Color degradation of acrylic resin denture teeth as a function of liquid diet: ultraviolet-visible reflection analysis

The effect of different beverages on acrylic resin denture teeth color degradation is evaluated. Ten acrylic resin denture teeth brands were evaluated: Art Plus (AP), Biolux (BX), Biotone IPN (BI), Magister (MG), Mondial 6 (MD), Premium 6 (PR), SR Vivodent PE (SR), Trilux (TR), Trubyte Biotone (TB), and Vipi Dent Plus (VP). Teeth were immersed in staining solutions (coffee, cola, and orange juice) or artificial saliva (control) (n = 6) for 1, 7, 15, or 30 days. Specimen colors were evaluated spectrophotometrically based on the Commission Internationale d'Eclairage L*a*b* system. Color differences (Delta E) were calculated between the baseline and post-staining results. Data were evaluated by analysis of variance and Tukey test (alpha = 0.05). BI (1.82 +/- 0.95) and TR (1.78 +/- 0.72) teeth exhibited the greatest Delta E values, while BX (0.88 +/- 0.43) and MD (1.09 +/- 0.44) teeth were the lowest, regardless of solution and measurement period, and were different from BI and TR teeth (P < 0.05). Cola and coffee promoted higher denture teeth color alterations than orange juice and saliva (P < 0.05). Saliva generated the lowest denture teeth color alterations. Greater immersion times caused higher denture teeth color changes. The lifespan of removable dentures and the aesthetic satisfaction of several edentulous patients may be increased with the use of stain-resistant artificial denture teeth. (C) The Authors.181

The role of superstructure material on the stress distribution in mandibular full-arch implant-supported fixed dentures. A CT-based 3D-FEA

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)This study evaluated the stress distribution in mandibular full-arch implant-supported fixed dentures with different veneering and metallic infrastructure materials, using three-dimensional finite element analysis. Ten models were obtained from an edentulous human mandible with a complete denture fixed by four implants. Acrylic resin (RES) and porcelain (POR) teeth were associated with infrastructures of titanium (Ti), gold (Au), silver-palladium (AgPd), chrome-cobalt (CoCr) and nickel-chrome (NiCr). A 100-N oblique was applied. The von Mises (sigma vM) and maximum (sigma max) and minimum (sigma min) principal stresses were obtained. The RES-AgPd group showed the lowest sigma vM values, while the RES-Ni-Cr group showed the highest. In the bone tissue, the RES-Au group was the only one that showed different sigma max values with a 12% increase in comparison to the other groups which had similar stress values. In the implants, the groups with Ti, Au and AgPd infrastructures, either with porcelain or resin teeth, showed sigma vM values similar and lower in comparison to the groups with CoCr and NiCr infrastructures. The tooth veneering material influenced the stress values in metallic infrastructures, in which the acrylic resin had the highest values. The veneering and infrastructure materials have influence on stress values of implant-supported dentures, except for the peri-implant bone tissue. (C) 2013 Elsevier B.V. All rights reserved.359299Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2010/09857-3

La administración pública en Colombia Reflexiones en torno a un escenario de transición: Privatización de lo público, excepcionalidad política y desafíos disciplinares

Este trabajo desarrolla de manera preliminar los desafíos de la administración pública -AP- y su formación ad portas de un escenario transicional en Colombia. Referidos los planteamientos generales de A. Rosembaum en torno a asumir la gestión gubernamental en la actualidad, movida entre una hegemonía privatizadora y una urgencia del llamado al sector público en el mundo, se aborda el caso colombiano en el que si bien es evidente la crisis del papel privatizador en la AP, se insiste en su acción. La hipótesis explicativa de dicha insistencia se da por una nueva excepcionalidad política acogida por el Estado dentro de la reestructuración capitalista neoliberal. Llegada la transición con la paz, se pregunta  si la AP hará la diferencia y qué retos desafiará su formación. 

