Lymphatic vessels in inflammed human dental pulp

Investigation has been performed on both the light and electron microscopic characteristics of the lymphatic vessels present in the dental pulp of human teeth which have been affected by serious carious lesions. These conditions provoke a severe inflammatory response resulting in structural and functional modifications of the tissue; increase of the tissue pressure is followed by the need for a more intensive lymphatic drainage. In the inflammed pulps, dilated lymphatic vessels with distended walls and »open junctions« between endothelial cells are detectable. On the other hand they lack certain endothelial structures which characterize the morphology of these vessels under normal conditions. In the pulpal regions affected by fibrotic proliferation shrinked vessels with irregular profiles are present. From these observations it is possible to obtain other information on the mechanisms regulating the lymphatic drainage in different structural and functional conditions of the interstitium.La recherche a eu pour but d’examiner au microscope optique et au microscope électronique les caractéristiques morphologiques des vaisseaux lymphatiques présents dans le tissu pulpaire de dents humaines atteintes de graves lésions dues aux caries. En de pareilles conditions, des processus inflammatoires s’instaurent dans le tissu pulpaire d’une telle intensité qu’ils provoquent des modifications structurelles et fonctionelles dans le tissu avec une augmentation de la tension tissulaire et donc un besoin majeur de drainage de la part du système lymphatique. Dans les pulpes enflammées, on a pu démontrer la présence de vaisseaux lymphatiques dilatés dans la paroi desquels on trouve des «jonctions ouvertes» alors, qu’il manque certaines des structures endothéliales qui caractérisent ces vaisseaux dans les conditions normales.Dans les zones de tissu pulpaire avec dégénérescence fibreuse, on trouve des vaisseaux lymphatiques aux parois contractées et irrégulières.Par ces observations, il a été possible de trouver d’autres informations sur les mécanismes qui règlent le drainage lymphatique dans differentes conditions structurelles et fonctionnelles de l’interstitium

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 sumitted 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.Il a été procédé à une recherche morphométrique relative à des composants importants de la dentine à l’aide d’un analyseur d’images computérisé. Le diamètre des tubules dentinaires et le pourcentage de la surface qu’ils occupent dans la dentine ont été mesurés. En outre, le pourcentage de la surface occupée par les fibres collagènes dans la matrice dentinale a été également mesuré. Ces valeurs ont été relevées dans des surfaces différentes de dentine, dans la racine et dans la couronne de dents permanentes. Les mesures ont été effectuées sur des dents décalcifiées ainsi que sur des dents traitées par digestion enzymatique afin d’enlever, après décalcification, la composante organique non collagène et séparer la trame des fibres collagènes.Les valeurs obtenues dans les différentes surfaces de la dent et dans des dents soumises à divers traitements ont été étudiées et confrontées au moyen d’analyse statistique.Le diamètre des tubules et leur pourcentage de surface diminuent significativement de la dentine la plus interne à celle périphérique, aussi bien dans les dents non décalcifiées que dans les dents décalcifiées et dans celles qui sont soumises à digestion enzymatique. Le pourcentage de la surface des fibres collagènes dans la matrice organique est significativement inférieure dans la dentine périphérique

Dynamics of stripe patterns in type-I superconductors subject to a rotating field

The evolution of stripe patterns in type-I superconductors subject to a rotating in-plane magnetic field is investigated magneto-optically. The experimental results reveal a very rich and interesting behavior of the patterns. For small rotation angles, a small parallel displacement of the main part of the stripes and a co-rotation of their very ends is observed. For larger angles, small sideward protrusions develop, which then generate a zigzag instability, ultimately leading to a breaking of stripes into smaller segments. The short segments then start to co-rotate with the applied field although they lag behind by approximately $10^\circ$. Very interestingly, if the rotation is continued, also reconnection of segments into longer stripes takes place. These observations demonstrate the importance of pinning in type-I superconductors.Comment: To appear in Phys. Rev.

Actuator Fault Reconstruction via Dynamic Neural Networks for an Autonomous Underwater Vehicle Model

This paper proposes the development of a scheme for the fault diagnosis of the actuators of a simulated model accurately representing the behaviour of an autonomous underwater vehicle. The Fossen model usually adopted to describe the dynamics of the underwater vehicle has been generalised in this paper to take into account time-varying sea currents. The proposed fault detection and isolation strategy uses a data-driven approach relying on multi-layer perceptron neural networks that include auto-regressive exogenous prototypes that provide the fault reconstruction. These tools are thus exploited to design a bank of dynamic neural networks for residual generation that are trained on the basis of the input and outputmeasurements acquired from the simulator. In this work, the residuals are designed to represent the reconstruction of the fault signals themselves. Moreover, the neural network bank is also able to perform the isolation task, in case of simultaneous and concurrent faults affecting the actuators. The paper firstly describes the steps performed for deriving the proposed fault diagnosis solution. Secondly, the effectiveness of the scheme is demonstrated by means of high-fidelity simulations of a realistic autonomous underwater vehicle, in the presence of faults and marine current

