scholarly journals PRECISION OF PRODUCTION CROWN MANUFACTURING USING 3D-PRINTING TECHNOLOGY. IMMEDIATE TEMPORARY RESTORATION AFTER DENTAL IMPLANTATION

2021 ◽  
Vol 16 (4) ◽  
pp. 109-114
Author(s):  
Yuri Melnikov ◽  
Sergey Zholudev ◽  
Elena Vladimirova ◽  
Dmitry Zaikin
Keyword(s):  
Electron Microscopy ◽  
3D Printing ◽  
Three Dimensional ◽  
Internal Surface ◽  
Implant Placement ◽  
Dental Implantation ◽  
Implant Abutment ◽  
Implant Crown ◽  
Simultaneous Loading ◽  
Microscopy Data

Subject. Currently, tooth loss prosthetics using implants are widely used. An important problem is the loss of bone tissue due to infections around the implant. Micro-gaps at the implant-abutment interface can contribute to infection with microorganisms.The aim of this study was to investigate the precision of connecting the implant-abutment components with simultaneous loading and temporary restoration. Methodology. The precision of the "implant – abutment – artificial crown" connection was studied on a clinical case with simultaneous removal of a tooth root, followed by implant placement and temporary restoration. Before installing the implant, specialized programs combined a three-dimensional CT model of the jaw with a 3D model of the dentition obtained as a result of scanning. To study precision, a duplicate plastic crown was made according to this virtual plan and fixed in a similar implant. The "implant-crown" model was fixed in plaster and a section was made up to the level of the "implant-abutment-artificial crown" connection, which was studied using electron microscopy at magnification of 50, 100 and 200 times. Results. Electron microscopy data showed that the junction of the internal surface of the implant with the plastic "abutment" had a gap width in the range of 54-77 microns. Conclusion. The exact fit of the restoration on the implant was confirmed by electron microscopy. In the presented example, due to the production of temporary restoration, it was possible to reduce the number of manipulations with the implant-abutment components. Modern milling and 3D printing technologies show high precision.

scholarly journals Three-Dimensional Printed Polylactic Acid (PLA) Surgical Retractors with Sonochemically Immobilized Silver Nanoparticles: The Next Generation of Low-Cost Antimicrobial Surgery Equipment

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 985 ◽  
Author(s):  
Lazaros Tzounis ◽  
Petros I. Bangeas ◽  
Aristomenis Exadaktylos ◽  
Markos Petousis ◽  
Nectarios Vidakis
Keyword(s):  
Electron Microscopy ◽  
3D Printing ◽  
Polylactic Acid ◽  
Low Cost ◽  
Three Dimensional ◽  
Film Deposition ◽  
Average Particle ◽  
Ag Nps ◽  
Fused Deposition ◽  
Vis Spectroscopy

A versatile method is reported for the manufacturing of antimicrobial (AM) surgery equipment utilising fused deposition modelling (FDM), three-dimensional (3D) printing and sonochemistry thin-film deposition technology. A surgical retractor was replicated from a commercial polylactic acid (PLA) thermoplastic filament, while a thin layer of silver (Ag) nanoparticles (NPs) was developed via a simple and scalable sonochemical deposition method. The PLA retractor covered with Ag NPs (PLA@Ag) exhibited vigorous AM properties examined by a reduction in Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli) bacteria viability (%) experiments at 30, 60 and 120 min duration of contact (p < 0.05). Scanning electron microscopy (SEM) showed the surface morphology of bare PLA and PLA@Ag retractor, revealing a homogeneous and full surface coverage of Ag NPs. X-Ray diffraction (XRD) analysis indicated the crystallinity of Ag nanocoating. Ultraviolent-visible (UV-vis) spectroscopy and transmission electron microscopy (TEM) highlighted the AgNP plasmonic optical responses and average particle size of 31.08 ± 6.68 nm. TEM images of the PLA@Ag crossection demonstrated the thickness of the deposited Ag nanolayer, as well as an observed tendency of AgNPs to penetrate though the outer surface of PLA. The combination of 3D printing and sonochemistry technology could open new avenues in the manufacturing of low-cost and on-demand antimicrobial surgery equipment.

