Search results for "Microscope"
showing 10 items of 1412 documents
Nature and origin of natural Zn clay minerals from the Bou Arhous Zn ore deposit: Evidence from electron microscopy (SEM-TEM) and stable isotope comp…
2016
International audience; Zn-clay minerals have been found in the non-sulfide deposit of Bou Arhous (High Atlas, Morocco). They occur as white or ochre clays embedding willemite (Zn2SiO4) and are commonly associated to red detrital clays in karstic cavities. Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) with Energy Dispersive X-ray (EDX) analyses were combined in order to characterize the clay minerals and to determine the mechanism of their formation. XRD patterns on oriented and powdered clays and Fourier Transform Infrared (FTIR) spectroscopic analyses suggest that fraipontite is the major Zn clay phase (with some smectite interstrat…
Fracture and deformation of ProTaper Next instruments after clinical use
2018
Background The aim of this study was to evaluate the fracture and defects observed in ProTaper Next files discarded after a normal clinical use. Material and Methods 571 ProTaper Next rotary instruments were collected after clinical use from the clinic of endodontics over 12 months. The length of the files was measured using a digital caliper to determine any fracture, later all the files were evaluated under a stereomicroscope to observe defects such as unwinding, curving or fracture. The data obtained were analyzed using a chi-square and z test. Results 13.83% of the discarded files showed defects, the most frequent defect was fracture (7.53%). The highest rate of fracture was observed in…
Komparativno istraživanje oblikovanja četiriju rotirajućih sustava
2015
Svrha: U ovom istraživanju analizirali smo rezno područje, vrijeme instrumentacije, održavanje anatomije korijenskog kanala i neinstrumentirana područja dobivena korištenjem instrumenata F360®, Mtwo®, RaCe® i Hyflex® u ISO veličini 35. Materijali i metode: Odabrano je 120 zuba s jednim ravnim kanalom i podijeljeni su u četiri grupe. Radna duljina određena je radiološki. Zubi su rezani dijamantnim diskom, a presjeci su promatrani stereoskopskim mikroskopom Nikon SMZ-2T pod svjetiljkom Intralux 4000-1. Grupe su oblikovane predoperativnom analizom AutoCAD. Zubi su rekonstruirani s pomoću K-proširivača #10 i epoksi ljepila. Svaka grupa instrumentirana je jednim od četiriju sustava. Vrijeme inst…
Microstructure alterations of rotary files after multiple simulated operative procedures.
2009
Aim: To assess morphological alterations of ProTaper rotary NiTi files before and after continuous use by scanning electron microscopy (SEM). Study Design: 30 root canals were chosen with an angle between 15 and 30º. Before starting to prepare the canals the files were observed microscopically using a scanning electronic microscope. The ProTaper sequence recommended by the manufacturer was used, with NaOCl as irrigant. The instruments were sterilised after every three canals were shaped. The instruments were observed with the same microscope after shaping each canal, until 30 root canals were shaped. The criteria used for checking the instruments were: blunt cutting edges, disruption of cut…
A preliminary analysis in the preparation and obturation of oval canals
2011
Objective: 1) to observe the appearance of uninstrumented recesses in oval canals after instrumentation using circumferential filing. 2) To determine the quality of obturation both with cold lateral compaction and thermo plasticized gutta-percha technique in these recesses Study design: Twenty non-carious, freshly extracted human mandibular incisors with single canals were divided into group I (n=10) and group II (n=10) according to the two different obturation methods. The sectioned roots were prepared with flexofiles (Dentsply, Maillefer) ranging from #15 to #40 by using circumferential filing. The obturated specimens were horizontally sectioned at 5 mm from the apex. Each section was obs…
Conical connection adjustment in prosthetic abutments obtained by different techniques
2019
Background The goal of this study is to compare the misfit (>150µm) generated once the restoration, made by different techniques, is retained to a single conical implant. Material and methods 15 internal connection implants (MIS C1 4'20x10mm) are embedded each one perpendicularly to an horizontal surface of the 1x1x2cm poliuretan resin model. The 15 samples obtained are divided in 5 groups depending on the framework process (n=3): 1/casting, 2/overcasting, 3/Ti-base, 4/milling and 5/laser sintering. The cobalt-chromium alloy frameworks are screw-retained to their respective implants to a 30-Ncm torque. Once it is retained the framework to the implant, the next step is to section the sample …
Comparison of Shaping Ability of 10 Rotary and Reciprocating Systems: an In Vitro Study with AutoCAD
2017
Cilj: Usporediti reznu površinu, očuvanje anatomije korijenskog kanala i neinstrumentiranu površinu nakon instrumentacije sustavima F360®, F6SkyTaper®, HyflexEDM®, iRace®, Neoniti®, O.Shape®, P.Next®, Reciproc®, Revo-S® i WaveOneGold® s veličinom instrumenta 25. Materijali i metode: Tristo zubi s jednim ravnim korijenom i okruglim ili eliptičnim presjekom korijenskog kanala podijeljeno je u 10 skupina (1-F360®, 2-F6SkyTaper®, 3-HyflexEDM®, 4-iRace®, 5-Neoniti®, 6-O Shape®, 7-P.Next®, 8-Reciproc®, 9-Revo-S® i 10-WaveOneGold®) i poprečno prerezano na trećine ultrafinim reznim diskovima. Uzorci su fotografirani pod stereomikroskopom i provedena je predinstrumentacijska analiza prije ponovnog s…
Filipin labelling and intramembrane particles on the membranes of early and later autophagic vacuoles in Ehrlich ascites cells
1987
Cholesterol and intramembrane particle distribution on autophagic vacuole membranes was studied in Ehrlich ascites cells using filipin labelling and freeze-fracture electron microscopy. Unsaturated fatty acids were stained using imidazole-buffered osmium tetroxide. Autophagocytosis was induced with vinblastine, and early autophagic vacuoles were accumulated by lowering the ATP level in the cells with iodoacetate. Filipin labelling was observed in the limiting membranes of later, apparently hydrolase-containing autophagic vacuoles, whereas the most newly-formed, doublemembrane limited vacuoles were not labelled. The limiting membranes of late, residual body-type vacuoles either showed patchy…
Preparation and photoactivity of nanostructured TiO2 particles obtained by hydrolysis of TiCl4
2005
This work reports the preparation of nanostructured polycrystalline TiO2 photocatalysts obtained by hydrolysis of TiCl4 in very mild conditions. Several samples were prepared as suspensions or colloidal dispersions by using TiCl4/H2O volume ratios ranging between 1:1 and 1:100. The samples were characterised by X-ray diffraction analysis, specific surface area determination, diffuse reflectance spectroscopy and scanning electron microscopy. 4-Nitrophenol photodegradation was used as probe reaction to test the photoactivity of the catalysts. Some samples revealed a photoactivity higher than that of Degussa P25 in similar experimental conditions and the most photoactive one was that prepared …
Behavior of Human Osteoblast Cells Cultured on Titanium Discs in Relation to Surface Roughness and Presence of Melatonin
2017
The aim of this work was to observe the behavior of osteoblast cells cultured in vitro on titanium discs in relation to disc surface roughness and the addition of melatonin to the culture medium. MG63 osteoblast cells were cultivated on 120 Grade 5 Ti divided into three groups: Group E, treated with dual acid etch; Group EP, treated with dual acid etch and calcium phosphate; and Group M, machined. Surface roughness was examined under a laser scanning confocal microscope (CLSM) and scanning electron microscopy (SEM). The proliferation and morphology of cells were determined under fluorescence microscopy and SEM. Messenger ribonucleic acid (mRNA) of different genes related to osteoblastic dif…