Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study examined the relationship between resin and dentin both in vitro and in vivo using phosphoric acid conditioning. Four groups of 10 teeth each had standardized Class V preparations made with the gingival cavosurface margin in the root. In Group 1, involving freshly extracted teeth, the enamel and dentin was conditioned with 37% phosphoric acid gel for 15 seconds. NTG-GMA/PMDM was applied to the enamel and dentin followed by an application of BIS-GMA/HEMA and restoration with P50. Group 2 served as a control omitting the conditioning step. Groups 3 and 4 were treated similarly to Groups 1 and 2 except in vivo and extracted 2 weeks after restoration placement. All teeth were sectioned longitudinally through the restoration. Impressions were taken of the tissue/restoration interface and examined by SEM for disclosure of gaps. The teeth were then demineralized and the fitting surface of the restoration was examined by SEM for evidence of resin penetration into the tissue. The results showed a total absence of gaps both in vitro and in vivo after acid conditioning compared to the controls commonly showing gaps. Penetration of resin into the dentin to form a zone of diffusion or hybrid layer was observed only in the conditioned specimens. The phenomenon was observed both in vivo and in vitro. It was concluded that a significant potential exists for phosphoric acid conditioning of dentin to promote bonding.
 ...
PMID:Micromorphological relationship between resin and dentin in vivo and in vitro. 138 27

It is well known that the bond strength of direct bonding adhesive to etched enamel is dependent upon the formation of resin tags. So it is considered that there is a significant correlation between the bond strength and the length and shape of resin tags. However, there are very few reports on this correlation. In this study, a method of combining halogenated methacrylate and electron-probe microanalyzer (EPMA) was applied for measurement of resin tag length in order to investigate the correlation between the bond strength and resin tag length. Two experimental light cured adhesives were prepared for this study. One (CI-U) was prepared by blending microfiller (30 wt%) to the mixture of di (1-methacryloyl-oxyethyl-2-chloromethyl)-2,2,4-trimethylhexamethylene dicarbamate (50 wt%) and triethylene glycol dimethacrylate (TEGDMA: 59 wt%) and the other (Br-B) was prepared by blending microfiller (30 wt%) to the mixture of Bis-GMA (22.2 wt%), TEGDMA (65.9 wt%) and tetrabromobisphenol-A-glycidyl methacrylate (4Br-Bis GMA: 11.9 wt%). Preparation of 2%, 10%, 37%, and 60% phosphoric acid solutions, 2%, 5%, 10%, and 30% maleic acid solutions and 2%, 5%, 10%, and 30% citric acid solutions was carried out for use as etchants. The consistency and the bond strength to etched enamel for the adhesives and the amount of decalcification for the etchants were measured. The etched enamel surfaces, the resin tags on resin surfaces and the interfaces between the resin and enamel were observed with a SEM. The results were as follows: 1) The consistency of Cl-U was higher than that of Br-B. 2) The amount of decalcification was proportional to acid concentration, except for phosphoric acid solution. The amount of decalcification decreased in the order of citric acid solution, maleic acid solution and phosphoric acid solution when the concentration was 2% and 10%. 3) The SEM micrographs revealed that the enamel surface treated with the etchants containing a high concentration of acid was rougher. 4) The bond strength increased with increasing the concentration of the etchants except for the bond strength of Cl-U after being immersed in 37 degrees C water for 30 days and being thermal cycled. The bond strength for Cl-U was reduced greater than that of Br-B by long-term water immersion and thermal cycling.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:[Relationship between length of resin tag and bond strength of bonding adhesive]. 215 13

A new resin dentin adhesive consisting of a primer (phosphonate dimethacrylate) and bonding agent (phosphonated BIS-GMA) was evaluated with bond strength tests, marginal microleakage studies, and SEM examination. The mean bond strength to dentin was 15.6 +/- 3.7 MPa. Microleakage studies found no marginal leakage at the enamel cavosurface margin and very minimal microleakage at the dentin/cementum margins. SEM examination showed that the primer was very effective in modifying the smear layer.
 ...
PMID:Shear bond strength, microleakage and SEM study of the XR Bond adhesive system. 253 77

243 experimental Class V restorations using a chemically cured composite resin were inserted in human third molars with the conventional acid-etch restorative procedure and eight modifications of this technique. The teeth were extracted after 4 months and, following demineralization, the filings were examined in SEM concerning their enamel and dentin replica patterns on the inner cavity faced surface. Results showed a significant correlation between the enamel replica patterns and the marginal adaptation of the restorations while the dentin replica patterns did not influence the in vivo adaptation. Furthermore it was found that the improved adaptation obtained by low viscous resin applied as an intermediary layer in etched cavities is due to fewer porosities in the restorative material interface with enamel and dentin. Beveling of preparations prevents stress-induced fractures of unsupported enamel prisms along the cavity periphery. Treatment of etched cavities with the surface active comonomer NPG-GMA increases the general interfacial contact between resin restoratives and cavity walls, and surface coating of finished and re-etched restorations fills up spaces created along cavity margins during the filling and finishing procedure.
 ...
PMID:Replica patterns on composite restorations performed in vivo with different acid-etch restorative procedures. 389 44

