scholarly journals Adhesion of Hydroxyapatite Nanoparticles to Dental Materials under Oral Conditions

Scanning ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12 ◽  
Author(s):  
Cíntia Mirela Guimarães Nobre ◽  
Norbert Pütz ◽  
Matthias Hannig
Keyword(s):  
Electron Microscopy ◽  
Dental Materials ◽  
Hydroxyapatite Nanoparticles ◽  
Pellicle Formation ◽  
Transmission Electron ◽  
Different Shapes ◽  
Oral Conditions ◽  
Dental Applications

Hydroxyapatite nanoparticles (nano-HAP) are receiving considerable attention for dental applications, and their adhesion to enamel is well established. However, there are no reports concerning the effects of HAP on other dental materials, and most of the studies in this field are based on in vitro designs, neglecting the salivary pellicle-apatite interactions. Thus, this in situ pilot study aims to evaluate the effects of three hydroxyapatite-based solutions and their interactions with different dental material surfaces under oral conditions. Hence, two volunteers carried intraoral splints with mounted samples from enamel and from three dental materials: titanium, ceramics, and polymethyl-methacrylate (PMMA). Three HAP watery solutions (5%) were prepared with different shapes and sizes of nano-HAP (HAP I, HAP II, HAP III). After 3 min of pellicle formation, 10 ml rinse was performed during 30 sec. Rinsing with water served as control. Samples were accessed immediately after rinsing, 30 min and 2 h after rinsing. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the particles, and SEM evaluated the pellicle-HAP interactions. SEM and TEM results showed a high variation in the size range of the particles applied. A heterogeneous HAP layer was present after 2 h on enamel, titanium, ceramics, and PMMA surfaces under oral conditions. Bridge-like structures were visible between the nano-HAP and the pellicle formed on enamel, titanium, and PMMA surfaces. In conclusion, nano-HAP can adhere not only to enamel but also to artificial dental surfaces under oral conditions. The experiment showed that the acquired pellicle act as a bridge between the nano-HAP and the materials’ surface.

scholarly journals Hydroxyapatite-Based Solution as Adjunct Treatment for Biofilm Management: An In Situ Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2452
Author(s):  
Cíntia M. G. Nobre ◽  
Belinda König ◽  
Norbert Pütz ◽  
Matthias Hannig
Keyword(s):  
Electron Microscopy ◽  
Microscopic Analysis ◽  
Adhesive Properties ◽  
Pellicle Formation ◽  
Adjunct Treatment ◽  
Dental Biofilm ◽  
In Situ Study ◽  
Transmission Electron ◽  
Oral Conditions

Synthetic hydroxyapatite-based solution is a bioinspired material that may present anti-adhesive properties, restraining the dental biofilm formation without causing adverse effects. This in situ study aims to evaluate the effects of three different hydroxyapatite (HAP) watery solutions as a mouthwash against biofilm adhesion on different dental material surfaces under oral conditions. Hence, four volunteers carried maxillary splints containing enamel, titanium, ceramics, and polymethyl-methacrylate resin (PMMA) samples. Three HAP watery solutions (5%) were prepared with HAP particles presenting different shapes and sizes (HAP I, HAP II, HAP III). During 24 h, the volunteers rinsed two times with one of the following selected tested solution: HAP I, HAP II, HAP III, water, or chlorhexidine 0.2% (CHX). The first rinse was performed 3 min after pellicle formation; the second rinse occurred after a 12 h interval. The surface analysis was performed by scanning electron microscopy (SEM), fluorescence microscopy (FM), and transmission electron microscopy (TEM). Statistical and microscopic analysis showed that most samples treated with any HAP solution revealed reduced biofilm coverage presenting comparable results to CHX treated samples, however without altering the microorganisms’ viability. In conclusion, the results of this investigation showed that a pure hydroxyapatite-based mouthrinse could be a promising bioinspired adjunct solution for biofilm management.

scholarly journals Generation of flagella by cultured mouse spermatids.

