scholarly journals “Toughening and stress-reducing effects in composites formulated with thiourethane-treated fillers: systematic evaluation of the influence of filler size, loading and surface treatment”

2021 ◽  
Author(s):  
Ana Fugolin ◽  
Ana Rosa Costa Correr ◽  
Lourenco Correr-Sobrinho ◽  
R. Crystal Chaw ◽  
Steven Lewis ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Thermogravimetric Analysis ◽  
Surface Treatment ◽  
Volume Fraction ◽  
Filler Particle ◽  
Laser Scanning Microscopy ◽  
Dental Composites ◽  
Confocal Laser ◽  
Filler Surface ◽  
Silane Layer

Abstract Objectives: Filler particle functionalization with thiourethane oligomers has been shown to increase fracture toughness and decrease polymerization stress in dental composites, though the mechanism is poorly understood. The aim of this study was to systematically characterize the effect of the type of filler surface functionalization on the physicochemical properties of experimental resin composites containing fillers of different size and volume fraction. Methods: Barium glass fillers (1, 3 and 10 µm) were functionalized with 2 wt% thiourethane-silane (TU-Sil) synthesized de novo and characterized by thermogravimetric analysis. Fillers treated with 3-(Trimethoxysilyl)propyl methacrylate (MA-Sil) and with no surface treatment (No-Sil) served as controls. Fillers (50, 60 and 70 wt%) were incorporated into BisGMA-UDMA-TEGDMA (5:3:2) containing camphorquinone/ethyl-4-dimethylaminobenzoate (0.2/0.8 wt%) and 0.2 wt% di-tert-butyl hydroxytoluene. The functionalized particles were characterized by thermogravimetric analysis and a representative group was tagged with methacrylated rhodamine B and analyzed by confocal laser scanning microscopy. Polymerization kinetics were assessed by near-IR spectroscopy. Polymerization stress was tested in a cantilever system, and fracture toughness was assessed with single edge-notched beams. Fracture surfaces were characterized by SEM. Data were analyzed with ANOVA/Tukey's test (α = 0.05). Results and Conclusions: The grafting of thiourethane oligomer onto the surface of the filler particles led to reductions in polymerization stress ranging between 41% and 54%, without affecting the viscosity of the composite. Fracture toughness increased on average by 35% for composites with the experimental fillers compared with the traditional methacrylate-silanized groups. SEM and confocal analyses demonstrate that the coverage of the filler surface was not homogeneous and varied with the size of the filler. The average silane layer for the 1 µm particle functionalized with the thiourethane was 206 nm, much thicker than reported for traditional silanes. In summary, this study systematically characterized the silane layer and established structure-property relationships for methacrylate and thiourethane silane-containing materials. The results demonstrate that significant stress reductions and fracture toughness increases are obtained by judiciously tailoring the organic-inorganic interface in dental composites.

scholarly journals Toughening and polymerization stress control in composites using thiourethane-treated fillers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ana Paula Piovezan Fugolin ◽  
Ana Rosa Costa ◽  
Lourenco Correr-Sobrinho ◽  
R. Crystal Chaw ◽  
Steven Lewis ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Thermogravimetric Analysis ◽  
Laser Scanning ◽  
Volume Fraction ◽  
Filler Particle ◽  
Laser Scanning Microscopy ◽  
Dental Composites ◽  
Confocal Laser ◽  
Filler Surface ◽  
Silane Layer

AbstractFiller particle functionalization with thiourethane oligomers has been shown to increase fracture toughness and decrease polymerization stress in dental composites, though the mechanism is poorly understood. The aim of this study was to systematically characterize the effect of the type of filler surface functionalization on the physicochemical properties of experimental resin composites containing fillers of different size and volume fraction. Barium glass fillers (1, 3 and 10 µm) were functionalized with 2 wt% thiourethane-silane (TU-Sil) synthesized de novo and characterized by thermogravimetric analysis. Fillers treated with 3-(Trimethoxysilyl)propyl methacrylate (MA-Sil) and with no surface treatment (No-Sil) served as controls. Fillers (50, 60 and 70 wt%) were incorporated into BisGMA-UDMA-TEGDMA (5:3:2) containing camphorquinone/ethyl-4-dimethylaminobenzoate (0.2/0.8 wt%) and 0.2 wt% di-tert-butyl hydroxytoluene. The functionalized particles were characterized by thermogravimetric analysis and a representative group was tagged with methacrylated rhodamine B and analyzed by confocal laser scanning microscopy. Polymerization kinetics were assessed by near-IR spectroscopy. Polymerization stress was tested in a cantilever system, and fracture toughness was assessed with single edge-notched beams. Fracture surfaces were characterized by SEM. Data were analyzed with ANOVA/Tukey's test (α = 0.05). The grafting of thiourethane oligomer onto the surface of the filler particles led to reductions in polymerization stress ranging between 41 and 54%, without affecting the viscosity of the composite. Fracture toughness increased on average by 35% for composites with the experimental fillers compared with the traditional methacrylate-silanized groups. SEM and confocal analyses demonstrate that the coverage of the filler surface was not homogeneous and varied with the size of the filler. The average silane layer for the 1 µm particle functionalized with the thiourethane was 206 nm, much thicker than reported for traditional silanes. In summary, this study systematically characterized the silane layer and established structure–property relationships for methacrylate and thiourethane silane-containing materials. The results demonstrate that significant stress reductions and fracture toughness increases are obtained by judiciously tailoring the organic–inorganic interface in dental composites.

