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Kinds of Ink Terms modified by Ink Selected AbstractsSealing evaluation of the cervical base in intracoronal bleachingDENTAL TRAUMATOLOGY, Issue 6 2003Luciane Dias De Oliveira Abstract,,, Discoloration of non-vital teeth is an esthetic deficiency frequently requiring bleaching treatment. The purpose of this study was to evaluate in vitro the cervical base efficacy in order to prevent or to minimize the leakage along the root canal filling and into the dentinal tubules. Thirty-eight extracted single-root human teeth were used, which were biomechanically prepared, filled, and divided into three experimental groups: G1, a cervical base was applied (3 mm of thickness) below the cemento-enamel junction, with resin-modified glass-ionomer cement (Vitremer); G2, the base was done with glass-ionomer cement (Vidrion R); and G3 (Control), did not receive any material as base. A mixture of sodium perborate and hydrogen peroxide 30% was placed inside the pulp chamber for 3 days, and the access opening was sealed with Cimpat. This procedure was repeated thrice. Soon after this, a paste of calcium hydroxide was inserted into the pulp chamber for 14 days. All teeth were covered with two layers of sticky wax, except the access opening, and immersed in blue India Ink for 5 days. The results did not show statistically significant differences between the three groups concerning the leakage inside the dentinal tubules. Regarding the apical direction, a statistical difference (anovaP < 0.05) was observed among the experimental group G1 and control group G3. No statistically significant difference was observed between G2 and G3 groups. Therefore, the placement of a cervical base before internal bleaching procedures is still recommended. [source] Rewritable Photonic Paper with Hygroscopic Salt Solution as InkADVANCED MATERIALS, Issue 42 2009Jianping Ge Flexible photonic paper is fabricated through the instant magnetic assembly of Fe3O4@SiO2 colloids, followed by a rapid photopolymerization to fix the photonic structures inside the PEGDA matrix. Solutions of LiCl, MgCl2, or CaCl2 are used as inks to print durable letters and patterns with color contrast based on the local swelling of the polymer matrix. The photonic paper is rewritable and benign to the environment as the ink marks can simply be removed by washing with water. [source] Age Determination of Ballpoint Pen Ink by Thermal Desorption and Gas Chromatography,Mass Spectrometry,JOURNAL OF FORENSIC SCIENCES, Issue 4 2008Jürgen H. Bügler Ph.D. Abstract:, Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography,mass spectrometry (GC,MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed. [source] Self-Assembled PEO-Peptide Nanotapes as Ink for Plotting Nonwoven Silica Nanocomposites and Mesoporous Silica Fiber NetworksMACROMOLECULAR RAPID COMMUNICATIONS, Issue 4 2008Stefanie Kessel Abstract Macroscopic networks of oriented polymer-silica composite fibers can be accessed via a convenient 2D-plotting process. By using self-assembled PEO-peptide nanotapes as an ink to draw the composite fibers, the macroscopic form of the fiber networks, the line width, and both network orientation as well as network anisotropy can be defined. The plotting process relies on a biomimetic silicification route, which combines self-assembly and peptide-directed silicification in a cooperative manner. The local injection of PEO-peptide nanotapes into a thin layer of a dilute solution of pre-hydrolyzed TMOS leads to the rapid formation of the composite fibers, which exhibit several levels of hierarchical order. It was shown, that the rate of plotting is a parameter, enabling one to control the line width and the orientation of the nano- and sub-micrometer structure elements in the network. Moreover, the plotted composite fibers can be used as precursors for networks of oriented, mesoporous silica-fibers. After calcination procedures, nonwoven silica fabrics can be obtained with high surface areas and cylindrical pores aligned in plot direction. [source] Heavy Metal Distribution in Soils near the Almalyk Mining and Smelting Industrial Area, UzbekistanACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 5 2009Obidjon KODIROV Abstract: The present study demonstrates distribution and chemical forms of heavy metals in soils of the Almalyk mining and smelting industrial area along five transects. The study area is located in Almalyk, Uzbekistan, where the intensification of industrial enterprises negatively impacts the environment. The distribution of 17 heavy metals (Cu, Zn, Pb, Sc, V, Cr, Co, Ni, Ga, Rb, Sr, Y, Zr, Nb, Ba, Th, and U) were studied in 21 sampling locations (21×3=63 soil samples) along five radial transects with a total length of 60 km downwind deposition