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 zirconia-ceramic 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-to-metal) 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 (1 µm) 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 metal-ceramic 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.

Commercial 3y-tzp and nanostructured zirconia for ceramic veneering: a sem study.

Short Communication selected from the Oral Presentations of the 56th Congress of the Groupèment International pour la Recherche Scientifique en Stomatologie et Odontologie, Peñafiel (Portugal) May 2012.

Radiographic evaluation of teeth subjected to high temperatures: experimental study to aid identification processes.

The radiographic evaluation of dental remains represents a significant aspect in the forensic identification process, particularly after an exposure to fire. The aim of this "in vitro" study was to evaluate the radiographic features of unrestored, endodontically treated and restored teeth after exposure to an experimental range of high temperatures. Ninety human teeth were divided into two groups: (1) unrestored teeth, as a control group and (2) teeth endodontically treated (condensation technique) and restored with amalgam or composite fillings. Before testing the high temperatures, periapical radiographs of all teeth were performed. The tests of exposure to heat were carried out in an oven for six different temperatures (200, 400, 600, 800, 1000 and 1100 degrees C (392, 752, 1112, 1472, 1832, 2012 degrees F)). After each exposure, periapical radiographs of all the teeth were taken. The radiographic appearance of all the teeth before and after the thermal stresses were evaluated and the differences were recorded. The results of the radiographic examination showed that a number of significant radiographic details were conserved: the composite fillings were in place maintaining the shape till 600 degrees C (1112 degrees F), the amalgam fillings were in place maintaining the shape till 1000 degrees C (1832 degrees F) and the endodontic treatments were recognisable till 1100 degrees C (2012 degrees F).

Further study of restored and un-restored teeth subjected to high temperatures.

Forensic dentistry has been shown to be of fundamental importance in medico-legal investigations aimed at identifying human remains involving high temperature incidents because dental remains and prosthetic devices are resistant to quite high thermal change. In this project we studied teeth containing class I and V amalgam and composite fillings and compared them to un-restored teeth when exposed to high temperatures. Twenty five un-restored teeth, 25 teeth with class I amalgam restorations, 25 teeth with class V amalgam restorations and 25 teeth with class I composite fillings were placed in a furnace and heated at a rate of 30 degrees C/min. The effects at the predetermined temperatures 200, 400, 600, 800, 1000 and 1100 degrees C were examined macroscopically and then observed microscopically by means of a stereomicroscope. Our observations showed that the class I amalgam restorations at the different temperature levels remained in place, maintaining their shape despite disintegration of the crowns, whilst the class I composite restorations remained in place but in an altered shape. Comparing restored with un-restored teeth we observed different responses in crown disintegration at the different temperature levels.

Observations on dental prostheses and restorations subjected to high temperatures: experimental studies to aid identification processes.

In large scale disasters associated with fire the damage caused by heat can make medico-legal identification of human remains difficult. Teeth, restorations and prostheses, all of which are resistant to even quite high temperatures can be used as aids in the identification process. In this project the behaviour and morphology of teeth and dental prostheses exposed to a range of high temperatures was studied. Healthy teeth, dental restorations and prostheses were placed in a furnace and heated at a rate of 30 degrees C/min and the effects of the predetermined temperatures 200, 400, 600, 800, 1000 and 1100 degrees C were examined by stereomicroscopy and scanning electron microscopy (SEM). Our observations show that some prostheses and restorative materials resist higher temperatures than theoretically predictable and that even when a restoration is lost because of detachment or change of state its ante-mortem presence can be confirmed and detected by both stereomicroscopic examination and SEM of the residual cavity. We further conclude that a reasonably reliable estimation of the temperature of exposure can be made from an analysis of the teeth and restorative materials.

[Elastomeric chains in orthodontics. An in vitro evaluation of ten different types]. / Le catenelle elastich in ortognatodonzia. Valutazione in vitro di dieci proposte.

