Download or read book A Scanning Electron Microscope Investigation of the Deterioration and Failure Mechanisms for Nickel titanium Rotary Endodontic Instruments written by Satish Babu Alapati and published by . This book was released on 2003 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Investigation of Phase Transformation Mechanisms for Nickel titanium Rotary Endodontic Instruments written by Satish B. Alapati and published by . This book was released on 2006 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Nickel-titanium rotary instruments based upon the intermetallic compound NiTi have gained considerable popularity among endodontists because the very low elastic modulus of NiTi enables these instruments to readily negotiate curved root canals during endodontic therapy with a slow-speed handpiece. However, concern about in vivo separation (fracture) of nickel-titanium instruments during treatment is still a major challenge confronting every manufacturer and endodontist, since this often happens without prior warning signs from permanent deformation. NiTi exists in two major microstructural phases: austenite, and martensite. Transformations between these NiTi phases occur rapidly by twinning on the atomic level and are reversible for stresses below the onset of permanent deformation. An intermediate R-phase is also sometimes observed for the transformation between austenite and martensite. The nickel-titanium rotary instruments are intentionally manufactured in the superelastic condition having the fully austenitic structure, which provides the capability of accommodating extensive elastic strain without fracture under clinical conditions associated with conventional root canal therapy. The overall objective of this study was to gain new insight into the microstructural phases in commercial NiTi rotary instruments and their transformations, which would be of scientific importance for development of new instruments with improved clinical performance. The phases present were identified by Micro-XRD (micro-x-ray diffraction) and TMDSC (temperature-modulated differential scanning calorimetry), using clinically popular ProFile GT and ProTaper nickel-titanium rotary instruments, which have two different cross-sectional designs. Instruments were analyzed in the as-received condition, after clinical use, and following elevated-temperature heat treatments. The first null hypothesis was that microstructural phases and phase transformations do not have an impact on clinical performance and instrument failure. The second null hypothesis was that appropriate heat treatments previously used for orthodontic wires would not result in beneficial changes in microstructural phases that may significantly affect the clinical life of these instruments. Based upon the present research and complimentary previous studies by this investigator, both null hypotheses were rejected. Information obtained from this research should aid future development of improved instruments with reduced likelihood of failure during clinical use.

Download or read book Textbook of Endodontology written by Lars Bjørndal and published by John Wiley & Sons. This book was released on 2018-08-06 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt: The third edition of Textbook of Endodontology provides lucid scholarship and clear discussion of endodontic principles and treatment to dental students and dental practitioners searching for current information on endodontic theories and techniques. Completely revised and updated new edition Features six new chapters Provides pedagogical features to promote understanding Includes clinical case studies to put the information in the clinical context Illustrated in full color throughout with clinical images and detailed diagrams Offers interactive multiple-choice questions on a companion website

Download or read book Fractographic and Fatigue Analyses of Nickel Titanium Rotary Endodontic Instruments written by Thomas A. Karn and published by . This book was released on 2003 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scanning Electron Microscope Examination of Wire Bonds from High reliability Devices written by Kathryn O. Leedy and published by . This book was released on 1973 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microvascular Corrosion Casting in Scanning Electron Microscopy written by S.H. Aharinejad and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several methods have been used to demonstrate the vasculature of different organs in man and other species. Many attempts to evaluate the precise microangioarchitecture of organ systems remained unproductive, others were controversial. The development of electron microscope in thirties opend new perspectives in researching microvascular systems. Transmission electron microscopy provided a two-dimensional view on microcirculatory system at higher magnifications, however, its standardization was delayed unnecessarily. The use of methyl methacrylate and related compounds for obtaining replicas of vascular beds, and their study in scanning electron microscope opened a new window in micromorphological research. For the first time, a three-dimensional image analysis of the vascular system was possible. The microvascular corrosion casting method has meanwhile attracted the interest of many contemporary scientists. Its application to medical and biological problems justify it to be used as a routine method for microvascular investigations. The first investigators who used this method, focused either on methodological details or they dealt with the normal microanatomy of organs. The advantages of this method in demonstrating pathological microvascular patterns are also evident.