gradient. Soil samples were collected from the upper layer (0,10 cm) at 4,6 km intervals. As a result of X-ray fluorescence spectrometry analyses by using X-ray fluorescence spectroscopy (XRF, Philips Analytical Ink, USA), a significant decrease in heavy metal (Cu, Zn, Pb) deposition was found going from the source in a downwind direction. Soil samples taken from the first location (near the pollution sources) showed higher concentrations of Cu, Zn and Pb, and lower concentrations with increasing distance from the source. Obtained data showed different impact of pollution sources to heavy metal deposition and distribution in soils. The Almalyk mining and smelting complex is the major source of Pb, Zn and Cu enrichment in soils. Distribution of other trace elements does not exceed background content and suggests lithogenic background. This allowed us to divide these elements into two groups: (1) technogenic (Cu, Zn and Pb); and (2) lithogenic (Sc, V, Cr, Co, Ni, Ga, Rb, Sr, Y, Zr, Nb, Ba, Th and U) origins. [source] Hydrophilic Sparse Ionic Monolayer-Protected Metal Nanoparticles: Highly Concentrated Nano-Au and Nano-Ag "Inks" that can be Sintered to Near-Bulk Conductivity at 150,°CADVANCED FUNCTIONAL MATERIALS, Issue 2 2010Bibin T. Anto Here, monolayer-protected gold and silver nanoparticles with extremely high solvent dispersibility (over 200,mg mL,1 in water and glycols) and low coalescence temperature (approximately 150,°C, measured by the percolation transition temperature Tp) are developed, to reach conductivities better than 1,×,105,S cm,1. These materials are suitable for inkjet and other forms of printing on substrates that may be solvent- and/or temperature-sensitive, such as for plastic electronics, and as bus lines for solar and lighting panels. This is achieved using a new concept of the sparse ionic protection monolayer. The metal nanoparticles are initially protected by a two-component mixed ligand shell comprising an ,-functionalized ionic ligand and a labile ligand. These are selectively desorbed to give a sparse shell of the ,-ionic ligands of ca. 25% coverage. Through a systematic study of different monolayer-protected Au nanoparticles using FTIR spectroscopy, supported by XPS and DSC, it is shown that Tp is not determined by thermodynamic size melting or by surface area effects, as previously thought, but by the temperature when ca. 80% of the dense monolayer is eliminated. Therefore, Tp depends on the thermal stability and packing density of the shell, rather than the size of the metal core, while the solubility characteristics depend strongly on the exposed terminal group. [source] Nanoparticle Inks for Directed Assembly of Three-Dimensional Periodic Structures,ADVANCED MATERIALS, Issue 19 2003Q. Li Colloidal inks, comprised of concentrated barium titanate nanoparticle gels, were directly assembled via a robotically controlled deposition technique. 3D periodic lattices were created through layer-by-layer patterning of parallel rods, whose periodicity far exceeded the dimension of the nanoparticle building blocks. The Figure shows a scanning electron microscopy image of a 3D periodic lattice (top view). [source] Comparison of Natural and Artificial Aging of Ballpoint InksJOURNAL OF FORENSIC SCIENCES, Issue 4 2008Claudia Berger-Karin Abstract:, Solvent evaporation caused by aging from ballpoint inks was measured by gas chromatography/mass spectroscopy (GC/MS). The sample preparation was carried out with two different thermal desorption systems. The results are compared. Thirteen inks were classified with regard to their solvents, polymers, and additives. The variation of the aforementioned compounds caused by aging was monitored for naturally and artificially aged samples. In this paper, the results are compared and discussed with respect to forensic casework. [source] Validation of LAB Color Mode as a Nondestructive Method to Differentiate Black Ballpoint Pen Inks,JOURNAL OF FORENSIC SCIENCES, Issue 4 2007Derek L. Hammond B.A. Abstract:, Nondestructive digital processing methods such as lab color mode (available in Adobe® Photoshop®) are emerging as alternative methods for forensic document examiners to use when attempting to differentiate writing instrument inks. Although these techniques appear to be viable, little data currently exists regarding the known or potential error rates associated with these techniques. Without adequate data, the validity and reliability of these techniques, including lab color, can not be established. In an attempt to begin to address these issues, 44 black ballpoint ink pens were obtained and used to create 990 pen-pair samples for analysis using established lab color mode techniques. No erroneous findings of "different" were reported following the examination of the known pen-pair