Biomechanical comparison of implantation approaches for the treatment of mandibular total edentulism

2020 ◽  
Vol 234 (10) ◽  
pp. 1139-1150
Author(s):  
Yunus Ziya Arslan ◽  
Derya Karabulut ◽  
Songul Kahya ◽  
Erol Cansiz
Keyword(s):  
Three Dimensional ◽  
Loading Conditions ◽  
Stress Concentrations ◽  
Implant Placement ◽  
Impact Forces ◽  
Alternative Approach ◽  
Implant Abutment ◽  
Biomechanical Responses ◽  
Three Dimensional Models ◽  
Biomechanical Comparison

Applying four anterior implants placed vertically or tilted in the mandible is considered to provide clinically reasonable results in the treatment of mandibular posterior edentulism. It is also reported that a combination of four anterior and two short posterior implants can be an alternative approach for the rehabilitation of severe atrophy cases. In this study, we aimed to evaluate the biomechanical responses of three different implant placement configurations, which represent the clinical options for the treatment of mandibular edentulism. Three-dimensional models of the mandible, prosthetic bar, dental implant, abutment, and screw were created. Finite element models of the three implant configurations (Protocol 1: Four anterior implants, Protocol 2: Four anterior and two short posterior implants, Protocol 3: Two anterior and two tilted posterior implants: All-on-4™ concept) were generated for 10 patients and analyzed under different loading conditions including chewing, biting, and impact forces. Protocol 2 led to the lowest stress concentrations over the mandible among the three protocols ( p < 0.016). Protocol 2 resulted in significantly lower stresses than Protocol 3 and Protocol 1 over prosthetic bars under chewing forces ( p < 0.016). None of the implant placement protocols consistently exhibited the lowest stress distribution over abutments. The lowest stresses over dental implants under the chewing, biting, and impact forces were obtained in Protocol 1, Protocol 2, and Protocol 3, respectively ( p < 0.016). Protocol 3 was the best option to obtain the lowest stress values over the screws under all types of loading conditions ( p < 0.016). In conclusion, Protocol 2 was biomechanically more ideal than Protocol 1 and Protocol 3 to manage the posterior edentulism.

scholarly journals Trends in the Electron Microscopy Data Bank (EMDB)

2017 ◽  
Vol 73 (6) ◽  
pp. 503-508 ◽  
Author(s):  
Ardan Patwardhan
Keyword(s):  
Electron Microscopy ◽  
Three Dimensional ◽  
Data Bank ◽  
Electron Microscopy Data ◽  
Technological Advances ◽  
Major Player ◽  
Leading Position ◽  
Microscopy Data ◽  
The Uk ◽  
Better Than

Recent technological advances, such as the introduction of the direct electron detector, have transformed the field of cryo-EM and the landscape of molecular and cellular structural biology. This study analyses these trends from the vantage point of the Electron Microscopy Data Bank (EMDB), the public archive for three-dimensional EM reconstructions. Over 1000 entries were released in 2016, representing almost a quarter of the total number of entries (4431). Structures at better than 6 Å resolution now represent one of the fastest-growing categories, while the share of annually released tomography-related structures is approaching 20%. The use of direct electron detectors is growing very rapidly: they were used for 70% of the structures released in 2016, in contrast to none before 2011. Microscopes from FEI have an overwhelming lead in terms of usage, and the use of theRELIONsoftware package continues to grow rapidly after having attained a leading position in the field. China is rapidly emerging as a major player in the field, supplementing the US, Germany and the UK as the big four. Similarly, Tsinghua University ranks only second to the MRC Laboratory for Molecular Biology in terms of involvement in publications associated with cryo-EM structures at better than 4 Å resolution. Overall, the numbers point to a rapid democratization of the field, with more countries and institutes becoming involved.