BACKGROUND: This study is an evaluation and a comparison assessment of ten different types of orthodontics elastomeric chains in an in vitro situation simulating the clinical therapy for the canine tooth distalisation. METHODS: We designed and produced two custom made systems in order to simulate the clinical movement and to measure the elastic recovery. The first device was suitable to activate the elastomeric chains up to 100% of its extension and successively to reduce this extension through the time, as it happens during the clinical practice. Simultaneously with the activation of the chains, it was possible to submit the device to two different termocycling procedures. The measuring system was a linear guide skid-mounted on a balance which provided two grasps in the order to achieve the activation rate and to measure it. The force showed by the elastic recovery was relieved at the starting of the experience and after 1, 7, 14, 21 days. RESULTS: We relieved that the elastomeric chains decreased their elastic recovery to the 50-70% of the starting rate during the first day of activation, after which the force holded fairly uniform and after three weeks it was the 20-40% of the value corresponding to the starting activation. CONCLUSIONS: The tested elastomeric chains provide forces reliable to produce the tooth movement for a maximum of a three/four weeks period; than they have to be changed since the induced movement is nullifying its efficacy. At the comparative analysis the diaphanous type shows a lower decrease of the elastic force than the gray type, and the Short& e X-Short shapes show the same behaviour and generate forces much more performing than Long shapes.

[Measurement technics]. / A propos des tecniques de mesure.

Aim of the research has been the evaluation of an image processing technique suggested for measuring procedures in the field of dental materials and devices studies. An analysis of measurement systems and largest employment's equipments in the biotechnologies field has been performed. Particularly, digital and image processing technologies have been considered and, between them, an evaluation of "Image Tool" software, made by UTHSCSA and available freeware on Internet has been carried out. The "Image Tool" software showed to be easy in handling and reliable on this results. Since it is based on image processing, the measuring precision is related to subject to be evaluated dimensions and always in the 1/1000 tolerance. This software also allow the direct surfaces measuring and comparing. The process accuracy is at the same level of mechanical regulation's measuring instruments (calipers, micrometres, surface probes) but it is not comparable to the laser controlled equipments, like CAD-CAM systems, micrometres and surface explores, precision which are much more sophisticated and expensives.

Endoarticular loose bodies and calcifications of the disk of the temporomandibular joint: morphological features and chemical composition.

We studied articular disks and endoarticular loose bodies taken from patients suffering from different types of temporomandibular joint (TMJ) pathology. The scanning electron microscopy (SEM) analysis of the disks and the endoarticular loose bodies was followed by a chemical-compositional analysis using an energy dispersive spectrometer (EDS) and by characterization of the crystalline phases by X-ray powder diffraction (XRD). The articular disks were composed of a central radiopaque area lacking any evident structural features, surrounded by compact bundles of collagen fibers. EDS and XRD analyses showed that endodiscal radio-opaque areas were hydroxyapatite. By SEM, we observed a fibrous network only in circumscribed areas of the endoarticular loose bodies. The chemical-compositional analysis showed that the loose bodies were composed of calcite (CaCO3). The results of this investigation, along with the clinical history of the patients, allow us to formulate some hypotheses regarding the etiopathogenesis of these structural anomalies. The endodiscal calcifications could be the result of a chronic inflammatory process that produces displastic alterations of the articular disk. Moreover, an acute inflammatory process with modifications in the mechanisms of the synovial fluid turnover seems to be the event that leads to the formation of endoarticular loose bodies.

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.

Observations on the enamel of odontomas.

The morphological study of odontomas provides an alternative model for observing the formation of dental tissues, since different maturing stages are present simultaneously. Investigations were performed on decalcified samples (using light microscopy and transmission electron microscopy) and on undecalcified samples of complex odontoma enamel (using transmission electron microscopy). Simultaneous presence of prismatic enamel at various maturing stages with different structural characteristics was observed. Such enamel was sometimes associated with layers of ameloblastic cells with characteristics of cells in functional activity. In other sites, the enamel did not present a prismatic structure but it appeared as unstructured material clusters with abundant organic component. It was concluded that the theory according to which an ecto-mesenchymal inductive failure occurs in odontomas is not confirmed. The defect seen at the beginning of the differentiated and anomalous tissue maturation may be related to latest events in the development of the enamel organ. In this regard, it was concluded that such events involve the efficiency of the ameloblasts and the possible alterations in the organic matrix.