combinations in which the same pen was used to create the samples (n = 44). Of the remaining 946 samples, 737 pen-pair samples were differentiated using the lab color mode method, while 209 samples were unable to be differentiated and were recorded as either being "similar" (n = 153) or "unsure" (n = 56). Comparison of the lab color mode results with the results obtained through additional testing using traditional infrared reflectance and infrared luminescence test methods showed that lab color differentiated 102 pen-pair samples (11%; 102/946) that were not differentiated using a VSC-4C. [source] Innentitelbild: Writing Self-Erasing Images using Metastable Nanoparticle "Inks" (Angew. Chem.ANGEWANDTE CHEMIE, Issue 38 200938/2009) Lichtempfindliche Tinten für selbstradierende Bilder wurden erzeugt, indem mit photoresponsiven Liganden umhüllte Metallnanopartikel (NPs) in einem Polymerfilm dispergiert wurden. Wie B.,A. Grzybowski und Mitarbeiter auf S.,7169,ff. schildern, bilden die NPs bei Bestrahlung mit UV-Licht metastabile Aggregate, deren Farbe vom Aggregationsgrad abhängt. Schaltet man das Licht aus, so zerfallen die Aggregate, und die Bilder radieren sich selbst aus. Mit nur einer NP-Tinte können sogar mehrfarbige Bilder erzeugt werden. [source] Writing Self-Erasing Images using Metastable Nanoparticle "Inks",ANGEWANDTE CHEMIE, Issue 38 2009Rafal Klajn Photoresponsive Liganden als Umhüllung machen Metallnanopartikel (NPs) zu ,Tinten" für selbstradierendes ,Papier", indem die lichtinduzierte Assoziation der NPs in lokale Farbwechsel übersetzt wird (siehe Bild). Je nach Ausmaß der Assoziation können vielfarbige Bilder mit nur einer Art von NP-Tinte geschrieben werden. Wie schnell das Bild ausradiert wird, hängt von der Oberflächenkonzentration der photoaktiven Gruppen ab; der Vorgang kann Sekunden bis Tage dauern. [source] Real-time simulation of watery paintCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3-4 2005Tom Van Laerhoven Abstract Existing work on applications for thin watery paint is mostly focused on automatic generation of painterly-style images from input images, ignoring the fact that painting is a process that intuitively should be interactive. Efforts to create real-time interactive systems are limited to a single paint medium and results often suffer from a trade-off between real-timeness and simulation complexity. We report on the design of a new system that allows the real-time, interactive creation of images with thin watery paint. We mainly target the simulation of watercolor, but the system is also capable of simulating gouache and Oriental black ink. The motion of paint is governed by both physically based and heuristic rules in a layered canvas design. A final image is rendered by optically composing the layers using the Kubelka,Munk diffuse reflectance model. All algorithms that participate in the dynamics phase and the rendering phase of the simulation are implemented on graphics hardware. Images made with the system contain the typical effects that can be recognized in images produced with real thin paint, like the dark-edge effect, watercolor glazing, wet-on-wet painting and the use of different pigment types. Copyright © 2005 John Wiley & Sons, Ltd. [source] Carbon Powder Based Films on Traditional Solid Electrodes as an Alternative to Disposable ElectrodesELECTROANALYSIS, Issue 11 2006Bogdan Yosypchuk Abstract The covering of conventional solid electrode with a film using an ink containing a conductive powder and a polymer enables to broaden the potential window of the original solid electrode. A solid silver amalgam electrode covered with such a film exhibits a potential window from ,600,mV to +1400,mV vs. SCE reference electrode. The renewal of the film is fast and simple: the electrode can be simply wiped with a filter paper to remove the old film and immersed into an ink solution or 1,2,,L of this ink solution can be applied to the surface of the electrode with a micro dispenser to form a new film. Therefore, just the inexpensive film at the electrode surface is disposable and there is no need to dispose the whole, more expensive electrode. Moreover, when a suitable electrochemical pretreatment of the film electrode is applied, the same film can be used for reproducible measurements for several days. [source] Integration of a carbon microelectrode with a microfabricated palladium decoupler for use in microchip capillary electrophoresis/ electrochemistryELECTROPHORESIS, Issue 1 2005Michelle L. Kovarik Abstract A method to integrate a carbon microelectrode with a microfabricated palladium decoupler for use in microchip capillary electrophoresis (CE) is detailed. As opposed to previous studies with decouplers for microchip CE, the working electrode material, which is made by micromolding of a