Avaliação da resistência torcional em instrumentos endodônticos Protaper Next, WaveOne e WaveOne Gold após uso único / Assessment of torsional resistance of Protaper Next, WaveOne and WaveOne Gold instruments after single use

Os instrumentos endodônticos de NiTi passam por contínuas modificações em suas características com o intuito de otimizar a instrumentação em agilidade, simplificação de técnicas e segurança clínica. Este trabalho teve como objetivo avaliar a resistência torcional de instrumentos: Protaper Next X1 (X1), Protaper Next X2 (X2), WaveOne Primary (WO) e WaveOne Gold Primary (WOG) antes e após o uso único em dentes extraídos, bem como analisar a influência das diferentes características de fabricação neste comportamento. Foi realizada a caracterização geométrica dos instrumentos através da mensuração do diâmetro e área da seção transversal a 3mm da ponta. A caracterização estrutural, para identificar as fases presentes nos instrumentos foi realizada por difratometria de raios-X (DRX). Os instrumentos foram divididos em grupo controle (GC) e grupo experimental (GE) cada grupo contendo sete (n=7) instrumentos de cada tipo. Para o GC, instrumentos novos foram ensaiados até a ruptura, em dispositivo de torção de acordo com a norma ISO 3630-1, para análise da resistência torcional antes do uso. Instrumentos do GE realizaram a formatação de dois canais mesias de um molar inferior cada, exceto instrumentos X1 e X2 que foram utilizados em sequência, nos mesmos dentes. Os instrumentos do GE tiveram sua superfície analisada por microscopia eletrônica de varredura (MEV) após o uso, a fim de se avaliar a presença de trincas decorrentes da instrumentação. Posteriormente foram ensaiados no mesmo dispositivo de torção até a ruptura. A análise estatística dos valores médios de torque máximo para os diferentes sistemas de instrumentos foi realizada através do teste ANOVA, considerando como significativo um valor de p<0.05. A resistência torcional foi maior para o sistema WO, seguido por WOG e Protaper Next X2 e X1. Estes valores sugerem uma relação direta com as características geométricas encontradas nestes instrumentos, uma vez que variam de forma crescente de acordo com o diâmetro real e área da seção transversal a 3mm da ponta. A análise da resistência torcional não mostrou diferenças estatisticamente significativas em valores de torque antes e após o uso simulado. Nas imagens de MEV não foram visualizadas trincas longitudinais decorrentes de fadiga torcional, nem aquelas transversais causadas pelo carregamento cíclico da fadiga flexural. Desta forma, concluiu- se que, independente se para instrumentos reciprocantes ou rotatórios, de uso único preconizado ou não, a formatação dos dois canais mesiais de um molar não demostrou comprometer a resistência torcional dos instrumentos nem levar à nucleação de trincas que pudessem ser visualizadas em MEV

NiTi instruments undergo continuous modofications to improve their performance on shaping canals. This study aimed to assess the torsional resistance among instruments: Protaper Next (X1), Protaper Next X2 (X2), WaveOne Primary (WO) e WaveOne Gold Primary (WOG) before and after use in extracted teeth and the influence of manufacturing characteristics on this behavior. The geometric characterization was performed by measure of diameter and cross-sectional are at 3mm from the tip...

ATP bioluminescence values are significantly different depending upon material surface properties of the sampling location in hospitals.

BACKGROUND: Our previous study into assessing hospital cleanliness in Japan by two common methods, ATP bioluminescence and the stamp agar method, revealed considerable variability in the data of both methods (BMC Research Notes, 7: 121, 2014). To investigate the reason(s) for the variability, we reanalyzed the data (n = 752) from the point of view of the material surface properties of sampling sites. METHODS: Data obtained from surfaces with unknown properties and different purposes such as floor were omitted, and the remaining data (n = 488) were used for this study. The material surface properties on sampling sites were divided into six categories: melamine coated (n = 216), vinyl chloride (n = 16), stainless steel (n = 144), wood (n = 63), and acrylonitrile-butadiene styrene resin coated (n = 48). The data between individual material properties were compared. RESULTS: The ATP values of high-touch places were significantly different depending on the type of surface, but no significant difference in stamp values between material properties was seen, indicating that in contrast to stamp values, ATP-accumulation more depends on the physical properties of the material surface such as electronic charges or roughness. To confirm this, we assessed a degree of roughness on vinyl chloride material surface (disutilized floor samples actually used for each of the hospitals) by observation with scanning electron microscope (SEM). As a result, SEM observation similarly revealed considerable roughness on the materials, which may allow microbes to contaminate the materials without noticing it. CONCLUSION: Material properties must be considered when evaluating hospital cleanliness with ATP values, and provide a strong warning into evaluating hospital cleanliness.

