Influence of desensitizers agents on the dentin bond strength after one-year water storage

Aim: Evaluate the effect of adhesives systems combined with desensitizer agents on the microtensile bond strength (µTBS) of a composite resin to dentin. Methods: Cervical dentin of thirty-two human molars were used to simulate hypersensitivity areas. The teeth were divided into four groups (n=8), according to the type of adhesive system and desensitizer agents. No desensitizer was used in the control (Clearfil SE Bond ­ CS). Two experimental groups were pretreated with either MS Coat Bond (MS) or Biofluorid 12 (BF) immediately prior to bonding with CS. The last group corresponded to Gluma Comfort Bond + Desensitizer (GC) application. After dentin treatments, a composite block was built-up on dentin surface and after 24 hours teeth were serially sectioned to obtain bonded bean specimens. Beams were stored in water for 24 hours or one year. Subsequently, the specimens were submitted to the µTBS test. Data were analyzed by two-way mixed ANOVA and Bonferroni's test (α = 0.05). Results: At 24 hours, there was no significant difference in µTBS among groups. However, at one year, dentin treated with MS or BF demonstrated significantly lower µTBS of CS to dentin compared to control and GC, which kept their µTBS stable. Conclusion: The effect of MS and BF desensitizer agents on the µTBS of CS to dentin did not reduce the µTBS at 24 hours, but it decreases significantly after one year

Reaction of brazilian cotton genotypes to white mold depends on pathogen aggressiveness and incubation conditions / Reação de genótipos brasileiros de algodoeiro ao mofo branco depende da agressividade do patógeno e das condições de incubação

The expansion of cotton crop into irrigated and high lands of Brazilian Cerrado, despite the possibility of increasing fiber yield, led to the occurrence of diseases previously considered secondary, such as white mold [Sclerotinia sclerotiorum (Lib.) de Bary]. Host genetic resistance is of extreme importance in integrated strategies to manage this disease. Resistance of Brazilian cotton genotypes, challenged with different strains of S. sclerotiorum, under two incubation conditions for disease progress was evaluated. In addition, possible correlation between oxalic acid and straw test methods to rank the genotypes was evaluated. Artificial inoculation was done when cotton plants reached the V2phenological stage with fungi isolated from naturally infected soybean (ScS) or cotton (ScC) commercial crops. Control plants were inoculated with culture medium. After inoculation, plants were kept for one week either in a growth chamber or in greenhouse and evaluated for disease symptoms and severity. The oxalic acid test consisted of stem submersion of rootless cotton plants in a 2-cm layer of 20 or 40 mM solutions for 20, 44 or 68 h. A wilting scale was used to distinguish genotype's sensibility to the acid. The data were submitted to individual, joint, and multivariate analysis, grouping cotton genotypes by the Scott-Knott's test (p < 0.05), the hierarchical UPGMA and the non-hierarchical Tocher methods. Difference in aggressiveness between strains was identified, in which ScC led to greater disease severity. This result suggests a possible physiological specialization ofS. sclerotiorum to different hosts. It was observed that the growth chamber environment provided more adequate conditions for S. sclerotiorum infection, thus allowing better selection of resistant cotton genotypes. UPGMA and Tocher grouping methods further confirmed that the evaluated genotypes differ from each other in resistance to white mold. No correlation between oxalic acid and straw test methods was observed.