carbon ink, is different from the decoupling electrode material (palladium). The manner in which the working electrode is made does not add additional etching or lithographic steps to the fabrication of the glass electrode plate. The hybrid poly(dimethylsiloxane)/glass device was characterized with fluorescence microscopy and by monitoring the CE-based separation of dopamine. Hydrodynamic voltammograms exhibited diffusion-limited currents occurring at potentials above +1.0 V. It was also shown that the half-wave potential does not shift as the separation potential is changed, as is the case in nondecoupled systems. Gated injections of dopamine in a 25 mM boric acid buffer (pH 9.2) showed a linear response from 200 to 5 ,M (r2 = 0.9992), with a sensitivity of 5.47 pA/,M and an estimated limit of detection of 2.3 ,M (0.621 fmol, S/N = 3). This is the first report of coupling a carbon electrode with a decoupler in microchip CE. [source] Improved Microcontact Printing of Proteins using Hydrophilic Thermoplastic Elastomers as Stamp Materials,ADVANCED ENGINEERING MATERIALS, Issue 12 2007C. Trimbach Recently, the microstructuring of biological species, such as proteins, using microcontact printing (,CP), has become very popular. Microstructuring of proteins is useful for a variety of applications, such as biosensors, controlled cell growth and adhesion and microarrays for bioanalytical detection. Here the authors investigated the microcontact printing of proteins using a hydrophilic thermoplastic elastomeric stamp material. The emphasis is placed on the quality of the printed patterns with respect to inking time and protein concentration in the ink. [source] Bottom-Up Synthesis of Biologically Active Multilayer Films Using Inkjet-Printed TemplatesADVANCED FUNCTIONAL MATERIALS, Issue 9 2010Joshua D. Swartz Abstract As a non-invasive, rapid prototyping technique, piezoelectric inkjet printing using the Dimatix Materials Printer (DMP) is incorporated to template 2D biologically active surfaces. In these studies, a bioinspired ink is synthesized and printed directly onto gold-coated silicon nitride substrates and into polymer-coated 96-well plates. Once deposited on a surface, these patterns are reacted with varying concentrations of a model enzyme glucose oxidase in the presence of a silica precursor, monosilicic acid. The reaction mechanism and order of reactant products within and along the patterns are shown to directly affect the integrity and overall microstructure of the biologically active films. Using profilometry measurements and scanning electron microscopy, a biologically active platform is optimized without significantly compromising the activity of the enzyme. In fact, enzyme activity, constrained within a thin film, is reported for the first time over variable reaction parameters. When compared to the enzyme free in solution, the immobilized enzyme is 25.9% active, where nearly 100% of the activity is retained after repeated usage. [source] High-Temperature Contact Formation on n-Type Silicon: Basic Reactions and Contact Model for Seed-Layer ContactsADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Matthias Hörteis Abstract Contact formation on n-type silicon, especially using a high-temperature process, has been the subject of research for more than 40 years. After its application in microelectronics, n-type silicon is widely used in silicon solar cells as the emitter layer. The formation of a low ohmic contact grid using an industrially feasible process step is one of the key features required to improve the solar-cell efficiency. The contact materials, typically deposited in a printing step, have to fulfil several functions: opening the dielectric antireflection layer and forming an intimate metal-semiconductor contact with good mechanical adhesion and low specific contact resistance. As the used contact inks typically contain several functional materials, such as silver and a glass frit, the detailed contact formation is still not entirely understood. Therefore, the chemical reactions during the contact firing process have been studied in detail by thermogravimetric differential thermal analysis in combination with mass spectroscopy. Based on these studies, a contact ink has been developed, optimized and tested on silicon solar cells. In this paper, the mechanism of the etching process, the opening of a dielectric layer, the influence of different atmospheres and the impact of the glass-frit content are investigated. The observed microscopic contact structure, the resulting electrical solar-cell parameters and the studied reactions are combined to clarify the physics behind the high-temperature contact formation. [source] Polymer Field-Effect Transistors Fabricated by the Sequential Gravure Printing of Polythiophene, Two