Expiration Date Effect on Mechanical and Chemical Properties of Glass Ionomer Cements

ABSTRACT: The glass ionomer cements (GICs) is a generic name given to a group of materials widely used in clinical dentistry which if used after the specified expiration date, material properties may be affected. to evaluate the Vick ers microhardness, surface morphology and the energy dispersive X-ray microanalysis (EDX), of GICs with different expiration dates that were stored at room temperature. specimens of highly viscous glass ionomer cement (HVGIC) (Ketac Cem and Ketac Molar) and resin-modified glass ionomer cement (RMGIC) (Vitrebond) with different expiration dates (current, close to their expiration and expired) were prepared for Vickers microhardness test and scanning electronic microscopy (SEM) with EDX, measuring 5 mm in diameter and 2 mm length, per the manufacturer's instructions, in standard cylindrical teflon molds. For the comparison of obtained values, the ANOVA test was used, while Tukey test was used for the multiple comparisons. In all the GICs used, the microhardness decreased as the expiration date approached, finding a significant statistical differen ce (P<0.05) in Ketac Molar and Vitrebond. SEM sample analysis revealed similar cohesive cracks in all tested materials. The EDX analysis revealed the presence of the elements F, Al and Si in all GICs and Ca only in Ketac Molar and Ketac Cem. The elements were found in a higher atomic percentage in the GICs with an current date and in a lower percentage in those with an expired date. HVGIC and RMGIC with an expiration date finish and that were stored at room temperature, suffer significant physical and chemical changes, which could put doubts its clinical effectiveness.

RESUMEN: El cemento de ionómero de vidrio (CIV) es un nombre genérico que se le da a un grupo de materiales ampliamente utilizados en odontología clínica que si se usan después de la fecha de vencimiento especificada, las propiedades del material pueden verse afectadas. evaluar la microdureza Vickers, la morfología superficial y el microanálisis de energía dispersa de rayos X (EDX), de CIV con diferentes fechas de caducidad almacenados a temperatura ambiente. Muestras de cemento de ionómero de vidrio de alta viscosidad (CIVAV) (Ketac Cem y Ketac Molar) y cemento de ionómero de vidrio modificado con resina (CIVMR) (Vitrebond) con diferentes fechas de vencimiento (vigente, próximo a su vencimiento y vencido) de 5 x 2 mm, fueron preparadas para microscopía electrónica de barrido (MEB) con EDX y microdureza Vickers, según las instrucciones del fabricante, en moldes de teflón cilíndricos estándar. Para la comparación de los valores obtenidos se utilizó la prueba ANOVA, mientras que para las comparaciones múltiples se utilizó la prueba de Tukey. En todos los CIV utilizados, la microdureza disminuyó a medida que se acercaba la fecha de vencimiento, encontrándose una diferencia estadística significativa (P <0.05) en Ketac Molar y Vitrebond. El análisis de la muestra en MEB reveló grietas cohesivas similares en todos los materiales probados. El análisis EDX reveló la presencia de los elementos F, Al y Si en todos los GIC y Ca solo en Ketac Molar y Ketac Cem. Los elementos se encontraron en mayor porcentaje atómico en los GIC con fecha vigente y en menor porcentaje en aquellos con una fecha vencida. Los CIVAV y CIVMR con fecha de caducidad vencida y que fueron alma- cenados a temperatura ambiente, sufrieron cambios físicos y químicos importantes, lo que podría poner en duda su efectividad clínica.

Comparación del sistema ProTaper Universal con homólogo adulterado: estudio descriptivo

