An X-ray Microtomographic Study of Natural White-spot Enamel Lesions

2011 ◽  
Vol 91 (2) ◽  
pp. 185-191 ◽  
Author(s):  
N.J. Cochrane ◽  
P. Anderson ◽  
G.R. Davis ◽  
G.G. Adams ◽  
M.A. Stacey ◽  
...  
Keyword(s):  
Surface Layer ◽  
Mineral Content ◽  
White Spot ◽  
Line Profiles ◽  
Surface Layers ◽  
Voxel Size ◽  
Early Presentation ◽  
X Ray ◽  
Non Invasive ◽  
Surface Layer Thickness

White-spot enamel lesions are an early presentation of dental caries and are ideally managed by non-invasive procedures. The aim of this study was to characterize white-spot enamel lesions by x-ray microtomography. In particular, mineral content across the lesion from the surface to the base of the lesion was measured and surface layers defined. Molars with long buccal white-spot enamel lesions were collected, photographed, and each sectioned to produce 3 500-µm-thick sections. The sections were mounted and imaged by quantitative x-ray microtomography at a 15-µm voxel size. We analyzed line profiles through the middle of each 3D image to determine mineral content and depth. The surface layer thickness of the lesions ranged from 35 to 130 µm, with the maximum mineral content in this layer being 74% to 100% of that of sound enamel. The average mineral content across the lesions ranged from 1.73 to 2.48 g/cm3. No significant differences could be found between lesions clinically categorized as active and those categorized as inactive. However, for depth-matched active and inactive lesions, the active lesions exhibited a more porous surface layer than the inactive lesions. White-spot enamel lesions are highly variable, with surface layers of considerable thickness.

scholarly journals Comparison of the Efficacy of Different Fluoride Varnishes on Dentin Remineralization During a Critical pH Exposure Using Quantitative X-Ray Microtomography

2018 ◽  
Vol 43 (6) ◽  
pp. E308-E316
Author(s):  
A Sleibi ◽  
A Tappuni ◽  
D Mills ◽  
GR Davis ◽  
A Baysan
Keyword(s):  
Calcium Phosphate ◽  
Amorphous Calcium Phosphate ◽  
Mineral Content ◽  
Test Group ◽  
Control Group ◽  
Mineral Concentration ◽  
Voxel Size ◽  
X Ray ◽  
Casein Phosphopeptide

SUMMARY Objectives: The objective of this in vitro study was to quantify the amount of mineral change in demineralized dentin at pH 5.5 after the application of dental varnishes containing fluoride with casein phosphopeptide–amorphous calcium phosphate, fluoride and bioglass, or fluoride alone. Methods and Materials: A total of 12 extracted human sound mandibular premolar root samples were coated with an acid-resistant varnish, leaving a 2 × 3 mm window at the outer root surface. These root specimens were then randomly divided into four groups and separately subjected to the demineralizing cycle at a pH of 4.8 for five days to create artificial caries-like lesions in dentin. Subsequently, each sample was imaged using quantitative x-ray microtomography (XMT) at a 15-μm voxel size. Each test group then received one of the following treatments: dental varnish containing casein phosphopeptide–amorphous calcium phosphate and fluoride (CPP-ACP, MI varnish, GC Europe), bioglass and fluoride (BGA, Experimental, Dentsply Sirona), or fluoride alone (NUPRO, Dentsply Sirona), as well as a control group, which received no treatment. These samples were kept in deionized water for 12 hours. The thin layer of varnish was then removed. All samples including the nonvarnish group were subjected to the second demineralizing cycle at pH 5.5 for five days. The final XMT imaging was then carried out following the second demineralizing cycle. XMT scan was also carried out to varnish samples at 25 μm voxel size. The change in mineral concentration in the demineralized teeth was assessed using both qualitative and quantitative image analysis. Results: There was an increase in radiopacity in the subtracted images of all varnish groups; a significant increase in mineral content, 12% for the CPP-ACP and fluoride (p≤0.05 and p≤0.001), 25% BGA (p≤0.001), and 104% fluoride alone varnish (p≤0.001). There was an increase in the size of radiolucency in the lesion area with a significant decrease in mineral content in the nonvarnish group, 10% (p≤0.05 and p≤0.001). Conclusions: There was encouraging evidence of a remineralization effect following the application of dental varnish on dentin and also an observed resistance to demineralization during the acidic challenge in all cases. However, a dental varnish containing fluoride alone appeared to have a much greater effect on dentin remineralization when compared with CPP-ACP with fluoride and bioglass with fluoride.