1984 ◽  
Vol 98 (2) ◽  
pp. 619-628 ◽  
Author(s):  
G L Gerton ◽  
C F Millette
Keyword(s):  
Electron Microscopy ◽  
Spermatogenic Cells ◽  
Fibrous Sheath ◽  
Acridine Orange Staining ◽  
Transmission Electron ◽  
Fetal Bovine ◽  
Outer Dense Fibers ◽  
Unit Gravity Sedimentation

During the short-term culturing of mouse spermatogenic cells, flagella were generated by round spermatids previously lacking tails. Unseparated germ cells were obtained by enzymatic treatments and round spermatids (greater than 90% pure) were purified by unit gravity sedimentation. As determined by Nomarski or phase-contrast microscopy, no cells had flagella immediately after isolation; flagella were first clearly detected after 6 1/2 h of culture in Eagle's minimal essential medium containing 10% fetal bovine serum and 6 mM lactate. After 24 h, approximately 20% of round spermatids had formed flagella. Multinucleated round spermatids often formed multiple flagella, the number never exceeding the number of nuclei per symplast. Round spermatids were the only spermatogenic cells capable of tail formation. Flagella elongation was blocked by 1 microM demecolcine, an inhibitor of tubulin polymerization. Indirect immunofluorescence localized tubulin in the flagella. As seen by scanning electron microscopy, flagella developed as early as 2 h after culture and continued to elongate over the next 20 h, reaching lengths of at least 19 micron. Transmission electron microscopy demonstrated that flagella formed in culture resembled flagella from Golgi-phase round spermatids in situ; the flagella consisted of "9+2" axonemes lacking other accessory structures such as outer dense fibers and the fibrous sheath. As determined by acridine orange staining of the developing acrosomes, all spermatids that formed flagella in culture were Golgi-phase spermatids. By these criteria, the structures are indeed true flagella, corresponding in appearance to what others have described for early mammalian spermatid flagella in situ. We believe this is the first substantiated report of limited in vitro differentiation by isolated mammalian spermatids.

Mechanical, microstructural properties and cell adhesion of Sr/Se-hydroxyapatite/graphene/polycaprolactone nanofibers

2020 ◽  
pp. 089270572091278 ◽  
Author(s):  
Reem Al-Wafi ◽  
SF Mansour ◽  
MK Ahmed
Keyword(s):  
Electron Microscopy ◽  
Tensile Strength ◽  
Microstructural Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nanofibrous Scaffolds ◽  
Transmission Electron ◽  
Fesem Micrographs

Electrospun nanofibrous scaffolds containing co-dopant of Sr/Se into carbonated hydroxyapatite has been synthesized in situ with graphene (G) nanosheets and carried on polycaprolactone at different contributions of G. The powder and the nanofibrous samples were investigated using X-ray diffraction, transmission electron microscopy, and field emission scanning electron microscopy (FESEM). The FESEM micrographs show that the highest content of G (0.2 G) was formed in non-oriented/rough/cracked fibers with diameters around 0.3–0.4 µm at the maximum. The tensile strength of nanofibrous scaffolds was improved with the addition of G nanosheets and the maximum tensile strength of 0.2 G was around 6.39 ± 0.24 MPa, while the minimum cell viability ratio was about 94.4 ± 3.2% for the free G nanofibers. The in vitro attachment of HFB4 cell lines was investigated and it showed that nanofibrous scaffolds have induced cells to be proliferated and spread on the nanofibrous scaffolds’ surface. This behavior of cells growth encourages more investigations for these nanofibrous scaffolds to be promoted for clinical applications.

