate the structural and biomechanical characteristics of these deposited coatings on the dental implants.EPD was used with different applied voltages and time periods to obtain a uniform layer of nano-zirconia on Ti-6Al-7Nb samples.The coated samples were weighed and the thickness of the product layer was measured.Surface analysis was performed by using optical microscopical examination,scanning electron microscope and X-ray diffraction phase analysis.For in vivo examination,48 screw-designed implants (24 uncoated and 24 nano-zirconia coated) were implanted in both tibiae of 12 white New Zealand rabbits and evaluated biomechanically after 4-and 12-week healing intervals.Results revealed that the use of different conditions for EPD affected the final coating film properties.Increasing the applied voltage and coating time period increased the deposited nano-zirconia film thickness and weight.By selecting the appropriate coating conditions,and analyzing scanning electron microscopical examination and XRD patterns,this technique could produce a thin and continuous nano-zirconia layer with a uniform thickness of the Ti-6Al-7Nb samples.Mechanically,the nano-zirconia-coated implants showed a highly statistically significant difference in removal torque values,while histologically these coated implants enhanced and promoted osseointegration after 4 and 12 weeks of healing,compared with the uncoated ones.In conclusion,EPD is an effective technique for providing a high quality nano-zirconia coating film on dental implant surfaces.Moreover,the osseointegration of these coated dental implants is improved compared with that of uncoated ones.
ABSTRACT
The clinical success of dental implants can be improved by achieving optimum implant properties,such as their biomechanical and surface characteristics.Nano-structured coatings can play an important role in improving the implant surface.The purpose of the present study was to determine the most appropriate conditions for electrophoretic deposition (EPD) of nano-zirconia coatings on Ti-6Al-7Nb substrates and to evaluate the structural and biomechanical characteristics of these deposited coatings on the dental implants.EPD was used with different applied voltages and time periods to obtain a uniform layer of nano-zirconia on Ti-6Al-7Nb samples.The coated samples were weighed and the thickness of the product layer was measured.Surface analysis was performed by using optical microscopical examination,scanning electron microscope and X-ray diffraction phase analysis.For in vivo examination,48 screw-designed implants (24 uncoated and 24 nano-zirconia coated) were implanted in both tibiae of 12 white New Zealand rabbits and evaluated biomechanically after 4-and 12-week healing intervals.Results revealed that the use of different conditions for EPD affected the final coating film properties.Increasing the applied voltage and coating time period increased the deposited nano-zirconia film thickness and weight.By selecting the appropriate coating conditions,and analyzing scanning electron microscopical examination and XRD patterns,this technique could produce a thin and continuous nano-zirconia layer with a uniform thickness of the Ti-6Al-7Nb samples.Mechanically,the nano-zirconia-coated implants showed a highly statistically significant difference in removal torque values,while histologically these coated implants enhanced and promoted osseointegration after 4 and 12 weeks of healing,compared with the uncoated ones.In conclusion,EPD is an effective technique for providing a high quality nano-zirconia coating film on dental implant surfaces.Moreover,the osseointegration of these coated dental implants is improved compared with that of uncoated ones.
ABSTRACT
Abstract In order to evaluate its application as a dental prosthesis material, a CoCrW alloy was subjected to in vitro cytotoxicity test, surface characterization and electrochemical studies performed in artificial saliva and 0.15 mol.L-1 NaCl medium. The used techniques were: anodic polarization curves, chronoamperometric measurements, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) analysis and X-ray photoelectron spectroscopy (XPS). Cytotoxicity test was also performed. The electrochemical behavior of CoCrW alloy was compared in both studied media, from corrosion potential (Ecorr) to a 600 mV anodic overvoltage. From the electrochemical measurements it was observed that the CoCrW alloy in both media presents only generalized corrosion. SEM and EDS analysis showed that the alloy presents carbide niobium and silicon and manganese oxides as nonmetallic inclusions. XPS results indicated that cobalt does not significantly contribute to the passivating film formation. Cytotoxicity test showed no cytotoxic character of CoCrW alloy. These results suggest that the CoCrW alloy can be used as biomaterial to be applied as prosthesis in dental implants.
Resumo Estudos eletroquímicos, caracterização de superfície e teste de citotoxicidade in vitro foram realizados da liga CoCrW em meios de saliva artificial e NaCl 0,15 mol.L-1, com o objetivo de avaliar a sua aplicação como material de prótese dentária. Foram usadas como técnicas, curvas de polarização anódica, medidas cronoamperométricas, espectroscopia de impedância eletroquímica (EIE), microscopia eletrônica de varredura (MEV), espectroscopia por energia dispersiva de raios X (EDS) e espectroscopia fotoeletrônica de raios X (XPS). O teste de citotoxicidade também foi realizado. O comportamento eletroquímico da liga CoCrW foi comparado nos dois meios estudados desde o potencial de corrosão (Ecorr) até uma sobretensão anódica de 600 mV. Foi observado, a partir de medidas eletroquímicas, que a liga CoCrW se encontra passivada em uma ampla faixa de potencial e que a sobretensões mais elevadas apresenta apenas corrosão generalizada nos dois meios. Análises por MEV e EDS mostraram que a liga apresenta inclusões não metálicas de carbeto de nióbio, de óxidos de silício e de manganês. Os resultados de XPS indicaram que o cobalto não contribui significativamente para a formação do filme passivo. O teste de citotoxicidade mostrou que a liga CoCrW não se apresenta citotóxica. Estes resultados sugerem que a liga estudada pode ser usada como biomaterial a ser aplicado como prótese sobre implantes dentários.
