scholarly journals Effect of Streptococcus mutans on surface-topography, microhardness, and mechanical properties of contemporary resin composites

2021 ◽  
Vol 19 ◽  
pp. 228080002110652
Author(s):  
América Monserrat Rios-Madrigal ◽  
Dulce Carolina Orea-Vega ◽  
Marina Vega-González ◽  
León Francisco Espinosa-Cristóbal ◽  
Ma. Concepción Arenas-Arrocena ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Streptococcus Mutans ◽  
Culture Media ◽  
Oral Bacteria ◽  
Resin Composites ◽  
Flexure Strength ◽  
Prevalent Disease ◽  
Diametral Tensile Strength ◽  
Scanning Electron ◽  
Surface Changes

Objective: Dental caries is the most prevalent disease globally, and Streptococcus mutans ( S. mutans) is a common associated oral bacteria. Additionally, S. mutans possess esterase activity capable of degrading resin composites (RC). However, the effect of degradation on the physical-mechanical properties of the RC has not been extensively studied. We evaluated the flexure strength (FS), the diametral tensile strength (DTS), the modulus of elasticity (ME), and the microhardness of three contemporary RC to establish if S. mutans could affect them. Methods: One hundred thirty-eight bar-shaped and 276 disc-shaped specimens were fabricated with Enamel Plus HRi, IPS Empress Direct, and Clearfil AP-X, and physical-mechanical testing was done after been incubated during 30 and 60 days in culture media with or without S. mutans. Also, a scanning electron microscope was used to identify surface changes. Results: None of the tested RC were affected in their mechanical properties (FS, ME, and DTS). However, Clearfil AP-X and Enamel Plus HRI showed eroded surfaces and a decreased microhardness after 30 and 60 days S. mutans incubation. IPS Empress Direct presented the lowest values in all the tests, but its physical-mechanical features and surface were not affected by bacteria’s exposure. Conclusions: Exposure to S. mutans could affect some contemporary RC; however, the effect seems superficial since its mechanical features were not affected.

scholarly journals Evaluation of the Degree of Conversion, Residual Monomers and Mechanical Properties of Some Light-Cured Dental Resin Composites

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2109 ◽  
Author(s):  
Marioara Moldovan ◽  
Robert Balazsi ◽  
Andrada Soanca ◽  
Alexandra Roman ◽  
Codruta Sarosi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Properties ◽  
Degree Of Conversion ◽  
Resin Composites ◽  
Mechanical Parameters ◽  
Dental Resin ◽  
Posterior Teeth ◽  
Commercial Resin ◽  
Diametral Tensile Strength

The novelty of this study consists in the formulation and characterization of three experimental dental composites (PM, P14M, P2S) for cervical dental lesion restoration compared to the commercial composites Enamel plus HRi® - En (Micerium S.p.A, Avengo, Ge, Italy), G-ænial Anterior® - Ge, (GC Europe N.V., Leuven, Belgium), Charisma® - Ch (Heraeus Kulzer, Berkshire, UK). The physio-chemical properties were studied, like the degree of conversion and the residual monomers in cured samples using FTIR-ATR (attenuated total reflectance) and HPLC-UV (ultraviolet detection), as well as the evaluation of the mechanical properties of the materials. The null hypothesis was that there would be no differences between experimental and commercial resin composites regarding the evaluated parameters. Statistical analysis revealed that water and saliva storage induced significant modifications of all mechanical parameters after three months for all tested materials, except for a few comparisons for each type of material. Storage medium seemed not to alter the values of mechanical parameters in comparison with the initial ones for: diametral tensile strength (DTS-saliva for Ge and PM, compressive strength (CS)-water for Ch, DTS-water and Young’s modulus YM-saliva for P14M and YM-water/ saliva for P2S (p > 0.05). Two of the experimental materials showed less than 1% residual monomers, which sustains good polymerization efficiency. Experimental resin composites have good mechanical properties, which makes them recommendable for the successful use in load-bearing surfaces of posterior teeth.