Clinical and laboratory studies of the effectiveness of a non-invasive method of treating caries in the stage of white chalky spot with Icon technology

2021 ◽  
pp. 32-36
Author(s):  
S.U. Maksyukov ◽  
D.V. Yogina ◽  
D.S. Maksyukov
Keyword(s):  
Three Dimensional ◽  
White Spot ◽  
Laboratory Studies ◽  
X Ray ◽  
Non Invasive ◽  
Before And After ◽  
Invasive Method ◽  
Tooth Dentin ◽  
Three Dimensional Models ◽  
Comparison Of The Results

The aim of the study was to evaluate the effectiveness of a non-invasive method of treating caries at the stage of a white chalky spot with the Infiltration Concept (Icon) technology. Materials and methods: the clinical and laboratory study included 5 teeth with caries in the white spot stage, removed according to orthodontic indications. The study included scanning in an X-ray computer microtomograph of selected samples of teeth with caries in the white spot stage before and after treatment of the caries area according to Icon technology. For each sample, 1601 X-ray projections were obtained, which were then reconstructed using the XRM Reconstructor software. The comparison of the mineralization density of the samples was carried out by calibrating the obtained images, reconstructing three-dimensional models of tooth samples and constructing maps of the mineralization fee. Results and conclusions. Data on the mineralization density before and after treatment according to Icon technology were obtained in the following areas of the studied teeth: caries in the white spot stage; dentin bordering on caries (the area touches the dentinoemal border as close as possible to the caries area); the area of healthy enamel on the opposite side of the tooth; dentin bordering on healthy enamel (near the dentinoemal border and as close as possible to the healthy enamel area). A comparison of the results obtained does not allow us to conclude about the effectiveness of treatment according to the Icon technology. Moreover, the mineralization density of the studied areas significantly decreased after the treatment.

Examination of the Structure and Micro-Hardness of a Laser-Constituted Surface Layer Deposited on the Constructional Steel

2008 ◽  
Vol 23 (1) ◽  
pp. 51-63
Author(s):  
Sylwester Kłysz ◽  
Anna Bień
Keyword(s):  
Surface Layer ◽  
Constructional Steel ◽  
Laser Hardening ◽  
Crystalline Lattice ◽  
Micro Hardness ◽  
Surface Layers ◽  
X Ray ◽  
Macroscopic Examination

Examination of the Structure and Micro-Hardness of a Laser-Constituted Surface Layer Deposited on the Constructional SteelThe paper has been intended to present results of the micro- and macroscopic examination of the structure, as well as measurements of micro-hardness of surface layers of specimens made from the toughening (heat-treatable) constructional steel 50H subjected to laser hardening. Basing on X-ray examination with the DRON-4 and the Seifert XRD 3003 diffractometers, parameters of crystalline lattice and quantitative contents of particular phases have been found.

scholarly journals Dual-energy X-ray absorptiometry for the measurement of gross body composition in rats

1996 ◽  
Vol 75 (6) ◽  
pp. 803-809 ◽  
Author(s):  
Susan A. Jebb ◽  
Stephen W Garland ◽  
Graham Jennings ◽  
Marinos Elia
Keyword(s):  
Body Composition ◽  
Mineral Content ◽  
Small Animal ◽  
Direct Analysis ◽  
Dual Energy ◽  
Invasive Technique ◽  
Small Animals ◽  
Limits Of Agreement ◽  
X Ray ◽  
Non Invasive

Dual-energy X-ray absorptiometry (DXA) is a novel, non-invasive technique for the measurement of gross body composition in small animals. In the present study the absolute accuracy of the Hologic QDR-lOOOW scanner was assessed by comparison with direct analysis in twelve rats with a range of body fat and bone mineral content (BMC) values. Fat masses measured by DXA and petroleumether extraction were significantly different (P<0·0023). The DXA technique consistently overestimated fat mass by approximately one third of the measured fatcontent. BMC derived from the measurement of Ca in asb gave a mean of 8·26 (range 1·57–15·71)g. BMC measured by DXA was not significantly different for the group as a whole. However, there was a trend for DXA to overestimate BMC in animals with low BMC and underestimate in those with higher BMC, compared with direct analysis, such that the 95% limits of agreement for the two techniques were +2·73 to −2·58g. These results suggest that the present small-animal software developed for use with currently available Hologic machines does not give an accurate measure of gross body composition compared with the results from classical direct analysis.

scholarly journals Boriding of steel surface with beams of boron atoms

2018 ◽  
Vol 226 ◽  
pp. 03004
Author(s):  
Yuri F. Migal ◽  
Andrey V. Sidashov
Keyword(s):  
Surface Layer ◽  
Oxidation State ◽  
Outer Surface ◽  
Photoelectron Spectroscopy ◽  
Steel Surface ◽  
Steel Sample ◽  
Small Concentration ◽  
Surface Layers ◽  
X Ray ◽  
Atomic Beams