In situ TEM observation of Au–Cu2O core–shell growth in liquids

Nanoscale ◽  
2019 ◽  
Vol 11 (21) ◽  
pp. 10486-10492 ◽  
Author(s):  
Fu-Chun Chen ◽  
Jui-Yuan Chen ◽  
Ya-Hsuan Lin ◽  
Ming-Yu Kuo ◽  
Yung-Jung Hsu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Shell Growth ◽  
Core Shell ◽  
In Situ Tem ◽  
Shell Nanoparticles ◽  
Transmission Electron ◽  
Liquid Cell ◽  
Different Shapes ◽  
Core Shell Nanoparticles

The formation of different shapes Au–Cu2O core–shell nanoparticles was investigated by in situ liquid cell transmission electron microscopy (LCTEM).

scholarly journals Longer-Term Postcure Measurement of Cuspal Deformation Induced by Dimensional Changes in Dental Materials

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
A. Falsafi ◽  
J. D. Oxman ◽  
P.-H. Tse ◽  
T. T. Ton
Keyword(s):  
Dental Materials ◽  
Displacement Transducer ◽  
Linear Variable Differential Transformer ◽  
Measuring Instrument ◽  
Direct Examination ◽  
Dimensional Changes ◽  
In Situ Techniques ◽  
Oral Conditions

Aim. This paper presents a simple, versatile in vitro methodology that enables indirect quantification of shrinkage and expansion stresses under clinically relevant conditions without the need for a dedicated instrument.Methods. For shrinkage effects, resulting cusp deformation of aluminum blocks with MOD type cavity, filled with novel filling compositions and commercial cements, has been measured using a bench-top micrometer and a Linear Variable Differential Transformer (LVDT, a displacement transducer) based instrument.Results. The results demonstrated the validity of the proposed simple methodology. The technique was successfully used in longer-term measurements of shrinkage and expansion stress for several dental compositions.Conclusions. In contrast to in situ techniques where a measuring instrument is dedicated to the sample and its data collection, the proposed simple methodology allows for transfer of the samples to the environment of choice for storage and conditioning. The presented technique can be reliably used to quantify stress development of curing materials under clinically relevant (oral) conditions. This enables direct examination and comparison of structural properties corresponding to the final stage of formed networks. The proposed methodology is directly applicable to the study of self-curing systems as they require mouth-type conditions (temperature and humidity) to achieve their designed kinetics and reactions.

scholarly journals Dental Applications of Systems Based on Hydroxyapatite Nanoparticles—An Evidence-Based Update

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 674
Author(s):  
Silvia Balhuc ◽  
Radu Campian ◽  
Anca Labunet ◽  
Marius Negucioiu ◽  
Smaranda Buduru ◽  
...  
Keyword(s):  
Dental Materials ◽  
Biological Properties ◽  
In Vivo Studies ◽  
Hydroxyapatite Nanoparticles ◽  
Randomized Controlled ◽  
Dental Applications ◽  
Oral Implantology

Hydroxyapatite is one of the most studied biomaterials in the medical and dental field, because of its biocompatibility; it is the main constituent of the mineral part of teeth and bones. In dental science, hydroxyapatite nanoparticles (HAnps) or nano-hydroxyapatite (nano-HA) have been studied, over the last decade, in terms of oral implantology and bone reconstruction, as well in restorative and preventive dentistry. Hydroxyapatite nanoparticles have significant remineralizing effects on initial enamel lesions, and they have also been used as an additive material in order to improve existing and widely used dental materials, mainly in preventive fields, but also in restorative and regenerative fields. This paper investigates the role of HAnps in dentistry, including recent advances in the field of its use, as well as their advantages of using it as a component in other dental materials, whether experimental or commercially available. Based on the literature, HAnps have outstanding physical, chemical, mechanical and biological properties that make them suitable for multiple interventions, in different domains of dental science. Further well-designed randomized controlled trials should be conducted in order to confirm all the achievements revealed by the in vitro or in vivo studies published until now.

Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

1977 ◽  
Vol 35 ◽  
pp. 460-461
Author(s):  
Tai-Te Chao ◽  
John Sullivan ◽  
Awtar Krishan
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Transmission Electron Microscopy ◽  
Tubulin Polymerization ◽  
Vinca Alkaloids ◽  
Antimitotic Activity ◽  
Transmission Electron ◽  
Flow Microfluorometry ◽  
Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