Objetivos: Describir las características macroscópicas, microscópicas y la caracterización del material de instrumentos rotatorios de Níquel-Titanio (NiTi), ProTaper Universal, en comparación con instrumentos similares de dudosa procedencia. Material y métodos: El análisis macroscópico se realizó por medio de fotografía macro de las cajas e instrumentos. Para el análisis microscópico, se utilizaron los instrumentos S1 y F1, los cuales fueron seccionados y analizados a través de Microscopía electrónica de barrido comparando las partes activas y las secciones transversales con una magnificación de 300 a 550X. Adicionalmente, se realizó la caracterización de los fragmentos, a través de microanálisis por dispersión de energías de rayos-X (EDX). Resultados: Al análisis macroscópico, las cajas de los sistemas presentaron diferencias en el diseño y especificaciones, los vástagos de los instrumentos presentaron diferencias de forma, color y acabado, y las partes activas de algunos instrumentos, presentaron diferencias de diámetro, forma y acabado. Al análisis microscópico, los instrumentos adulterados presentaron ángulos de corte menos afilados y ausencia de convexidades triangulares. Al comparar la composición química de los instrumentos, el análisis EDX mostró que ambos instrumentos tienen una composición Ni-Ti similar. Conclusiones: Las mayores diferencias entre el sistema ProTaper Universal y su homólogo adulterado se presentaron en el análisis macroscópico. El análisis microscópico presentó diferencias principalmente en el formato de la sección transversal.

Objectives: To describe the macroscopic, microscopic characteristics and material characterization of nickel titanium (NiTi) ProTaper Universal system scompared to similar instruments of dubious origin. Material and methods: Macroscopic analysis was performed using macro photography of the boxes and files. For microscopic analysis, S1 and F1 files were used, which were sectioned and analyzed by scanning electron microscopy comparing active parts and cross-sections at 300-550X magnification. Additionally, the characterization of fragments was performed by energy dispersive x-ray microanalysis (EDX). Results: Macroscopic analysis showed that boxes differed in design and specifications. File shanks showed differences in shape, color, finish. The active part of some files showed differences in diameter, shape and finish. Microscopic analysis indicated that adulterated files showed less sharp cutting angles and absence of triangular convexities. By EDX, comparing the chemical composition of the instruments, it was shown that both instruments have a composition Ni-Ti like. Conclusions: The major differences between ProTaper Universal system and its counterpart adulterated, were presented in macroscopic analysis. Microscopic analysis showed differences mainly in cross-section configuration.

Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness

PURPOSE: The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS: Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 x 2 x 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukey's HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant. RESULTS: The general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 +/- 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 +/- 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 A). CONCLUSION: After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic substructures. The dentists should be familiar with the materials that are used in clinic for prosthodontics treatments.

Efeito do silício na intensidade da cercosporiose e na nutrição mineral de mudas de cafeeiro / Effect of silicon on the intensity of brown eye spot and on the mineral nutrition of coffee seedlings

O presente trabalho objetivou estudar o efeito do silício na intensidade da cercosporiose e na nutrição mineral de mudas de cafeeiro. No experimento 1, testou-se seis doses de ácido silícico (0, 0,5; 1; 2; 4 e 6 g kg­1 de solo) em mudas da cultivar Catuaí Vermelho IAC 99 inoculadas com o fungo Cercospora coffeicola. No experimento 2, foram realizadas microanálises de raios-X para a avaliação de nutrientes presentes nas folhas das mudas de cafeeiro das cultivares Topázio MG1190 e Icatu Precoce IAC 3282, inoculadas e não inoculadas com C. coffeicola, com e sem silicato de cálcio (1 g kg-1 de solo). Com o aumento das doses de ácido silícico observou-se redução na área abaixo da curva de progresso do número de lesões por folha (AACPNLF), redução linear nos teores foliares de magnésio e fósforo e aumento nos teores de enxofre e cobre. Os teores foliares de boro apresentaram comportamento quadrático, diminuindo com o aumento das doses de ácido silícico e aumentando a partir da dose de 4 g kg-1 de solo. Em microanálise de raio X, mudas de cafeeiro com cercosporiose apresentam menores picos de potássio e cálcio, independente da cultivar utilizada.