A expansão da cultura do algodoeiro para terras altas e irrigadas do Cerrado brasileiro, apesar da possibilidade de aumentar a produção de fibras, levou à ocorrência de doenças antes consideradas secundárias, como o mofo branco [Sclerotinia sclerotiorum (Lib.) de Bary]. A resistência genética do hospedeiro é de extrema importância nas estratégias de manejo integrado dessa doença. Avaliou-se a resistência de genótipos brasileiros de algodão, desafiados com diferentes isolados de S. sclerotiorum, sob duas condições de incubação para o progresso da doença. Além disso, foi avaliada a possível correlação entre os métodos do ácido oxálico e do straw test para ranquear os genótipos. A inoculação artificial foi realizada quando as plantas de algodoeiro atingiram o estágio fenológico V2, com fungos isolados de culturas comerciais de soja (ScS) ou de algodão (ScC) naturalmente infectadas. O controle consistiu de plantas inoculadas somente com meio de cultura. Após a inoculação, as plantas foram mantidas em câmara de crescimento ou em casa de vegetação durante uma semana e avaliadas quanto aos sintomas e severidade da doença. O teste do ácido oxálico consistiu na submersão da haste das plantas de algodão, após remoção das raízes, em uma solução de 20 ou 40 mM por 20, 44 ou 68 h. Uma escala visual de murcha foi usada para distinguir a sensibilidade dos genótipos ao ácido. Os dados foram submetidos à análise individual, conjunta e multivariada, agrupando os genótipos de algodoeiro pelo teste de Scott-Knott (p < 0,05) e pelos métodos UPGMA e de Tocher. Diferença na agressividade entre os isolados foi identificada, na qual ScC resultou em maior severidade da doença. Isto sugere possível especialização fisiológica de S. sclerotiorum para diferentes hospedeiros. Observou-se que o ambiente da câmara de crescimento proporcionou condições mais adequadas para infecção por S. sclerotiorum comparativamente à casa de vegetação, permitindo melhor seleção de genótipos resistentes. Os métodos de agrupamento UPGMA e Tocher confirmaram que os genótipos avaliados diferem entre si na resistência ao mofo branco. Não foi observada correlação entre o ácido oxálico e o straw test.

Comparación de la conductancia hidráulica dentinaria, de acuerdo al tiempo de aplicación de desensibilizantes con base de oxalatos / Comparison of dentinal hydraulic conductance according to the application time of oxalate-based desensitizers

Introdución: se utilizó un modelo in vitro, para medir la conductancia hidráulica en discos de dentina humana, tratados con ácido oxálico por 15, 30 o 60 s y la mantención del efecto oclusivo, medido a los 7 y 14 días post aplicación. Métodos: 45 discos dentinarios de 1mm de grosor fueron obtenidos de terceros molares humanos libres de caries, en inoclusión, de pacientes entre 16 a 30 años de edad. Los discos fueron divididos en tres grupos de estudio (n = 15), dependiendo del tiempo de aplicación de una solución comercial de desensibilizante dentinario (DD) a base de oxalato (BisBlock®), que contiene ˂ 5% ácido oxálico pH 1,5-1,8: grupo A aplicación del agente por 15 s, grupo B aplicación por 30 s y grupo C por 60 s. La conductancia hidráulica de cada disco fue calculada posterior al grabado ácido, lo que corresponde a la máxima permeabilidad de dicho disco (100%), inmediatamente tras la aplicación del ácido oxálico y tras siete y 14 días de mantención en suero fisiológico.El análisis estadístico se hizo mediante test de ANOVA y post hoc de Games-Howell. Resultados: 35,46 ± 23,41% para el grupo A, 36,34 ± 15,88% para el grupo B y 24,99 ± 14,99% para el grupo C, por lo que la utilización de DD por 15, 30 ó 60 s generó una disminución en la permeabilidad que fue estadísticamente significativa (p ˂ 0,05). Conclusiones: el DD fue eficaz en reducir la conductancia hidráulica independiente del tiempo de aplicación, siendo esta reducción sólo temporal, ya que tras siete días la permeabilidad retorna a valores cercanos a los iniciales.

Introduction: an in vitro model was used to measure the hydraulic conductance in human dentin discs treated with oxalic acid for 15, 30 or 60 s maintaining the occlusive effect and measuring 7 and 14 days after application. Methods: 45 dentin discs measuring 1 mm thick were obtained from human third molars which were free of caries and in no occlusion; the samples were obtained from patients aged 16 to 30 years. Discs were sorted out into three study groups (n = 15) depending on the time of application of a commercial solution of oxalate-based dentin desensitizer (DD) (BisBlock®) which contains ˂ 5% oxalic acid of 1.5-1.8 pH: in group A the agent was applied for 15 s, in group B it was applied for 30 s, and in group C for 60 s. The hydraulic conductance of each disc was calculated after acid etching, which corresponds to the maximum permeability of discs (100%) after immediate application of oxalic acid, as well as seven and fourteen days of storage in saline solution. The statistical analysis was done with ANOVA test and post-hoc Games-Howell test. Results: 35,46 ± 23.41% in Group A, 36.34 ± 15.88% in Group B and 24.99 ± 14.99% in Group C, showing that the use of DD for 15, 30 or 60 s decreased permeability in a statistically significant manner (p <0.05). Conclusions: DD was effective in reducing hydraulic conductance regardless of application time, but this reduction was temporary only, since after seven days permeability returns to values close to those of baseline.

