Efeitos de diferentes sistemas de clareamento dental sobre a rugosidade e morfologia superficial do esmalte e de uma resina composta restauradora

The aim of this study was to evaluate and compare the roughness and superficial morphology of enamel and a composite restorative resin after different bleaching techniques application. Material and Methods: Bovine incisors were selected and standardized cavities were prepared on the buccal surface, which were restored with composite resin. The teeth were distributed according to the following treatments: G1- bleaching with 10% carbamide peroxide (CP); G2 - bleaching with 38% hydrogen peroxide (HP); and G3 - bleaching with 38% of HP associated to light irradiation. For G1, the bleaching gel was applied for 8 hours daily during 21 days. For G2 and G3, 3 sessions were performed, consisting of 3 applications of 15 minutes each, with 7 days of intervals between the sessions. For G3, the LED (470nm) light was used to activate the bleaching agent for 6 minutes. The surface of enamel and composite resin were evaluated before and after the bleaching procedures using a roughness tester and an atomic force microscope. Results: The results showed significant differences in surface roughness of enamel after bleaching only for G1 (Wilcoxon, p<0.05). For composite resin, neither group showed a statistical difference compared to control (Mann-Whitney, p>0.05). Conclusion: It was concluded that the increase in the roughness of enamel occurred only after bleaching therapy using a gel with 10% of CP. The bleaching procedures evaluated in this investigation did not increase the roughness or cause changes in the superficial morphology of the composite resin.

Microdureza e rugosidade superficial do esmalte submetido ao clareamento: uma revisão de literatura

The increasing importance of aesthetic in the Dentistry for the patients and the consumers brought a constant rise in the number of products and procedures to facilitate the confection of the dental bleaching. Concomitantly, thone was a sudden increase in the number of research and publications, in vitro and in vivo, about its possible adverse reactions. Through literature revision this study aims to verify the possible morphologic alterations of the submitted enamel and dentine with different bleaching agents making critical analysis of the results of the current research with relation to the study of the microhardness and superficial roughness.

Análise comparativa da rugosidade superficial de resinas compostas de alta densidade

The success achieved by the use of composite resins in anterior teeth precipitately leads their use in posterior teeth. However, the indiscriminate application of these materials in cavities with several diverse sizes rapidly pointed out their lack of resistance to oclusal and proximal wear. OBJECTIVE: To evaluate the surface roughness of composite resin in relation to finishing and polishing technique. MATERIAL AND METHODS: Eight experimental groups (n = 15) were divided according to finishing and polishing technique: G1 – Z250TM composite resin without surface finishing and polishing; G2 – Z250TM composite resin plus surface finishing and polishing; G3 – P60TM composite resin without surface finishing and polishing; G4 – P60TM composite resin plus surface finishing and polishing; G5 – Prodigy CondensableTM composite resin without surface finishing and polishing; G6 – Prodigy CondensableTM composite resin plus surface finishing and polishing; G7 – SurefillTM composite resin without surface finishing and polishing; G8 – SurefillTM composite resin plus surface finishing and polishing. Three packable and one microhybrid (control group) composite resin was used. The surface roughness was measured using a profilometer at three points in each sample. The results were evaluated by ANOVA and Tukey test (p < 0.05). RESULTS: Prodigy CondensableTM composite resin showed the lowest surface roughness, while SurefillTM showed the highest surface roughness. Comparing the resins used, only between P60TM and SurefillTM there were no statistically significant differences (p > 0,05). CONCLUSION: Surface roughness was lower in all types of resin composites surfaces in contact with Mylar matrix strip than in areas submitted to finishing and polishing procedure.

Effects of immersion media and repolishing on color stability and superficial morphology of nanofilled composite resin

This study evaluated the influence of fluoride mouth rinses and repolishing on the superficial morphology and color stability of nanofilled resin. About 150 specimens were prepared and polished using aluminum oxide discs for 15 s with a pressure of 2 kg. The experimental groups were divided according to the immersion medium (artificial saliva, 0.5% sodium fluoride, Fluordent Reach, Oral B, Fluorgard) and repolishing procedure (without and with). The specimens were continuously immersed for 1 week. Thereafter, half of each sample was repolished. A color reading was performed after 24 h of immersion in the artificial saliva baseline, after continuous immersion, and after repolishing. The superficial morphology was examined using scanning electron microscopy (SEM) in a qualitative way. Color change (∆E) data were submitted to a mixed analysis of variance using a Shapiro-Wilk test (p>0.05 for the different immersion media) and Sidak's test (p<0.05 for the differences between groups). In the interaction between the repolishing and the immersion media, Fluorgard showed a statistical difference between the ∆E values with and without repolishing (p<0.0001). On the SEM observations, both Fluordent Reach and Fluorgard caused degradation of the superficial resinous matrix of the composite after continuous immersion. This matrix was removed after repolishing.