Our objective was to verify the effect of silicon on the intensity of brown eye spot and on the mineral nutrition of coffee seedlings. In the first experiment, 6 doses of silicic acid (0, 0.5, 1, 2, 4 and 6 g kg-1 soil) were tested using a complete randomized block design with 4 replicates with 6 coffee seedlings cultivar Catuaí Vermelho IAC 99 inoculated with the fungus Cercospora coffeicola. In the second experiment, X-ray microanalysis in a scanning electron microscope was performed on 2 coffee cultivars (Topazio MG1190 and Icatu Precoce IAC 3282), inoculated and non-inoculated with C. coffeicola, treated and untreated with calcium silicate (1 g kg-1 of soil). With the increase of the silicic acid doses, there was observed a reduction in the area under the disease progress curve of the number of lesions per leaf (AUPCNLL), coupled with a linear reduction in the foliar contents of magnesium and phosphorus as well as an increase in the contents of sulfur and copper. The foliar contents of boron presented a quadratic behavior, decreasing with the increase of silicic acid and increasing with the dose of 4 g kg-1 of soil. In X-ray microanalysis, coffee seedlings with brown eye spot presented lower peaks of potassium and calcium, regardless of the cultivar used.

Dynamic Changes of Mineral Element in The Cell Wall of Growth Cells Detected by CSEM-EDX / 生物化学与生物物理进展

Aerenchyrna formation has been described in depth in a number of species at a histological level. But large gaps remain in our understanding of its regulation as a developmental process. It is attempted to analyse essential mineral elements like K, Mg, Cu, Zn, Ca and P in the cell wall of aerenchyma cells in petioles ofS. trifolia at five different developmental stages by CSEM-EDX technique. At early stage, K and Cl concentrations in cell wall were high up to 36% and 4.3% of dry weight, respectively. It supported the hypotheses that aerenchyma spaces are filled with liquid at early developmental stages of aerenchyma in S. trifolia petiole. Mg concentration was high at stage 2, up to 0.86% of dry weight. Zinc and Cu were detected only at rapid expansion stages, during which the concentrations were up to 1.5% and 2.5%, respectively. Calcium was detected in the cell wall only at mature stages, the concentration was high up to 1.3% of dry weight at stages 4 and 5. These results confirmed that the element concentration of aerenehyma cell wall undergoes dynamic changes during different developmental stages, and a low Ca with high Zn and Cu concentration are needed for cell expansion. Copper and Zn deposition in the cell wall showed a significant positive linear correlation, suggesting that these two elements share same or similar uptake and transport mechanism in plants.

Morphological and chemical analysis of bone substitutes by scanning electron microscopy and microanalysis by spectroscopy of dispersion energy

This study evaluated the morphological and chemical composition of the following bone substitutes: cancellous and cortical organic bovine bone with macro and microparticle size ranging from 1.0 to 2.0 mm and 0.25 to 1.0 mm, respectively; inorganic bovine bone with particle size ranging from 0.25 to 1.0 mm; hydroxyapatite with particle size ranging from 0.75 to 1.0 mm; and demineralized freeze-dried bone allograft with particle size ranging from 0.25 to 0.5 mm. The samples were sputter-coated with gold in an ion coater, the morphology was observed and particle size was measured under vacuum by scanning electron microscopy (SEM). The chemical composition was evaluated by spectroscopy of dispersion energy (EDS) microanalysis using samples without coating. SEM analysis provided visual evidence that all examined materials have irregular shape and particle sizes larger than those informed by the manufacturer. EDS microanalysis detected the presence of sodium, calcium and phosphorus that are usual elements of the bone tissue. However, mineral elements were detected in all analyzed particles of organic bovine bone except for macro cancellous organic bovine bone. These results suggest that the examined organic bovine bone cannot be considered as a pure organic material.

Neste estudo foram avaliados a morfologia, o tamanho e a composição química dos seguintes substitutos ósseos: osso bovino orgânico cortical e esponjoso com micropartículas medindo entre 0,25 e 1,0 mm e macropartículas medindo entre 1,0 e 2,0 mm; osso bovino cortical inorgânico com partículas medindo entre 0,25 e 1,0 mm; hidroxiapatita com partículas medindo entre 0,75 e 1,0 mm; e osso humano descalcificado, congelado e seco medindo entre 0,25 a 0,5 mm. Para a analise da morfologia e tamanho das partículas, as amostras foram preparadas em porta-espécime, metalizadas em ouro e analisadas a vácuo em microscopia eletrônico de varredura (MEV). Para a análise da composição química, as partículas não foram metalizadas e foram analisadas por microanálise por espectroscopia por dispersão de energia (EDS). A análise em MEV, demonstrou que as partículas substitutos ossos apresentaram formato irregular e tamanho variável, maior do que o mencionado pelo fabricante. A microanálise por EDS detectou a presença de elementos como sódio, cálcio e fósforo, que são comuns à composição do tecido ósseo, porém revelaram a presença de elementos químicos nas partículas de osso bovino orgânico, exceto para a macropartícula de osso bovino orgânico esponjoso. Esses resultados sugerem que o osso bovino orgânico não pode ser considerado um material orgânico puro.