scholarly journals FluoEM, virtual labeling of axons in three-dimensional electron microscopy data for long-range connectomics

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Florian Drawitsch ◽  
Ali Karimi ◽  
Kevin M Boergens ◽  
Moritz Helmstaedter
Keyword(s):  
Electron Microscopy ◽  
Long Range ◽  
Three Dimensional ◽  
Tissue Imaging ◽  
Fluorescent Light ◽  
Multiple Sources ◽  
Long Distance ◽  
Mouse Cortex ◽  
Microscopy Data ◽  
3D Em

The labeling and identification of long-range axonal inputs from multiple sources within densely reconstructed electron microscopy (EM) datasets from mammalian brains has been notoriously difficult because of the limited color label space of EM. Here, we report FluoEM for the identification of multi-color fluorescently labeled axons in dense EM data without the need for artificial fiducial marks or chemical label conversion. The approach is based on correlated tissue imaging and computational matching of neurite reconstructions, amounting to a virtual color labeling of axons in dense EM circuit data. We show that the identification of fluorescent light- microscopically (LM) imaged axons in 3D EM data from mouse cortex is faithfully possible as soon as the EM dataset is about 40–50 µm in extent, relying on the unique trajectories of axons in dense mammalian neuropil. The method is exemplified for the identification of long-distance axonal input into layer 1 of the mouse cerebral cortex.

Structural organization of escherichia coli ribosomes as determined by immuno electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 166-167 ◽  
Author(s):  
G. Stöffler ◽  
R.W. Bald ◽  
J. Dieckhoff ◽  
H. Eckhard ◽  
R. Lührmann ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Ribosomal Subunit ◽  
Spatial Arrangement ◽  
Small Subunit ◽  
Antibody Binding ◽  
Immuno Electron Microscopy

A central step towards an understanding of the structure and function of the Escherichia coli ribosome, a large multicomponent assembly, is the elucidation of the spatial arrangement of its 54 proteins and its three rRNA molecules. The structural organization of ribosomal components has been investigated by a number of experimental approaches. Specific antibodies directed against each of the 54 ribosomal proteins of Escherichia coli have been performed to examine antibody-subunit complexes by electron microscopy. The position of the bound antibody, specific for a particular protein, can be determined; it indicates the location of the corresponding protein on the ribosomal surface.The three-dimensional distribution of each of the 21 small subunit proteins on the ribosomal surface has been determined by immuno electron microscopy: the 21 proteins have been found exposed with altogether 43 antibody binding sites. Each one of 12 proteins showed antibody binding at remote positions on the subunit surface, indicating highly extended conformations of the proteins concerned within the 30S ribosomal subunit; the remaining proteins are, however, not necessarily globular in shape (Fig. 1).

Three-Dimensional Visualization of the T-System of Frog Muscle Using High Voltage Electron Microscopy and a Lanthanum Stain

1977 ◽  
Vol 35 ◽  
pp. 570-571 ◽  
Author(s):  
Lee D. Peachey ◽  
Clara Franzini-Armstrong
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
Three Dimensional ◽  
Biological Tissues ◽  
High Voltage Electron Microscopy ◽  
Transverse Tubular System ◽  
Peroxidase Reaction ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
T System

The effective study of biological tissues in thick slices of embedded material by high voltage electron microscopy (HVEM) requires highly selective staining of those structures to be visualized so that they are not hidden or obscured by other structures in the image. A tilt pair of micrographs with subsequent stereoscopic viewing can be an important aid in three-dimensional visualization of these images, once an appropriate stain has been found. The peroxidase reaction has been used for this purpose in visualizing the T-system (transverse tubular system) of frog skeletal muscle by HVEM (1). We have found infiltration with lanthanum hydroxide to be particularly useful for three-dimensional visualization of certain aspects of the structure of the T- system in skeletal muscles of the frog. Specifically, lanthanum more completely fills the lumen of the tubules and is denser than the peroxidase reaction product.

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