Correlative Light and Scanning Electron Microscopy for Observing the Three-Dimensional Ultrastructure of Membranous Cell Organelles in Relation to Their Molecular Components.

Although the osmium maceration method has been used to observe three-dimensional (3D) structures of membranous cell organelles with scanning electron microscopy (SEM), the use of osmium tetroxide for membrane fixation and the removal of cytosolic soluble proteins largely impairs the antigenicity of molecules in the specimens. In the present study, we developed a novel method to combine cryosectioning with the maceration method for correlative immunocytochemical analysis. We first immunocytochemically stained a semi-thin cryosection cut from a pituitary tissue block with a cryo-ultramicrotome, according to the Tokuyasu method, before preparing an osmium-macerated specimen from the remaining tissue block. Correlative microscopy was performed by observing the same area between the immunostained section and the adjacent face of the tissue block. Using this correlative method, we could accurately identify the gonadotropes of pituitary glands in various experimental conditions with SEM. At 4 weeks after castration, dilated cisternae of rough endoplasmic reticulum (RER) were distributed throughout the cytoplasm. On the other hand, an extremely dilated cisterna of the RER occupied the large region of the cytoplasm at 12 weeks after castration. This novel method has the potential to analyze the relationship between the distribution of functional molecules and the 3D ultrastructure in different composite tissues.

Curvelet based offline analysis of SEM images.

Manual offline analysis, of a scanning electron microscopy (SEM) image, is a time consuming process and requires continuous human intervention and efforts. This paper presents an image processing based method for automated offline analyses of SEM images. To this end, our strategy relies on a two-stage process, viz. texture analysis and quantification. The method involves a preprocessing step, aimed at the noise removal, in order to avoid false edges. For texture analysis, the proposed method employs a state of the art Curvelet transform followed by segmentation through a combination of entropy filtering, thresholding and mathematical morphology (MM). The quantification is carried out by the application of a box-counting algorithm, for fractal dimension (FD) calculations, with the ultimate goal of measuring the parameters, like surface area and perimeter. The perimeter is estimated indirectly by counting the boundary boxes of the filled shapes. The proposed method, when applied to a representative set of SEM images, not only showed better results in image segmentation but also exhibited a good accuracy in the calculation of surface area and perimeter. The proposed method outperforms the well-known Watershed segmentation algorithm.

Evaluación radiográfica y microscópica de la acción de quelantes en la remoción del barro dentinario / Radiographic and microscopic evaluation of the action of chelating agents in dental smear layer removal

Introducción: el tratamiento endodóntico realiza la limpieza y conformación del sistema de conductos radiculares, ya que virutas de dentina y materiales orgánicos, como los microorganismos, creadas por la acción de la instrumentación, forman el llamado barro dentinario. Objetivo: evaluar in vitro la remoción del barro dentinario y la disminución de la densidad de túbulos dentinarios, con soluciones irrigadoras quelantes. Métodos: se trata de un estudio experimental para el cual fueron seleccionados 30 dientes unirradiculares de humanos después del examen radiográfico inicial, y en el que se constató la presencia de canal único, ausencia de calcificación, reabsorción interna y tratamiento endodóntico concluido o en proceso. Luego se procedió a la instrumentación con tres diferentes soluciones irrigadoras: ácido etilenodiaminetetracético 17 por ciento, ácido cítrico 10 por ciento e hipoclorito de sodio 5,25 por ciento (grupo control). Posteriormente se evaluó radiográficamente cada diente instrumentado con el uso de una escala de densidad que fue confeccionada de aluminio con diferentes marcadores de densidades. Para el análisis por microscopio electrónico de barrido se utilizaron tres dientes de cada grupo, tratados con diferentes soluciones irrigadoras. Siete dientes de cada grupo se infiltraron con azul de metileno para la lectura de la infiltración marginal en el microscopio estereoscópico. Los dientes fueron evaluados en sus tres tercios: cervical, medio y apical. Resultados: se encontró que radiográficamente no hubo diferencia estadísticamente significativa entre los promedios de las densidades de los grupos de dientes en todos los tercios. Por microscopio electrónico de barrido se encontró una diferencia estadísticamente significativa entre los tres grupos de sustancias irrigadoras (p < 0,001), en el tercio cervical la remoción del barro dentinario fue mayor. Y por microscopio óptico se observó una mayor infiltración en el grupo de ácido etilenodiaminetetracético seguido del grupo ácido cítrico y por último el grupo control. Conclusión: el análisis de la densidad radiográfica y microscópica mostró que las sustancias quelantes fueron eficientes en la remoción del barro dentinario, excepto en el grupo control. Ninguna de las sustancias demostró alteraciones de densidad radiográfica de los túbulos dentinarios(AU)