Comparative study of Aretemisia princeps Pamp. grown in Japan and China / 全日本鍼灸学会雑誌

Microstructure and elemental composition of dried <I>Artemisa princeps</I> Pamp. (Yomogi) leaves produced in Japan and China were investigated by scanning electron microscopy and X-ray microanalysis. Trichomes and T-foem hairs were found in higher density on the reverse side of the leaf of Yomogi. Cilium hairs were observed in Japanese Yomogi, while those in Chinese Yomogi, were distributed. Concentrations of K, Ca, Si and Cl were determined in plant fibers of the trichome in both Yomogi. In the head-style hairs of Japanese Yomogi, K, Ca, and Cl, S, P, Si were found, while K, Ca, Si, S, Mg and Fe were observed in the Chinese Yomogi.<BR>These results suggest that there were differences in morphological and elemental composition between Japanese and Chinese dried Yomogi leaves. These differences will affect the moxa quality even after the purifying process.

SCANNING ELECTRON MICROSCOPIC AND X-RAY MICROANALYTIC METHODS OF 5'-NUCLEOTIDASE AND p-NITROPHENYLPHOSPHATASE IN ISOLATED NEURONS / 解剖学报

The reaction product of cerium used for. localization of 5'-nuclcotidase (5'- Nase) and p-nitrophenylphosphatase(p-NPPase) is highly electron-dense but lacks sufficient contrast at the light microscopic level. We describe two methods for converting the reaction product of cerium to colored compounds visible by light microscopy. Using the Ce-Pb method and Ce-Pb-AgS method, the reaction prod- ucts of 5'-Nase and p-NPPase in isolated neurons of frontal cortex of rabbit were visualized by light microscopy. Aftcr application of the Ce-Pb-AgS method, surface of isolated neurons exhibtied crystalline precipitates by scanning electron microscopy(SEM). X-ray microanalysis of these crystals revealed the presence of high amounts of Ce, S/Pb and Ag. These results demonstrate that enzyme activity could be verified by SEM in conjunction with elementary microprobe analysis.

ANALYSIS OF QUALITATIVE AND QUANTITATIVE MORPHOLOGICAL CHANGES AND Ca~(2+) REGULATION OF ORGANELLES IN AGING MYOCARDIUM / 解剖学报

Objective To study the mechanism of myocardical aging. Methods Wistar rats used were divided aging group (22 months old) and adult group (7 months old). Qualitative morphological changes of organelles of myocardium were observed by TEM. Quantitative morphological changes of organelles of myocardium were determined by stereological method, Ca 2+ regulation of organelles of myocardium were analysed by EDS. Results Compared with adult group, aging group:(1) The nuclei were indented, myofibril were arranged irregularly, intercalated disk were separated, mitochondria and sarcoplasmic reticulum were swelled, lipofuscin and residual body were increased. (2) The volume of myocardium not occupied by myocyte were increased, the volume density of mitochondria and sarcoplasmic reticulum were reduced, specific surface of outer membrance of mitochondria inter membrane plus cristae of mitochondria and the membrane of sarcoplasmic reticulum were also reduced. (3) Ca 2+ in myofibril and mitochondria were increased, but Ca 2+ in sarcoplasmic reticulum were decreased. Conclusion The contractility of aging myocardium were declined, the morphological changes and Ca 2+ regulation of mitochondria and sarcoplasmic reticulum might be directly related to myocardical aging.