Insulator Layers, and a Metal Ink GateADVANCED FUNCTIONAL MATERIALS, Issue 2 2010Monika M. Voigt Abstract The mass production technique of gravure contact printing is used to fabricate state-of-the art polymer field-effect transistors (FETs). Using plastic substrates with prepatterned indium tin oxide source and drain contacts as required for display applications, four different layers are sequentially gravure-printed: the semiconductor poly(3-hexylthiophene-2,5-diyl) (P3HT), two insulator layers, and an Ag gate. A crosslinkable insulator and an Ag ink are developed which are both printable and highly robust. Printing in ambient and using this bottom-contact/top-gate geometry, an on/off ratio of >104 and a mobility of 0.04,cm2 V,1 s,1 are achieved. This rivals the best top-gate polymer FETs fabricated with these materials. Printing using low concentration, low viscosity ink formulations, and different P3HT molecular weights is demonstrated. The printing speed of 40,m min,1 on a flexible polymer substrate demonstrates that very high-volume, reel-to-reel production of organic electronic devices is possible. [source] Investigation of a Novel Catalyst Coated Membrane Method to Prepare Low-Platinum-Loading Membrane Electrode Assemblies for PEMFCsFUEL CELLS, Issue 2 2009X. Leimin Abstract In this work, a novel catalyst coated membrane (CCM) approach,a catalyst-sprayed membrane under irradiation (CSMUI),was developed to prepare MEAs for proton exchange membrane fuel cell (PEMFC) application. Catalyst ink was sprayed directly onto the membrane and an infrared light was used simultaneously to evaporate the solvents. The resultant MEAs prepared by this method yielded very high performance. Based on this approach, the preparation of low-platinum-content MEAs was investigated. It was found that for the anode, even if the platinum loading was decreased from 0.2 to 0.03,mg,cm,2, only a very small performance decrease was observed; for the cathode, when the platinum loading was decreased from 0.3 to 0.15,mg,cm,2, just a 5% decrease was detected at 0.7,V, but a 35% decrease was observed when the loading was decreased from 0.15 to 0.06,mg,cm,2. These results indicate that this approach is much better than the catalyst coated gas diffusion layer (GDL) method, especially for the preparation of low-platinum-content MEAs. SEM and EIS measurements indicated ample interfacial contact between the catalyst layer and the membrane. [source] The Effect of the Anode Loading and Method of MEA Fabrication on DMFC PerformanceFUEL CELLS, Issue 3 2007T. V. Reshetenko Abstract The influence of the Pt-Ru anode loading and MEA preparation techniques on direct methanol fuel cell (DMFC) performance is studied. Two different anode catalyst layer preparation techniques are employed. One is the direct coating of anode catalyst ink on a membrane to form a catalyst coated membrane, CCManode, and the other is the coating of the ink on the diffusion layers, which generates a catalyst coated substrate, CCSanode. The power density of a combined CCManode/CCScathode MEA is higher than for a CCSanode/CCScathode MEA. The main difference in the performance is observed in the high current density region, where two-phase flow is present and mass transfer processes govern the performance. The CCManode and CCSanode have different macroscopic structures, while showing the same microscopic morphology. Based on their morphological differences, it is expected that the combination of the CCManode and carbon paper provides the more homogeneous removal of CO2 at high currents. The authors suggest that the application of the CCManode with an optimal anode loading improves anode mass transfer, reduces methanol crossover, and enhances the electrochemical reactions. [source] Printed Origami Structures (Adv. Mater.ADVANCED MATERIALS, Issue 20 201020/2010) Bok Y. Ahn, Jennifer Lewis, and co-workers report on p.,2251 a new method for creating complex 3D structures that combines direct-write assembly with a wet-folding origami technique. Planar lattices composed of a titanium hydride ink are printed, and then folded, rolled, or molded into the desired shape. These 3D objects are then transformed into metallic or ceramic structures by thermal annealing. [source] Photovoltaic Devices: High-Efficiency Solar Cell with Earth-Abundant Liquid-Processed Absorber (Adv. Mater.ADVANCED MATERIALS, Issue 20 201020/2010) The image shows a thin-film solar cell, deposited from a hybrid solution-nanoparticle ink, with a background scanning electron microscopy (SEM) image of the zinc-compound particle component of the ink. A cross-sectional SEM image of the device shows the large-grained kesterite absorber layer composed of readily available elements: Cu-Zn-Sn-S-Se. The solution-processed devices offer record power