Influência do tratamento superficial 3IP na vida em fadiga dos aços ABNT 4340 e 15-5PH para aplicação aeronáutica

Pós-graduação em Engenharia Mecânica - FEG

Equipamento e processo de enriquecimento superficial seletivo de ligas metálicas

Equipamento e processo de enriquecimento superficial seletivo de ligas metálicas. É descrito um equipamento e processo de enriquecimento superficial seletivo de ligas metálicas com controle da velocidade e da intensidade do processo, de forma a permitir controlar a espessura da camada enriquecida e a diminuição do tempo necessário para ser obtida camada enriquecida com espessura desejada.

Calagem superficial e aplicação de gesso em sistema plantio direto de longa duração: efeitos no solo e na sucessão milho/crambe/feijão-caupi

Pós-graduação em Agronomia (Agricultura) - FCA

A influência do tamanho de grão ferrítico da peça na integridade superficial de peças erodidas

Pós-graduação em Engenharia Mecânica - FEIS

Análise do acabamento superficial e força de corte no torneamento de alumina a verde

In experimental conditions, cutting forces were studied during turning of green alumina billets, including their correlation with surface aspects of the workpiece. The correlation between cutting power and the removal rate are important parameters for defining the design of ceramic products, since inadequate parameters can produce excessive surface damage to the workpiece. This study examined the forces obtained during turning of alumina workpieces with 99.8% purity in their green state, by means of a three-point dynamometer, evaluating the cutting, feed and depth forces, using a cermet tool under constant machining conditions. Variables were compared with the forces, including surface finish, tool wear and temperature during machining. In the study, it was found that the depth of cut had no significant effect on the surface quality, and the cutting speed and feed influencing the finish. However, preliminary tests for selecting the cutting conditions showed that unsuitables cutting speeds and feeds generate severe damage to the workpiece surface. The best condition was 1.00 mm depth of cut, and the forces increasedfor with each pass performed, with the feed force the variable with greatest increases in relation to the cutting and depth forces, and wear of the cutting tool directly influenced the surface finish, generated by the highly abrasive nature of the alumina particles of the green compact. It is emphasized that the alumina in its green state showed high abrasive effect on the cutting tool during the turning process and the surface finishing of the green workpiece had a direct influence on the sintered workpiece.

Natural formations at the Earth-Moon triangular point in perturbed restricted problems

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Luminescence properties of Eu-complex formations into ordered mesoporous silica particles obtained by the spray pyrolysis process

Ordered mesoporous, highly luminescent SiO2 particles have been synthesized by spray pyrolysis from solutions containing tetraethylorthosilicate (TEOS), Eu(NO3)3.6H2O, and cetyltrimethylammonium bromide (CTAB) as structure-directing agents. The 1,10-phenantroline (Phen) molecules were coordinated in a post-synthesis step by a simple wet impregnation method. In addition, other matrices were also prepared by the encapsulation of europium complex Eu(fod)3 (where fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato) into mesoporous silica, and then the Phen molecules were encapsulated by different impregnation steps, after which the luminescence properties were investigated. The obtained materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Powders with polydisperse spherical grains were obtained, displaying an ordered hexagonal array of mesochannels. Luminescence results revealed that Phen molecules had been successfully coordinated as an additional ligand in the Eu(fod)3 complex into the channels of the mesoporous particles without disrupting the structure.

Injeção de ar via irrigação por gotejamentos superficial e subsuperficial na cultura da alface

Pós-graduação em Agronomia (Irrigação e Drenagem) - FCA

Otimização de método para analise de tebutiurom, diurom e seus produtos de degradação em água superficial

In 2001, it was estimated that pesticide used worldwide exceeded 2.27 billion kilograms, over 35%, of which, were herbicides. Brazil is considered one of the leaders in the production of sugarcane and mainly ethanol as fuel. The monoculture of sugarcane requires the usage of a range of pesticides, among these, the herbicides diuron and tebuthiuron. The degradation products most studied (DCA and DCPU) are diuron's, especially for toxicological characteristics of this herbicide that is identified as carcinogen and suspected to be endocrine disruptor in mammals. After optimization of the chromatographic separation using HPLC-UV, the analytical curve was constructed in solvent and subsequently in the matrix (surface water). The extraction method contains the usage of SPE (solid phase extraction) (Strata-X, 200 mg/6 mL), applicating 1L of sample and elution with 5 mL of acetonitrile / methanol (50:50, v/v). Analysis by HPLC/UV was performed in gradient mode, acetonitrile/water (70/30-74/26 by 1 min, 74/26 - 78/22 till 3.2 min, returning to initial conditions and remaining this way until 10 min), 018 column (Phenomenex, 4.6 mm diameter, 250 mm long and 5pm particle size) and detection at 254 nm. Tests F and t were performed to verify the presence of the matrix effect. There was matrix effect to all analytes, ranging from -33% (DCA) and 38% (tebuthiuron). Thereby the method was optimized and validated for analysis of diuron, tebuthiuron, and DCPU DCA in surface water using HPLC/UV. The data obtained show that in order to assure the analytical reliability desired the use of the analytical curves in the matrix for the quantification of these analytes in water is required.

Análise de materiais para sistemas de fechamento ósseo através da caracterização superficial e comportamento mecânico

Pós-graduação em Engenharia Mecânica - FEB