Latex Spheres as Immunologic Markers to Demonstrate the Binding of Human Salivary Immunoglobulins to Streptococcus mutans

1976 ◽  
Vol 55 (5) ◽  
pp. 879-885 ◽  
Author(s):  
G.R. Riviere ◽  
W.R. Cotton ◽  
J.L. Derkowski
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Streptococcus Mutans ◽  
Bacterial Cell ◽  
Oral Bacteria ◽  
Scanning Electron Microscopy Technique ◽  
Microscopy Technique ◽  
Immunologic Markers ◽  
Latex Beads ◽  
Scanning Electron

A scanning electron microscopy technique is described that uses latex beads as immunologic markers for detecting the interaction of salivary antibody with Streptococcus mutans. A Labeling Index (beads per bacterial cell) demonstrated that human salivary antibodies bound at a significantly greater degree to S mutans than to non oral bacteria.

Influence of Ketones on Selected Mechanical Properties of Resin Composites

1992 ◽  
Vol 71 (11) ◽  
pp. 1847-1850 ◽  
Author(s):  
A. Peutzfeldt ◽  
E. Asmussen
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Flexural Strength ◽  
Modulus Of Elasticity ◽  
Cross Linking ◽  
Resin Composites ◽  
Light Curing ◽  
Resistance To Wear ◽  
Modulus Of Resilience ◽  
Diametral Tensile Strength

The present study investigated a concept for additional crosslinking of dental polymers, by which resistance to wear of resin composites might be increased. Bifunctional ketones were added to monomer mixtures, which were then made light-curing and loaded with filler. The monomer mixtures were varied with respect to type and ratio of monomer and ketone. For measurement of possible effects of the cross-linking agents added, four mechanical properties of the experimental resin composites were determined. Addition of the bifunctional ketone diacetyl resulted in the following increases in mechanical properties: diametral tensile strength, 11%; flexural strength, 29%; modulus of elasticity, 19%; and modulus of resilience, 50%.

scholarly journals The Effect of Fiber Length on Tensile Properties of Polyester Resin Composites Reinforced by the Fibers of Sansevieria trifasciata

2014 ◽  
Vol 8 ◽  
pp. 7-13 ◽  
Author(s):  
Palla Hari Sankar ◽  
Y.V. Mohana Reddy ◽  
K. Hemachandra Reddy ◽  
M. Ashok Kumar ◽  
A. Ramesh
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Tensile Properties ◽  
Tensile Testing ◽  
Fiber Length ◽  
Polyester Resin ◽  
Resin Composites ◽  
Elongation At Break ◽  
Polyester Composites ◽  
Scanning Electron

This paper presents the study of the tensile properties of Sansevieria trifasciata – fiber (here after called STF) reinforced polyester composites. The composite sample was fabricated with five different fiber lengths of STF (2, 4, 6, 8 and 10 mm). The fabrication was made by hand lay-up technique. Mechanical properties were determined using tensile testing. An interact between fiber and matrix was observed from the SEM (scanning electron microscope) micrographs. The study reveals that the tensile strength increased with fiber length without effecting the elongation at break of the composite.

scholarly journals Comparison of growth of viable oral bacteria and Streptococcus mutans in biofilm models using three different culture media

2015 ◽  
Vol 9 (6) ◽  
pp. 388-393 ◽  
Author(s):  
L Peralta Sonia ◽  
B de Leles Savio ◽  
L Dutra Andre ◽  
R Cocco Alexandra ◽  
T B Radaelli Manuel ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Culture Media ◽  
Oral Bacteria

Electron Microscopic Observation of the Longitudinal Organization of Poly (p-Phenylene Terephthalamide) Fibers

1982 ◽  
Vol 40 ◽  
pp. 680-681
Author(s):  
Li Li-Sheng ◽  
L.F. Allard ◽  
W.C. Bigelow
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Microscopic Observation ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Aromatic Polyamides ◽  
Radial Arrangement ◽  
Scanning Electron ◽  
Better Than

The aromatic polyamides form a class of fibers having mechanical properties which are much better than those of aliphatic polyamides. Currently, the accepted morphology of these fibers as proposed by M.G. Dobb, et al. is a radial arrangement of pleated sheets, with the plane of the pleats parallel to the axis of the fiber. We have recently obtained evidence which supports a different morphology of this type of fiber, using ultramicrotomy and ion-thinning techniques to prepare specimens for transmission and scanning electron microscopy.