conversion efficiency for kesterite absorber layers, as presented by D. B. Mitzi et al. on page E156. [source] Ultraviolet-Assisted Direct-Write Fabrication of Carbon Nanotube/Polymer Nanocomposite MicrocoilsADVANCED MATERIALS, Issue 5 2010Louis Laberge Lebel The UV-assisted direct-write fabrication of microcoils is shown using a UV-photocurable carbon nanotube nanocomposite ink. The method employs the robotically controlled microextrusion of a filament combined with a UV exposure that follows the extrusion point. Upon curing, the increased rigidity of the extruded filament enables the creation of complex multi-directional shapes. [source] Microcontact Printing: Limitations and AchievementsADVANCED MATERIALS, Issue 22 2009András Perl Abstract Microcontact printing (µCP) offers a simple and low-cost surface patterning methodology with high versatility and sub-micrometer accuracy. The process has undergone a spectacular evolution since its invention, improving its capability to form sub-100,nm SAM patterns of various polar and apolar materials and biomolecules over macroscopic areas. Diverse development lines of µCP are discussed in this work detailing various printing strategies. New printing schemes with improved stamp materials render µCP a reproducible surface-patterning technique with an increased pattern resolution. New stamp materials and PDMS surface-treatment methods allow the use of polar molecules as inks. Flat elastomeric surfaces and low-diffusive inks push the feature sizes to the nanometer range. Chemical and supramolecular interactions between the ink and the substrate increase the applicability of the µCP process. [source] Root and canal morphology of permanent mandibular molars in a Sudanese populationINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2007H. A. Ahmed Abstract Aim, To investigate variations in the root canal systems of first and second permanent mandibular molar teeth in a Sudanese population using a clearing technique. Methodology, Two hundred extracted first and second permanent mandibular molars from three cities in the state of Khartoum were studied. Access cavities were prepared and pulp tissue was removed by immersion in 5% sodium hypochlorite under ultrasonication; Indian ink was then injected into the root canal systems assisted by a vacuum applied apically. The teeth were rendered clear by demineralization and immersion in methyl salicylate before evaluation. The following observations were made (i) number of roots and their morphology; (ii) number of root canals per tooth; (iii) number of root canals per root and (iv) root canal configuration. Results, Overall 59% of mandibular first molars had four canals with 3% having a third distolingual root. Seventy-eight per cent of second mandibular molars had two separate flat roots, whilst 10% were C-shaped. The most common canal system configurations were type IV (73%) and type II (14%). Inter-canal communications were more common in the mesial roots. The prevalence of inter-canal communications was 65% in first molars and 49% in second molars. Conclusions, In this sample of Sudanese teeth, 59% of the mandibular first permanent molars had four root canals whilst 10% of the mandibular second molars had C-shaped roots/canals. [source] Root and canal morphology of maxillary first and second permanent molar teeth in a Ugandan populationINTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2007C. M. Rwenyonyi Abstract Aim, To investigate the root and canal morphology of permanent maxillary molar teeth from a Ugandan population. Methodology, Maxillary first (n = 221) and second molar (n = 221) teeth were collected from patients attending dental clinics in Kampala. Teeth were prepared using a clearing technique: the pulp chambers were accessed and the teeth placed consecutively into 5% sodium hypochlorite, 10% nitric acid, then methyl salicylate. Indian ink was injected into the pulp chambers to demonstrate the canal system. Results, In the first molars, 95.9% of the teeth had separate roots. The mesiobuccal root was fused with the palatal root in 3% of specimens and with the distobuccal root in 0.5% of teeth. In the second molars, 86% of the teeth had separate roots. The mesiobuccal root was fused with the palatal root in 6.3% of specimens and with the distobuccal root in 6.8% of teeth. Apical deltas were more frequent in the mesiobuccal root when compared with distobuccal and palatal roots of both the first and second molars. A type I canal configuration (>75%) was the most frequent in all the roots of both the first and second molars. Canal intercommunications and lateral canals were more frequent in the mesiobuccal root when compared with other roots. Conclusions, The mesiobuccal root tended to have more variations in the canal system followed