Download or read book Characterization of New Rotary Endodontic Instruments Fabricated from Special Thermomechanically Processed NiTi Wire written by Jie Liu and published by . This book was released on 2009 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Although NiTi rotary instruments are very popular for endodontic treatment, instrument separation is still a challenge in clinic. A new NiTi rotary instrument has recently been marketed that is machined from M-Wire that has been subjected to a proprietary novel thermomechanical processing procedure. The manufacturer has claimed that this new M-Wire instrument has considerably improved flexibility and resistance to cyclic fatigue, compared to conventional rotary instruments that are machined from superelastic (SE) austenitic NiTi wire. Clinical use has confirmed that these new M-Wire rotary instruments have outstanding clinical fatigue resistance. However, the mechanism for the improved clinical performance of these instruments is unknown. The objective of this study was to employ a variety of metallurgical laboratory techniques to determine the origin of these improved mechanical properties for the new rotary instruments. Specimens from as-received M-Wire instruments, clinically used M-Wire instruments, and conventional instruments were prepared for evaluation. The temperature range for phase transformation was examined by differential scanning calorimetry (DSC). Vickers hardness measurements were made since hardness variations for the same type of alloy has been found to correlate with variations in mechanical properties. The microstructures of the NiTi alloys were revealed by acid etching and examined with an optical microscope and a scanning electron microscope. Wear resistance of clinically used M-Wire instruments was investigated by examining their surfaces with an SEM. In a complementary study, bright-field images of M-Wire blanks were obtained by scanning transmission electron microscopy (STEM). DSC study showed that M-Wire instruments have much higher Af (austenite-finish) temperatures (over 40°C) than conventional superelastic rotary instruments (below room temperature), and are a mixture of martensite, R-phase and austenite at room temperature. The Vickers hardness of M-Wire instruments is significantly higher than that of conventional rotary NiTi instruments. Mean Vickers hardness number for the tip, intermediate region and shank region of size 30/.04 taper M-Wire instruments were about 374, 380 and 392 each. Better wear resistance was observed with the SEM on clinically used M-Wire instruments, which presented less microcracks and evidence of permanent deformation on the surface compared with surfaces of clinically used conventional NiTi instruments. This improved wear resistance is attributed to increased hardness for surface region of the M-Wire instrument. Acid-etched M-Wire instruments presented a classical lenticular martensite structure when observed with the optical microscope and SEM. EDS analyses of the microstructures of the M-Wire instruments revealed titanium-rich precipitates. STEM examinations of M-Wire blanks revealed much coarser grains, twinning, and a high density of dislocations, which were not observed in starting superelastic NiTi wire blanks for conventional instruments. In summary, increased hardness was found for M-Wire instruments, compared with conventional superelastic NiTi rotary instruments, which served as a control for this study. The STEM observations show that the improved mechanical properties of the starting M-Wire (and the rotary instruments manufactured from this special NiTi wire) arise from strengthening mechanisms in the martensitic structure, which were induced by extensive thermomechanical processing.

Download or read book Impact of Electron and Scanning Probe Microscopy on Materials Research written by David G. Rickerby and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 503 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Advanced Study Institute provided an opportunity for researchers in universities, industry and National and International Laboratories, from the disciplines ofmaterials science, physics, chemistry and engineering to meet together in an assessment of the impact of electron and scanning probe microscopy on advanced material research. Since these researchers have traditionally relied upon different approaches, due to their different scientific background, to advanced materials problem solving, presentations and discussion within the Institute sessions were initially devoted to developing a set ofmutually understood basic concepts, inherently related to different techniques ofcharacterization by microscopy and spectroscopy. Particular importance was placed on Electron Energy Loss Spectroscopy (EELS), Scanning Probe Microscopy (SPM), High Resolution Transmission and Scanning Electron Microscopy (HRTEM, HRSTEM) and Environmental Scanning Electron Microscopy (ESEM). It was recognized that the electronic structure derived directly from EELS analysis as well as from atomic positions in HRTEM or High Angle Annular Dark Field STEM can be used to understand the macroscopic behaviour of materials. The emphasis, however, was upon the analysis of the electronic band structure of grain boundaries, fundamental for the understanding of macroscopic quantities such as strength, cohesion, plasticity, etc.

Download or read book An Atlas of Metal Damage written by Lothar Engel and published by Prentice Hall. This book was released on 1981 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book SEM of Plastics Failure written by Gottfried W. Ehrenstein and published by . This book was released on 2011 with total page 267 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Scanning Electron Microscope Study of Failure Initation and Propagation in Model Microstructures Subject to Uniaxial Tensile Stressing written by Gerald Anthony Karelus and published by . This book was released on 1975 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measuring Cumulative Stress of Nickel Titanium Rotary Endodontic Files written by Barton William Putnam and published by . This book was released on 1998 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book FAILURE ANALYSIS AND THE SCANNING ELECTRON MICROSCOPE PROCEEDINGS OF A WORKSHOP written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scanning electron microscope Study of Normal impingement Erosion of Ductile Metals written by William A. Brainard and published by . This book was released on 1980 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fracture Resistance of Electropolished Rotary Nickel Titanium Endodontic Instruments written by Margot Elizabeth Anderson and published by . This book was released on 2006 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Atlas of Metal Damage written by Lothar Engel and published by . This book was released on 1974 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Atlas of Metal Damage written by Lothar Engel and published by Manson Publishing. This book was released on 1981 with total page 271 pages. Available in PDF, EPUB and Kindle. Book excerpt: Good,No Highlights,No Markup,all pages are intact, Slight Shelfwear,may have the corners slightly dented, may have slight color changes/slightly damaged spine.