Toxicity Evaluation of Two Dental Composites: Three-Dimensional Confocal Laser Scanning Microscopy Time-Lapse Imaging of Cell Behavior

2013 ◽  
Vol 19 (3) ◽  
pp. 596-607 ◽  
Author(s):  
Ghania Nina Attik ◽  
Nelly Pradelle-Plasse ◽  
Doris Campos ◽  
Pierre Colon ◽  
Brigitte Grosgogeat
Keyword(s):  
Confocal Laser Scanning Microscopy ◽  
Laser Scanning ◽  
Cell Metabolism ◽  
Three Dimensional ◽  
Time Lapse ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Dental Composites ◽  
Confocal Laser ◽  
Time Lapse Imaging

AbstractThe purpose of this study was to investigate thein vitrobiocompatibility of two dental composites (namely A and B) with similar chemical composition used for direct restoration using three-dimensional confocal laser scanning microscopy (CLSM) time-lapse imaging. Time-lapse imaging was performed on cultured human HGF-1 fibroblast-like cells after staining using Live/Dead®. Image analysis showed a higher mortality rate in the presence of composite A than composite B. The viability rate decreased in a time-dependent manner during the 5 h of exposure. Morphological alterations were associated with toxic effects; cells were enlarged and more rounded in the presence of composite A as shown by F-actin and cell nuclei staining. Resazurin assay was used to confirm the active potential of composites in cell metabolism; results showed severe cytotoxic effects in the presence of both no light-curing composites after 24 h of direct contact. However, extracts of polymerized composites induced a moderate decrease in cell metabolism after the same incubation period. Composite B was significantly better tolerated than composite A at all investigated end points and all time points. The finding confirmed that the used CLSM method was sufficiently sensitive to differentiate the biocompatibility behavior of two composites based on similar methacrylate monomers.

Asphaltene Aggregation Kinetics in Crude Oil Using Confocal Microscopy

2001 ◽  
Vol 7 (S2) ◽  
pp. 542-543
Author(s):  
Robert J. Johnston ◽  
Thomas G. Mason
Keyword(s):  
Crude Oil ◽  
Laser Scanning ◽  
Volume Fraction ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Heavy Crude Oil ◽  
Aggregation Kinetics ◽  
Heavy Crude ◽  
Poor Solvent ◽  
Microscope Stage

Confocal laser scanning microscopy (CLSM) has been used to study asphaltene aggregation kinetics by employing the microscope's automated acquisition to generate time-lapsed projection maps of aggregating asphaltenes in the autofluorescent matrix of crude oil. Heavy crude oils contain asphaltene particles resulting in the production of optically observable micron-sized asphaltene aggregates. These aggregates form as a result of attractive interactions induced by mixing the heavy crude oil with a poor solvent. This technique has been employed to determine the volume fraction of aggregated asphaltenes, ϕagg, and the time evolution of this phenomenon. The measurements cover a range of various concentrations of asphaltene volume fractions of the heavy asphaltenic oil, ϕm, from ϕm =0.001 to ϕm =0.4.At each ϕm,after the mixtures have been made, approximately 20 μl of the crude oil is placed in a 20 μm deep flat-well quartz cell and immediately placed on a microscope stage.