Subject(s)
Dental Alloys/chemistry , Saliva, Artificial/chemistry , In Vitro Techniques , Surface PropertiesABSTRACT
The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods. The corrosion rates were obtained from the current-potential curves and electrochemical impedance spectroscopy (EIS). The effect of artificial saliva on the corrosion of dental alloys was dependent on alloy composition. Dissolution of the ions occurred in all tested dental alloys and the results were strongly dependent on the general alloy composition. Regarding the alloys containing nickel, the Ni-Cr and Ni-Cr-Ti alloys released 0.62 mg/L of Ni on average, while the Co-Cr dental alloy released ions between 0.01 and 0.03 mg/L of Co and Cr, respectively.The open-circuit potential stabilized at a higher level with lower deviation (standard deviation: Ni-Cr-6Ti = 32 mV/SCE and Co-Cr = 54 mV/SCE). The potenciodynamic curves of the dental alloys showed that the Ni-based dental alloy with >70 wt% of Ni had a similar curve and the Co-Cr dental alloy showed a low current density and hence a high resistance to corrosion compared with the Ni-based dental alloys. Some changes in microstructure were observed and this fact influenced the corrosion behavior for the alloys. The lower corrosion resistance also led to greater release of nickel ions to the medium. The quantity of Co ions released from the Co-Cr-Mo alloy was relatively small in the solutions. In addition, the quantity of Cr ions released into the artificial saliva from the Co-Cr alloy was lower than Cr release from the Ni-based dental alloys.
O objetivo deste estudo foi determinar o efeito do ambiente bucal na corrosão de diferentes ligas odontológicas, utilizando métodos eletroquímicos. Os índices de corrosão foram obtidos por meio das curvas de corrente-potencial e impedância eletroquímica (EIS). O efeito de saliva artificial na corrosão de ligas odontológicas foi dependente da composição. A dissolução dos íons ocorreu em todas as amostras e os resultados foram dependentes da composição da liga. Algumas mudanças na microestrutura foram observadas durante o estudo e influenciou o comportamento corrosivo das ligas investigadas. As ligas de Ni-Cr e Ni-Cr-Ti libertaram quantidade de 0,62 mg/L de íons Ni enquanto a liga de Co-Cr liberou entre 0,01 e 0,03 mg/L. As curvas potenciodinâmicas das ligas odontológicas mostraram que as ligas a base >70 wt% de Ni obtiveram curvas similares e a liga de Co-Cr apresentou a menor densidade de corrente e em consequência uma resistência alta a corrosão quando comparada as ligas à base de Ni. A baixa resistência à corrosão também levou a maior libertação de íons de níquel para o meio e a quantidade de Co liberado pela liga de Co-Cr-Mo foi relativamente pequena nas soluções. As quantidades de Cr liberada na saliva artificial pela liga de Co-Cr foi menor que a libertação de Cr pela liga à base de Ni.
Subject(s)
Corrosion , Dental Alloys/chemistry , Saliva, Artificial/chemistry , Dielectric Spectroscopy , Electrochemistry , Ions , Potentiometry , Surface PropertiesABSTRACT
INTRODUÇÃO: Superfícies de titânio modificadas por diferentes métodos foram estudadas com base nos parâmetros físicos e químicos de caracterização superficial e sua influência no comportamento de células pré-osteoblásticas (MC3T3) in vitro. MÉTODOS: Discos de titânio comercialmente puro grau II foram submetidos a três métodos de modificação de superfície (polimento, nitretados em plasma em configuração planar e gaiola catódica). As diferentes superfícies foram caracterizadas para observar o efeito do processamento na estrutura da camada superficial, na rugosidade e molhabilidade. Ensaios de adesão e proliferação celular usando linhagens de células pré-osteoblásticas MC3T3 foram realizados para avaliar o efeito das novas superfícies no comportamento celular in vitro. RESULTADOS: Os resultados demonstraram que a nitretação em plasma na configuração de gaiola catódica produz superfícies mais rugosas (p<0,02) e com menores ângulos de contato com a água. CONCLUSÕES: A adesão celular é maior nas superfícies mais rugosas do que nas superfícies polidas (p<0,05) e reagem de modo diferente a composição química do substrato e à topografia da superfície.
PURPOSE: The aim of this study was to evaluated the physico-chemical properties of different titanium surfaces modified by means of low temperature plasma nitridind on rat osteoblast cell adhesion and proliferation. METHODS: Pure Titanium discs grade II was submitted to three different surface preparations (polishing, glow discharge plasma nitriding in planar and cathodic cage configurations). Surface parameters as roughness, wettability and chemichal composition was determined to compare influency of gas mixture on the modified surface material properties. Cellular morphology was observed by scanning electron microscopy. To evaluate the effect of the surface on cellular response, osteoblast cells (MC3T3) adhesion and proliferation was quantified and data analised by Kruskal-Wallis and Friedman statistical tests. RESULTS: plasma nitriding discs shows rougher surfaces( p<0,02) in cathodic cage configuration and lower contact angle values. MC3T3 cells attached on rough surfaces produced by cathodic cage configuration was statistically significant p<0,05 compared to polished discs. CONCLUSIONS: Glow discharge plasma nitriding improve titanium surface roughness and wettability. MC3T3 cell adhesion behavior is related to substrate chemical composition and topography.