We consider a new method for hardening the steel surface, which differs from the known CHT boriding method in the possibility of creating a surface with a lower fragility. Within this approach, the boriding is carried out by treating the steel surface with atomic beams of boron at a temperature below 750 °C. In this case, a friable layer of pure boron appears on the outer surface of the steel. Then, boron atoms diffuse from this layer into the surface layers of the steel. To detect boron in a steel sample, we used the X-ray photoelectron spectroscopy method. With its help we have obtained spectra of both the outer surface of a steel sample and surface layers at depths up to 8 nm. The spectra of the surface layers showed that as a result of boriding in the sample there appeared the boron in the zero oxidation state. This fact is consistent with the notion that, in the case of a small concentration of boron, it is located on the boundaries between the grains in the surface layer of steel and strengthens the bonds between the boundaries.

Elaboration of methodological base of quality evaluation of nitrogenization of steels of tribotechnical application

2021 ◽  
Vol 77 (1) ◽  
pp. 34-45
Author(s):  
L. I. Kuksenova ◽  
M. S. Alekseeva ◽  
M. A. Gress ◽  
D. A. Kozlov
Keyword(s):  
Solid Solution ◽  
Wear Resistance ◽  
Surface Layer ◽  
Sliding Friction ◽  
Quality Parameters ◽  
Friction Couple ◽  
Surface Layers ◽  
X Ray ◽  
Iron Based ◽  
And Performance

Nitrogenization is one of most spread methods of surface hardening of critical parts of machines. To elaborate methodological base of structural evaluation of quality parameters of nitrogenized surface layers of sliding friction couple by methods of X-ray structural analysis and tribotechnical tests, structure and performance properties of nitrogenized structural steels and alloys were studied. Namely pearlitic and martensitic steels (40Х, 38Х2МЮА, ВКС-7), model iron-based alloys with a BCC lattice, steels alloyed by Cr, Mo, Al in amount of up to 4 % (at.), iron-based alloys with FCC lattice, alloyed by Ni (29 % (at.)), Cr, Al, Ti in the amount of up to 4 % (at.), as well as austenitic high-chromium steels 12Х18Н10Т, 08Х16Г15Н5МАФ, steel 16Х3НВФМБ-Ш and high manganese steel 40Г14Н8Х3Б1. The surface saturation of the samples was made by gas, ion, gas-baric nitrogenizing and by ion implantation of nitrogen. The sum of macroscopic (tribotechnical) and microscopic (structural) indicators was evaluated, which characterize the physics and mechanics of friction process at various hierarchical levels. This sum of indicators also provides information on properties of antifriction coatings, modified layers and performance ability of the friction couple under conditions of contact deformation. It was established, that increasing of the nitrogenizing temperature from 540 up to 700 °C for alloys with a ferrite matrix results in a decrease of the hardness of the surface layer and physical broadening of X-ray lines. In this case, the relative wear resistance reaches maximum at 620 °C. For alloys with an austenitic matrix, an increase of hardness, broadening of X-ray lines and relative wear resistance occurs with increasing of temperature. These parameters grow in the sequence Fe−Ni, Fe−Ni−Al, Fe−Ni−Cr, Fe−Ni−Ti. Gas-baric nitrogenizing enables to obtain higher performance characteristics of parts (wear resistance and contact strength). Based on the generalization of the results of experimental studies of nitrogenized steels and alloys with various compositions and various crystal lattices, the most significant characteristics of the structural state and properties of near-surface microvolumes were established, that affect the level of surface destruction during friction, as follows: the size of the alloying element nitrides particles, the distance between them, the micro-deformation of the crystal lattice of the solid solution, the values of the physical broadening of the X-ray lines of the solid solution, its hardness and the change in hardness during friction, the plasticity reserve. Generalized criteria for the properties of the surface layer, taking into account the characteristics of the structure and properties of the nitrogenized layer and the zone of surface contact plastic deformation elaborated. Also methodological foundations for the structural assessment of the quality parameters of the surface layers of sliding friction couples elaborated. Bench tests have confirmed the effectiveness of the application of the generalized structure parameter and properties of surface layers for the selection of materials for the friction unit. The formulated conditions are recommended for optimizing the nitrogenizing technological process from the standpoint of tribology and choice of materials for friction couple.

scholarly journals Conditions for the Formation of Wear-Resistant Structures When Strengthening the Surface Layers of Parts

2018 ◽  
Vol 7 (4.3) ◽  
pp. 76
Author(s):  
Oleg Cherneta ◽  
Vadim Kubich ◽  
Roman Voloshchuk ◽  
Alexander Sasov ◽  
Yuriy Korzhavin ◽  
...  
Keyword(s):  
Surface Layer ◽  
Heat Removal ◽  
High Strength ◽  
Structural Materials ◽  
Carbon Steels ◽  
Technological Parameters ◽  
Surface Layers ◽  
X Ray ◽  
The Given ◽  
Technological Methods