Fracture Toughness Analysis of Ceramic and Resin Composite CAD/CAM Material

2019 ◽  
Vol 44 (4) ◽  
pp. E190-E201 ◽  
Author(s):  
R Hampe ◽  
B Theelke ◽  
N Lümkemann ◽  
M Eichberger ◽  
B Stawarczyk
Keyword(s):  
Fracture Toughness ◽  
Composite Materials ◽  
Resin Composite ◽  
Lithium Disilicate ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Testing Specimen ◽  
High Class ◽  
Fracture Surfaces ◽  
Cad Cam

SUMMARY Objectives: To evaluate and compare the fracture toughness of dental CAD/CAM materials of different material classes intended for in-office milling (glass ceramics, hybrid, resin composites) and the influence of aging on this property. Methods and Materials: The fracture toughness (critical intensity factor, KIc) values of 9 CAD/CAM restorative materials (Ambarino High-Class, Brilliant Crios, Cerasmart, exp. CAD/CAM composite, Katana Avencia, Lava Ultimate, VITA Enamic, IPS Empress CAD, and IPS e.max CAD) were determined using the SEVNB method in a four-point bending setup. Twenty bending bars of each material with a 4 × 3 cross and a minimum length of 12 mm were cut out of CAD/CAM milling blocks. Notching was done starting with a pre-cut and consecutive polishing and v-shaping with a razor blade, resulting in a final depth of v-shaped notches of between 0.8 and 1.2 mm. Half of the specimens were selected for initial fracture toughness measurements. The others were thermocycled in distilled water for 30,000× (5/55°C; 30-second dwell time) before testing. Specimen fracture surfaces were analyzed using confocal laser scanning microscopy. Results: All specimens for each material fractured into two fragments and showed the typical compression curl and brittle failure markings. Comparing initial KIc values, lithium disilicate ceramic IPS e.max CAD showed significantly the highest and leucite-reinforced ceramic IPS Empress CAD significantly the lowest KIc values (p<0.001). All tested CAD/CAM materials with a resin component ranged in the same KIc value group (p>0.999-0.060). After thermal cycling, the highest KIc values were measured for lithium disilicate ceramic IPS e.max CAD, followed by resin composite materials Ambarino High-Class (p<0.001-0.006) and hybrid material VITA Enamic (p<0.001-0.016), while the significantly lowest values were reflected for the resin composite materials Cerasmart, LAVA Ultimate (p<0.001-0.006), and Katana Avencia (p<0.001-0.009). The roughness of the fracture surfaces varied depending on the microstructure of the respective material. The ceramic surfaces showed the smoothest surfaces. The fracture surface of VITA Enamic revealed microstructural inhomogeneities and microcracks. For CAD/CAM resin composite materials, crack paths through the matrix and interfaces of matrix and fillers could be observed at the microstructure level. Conclusions: The materials tested show differences in fracture toughness typical for the class they belong to. With one exception (Ambarino High-Class), thermocycling affected the fracture toughness of materials with a resin component negatively, whereas the leucite and lithium disilicate ceramic showed stability.

Asphaltene Aggregation Studies of Crude Oil Using 3-D Confocal Microscopy

2000 ◽  
Vol 6 (S2) ◽  
pp. 22-23
Author(s):  
Robert J. Johnston ◽  
Thomas G. Mason
Keyword(s):  
Crude Oil ◽  
Laser Scanning ◽  
Laser Light ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Crude Oils ◽  
Confocal Laser ◽  
Heavy Crude ◽  
Optical Laser

Confocal laser scanning microscopy (CLSM) has been used to generate three dimensional projection maps of less fluorescent domains caused by asphaltene aggregates in the autofluorescent matrix of crude oil. Heavy crude oils contain asphaltene particles resulting in the production of optically observable micron sized asphaltene aggregates. This technique has been employed to determine the volume fraction of aggregated asphaltenes, øagg, and the time evolution of this phenomenon. The measurements cover a range of various concentrations of asphaltene volume fractions of the heavy asphaltenic oil, øm, from øm = 0 to øm = 0.6.Examining crude oils for asphaltenes aggregates using CLSM presents a challenge due to the strong absorption of the oils. This is because some molecules of the crude oil fluoresce when excited by optical laser light used as a source in the CLSM. Other molecules of the crude oils absorb light at similar wavelengths.

scholarly journals Effect of Exclusive Primer and Adhesive on Microtensile Bond Strength of Self-Adhesive Resin Cement to Dentin

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2353
Author(s):  
Bit-Na Kim ◽  
Sung-Ae Son ◽  
Jeong-Kil Park
Keyword(s):  
Bond Strength ◽  
Surface Treatment ◽  
Resin Cement ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Microtensile Bond Strength ◽  
Adhesive Resin ◽  
Dentin Surface ◽  
Significant Difference ◽  
Adhesive Resin Cement