Introduction: as part of endodontic treatment, root canals are cleaned and shaped, since shavings of dentin and organic materials, such as microorganisms, resulting from the action of instrumentation, create the so-called dental smear. Objective: carry out an in vitro evaluation of smear layer removal and dentinal tubule density reduction using chelating irrigation solutions. Methods: an experimental study was conducted for which 30 single-rooted human teeth were selected after initial radiographic examination to verify the presence of a single canal, absence of calcification, internal resorption and endodontic treatment either completed or underway. Next, instrumentation was performed with three different irrigation solutions: 17 percent ethylenediaminetetraacetic acid, 10 percent citric acid and 5.25 percent sodium hypochlorite (control group). Each instrumented tooth was then evaluated radiographically using a density scale made of aluminum with different density markers. Scanning electron microscope analysis was performed on three teeth from each group, which were treated with different irrigation solutions. Seven teeth from each group were infiltrated with methylene blue to determine marginal infiltration under the stereomicroscope. The teeth were evaluated on their three thirds: cervical, middle and apical. Results: radiographs did not reveal any statistically significant difference between the mean densities of the different groups of teeth in all thirds. Scanning electron microscopy showed a statistically significant difference between the three groups of irrigation substances (p < 0,001), with greater smear layer removal from the cervical third. Optical microscopy showed that infiltration was greatest in the ethylenediaminetetraacetic acid group, followed by the citric acid group, and lowest in the control group. Conclusion: analysis of radiographic and microscopic density revealed that except for the control group, chelating agents were efficient in removing dental smear. None of the substances showed any alteration in the radiographic density of dentinal tubules(AU)

Macromolecular 3D SEM reconstruction strategies: signal to noise ratio and resolution.

Three-dimensional scanning electron microscopy generates quantitative volumetric structural data from SEM images of macromolecules. This technique provides a quick and easy way to define the quaternary structure and handedness of protein complexes. Here, we apply a variety of preparation and imaging methods to filamentous actin in order to explore the relationship between resolution, signal-to-noise ratio, structural preservation and dataset size. This information can be used to define successful imaging strategies for different applications.

Beyond the lateral resolution limit by phase imaging.

We present a theory to extend the classical Abbe resolution limit by introducing a spatially varying phase into the illumination beam of a phase imaging system. It allows measuring lateral and axial distance differences between point sources to a higher accuracy than intensity imaging alone. Various proposals for experimental realization are debated. Concretely, the phase of point scatterers' interference is experimentally visualized by high numerical aperture (NA = 0.93) digital holographic microscopy combined with angular scanning. Proof-of-principle measurements are presented by using sub-wavelength nanometric holes on an opaque metallic film. In this manner, Rayleighs classical two-point resolution condition can be rebuilt. With different illumination phases, enhanced bandpass information content is demonstrated, and its spatial resolution is theoretically shown to be potentially signal-to-noise ratio limited.

Use of Autostitch for automatic stitching of microscope images.

Image stitching is the process of combining multiple images to produce a panorama or larger image. In many biomedical studies, including those of cancer and infection, the use of this approach is highly desirable in order to acquire large areas of certain structures or whole sections, while retaining microscopic resolution. In this study, we describe the application of Autostitch, viz. software that is normally used for the generation of panoramas in photography, in the seamless stitching of microscope images. First, we tested this software on image sets manually acquired by normal light microscopy and compared the performance with a manual stitching approach performed with Paint Shop Pro. Secondly, this software was applied to an image stack acquired by an automatic microscope. The stitching results were then compared with that generated by a self-programmed rectangular tiling macro integrated in Image J. Thirdly, this program was applied in the image stitching of images from electron microscopy. Thus, the automatic stitching program described here may find applications in convenient image stitching and virtual microscopy in the biomedical research.