by the distobuccal root, whereas the palatal root had the least. The findings in root and canal morphology of this Ugandan population were different from previous studies, which may partly be attributed to racial differences. [source] Ex vivo microscopic assessment of factors affecting the quality of apical seal created by root-end fillingsINTERNATIONAL ENDODONTIC JOURNAL, Issue 8 2007S. I. Tobón-Arroyave Abstract Aim, (i) To evaluate the incidence of microcracks around root-end preparations completed with ultrasonic tips and their relationship with the root filling technique and thickness of surrounding dentine. (ii) To investigate the effect of rapid exposure to a water-soluble dye of Intermediate Restorative Material (IRM), Super Ethoxybenzoic Acid (sEBA) and Mineral Trioxide Aggregate (MTA), on the marginal adaptation and microleakage of root-end fillings. (iii) To describe the microstructure of the surface of root-end filling materials. Methodology, Ninety-two single-rooted teeth were divided into two groups (n = 46) according to the root canal instrumentation/filling techniques. Group 1 consisted of specimens in which canal preparation was completed using a crown-down technique and then filled with the Thermafil system (TF group); Group 2 consisted of specimens in which canal preparation was completed using a step-back technique and lateral condensation (LC group). Following root-end resection and ultrasonic cavity preparation, the samples were further divided into three subgroups (n = 24) for root-end filling with IRM, sEBA or MTA. The ultrasonic preparation time was recorded. Eight teeth were kept as positive and 12 as negative controls. Following immersion in Indian ink for 7 days, all resected root surfaces were evaluated for the presence of microcracks and the cross-sectional area of root-end surface and root-end filling were measured to evaluate the thickness of the dentinal walls. Thereafter, the samples were sectioned longitudinally so as to assess the depth of dye penetration and marginal adaptation of root-end fillings. Negative controls longitudinally sectioned were used to describe microstructural characteristics of the root-end filling materials using scanning electron microscopic (SEM) techniques. Results, Although the thickness of dentinal walls between groups 1 and 2 was similar, the ultrasonic preparation time and number of microcracks were significantly higher (P < 0.001) in the TF group. Both groups had a significant correlation between microcracks and ultrasonic preparation time (P < 0.001). sEBA and IRM had better adaptation and less leakage compared with MTA. A SEM analysis displayed microstructural differences between the root-end filling materials. Conclusion, Microcracks can occur independently of the thickness of dentinal walls and may be associated with the prolonged ultrasonic preparation time required for the removal of the root filling during root-end cavity preparation. Although sEBA and IRM had better behaviour than MTA regarding microleakage and marginal adaptation, it is possible that exposure of MTA to a water-soluble dye before achieving full set and its porous microstructure contributed to the results. [source] Assessment of a contrast medium as an adjunct to endodontic radiographyINTERNATIONAL ENDODONTIC JOURNAL, Issue 12 2004J. M. Bedford Abstract Aim, To assess if a contrast medium improved diagnostic yield of endodontic radiographs. Methodology, Forty-five extracted mandibular premolar teeth were radiographed in bucco-lingual and mesio-distal planes. Access cavities were prepared, pulpal tissue extirpated and Ultravist® contrast medium introduced under pressure. Radiographs were retaken and the teeth cleared following perfusion with India ink. Three examiners assessed all the films for: number of roots, number of root canals, curvature of root and/or root canal, presence of lateral canals, presence of a single foramen or apical delta and the presence or absence of canal obstructions. The examiners' interpretations were compared with the anatomy revealed by clearing. Results, Kappa scores were calculated for each of the examiners, for each set of radiographs, to assess the level of intra- and inter-examiner agreement. Only moderate agreement was found throughout (, = 0.40,0.61). For multiple root canals a false-positive result was significantly more likely with contrast (P < 0.05). The use of contrast did not significantly improve the sensitivity of diagnosis of lateral canals or a single apical foramen. Contrast significantly increased the risk of falsely perceiving lateral canals (P < 0.002). Overall there was no statistically significant difference in the overall assessment of the anatomy of the root canals using contrast or plain radiographs (P > 0.2). Conclusions, Plain film radiographs