The aim of this study was to investigate the effect of G-CEM One Primer (GCOP) and self-etching adhesive on the microtensile bond strength (µTBS) between self-adhesive resin cement G-CEM One (GCO) and dentin. Teeth were sectioned to expose the flat dentin surface and randomly assigned into five groups (n = 15) according to the dentin surface treatment: 1) no surface treatment, 2) GCOP, 3) All-Bond Universal (ABU), 4) GCOP followed by ABU (GCOP/ABU), 5) ABU followed by GCOP (ABU/GCOP). The composite resin blocks were bonded to the dentin surface using GCO. The specimens were stored in distilled water at 37 °C for 24 h, then sectioned into sticks (1 mm × 10 mm). The μTBS values were statistically analyzed using 1-way analysis of variance (ANOVA) and Tukey’s honestly significant difference (HSD) test (α = 0.05) and failure mode was examined under a stereomicroscope. The bonding interface of each specimen was evaluated using confocal laser scanning microscopy. The GCOP group exhibited the highest µTBS value and there were no significant differences observed between GCOP, GCOP/ABU, ABU/GCOP groups (p > 0.05). The use of GCOP with GCO results in the improved µTBS between GCO and dentin. In conclusion, using only GCOP with GCO for bonding of indirect restoration is extremely simple and increasing bond strength.

3-D imaging of cells using a confocal laser scanning microscope and digital image processing

1988 ◽  
Vol 46 ◽  
pp. 96-97
Author(s):  
Thomas M. Jovin ◽  
Michel Robert-Nicoud ◽  
Donna J. Arndt-Jovin ◽  
Thorsten Schormann
Keyword(s):  
Laser Scanning ◽  
Confocal Laser Scanning Microscope ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Confocal Laser ◽  
Scanning Microscope ◽  
Laser Scanning Microscope ◽  
Biochemical Processes ◽  
Adjacent Structures

Light microscopic techniques for visualizing biomolecules and biochemical processes in situ have become indispensable in studies concerning the structural organization of supramolecular assemblies in cells and of processes during the cell cycle, transformation, differentiation, and development. Confocal laser scanning microscopy offers a number of advantages for the in situ localization and quantitation of fluorescence labeled targets and probes: (i) rejection of interfering signals emanating from out-of-focus and adjacent structures, allowing the “optical sectioning” of the specimen and 3-D reconstruction without time consuming deconvolution; (ii) increased spatial resolution; (iii) electronic control of contrast and magnification; (iv) simultanous imaging of the specimen by optical phenomena based on incident, scattered, emitted, and transmitted light; and (v) simultanous use of different fluorescent probes and types of detectors.We currently use a confocal laser scanning microscope CLSM (Zeiss, Oberkochen) equipped with 3-laser excitation (u.v - visible) and confocal optics in the fluorescence mode, as well as a computer-controlled X-Y-Z scanning stage with 0.1 μ resolution.

Vacuoles Induced in Mammalian Cells by Helicobacter Cytotoxin are Acidic Organelles

1990 ◽  
Vol 48 (3) ◽  
pp. 168-169
Author(s):  
M. H. Chestnut ◽  
C. E. Catrenich
Keyword(s):  
Acridine Orange ◽  
Mammalian Cells ◽  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Ulcer Disease ◽  
Gastroduodenal Disease ◽  
H Pylori

Helicobacter pylori is a non-invasive, Gram-negative spiral bacterium first identified in 1983, and subsequently implicated in the pathogenesis of gastroduodenal disease including gastritis and peptic ulcer disease. Cytotoxic activity, manifested by intracytoplasmic vacuolation of mammalian cells in vitro, was identified in 55% of H. pylori strains examined. The vacuoles increase in number and size during extended incubation, resulting in vacuolar and cellular degeneration after 24 h to 48 h. Vacuolation of gastric epithelial cells is also observed in vivo during infection by H. pylori. A high molecular weight, heat labile protein is believed to be responsible for vacuolation and to significantly contribute to the development of gastroduodenal disease in humans. The mechanism by which the cytotoxin exerts its effect is unknown, as is the intracellular origin of the vacuolar membrane and contents. Acridine orange is a membrane-permeant weak base that initially accumulates in low-pH compartments. We have used acridine orange accumulation in conjunction with confocal laser scanning microscopy of toxin-treated cells to begin probing the nature and origin of these vacuoles.

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