Alginate-coated alginate-polyethyleneimine beads for prolonged release of furosemide in simulated intestinal fluid.

Furosemide-loaded calcium alginate (ALG), calcium alginate-polyethyleneimine (ALG-PEI) and alginate-coated ALG-PEI (ALG-PEI-ALG) beads were prepared by ionotropic/polyelectrolyte complexation method to achieve controlled release of the drug. Effects of several formulation factors on the characteristics of the beads were investigated. Although variation in formulation factors did not influence the drug-loading efficiency (DLE) of ALG beads, rapid release of the drug in simulated intestinal fluid (SIF) could not be prevented. PEI treatment of ALG beads, however, prolonged the drug release considerably. Ionic interaction, as appeared from FTIR studies, between alginate and PEI led to the formation of polyelectrolyte complex membrane, the thickness of which was dependent on the conditions of PEI treatment as demonstrated by scanning electron microscopy (SEM). The membrane acted as a physical barrier to drug release from ALG-PEI beads. Alginate coating of ALG-PEI beads further prolonged the release of the drug by increasing membrane thickness and reducing swelling of the beads possibly by blocking the surface pores. Differential scanning calorimetry (DSC) study indicated that drug was not degraded by PEI treatment. The release data from ALG-PEI beads showed a good fit in power law expression, whereas the release data from ALG-PEI-ALG beads were found to fit in modified power law expression, and the mechanism of drug release changed from super case II transport to nearly Fickian transport, depending on the degree of gelation and formation of polyelectrolyte complex membrane.

Automated analysis of SEM X-ray spectral images: a powerful new microanalysis tool.

Spectral imaging in the scanning electron microscope (SEM) equipped with an energy-dispersive X-ray (EDX) analyzer has the potential to be a powerful tool for chemical phase identification, but the large data sets have, in the past, proved too large to efficiently analyze. In the present work, we describe the application of a new automated, unbiased, multivariate statistical analysis technique to very large X-ray spectral image data sets. The method, based in part on principal components analysis, returns physically accurate (all positive) component spectra and images in a few minutes on a standard personal computer. The efficacy of the technique for microanalysis is illustrated by the analysis of complex multi-phase materials, particulates, a diffusion couple, and a single-pixel-detection problem.

A simple low-vacuum environmental cell.

The environmental cell device discussed in this paper provides a modest low-vacuum scanning electron microscopy (SEM) capability to a standard SEM without requiring additional pumping. This environmental cell confines a volume of low vacuum in contact with the sample surface using a container that has an aperture for admitting the primary electron beam. The aperture is large enough to permit a limited field of view of the sample, and small enough to limit the outflow of gas into the SEM chamber to that which can be accommodated by the standard SEM pumping system. This environmental cell also functions as a gaseous detector device.

Statistical modeling of protein spray drying at the lab scale.

The objective of this study was to examine the effects of formulation and process variables on particle size and other characteristics of a spray-dried model protein, bovine serum albumin (BSA), using a partial factorial design for experiments. Formulation variables tested include concentration and zinc:protein complexation ratio. Process variables explored were inlet temperature, liquid feed rate, drying air flow rate, and atomizing nitrogen pressure on a lab-scale spray dryer. Statistical data analysis was used to determine F ratios for each of the inputs, which provided a means of ranking the importance of variables relative to one another for each powder characteristic of interest. It was found that protein concentration and atomizing nitrogen pressure had the greatest effects on the particle size of the protein powder. For determining product yield, results showed that protein concentration was the critical variable. Finally, the outlet temperature was mostly influenced by inlet temperature and liquid feed rate. Mathematical models based on these input-output relationships were constructed; these models provide insight into some of the controllable variables of the spray-drying process.