Forensic Identifications Aided by Scanning Electron Microscopy of Silicone-Epoxy Microreplicas of Calcified and Cornified Structures

1975 ◽  
Vol 33 ◽  
pp. 678-679 ◽  
Author(s):  
R.F. Sognnaes
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Forensic Science ◽  
George Washington ◽  
Epithelial Surface ◽  
Extended Application ◽  
Tissue Surfaces ◽  
Non Destructive ◽  
Scanning Electron ◽  
Surface Changes

Sufficient experience has been gained during the past five years to suggest an extended application of microreplication and scanning electron microscopy to problems of forensic science. The author's research was originally initiated with a view to develop a non-destructive method for identification of materials that went into objects of art, notably ivory and ivories. This was followed by a very specific application to the identification and duplication of the kinds of materials from animal teeth and tusks which two centuries ago went into the fabrication of the ivory dentures of George Washington. Subsequently it became apparent that a similar method of microreplication and SEM examination offered promise for a whole series of problems pertinent to art, technology and science. Furthermore, what began primarily as an application to solid substances has turned out to be similarly applicable to soft tissue surfaces such as mucous membranes and skin, even in cases of acute, chronic and precancerous epithelial surface changes, and to post-mortem identification of specific structures pertinent to forensic science.

scholarly journals Analysis of PLA Composite Filaments Reinforced with Lignin and Polymerised-Lignin-Treated NFC

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2174
Author(s):  
Diana Gregor-Svetec ◽  
Mirjam Leskovšek ◽  
Blaž Leskovar ◽  
Urška Stanković Elesini ◽  
Urška Vrabič-Brodnjak
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Tensile Strength ◽  
Glassy State ◽  
Nanofibrillated Cellulose ◽  
Dynamic Mechanical Properties ◽  
Initial Modulus ◽  
Surface Modified ◽  
Scanning Electron

Polylactic acid (PLA) is one of the most suitable materials for 3D printing. Blending with nanoparticles improves some of its properties, broadening its application possibilities. The article presents a study of composite PLA matrix filaments with added unmodified and lignin/polymerised lignin surface-modified nanofibrillated cellulose (NFC). The influence of untreated and surface-modified NFC on morphological, mechanical, technological, infrared spectroscopic, and dynamic mechanical properties was evaluated for different groups of samples. As determined by the stereo and scanning electron microscopy, the unmodified and surface-modified NFCs with lignin and polymerised lignin were present in the form of plate-shaped agglomerates. The addition of NFC slightly reduced the filaments’ tensile strength, stretchability, and ability to absorb energy, while in contrast, the initial modulus slightly improved. By adding NFC to the PLA matrix, the bending storage modulus (E’) decreased slightly at lower temperatures, especially in the PLA samples with 3 wt% and 5 wt% NFC. When NFC was modified with lignin and polymerised lignin, an increase in E’ was noticed, especially in the glassy state.

scholarly journals Effects of Various Types of Expandable Graphite and Blackcurrant Pomace on the Properties of Viscoelastic Polyurethane Foams

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1801
Author(s):  
Rafał Oliwa ◽  
Joanna Ryszkowska ◽  
Mariusz Oleksy ◽  
Monika Auguścik-Królikowska ◽  
Małgorzata Gzik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Structure ◽  
Oxygen Index ◽  
Polyurethane Foams ◽  
Expandable Graphite ◽  
Ftir Analysis ◽  
Limiting Oxygen Index ◽  
Peak Heat Release Rate ◽  
Physical And Chemical ◽  
Scanning Electron

We investigated the effect of the type and amount of expandable graphite (EG) and blackcurrant pomace (BCP) on the flammability, thermal stability, mechanical properties, physical, and chemical structure of viscoelastic polyurethane foams (VEF). For this purpose, the polyurethane foams containing EG, BCP, and EG with BCP were obtained. The content of EG varied in the range of 3–15 per hundred polyols (php), while the BCP content was 30 php. Based on the obtained results, it was found that the additional introduction of BCPs into EG-containing composites allows for an additive effect in improving the functional properties of viscoelastic polyurethane foams. As a result, the composite containing 30 php of BCP and 15 php of EG with the largest particle size and expanded volume shows the largest change in the studied parameters (hardness (H) = 2.65 kPa (+16.2%), limiting oxygen index (LOI) = 26% (+44.4%), and peak heat release rate (pHRR) = 15.5 kW/m2 (−87.4%)). In addition, this composite was characterized by the highest char yield (m600 = 17.9% (+44.1%)). In turn, the change in mechanical properties is related to a change in the physical and chemical structure of the foams as indicated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis.

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