Effect of bleaching agents and soft drink on titanium surface topography

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The effects of carbamide peroxide, hydrogen peroxide and cola soft drink on the topographic modifications of commercially-pure titanium (CP-Ti) and Ti-6Al-4V were investigated. Ti discs were divided into 18 groups (n=4) based on the solution treatment and Ti type. Specimens were immersed in 3 mL of each solution for 4 h per day (for the remaining 20 h, discs were left dry or immersed in artificial saliva) for 15 days. For control, specimens were immersed in only artificial saliva. Ti surfaces were examined using scanning electron (SEM) and atomic force (AFM) microscopes and their surface roughness (in mu m) and surface chemical modifications were investigated. Data were analyzed by ANOVA and Tukey's test (=0.05). Groups immersed in 35% hydrogen peroxide showed the highest roughness (Ra) (171.65 +/- 4.04 for CP-Ti and 145.91 +/- 14.71 for Ti-6Al-4V) (p0.05). SEM and AFM revealed dramatic changes in the specimens surfaces immersed in the 35% hydrogen peroxide, mainly for CP-Ti. No detectable chemical modifications on the Ti surface were observed. Bleaching agents promoted significant changes in Ti topography, which could affect the longevity of implants treatments. (c) 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 22-30, 2014.10212230Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação para o Desenvolvimento da UNESP (FUNDUNESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAPESP [2010/13971-6]CNPq [132731/2010-0]FUNDUNESP [01010/11 DFP

La mondialisation au Sud : espaces et populations

Diabetes and infections are associated with a high risk of implant failure. However, the effects of such conditions on the electrochemical stability of titanium materials remain unclear. This study evaluated the corrosion behavior of a Ti-6Al-4V alloy, with a smooth surface or conditioned by double-acid-etching, in simulated body fluid with different concentrations of dextrose and lipopolysaccharide. For the electrochemical assay, the open-circuit-potential, electrochemical impedance spectroscopy, and potentiodynamic test were used. The disc surfaces were characterized by scanning electron microscopy and atomic force microscopy. Their surface roughness and Vickers microhardness were also tested. The quantitative data were analyzed by Pearson's correlation and independent t-tests (alpha = 0.05). In the corrosion parameters, there was a strong lipopolysaccharide correlation with the I-pass (passivation current density), C-dl (double-layer capacitance), and R-p (polarization resistance) values (p<0.05) for the Ti-6Al-4V alloy with surface treatment by double-acid-etching. The combination of dextrose and lipopolysaccharide was correlated with the I-corr (corrosion current density) and I-pass (p<0.05). The acid-treated groups showed a significant increase in C-dl values and reduced R-p values (p<0.05, t-test). According to the topography, there was an increase in surface roughness (R-2 = 0.726, p<0.0001 for the smooth surface; R-2 = 0.405, p = 0.036 for the double-acid-etching-treated surface). The microhardness of the smooth Ti-6Al-4V alloy decreased (p<0.05) and that of the treated Ti-6Al-4V alloy increased (p<0.0001). Atomic force microscopy showed changes in the microstructure of the Ti-6Al-4V alloy by increasing the surface thickness mainly in the group associated with dextrose and lipopolysaccharide. The combination of dextrose and lipopolysaccharide affected the corrosion behavior of the Ti-6Al-4V alloy surface treated with double-acid-etching. However, no dose-response corrosion behavior could be observed. These results suggest a greater susceptibility to corrosion of titanium implants in diabetic patients with associated infections

The influence of bone quality on the biomechanical behavior of full-arch implant-supported fixed prostheses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)We evaluated the influence of bone tissue type on stress distribution in full-arch implant-supported fixed prostheses using a three-dimensional finite element analysis. Stresses in cortical and trabecular bones were also investigated. Edentulous mandible models with four implants inserted into the interforaminal region were constructed from different bone types: type 1 - compact bone; type 2 - compact bone surrounding dense trabecular bone; type 3 a thin layer of compact bone surrounding trabecular bone; and type 4 - low-quality trabecular bone. The mandible was restored with a full-arch implant-supported fixed prosthesis. A 100-N oblique load was applied to the left lower first molar of the prosthesis. The maximum (sigma max) and minimum (sigma min) principal stress values were determined. The sigma max in the type 4 cortical bone was 22.56% higher than that in the type 1 bone. The sigma min values in the cortical bone were similar among all the bone types. For the superstructure, increases of 9.04% in the sigma max and 11.74% in the sigma min in G4 (type 4 bone) compared with G1 (type 1 bone) were observed. For the implants, the highest stress values were located in G4, and the lowest values were observed in GI. In the trabecular bone, the highest stress was generated in G1 and G2. In conclusion, the more compact bones (types 1 and 2) are the most suitable for supporting full-arch implant-supported fixed prostheses, and poor bone quality may increase the risk of biological and mechanical failure. (C) 2014 Elsevier B.V. All rights reserved.37164170Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2010/09857-3