Equivalente esférico e valores da espessura da camada de fibras narvosas obtidas com o GDX tm Scanning Laser System / Spherical equivalent and nerve fiber layer thickness assessed with GDX tm Scanning Laser System

Objetivo: Estudar a influência do equivalente esférico nos valores obtidos pelo GDX tm Scanning Laser System.Métodos: Foram avaliados 41 voluntários sem doenças oculares e com campo visual sem alteraçöes.Foi realizada a polarimetria de varredura a laser como GDX tm Scanning Laser System de acordo com as instruçöes contidas no manual do aparelho.Foram comparados os valores obtidos nesse axame em um grupo de pacientes com equivalente esférico positivo e em um outro com este valor nulo ou negativo, pelo teste de Mann-Whitney.Resultados: Näo se verificou diferença estatística entre os valores obtidos nos olhos de pacientes do grupo I e os do grupo II.Näo foi encontrada correlaçäo entre o equivalente esférico e os valores obtidos com o GDX tm Scanning Laser System.Conclusöes: Na amostra estudada näo houve diferença estatística entre os valores obtidos em um grupo de olhos com equivalente esférico positivo e outro com este valor negativo ou nulo, usando-se o GDX tm Scanning Laser System.

Calcium phosphates produced by physical methods in the treatment of dentin hypersensitivity.

BACKGROUND: The aim of this paper is to study the properties of innovative materials based on defective calcium phosphates produced by physical methods in the therapy of dentin hypersensitivity. METHODS: In particular, the effects of gels, aqueous solutions and toothpastes containing the above mentioned materials on dentinal permeability measured as dentin hydraulic conductance have been studied. The calcium phosphates have been characterized by X-ray powder diffraction (Rietveld analysis) and Fourier transform infra-red analysis. In addition, scanning electron microscopy has been performed to study the surface of dentin and enamel after treatment with the phosphates. In particular sound occlusal dentin, sound cervical dentin, carious occlusal dentin, sound buccal enamel and carious buccal enamel have been observed. RESULTS: The results have shown that these biocompatible materials can be produced with chemical and physical characteristics very similar to dentin and/or enamel. By forming a protective layer inside and outside the dentin tubuli, the calcium phosphates significantly reduce the dentinal hypersensitivity. CONCLUSIONS: These phosphates seem to be a promising material for clinical application.

Scanning and electron microprobe analysis of metal-porcelain interface.

The purpose of this study was to analyze the interfacial region between porcelain and base metal alloy using scanning electron microscope with electron microprobe analyzer. Results gave evidence of formation of Nio and Cr2O3 with evidence of more migration of NiO towards the porcelain. Sandblasting of oxidized and fired metal samples (simulating firing of porcelain without its application) showed appearance of crystalline structure of Ni and Cragain, indicating delamination of oxide layer by sandblasting. At porcelain side analysis showed NiO and Cr2O3 and iron oxide plus Si, K, CI, Sn and Cu.

Energy-dispersive X-ray analysis and scanning electron microscopy of pleura. Study of reference, exposed non-pneumoconiotic, and silicotic populations.

Inorganic element content in pleura and lung was studied by energy-dispersive X-ray analysis (EDXA) and scanning electron microscopy (SEM) in reference, exposed non-pneumoconiotic, and silicotic populations. Samples of parietal pleura, visceral pleura, and lung in 11 subjects with no measurable exposure to inorganic dust and of visceral pleura and lung samples of 10 exposed non-pneumoconiotic individuals and eight silicotic patients were examined. Constant depositions of silicon and calcium were detected in visceral pleura, parietal pleura, and lung of the reference group and in visceral pleura and lung of the exposed non-pneumoconiotic and silicotic groups. Other elements, such as aluminum and iron, were also detected in the exposed non-pneumoconiotic and silicotic patients and, less frequently, in the reference group. There was no difference in silicon content between parietal and visceral pleura in the reference group. Silicon content in silicotic patients was higher and more irregularly distributed in the pleura (p = 0.005 and p < 0.01, respectively) and in the lung (p = 0.005 and p < 0.01, respectively) than in the reference group. Comparison of the silicon content in pleura between silicotic and exposed non-pneumoconiotic subjects showed a nonsignificant probability of difference (p = 0.052), whereas there were no differences with respect to the silicon content in lung. There were no differences in the pleural and lung silicon content between the exposed non-pneumoconiotic and reference groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Referencia comprensiva de una nueva aleación para amalgama dental / Comprensive strength of the new alloys for dental amalgam