Carambola (Averrhoa carambola): sua neurotoxicidade e abordagens terapêuticas / Starfruit (carambola Averrhoa): its neurotoxicity and therapeutic approaches

A insuficiência renal crônica é uma doença de elevada morbimortalidade e é consenso que sua incidência e prevalência, em estágio terminal, vêm aumentando de forma significativa. Como relevância nos cuidados nutricionais está o consumo da carambola. A Averrhoa carambola, da família das oxalidáceas, conhecida popularmente como carambola, é uma fruta originária da Ásia e comum em países tropicais, entre eles o Brasil. Apesar do uso como terapia alternativa na medicina de alguns países, essa fruta recebe destaque por ter em sua composição o ácido oxálico, possível causador de efeitos deletérios aos doentes renais crônicos. Além disso, possui uma neurotoxina capaz de provocar alterações neurológicas nestes pacientes renais crônicos. Essa neurotoxina parece apresentar especificamente inibição sobre o sistema de condução GABAérgico, o que aumenta a excitabilidade do sistema nervoso central. As manifestações clínicas da intoxicação pela carambola podem ser desde soluços e confusão mental, até convulsões e morte. Diante da descrição de alguns relatos de casos sobre o consumo da carambola, percebe-se que a abordagem terapêutica mais indicada é a hemodiálise, com ou sem hemoperfusão. Assim a recomendação é evitar o consumo desta fruta, já que suas complicações além de imprevisíveis são potencialmente fatais.

Use of Aspergillus niger in the bioleaching of colemanite for the production of boric acid

Colemanite is one of the most important underground riches of Turkey, having approximately 60 percent of the world boron deposits, and it has a large portion in the deposits. In this study, chemical leaching and biological leaching methods were used for production of boric acid from colemanite (2CaO · 3B3O3 · 5H2O) (Emet-Kütahya, Turkey). Oxalic acid concentration, temperature, stirring time and solid-to-liquid ratio were taken as parameters in the chemical leaching process. It was found that the dissolution rate increases with increasing oxalic acid concentration and temperature but it decreases at higher solid-to-liquid ratios in the chemical leaching process. Using optimum conditions (d100 = 0.075 mm; 5 percent solids by weight; 0.55 M oxalic acid; 80 +/- 2 ºC leaching temperature; 150 rpm stirring speed; 90 min leaching time) for colemanite sample (28.05 percent B2O3) on chemical leaching with oxalic acid experiments, the calculated boric acid extraction efficiency from colemanite ore was 97.89 percent. Optimum conditions on bioleaching of Emet-Kütahya, Turkey colemanite ores using the fungus Aspergillus niger were found to be as follows: reaction temperature 25 +/- 2ºC; solid-to-liquid ratio 5 percent solids by weight; d100 = 0.075 mm; stirring speed 150 rpm; initial the fungus populations in the inocula about 3 x 10(7) cells/ml and reaction time 21 days. The calculated boric acid extraction efficiency from colemanite ore was 90.18 percent under the optimum conditions. Bioleachate contained 12.95 g/l B2O3, 6.60 g/l Ca and 0.087 g/l Mg. Compared with chemical leaching at 5 percent pulp density, the fungus was less efficient in the extraction of B2O3 from colemanite but the difference in the extraction yields between the two processes was less than 10 percent. Although bioleaching generally requires a longer period of operation compared to chemical leaching, these results suggest that bioleaching by A...