Note sur les effets du laser CO2 sur la dentine et le cément humains

Polarizing microscopy, scanning electron microscopy and X-ray diffraction analysis have been used to study the effects of the radiations of a C02 laser equipment on the dentine and cementum of sound human permanent teeth.The typical lesions induced in dentine and cementum differ only lightly because of the different composition of the tissues. They assume a crater-like aspect and show structural alterations, less and less severe when moving away from the beam focal center.The morphological analysis of the tissues, which loose their organic components through combustion, suggests that such lesions are the consequences of a very fast overheating followed by a fast cooling.X-ray diffraction analysis shows that the hydroxyapatite of the tissues submitted to the thermic stress does not undergo phase transformation, which means that the temperatures remain lower than 1200ºC.Ont été étudiés les effets des radiations d’un laser C02 spécifiquement conçu pour une utilisation en odontologie, sur la dentine et le cément de dents humaines permanentes saines, au moyen de la microscopie classique en lumière polarisée, de la microscopie électronique à balayage et de la diffraction X.Les lésions induites dans le cément et la dentine, très caractéristiques, diffèrent seulement légèrement en fonction de la composition différente des deux tissus. Elles ont un aspect en forme de cratère. Les altérations structurales diminuent d’importance au fur et à mesure que l’on s’éloigne du centre focal du rayon laser.L’étude morphologique suggère que ces lésions sont la conséquence d’un surchauffement rapide, suivi d’un refroidissement tout aussi rapide des tissus qui, par suite de la combustion, perdent leur composante organique.L’analyse en diffraction X révèle que l’hydroxyapatite des tissus intéressés par le stress thermique ne change pas de phase et que, par conséquent, les températures atteintes sont inférieures à 1200ºC

FIB/SEM and SEM/EDS microstructural analysis of metal-ceramic and zirconia-ceramic interfaces

Recently introduced FIB/SEM analysis in microscopy seems to provide a high-resolution characterization of the samples by 3D (FIB) cross-sectioning and (SEM) high resolution imaging. The aim of this study was to apply the FIB/SEM and SEM/EDS analysis to the interfaces of a metal-ceramic vs. two zirconiaceramic systems. Plate samples of three different prosthetic systems were prepared in the dental lab following the manufacturers’ instructions, where metal-ceramic was the result of a ceramic veneering (porcelain-fused-tometal) and the two zirconia- ceramic systems were produced by the dedicated CAD-CAM procedures of the zirconia cores (both with final sintering) and then veneered by layered or heat pressed ceramics. In a FIB/SEM equipment (also called DualBeam), a thin layer of platinum (1μm) was deposited on samples surface crossing the interfaces, in order to protect them during milling. Then, increasingly deeper trenches were milled by a focused ion beam, first using a relatively higher and later using a lower ion current (from 9 nA to 0.28 nA, 30KV). Finally, FEG-SEM (5KV) micrographs (1000–50,000X) were acquired. In a SEM the analysis of the morphology and internal microstructure was performed by 13KV secondary and backscattered electrons signals (in all the samples). The compositional maps were then performed by EDS probe only in the metal-ceramic system (20kV). Despite the presence of many voids in all the ceramic layers, it was possible to identify: (1) the grain structures of the metallic and zirconia substrates, (2) the thin oxide layer at the metalceramic interface and its interactions with the first ceramic layer (wash technique), (3) the roughness of the two different zirconia cores and their interactions with the ceramic interface, where the presence of zirconia grains in the ceramic layer was reported in two system possibly due to sandblasting before ceramic firing

Collagen Fiber Arrangement in Temporo-Mandibular Joint (TMJ) Disks from Human Subjects with Functional Diseases. Scanning Electron Microscopy Investigations

Twelve articular disks from patients with temporo-mandibular joint (TMJ) arthropathy were studied and compared with two normal disks. Scanning electron microscopy (SEM) examination of the surfaces and of longitudinal and cross-sections of the disks allowed the observation of the arrangement of the collagen fiber component in different parts of the disk. The superficial part of the articular disks appears to be formed by rather compact fibers. The internal portion is usually formed by bundles of collagen fibers in sheets, alternating with isolated fibers arranged in a parallel or irregular way. In some samples, blood vessels were observed. Our investigations suggested that the appearance of vascularization is the first remarkable histological change that can be observed in functionally abnormal articular disks

La couche externe aprismatique des dents temporaires et permanentes

The authors wanted to verify the presence of an aprismatic layer on the surface of human deciduous and permanent, erupted and non erupted teeth, by means of the polarizing and scanning electron microscope.The results allowed the authors to conclude that the presence of different extents of aprismatic enamel on the human teeth surface should be regarded as a constant and normal feature, with some different frequency and organization patterns between different tooth types.Les auteurs se sont proposés de vérifier la présence d’émail «aprismatique» sur les surfaces de dents humaines temporaires et permanentes, ayant effectué leur éruption et incluses, en utilisant le microscope à lumière polarisée et le microscope électronique à balayage. Les résultats obtenus nous ont permis de conclure que la présence de zones plus ou moins vastes d’émail aprismatique sur la surface des dents humaines doit être considérée comme constante et normale, avec quelques différences de fréquence et de modalités d’organisation entre les différents types de dents

Investigation on the Collagen Fiber Network in Human Dental Tissues - Transmission and Scanning Electron Microscopy

The collagen fiber component of pulp, dentine and cementum, has been studied by isolating it from the inorganic component and the organic non-collagen matrix. This study was carried out on healthy molar and premolar adult teeth. Following demineralization all of the non-collagenous components of the tooth were removed by sequential treatment with H202, with different concentrations of trypsin and with EDTA. The transmission (TEM) and scanning (SEM) electron microscopy investigation confirmed that such a technique is an accurate method for isolating the collagen fibers while preserving their position and their ultrastructure in the dental tissue. The use of TEM and SEM in the observation of homogeneous samples provided further information regarding the structural characteristics of the collagen fiber network of dental tissues. Our main concern was the characterization of interodontoblastic fibers and the different distribution and arrangement of collagen fibers in different dental zones