El presente trabajo de investigación tuvo como objetivo deteminar la resistencia comprensiva de una nueva aleación para amalgama dental y comparar los resultados de esta propiedad mecánica con otras tres amalgamas de su mismo género. Así mismo se realizó una evaluación del tamaño y forma de las partículas de cada uno de los sistemas de aleaciones a través de la observación del microscopio electrónico de barrido. Para el logro del objetivo principal, se utilizó la Norma Venezolana 773-89 de Control de Calidad para Productos Odontológicos, aleaciones para amalgamas dentales que permitió evaluar la resistencia comprensiva. La presente investigación concluyó que esta nueva aleación para amalgama dental producida en la República del Perú supera el valor mínimo aceptable que la Norma de Control de Calidad exige

Fine structure and histometry of the enamel prismless layer of unerupted third molar teeth

Se examina la capa aprismática de 20 terceros molares humanos no erupcionados, usando microscopía electrónica de barrido. Los dientes se conservaron en alcohol al 70 por ciento y luego fracturados en dirección buco-lingual. Las caras bucal y lingual se subdividieron en tres regiones: cervical, media y oclusal. Nuestros resultados demostraron que la capa aprismática se encuentra en tres regiones, en ambas caras, bucal y lingual, de los terceros molares no erupcionados, presentando valores de 5,01µm en la superior y 5,58µm en la inferior. En las caras bucal y lingual y en las tres regiones; oclusal, media y cervical, el grosor de la capa de esmalte aprismático presenta un valor que aumenta desde oclusal hacia cervical 3,36µm; 5,28µm y 8,11µm. La capa aprismática esta compuesta por cristales de hidroxiapatita dispuestos en forma paralela entre sí, y perpendicularmente a la superficie de la capa externa del esmalte

Morphometric computerized analysis on the dentinal tubules and the collagen fibers in the dentine of human permanent teeth.

A morphometric analysis has been performed on important components of human dentine using an image computerized analyzer. The dentinal tubule diameter and their area percentage were calculated. Moreover the area percentage of the collagen fibers in the dentinal matrix was measured. These parameters have been evaluated in different areas of the coronal and the radicular dentine in permanent teeth. Measurements have been performed on undecalcified and decalcified teeth and on teeth treated with enzymatic digestion to remove the organic non collagen matrix and to evidentiate the collagen fiber network. The values obtained in different areas of the tooth and in samples submitted to different treatments were evaluated by statistical analysis. Dentinal tubule diameter and area percentage significatively decrease from the inner to the peripheral dentine both in the undecalcified teeth as in the decalcified ones and in the samples undergone to enzymatic digestion. The collagen fiber percentage in the organic matrix is significatively lower in the mantle dentine.

Aplicación de la microscopia electrónica al estudio de la sangre periférica en el síndrome de inmunodeficiencia adquirida (SIDA) / Aplication of the electronic microscopy to peripheral blood study in the acquired immunodeficiency syndrome (AIDS)

El síndrome de inmunodeficiencia adquirida (SIDA), es producido por los virus de la inmunodeficiencia humana (VIH 1 y VIH 2), los cuales inducen en los pacientes trastornos progresivos de la inmunidad celular. A los fines de detectar si ocurren alteraciones a nivel ultraestructural de los leucocitos, que ayuden a clarificar la patogenia del SIDA, se procesó sangre periférica de 10 pacientes seropositivos sintomáticos, 15 seropositivos asintomáticos y 9 personas sanas, según los métodos de Watanabe y Donahue modificado por Pirela y col. para su estudio con el microscopio electrónico de transmisión (MET), y de Boyum y col. y Nakstad y col. para ser estudiados con el microscopio electrónico de barrido (MEB). Se detectaron en linfocitos y monocitos estructuras tubuloreticulares (TRS) en el interior del retículo endoplasmático rugoso en el 72,7% de los pacientes seropositivos sintomáticos y en 20% de los asintomáticos, y cisternas cilíndricas confrontadas (CCC) en un paciente seropositivo sintomático y en uno asintomático. Estas estructuras estan relacionadas con interferon tipo I y nuestros hallazgos coinciden con los reportados por la mayoría de otros autores. La presencia de estas inclusiones ha sido asociada con la evolución y pronóstico de los pacientes con SIDA