confidently predict the presence of root or canal curvature but apical anatomy was assessed accurately in only 46% of cases. Plain radiographs were insensitive in assessing the number of root canals present, the presence of lateral canals and the occurrence of canal obstructions. The use of Ultravist® contrast medium to improve diagnosis of root canal morphology of premolars is not supported. [source] Evaluation of root-end cavity preparation using ultrasonic retrotipsINTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2003H. Ishikawa Abstract Aim, To evaluate and compare the efficiency of root-end preparations using ultrasonic retrotips coated with diamond and zirconium nitride. Methodology, Eighty-five extracted single-rooted teeth were root filled, and then resected 3 mm from their apices. Root-end cavities were prepared with KiS (zirconium nitride-coated retrotip), CT-5 (stainless steel tip) or diamond-coated (DC) ultrasonic retrotips, and 10 teeth served as controls. Thirty teeth were used for evaluation of the time required to prepare the root-end cavity, the number of microcracks produced on the resected surface and the number of dentinal tubule openings on the root-canal wall using scanning electron microscope (SEM) images. A further 55 teeth were used for evaluation of dye penetration following filling of the root-end cavities with Super EBA. The degree of dye penetration in millimetres was measured under the microscope after 7 days of immersion in India ink. Statistical analyses were performed using the one-way anova and Scheffe's F -test as the post hoc test. Results, There was no significant difference in the number of microcracks and dentinal tubule openings present in the root apices prepared by the three retrotips. The time required for root-end cavity preparation using the DC retrotip was significantly less than that using the other groups (P < 0.01). Positive controls showed dye penetration throughout the length of the root-end cavity, and negative controls showed no dye penetration. There was no significant difference between the three experimental groups in dye penetration. Conclusions, In this laboratory study, the time required to prepare root-end cavities using KiS retrotips was the same as that using CT-5 retrotips, and longer than that using DC retrotips. There was no significant difference in the number of microcracks or dye penetration between the three kinds of retrotips. [source] An in vitro comparison of three thermal gutta percha systemsINTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2001M. P. Horrocks Aim,The aim of this study was to compare the ability of three contemporary obturation techniques to resist microleakage, using root canals prepared in extracted single rooted teeth by a standardized method. Methodology,The shaping technique involved the use of tapered nickel titanium rotary files to create a uniform 0.08-mm/mm taper. Six groups were compared, two representing control groups, a third group being obturated with a warm vertical condensation technique, a fourth group by an injection thermoplasticized system, a fifth group with a thermomechanical compaction method and a sixth group using cold lateral condensation. A zinc oxide/eugenol sealer was used as the sealant in all the obturation procedures. Forty-six extracted teeth were used in the study, three teeth in each control group and 10 teeth in each of the remaining four groups. Microleakage was compared using dye leakage with Indian ink. Penetration of the dye at the gutta percha/dentine interface was visualized after the root had been rendered transparent. Dye leakage was then measured from four aspects with the use of a stereomicroscope and export of a digital image to a software package, to facilitate accurate assessment of dye penetration. Two parameters were measured for each sample, the mean dye penetration and maximum dye penetration. Results,The mean values for linear dye leakage in the thermomechanical compaction group was 0.53 mm, the warm vertical condensation group was 0.73 mm, the injection thermoplasticized group was 0.15 mm and the cold lateral condensation group was 0.53 mm. There was no statistical difference between the means of the different groups (P > 0.05). The mean of the maximum values for dye leakage in the thermomechanical compaction group was 0.65 mm, the warm vertical condensation group was 1.02 mm, the injection-thermoplasticized group was 0.28 mm and the cold lateral condensation group was 0.74 mm. There was no statistical difference between the means of the different groups (P > 0.05). Conclusions,Within the conditions of this study, there was no statistical difference between the different groups with respect to either mean or maximum dye leakage. [source] | ||||||||||||||||||||||||||||||||||