In situ observations of electromigration induced void behavior

1995 ◽  
Vol 53 ◽  
pp. 244-245
Author(s):  
T. Marieb ◽  
J. C. Bravman ◽  
P. Flinn ◽  
D. Gardner ◽  
M. Madden
Keyword(s):  
Electron Microscopy ◽  
Void Nucleation ◽  
Plan View ◽  
Transmission Electron ◽  
Nucleation Sites ◽  
Microelectronics Industry ◽  
In Situ Observations ◽  
Backscatter Electron Detector ◽  
Voltage Scanning

Electromigration and stress voiding have been active areas of research in the microelectronics industry for many years. While accelerated testing of these phenomena has been performed for the last 25 years[1-2], only recently has the introduction of high voltage scanning electron microscopy (HVSEM) made possible in situ testing of realistic, passivated, full thickness samples at high resolution.With a combination of in situ HVSEM and post-testing transmission electron microscopy (TEM) , electromigration void nucleation sites in both normal polycrystalline and near-bamboo pure Al were investigated. The effect of the microstructure of the lines on the void motion was also studied.The HVSEM used was a slightly modified JEOL 1200 EX II scanning TEM with a backscatter electron detector placed above the sample[3]. To observe electromigration in situ the sample was heated and the line had current supplied to it to accelerate the voiding process. After testing lines were prepared for TEM by employing the plan-view wedge technique [6].

Correlation Between Cellular Functions and Morphological Changes of Human Trophoblast in Vitro

1975 ◽  
Vol 33 ◽  
pp. 600-601
Author(s):  
John C. Garancis ◽  
Robert O. Hussa ◽  
Michael T. Story ◽  
Donald Yorde ◽  
Roland A. Pattillo
Keyword(s):  
Electron Microscopy ◽  
Cellular Proliferation ◽  
Morphological Changes ◽  
Culture Fluid ◽  
Cellular Functions ◽  
Human Trophoblast ◽  
Transmission Electron ◽  
Marked Activity ◽  
Malignant Trophoblast

Human malignant trophoblast cells in continuous culture were incubated for 3 days in medium containing 1 mM N6-O2'-dibutyryl cyclic adenosine 3':5'-monophosphate (dibutyryl cyclic AMP) and 1 mM theophylline. The culture fluid was replenished daily. Stimulated cultures secreted many times more chorionic gonadotropin and estrogens than did control cultures in the absence of increased cellular proliferation. Scanning electron microscopy revealed remarkable surface changes of stimulated cells. Control cells (not stimulated) were smooth or provided with varying numbers of microvilli (Fig. 1). The latter, usually, were short and thin. The surface features of stimulated cells were considerably different. There was marked increase of microvilli which appeared elongated and thick. Many cells were covered with confluent polypoid projections (Fig. 2). Transmission electron microscopy demonstrated marked activity of cytoplasmic organelles. Mitochondria were increased in number and size; some giant forms with numerous cristae were observed.

Epitaxy and texture analysis of Bi-Sr-Ca-Cu-O thin films on (100) MgO using Transmission Electron Microscopy

1990 ◽  
Vol 48 (4) ◽  
pp. 68-69
Author(s):  
J. T. Sizemore ◽  
D. G. Schlom ◽  
Z. J. Chen ◽  
J. N. Eckstein ◽  
I. Bozovic ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Critical Currents ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Cell Axis ◽  
Transmission Electron ◽  
Synthesis Procedure

Investigators observe large critical currents for superconducting thin films deposited epitaxially on single crystal substrates. The orientation of these films is often characterized by specifying the unit cell axis that is perpendicular to the substrate. This omits specifying the orientation of the other unit cell axes and grain boundary angles between grains of the thin film. Misorientation between grains of YBa2Cu3O7−δ decreases the critical current, even in those films that are c axis oriented. We presume that these results are similar for bismuth based superconductors and report the epitaxial orientations and textures observed in such films.Thin films of nominally Bi2Sr2CaCu2Ox were deposited on MgO using molecular beam epitaxy (MBE). These films were in situ grown (during growth oxygen was incorporated and the films were not oxygen post-annealed) and shuttering was used to encourage c axis growth. Other papers report the details of the synthesis procedure. The films were characterized using x-ray diffraction (XRD) and transmission electron microscopy (TEM).

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