In the given article special attention is paid to the transformation of the structure of average carbon steels, depending on technological methods of strengthening, the identification of factors influencing the emergence of high-strength structures.  With the help of microstructural, X - ray phase studies, microhardness measurements of certain layers, the main technological parameters and modes of reinforcing workings have been identified, new and innovative combined technologies have been proposed. Based on the analysis of a number of existing technological methods of strengthening the surface layer of structural materials, the dynamics of transformation of their microstructures was researched.  After laser treatment, due to the ultra-high velocity of cooling of crystallized volumes, due to intensive heat removal through the main volume of samples on the surface, a light zone, which is not digestible, is identified and is identified as "structurally martensitic" - gardenain, which is  a kind of classical martensite. Based on the analysis of a number of existing technological methods of strengthening the surface layer of structural materials, the dynamics of transformation of their microstructures was researched.     

scholarly journals Surface-layer protein fromCaulobacter crescentus: expression, purification and X-ray crystallographic analysis

2016 ◽  
Vol 72 (9) ◽  
pp. 677-680 ◽  
Author(s):  
Michael D. Jones ◽  
Anson C. K. Chan ◽  
John F. Nomellini ◽  
Michael E. P. Murphy ◽  
John Smit
Keyword(s):  
Surface Layer ◽  
Caulobacter Crescentus ◽  
Expression System ◽  
Crystallographic Analysis ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
X Ray ◽  
Surface Layer Protein ◽  
Surface Layer Proteins ◽  
Self Assembling

Protein surface layers are self-assembling, paracrystalline lattices on the surface of many prokaryotes. Surface-layer proteins have not benefited from widespread structural analysis owing to their resistance to crystallization. Here, the successful expression of a truncated version of RsaA, the surface-layer protein fromCaulobacter crescentus, from aCaulobacterprotein-expression system is reported. The purification, crystallization and initial X-ray diffraction analysis of the truncated RsaA, the largest surface-layer protein studied to date and the first from a Gram-negative bacterium, are also reported.

CHANGES OF SURFACE LAYER PROPERTIES IN GEAR TEETH AFTER SHOT PEENING

Tribologia ◽  
2016 ◽  
Vol 267 (3) ◽  
pp. 171-181
Author(s):  
Michał TAGOWSKI ◽  
Henryk CZARNECKI
Keyword(s):  
Surface Layer ◽  
Shot Peening ◽  
Retained Austenite ◽  
Tooth Surface ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
X Ray ◽  
Gear Teeth ◽  
The Core ◽  
Etched Surface

Considering the phenomenon during teeth cooperation in a toothed gear and produced loads within the macro and micro areas of contact surface, one should be paying attention to the type and condition of the surface layer. Shot peening is often recommended, especially for gears particularly loaded in addition to hardening by heat treatment. Therefore, the study presents hardness changes in tooth surface layers after shot peening, when the surfaces had been previously carburized and quenched. The article presents hardness distribution over the depth of the teeth. Measurements were made on oblique polished and etched surface, which allows the identification of the microhardness near the outer surface and through the depth up to the core. Furthermore, based on data analysis obtained from X-ray diffraction, the amount of retained austenite was estimated and changes in the metallographic structure after shot peening were illustrated.

X-ray microtomography

1988 ◽  
Vol 46 ◽  
pp. 998-999
Author(s):  
H.W. Deckman ◽  
B.F. Flannery ◽  
J.H. Dunsmuir ◽  
K.D' Amico
Keyword(s):  
Computed Tomography ◽  
Internal Structure ◽  
Imaging Technique ◽  
Three Dimensional ◽  
Tissue Structure ◽  
Individual Element ◽  
X Ray ◽  
Non Invasive ◽  
Panoramic Imaging ◽  
Three Dimensional Images

We have developed a new X-ray microscope which produces complete three dimensional images of samples. The microscope operates by performing X-ray tomography with unprecedented resolution. Tomography is a non-invasive imaging technique that creates maps of the internal structure of samples from measurement of the attenuation of penetrating radiation. As conventionally practiced in medical Computed Tomography (CT), radiologists produce maps of bone and tissue structure in several planar sections that reveal features with 1mm resolution and 1% contrast. Microtomography extends the capability of CT in several ways. First, the resolution which approaches one micron, is one thousand times higher than that of the medical CT. Second, our approach acquires and analyses the data in a panoramic imaging format that directly produces three-dimensional maps in a series of contiguous stacked planes. Typical maps available today consist of three hundred planar sections each containing 512x512 pixels. Finally, and perhaps of most import scientifically, microtomography using a synchrotron X-ray source, allows us to generate maps of individual element.

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