Lipoma of the corpus callosum in a neonate: sonographic evaluation.

Lipomas of the corpus callosum are benign neoplasms which are rarely diagnosed in pediatric patients. In infants they are congenital lesions consisting of collections of adipose tissue; their etiology is unclear. We describe a case of callosal lipoma discovered by sonography in a 2-day-old neonate.

Darrow-Gamble disease: ultrasonographic and radiographic findings.

A case of Darrow-Gamble disease is presented with review of the radiographic and ultrasonographic appearance of this rare cause of profound chronic diarrhea beginning at birth. The disease is caused by a defect of active intestinal chloride transport which results in a large loss of the electrolytes and water. To prevent growth retardation and renal involvement an adequate replacement therapy is necessary. This uncommon anomaly was detected by ultrasound 3 weeks before delivery. Both sonography and radiography were useful diagnostic tools in the postnatal period. The clinical features of the lesion are also discussed.

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.

[Light and electron microscopy observations on different tissues of a complex odontoma]. / Observations en microscopie photonique et électronique sur différents tissus d'un odontome complexe.

Several aggregates of dental tissues constitute the complex odontoma. They are almost completely covered by a layer of prismatic enamel. By the observations at transmission and scanning electron microscope enamel present the characteristics of a not fully developed tissue. The organic component is still abundant and the enamel surface is covered by a cellular layer having the morphological features of the mature ameloblasts. Therefore this enamel results to be yet actively engaged in the maturation phase although the tissues of the odontoma have generally a limited developing time.

[A case of congenital chloridorrhea: the diagnostic contribution of pre- and postnatal echography]. / Un caso di cloridrorrea congenita: contributo diagnostico ecografico pre-postnatale.

The authors describe a case of "congenital chloride diarrhea" in a preterm female infant with a profound chronic diarrhea beginning at birth. The disease lies in a defect of active intestinal Cl- transport which results in a large loss of the electrolytes and water. To prevent a reduced growth and the renal involvement an adequate replacement therapy is necessary.

[An ultrastructural study of the fibrillary component of dental tissues]. / Etude ultrastructurale de la composante fibrillaire de certains tissus dentaires.

The recent interest for highly sophisticated techniques of dental tissue preparation aiming to display very particular structures, moved the AA. to improve the literature suggestions. In particular they made TEM and SEM observations of transitional zones between healthy and normal pulp and dentin after decalcification and trypsin at different concentrations treatment. The images obtained draw in the attention the study facilities of a technique that really removes all the non collagenic material. The data obtained in the pericellular zones also allowed some interventions in the recent literature discussion about inter-odontoblastic fibres.

[Guided tissue regeneration: an ultrastructural observation by transmission electron microscopy and scanning electron microscopy]. / Régénération tissulaire guidée: observation ultrastructurale au microscope électronique à transmission et au microscope électronique à balayage.

PTFE membranes are used for guided tissue regeneration in order to treat angular bone defects or forcation involvements in surgical treatment. Ultrastructural investigations have been performed by means of electron transmission and scanning microscopy. In agreement with previous reports, fibroblast cells adhering to the reticular structure of PTFE membrane were observed; these were interposed among coagulated clusters of fibrinous material and blood cells round shaped. Elongated bacterial cells were always present in the microscope fields analysed. These observations were confirmed by means of transmission microscopy; moreover specific techniques enabled us to demonstrate that fibroblast cells were synthetizing collagen, which was present in the form of extracellular fibers mixed to fibrin clusters. Roundish and elongate bacterial cells were always observed both in the extracellular matrix and into macrophages.

[Dental tissue-composite bonding. SEM study]. / Giunzione tessuti dentari-composito. Osservazioni al SEM.

The Authors investigated the different operative methods effects in the transition zone between human fresh teeth calcified tissues and a composite material. Morphological observations, done by means of standard and back scattered scanning electron microscopy, demonstrated the Gluma adhesion system efficiency towards enamel and dentin if manufacturing's applying systems are carefully followed, by showing a structure with no solutions of continuity between tooth and restoration.