29 experimental Class V restorations using a chemically cured composite resin were inserted in human third molars in cavities which after acid-etching had been treated with absolute ethanol. After extraction and demineralization of the teeth, the fillings were examined in SEM concerning their enamel and dentin replica patterns on the inner cavity-faced surface. The SEM findings were compared with previous findings concerning the replica patterns on fillings from acid-etched cavities and from cavities which after acid-etching had been treated with an ethanol solution of the surface active comonomer N-phenylglycine-glycidyl methacrylate (NPG-GMA). It was found that cavity treatment with absolute ethanol further improved the increased enamel replica patterns obtained with the NPG-GMA/ethanol comonomer solution while only the NPG-GMA/ethanol treatment improved the dentin replica patterns. Based on these results the effect of each of the two main components in the comonomer solution on replica patterns on resin restorations could be disclosed.
 ...
PMID:Effect of ethanol and NPG-GMA on replica patterns on composite restorations performed in vivo in acid-etched cavities. 389 45

In order to examine semi-thin section for light microscopy with the backscattered electron mode (BE mode), identical sites in tissue sections were comparatively observed with both light microscopy and BE mode. Tissue blocks (ca. 3 X 3 X 1 mm) were fixed in glutaraldehyde or combined formaldehyde-glutaraldehyde solution. After dehydration in alcohol, they were embedded in Kushida's GMA-Quetol 523. 1.0 micron sections on glass slides coated with indium oxide were stained with hematoxylin-eosin or toluidine blue or by the Giemsa method, and then treated with osmium tetroxide vapor or aqueous KMnO4 solution or uranyl acetate-lead citrate solution. The identical places of such sections could be examined with the accelerating potential of 6 kV and the probe current of 8 X 10(-10) A using a JSM-35C SEM with BEIS BE detector. Photographs were taken with the 2500-line resolution cathode ray tube and the time of exposure was 100 sec. The sections were placed at a distance of 5mm from the BE detector. BE images from osmium tetroxide vapor staining showed a distinctly improved contrast especially when the sections were previously stained with hematoxylin and eosin. The cellular structure was clearly demonstrated under the electron microscope in the BE mode. Identical sites in tissue samples could be compared exactly with both light and electron micrographs.
 ...
PMID:Observation on backscattered electron image (BEI) of a scanning electron microscope (SEM) in semi-thin sections prepared for light microscopy. 641 5

In this paper a technique is described, using Araldite CY 223 and hardener HY 2967 as injection material, for preparing corrosion casts or histological sections. The plastic has a viscosity (at 39-40 degrees C) similar to that of blood, a gelling time of approximately 17 min (at 40 degrees C), and an exothermic transition energy of delta H = 80.28 +/- 3.20 cal/gm. The influence of the plastic on the tissue is discussed. The histological sectioning of fixed tissue containing Araldite-filled blood vessels after embedding in 2-hydroxyethyl-methacrylate (GMA) is described. When using GMA in a modification of the mixtures of Ruddell (1967) and Sims (1974), methylbenzoate is recommended as an intermedium in order to obtain a more uniform infiltration and reproducible section thickness. At the same time methylbenzoate is recommended as a storing fluid. Sections of 2-3 micrometers afford satisfying morphologic and morphometric results. This method allows various arterial wall dimensions to be measured easily, and provides a suitable means to compare histometric values with SEM data derived from corrosion casts.
 ...
PMID:A new plastic for morphometric investigation of blood vessels, especially in large organs such as the human liver. 711 2

Recently, dentin bonding systems have been released separately from the resin composites, because the adhesive systems have been quickly improved. Since the merit of each material should be effectively utilized for each clinical case, the bonding systems and resin composites produced by different manufacturers may be combined according to the clinical purpose. The current restorative resins are basically categorized into two groups according to the main resin monomer, bis-GMA or UDMA resins. The purpose of this study was to evaluate the interchangeability between the bonding systems and resin composites, which were made by different manufacturers. Two bonding systems and five resin composites based on bis-GMA or UDMA were used in this study. The evaluation was performed by the tensile bond strength, fracture modes, and SEM observation, using the dentin surface of freshly-extracted bovine teeth. The highest bond strength (19.2 MPa) was shown by the combination of LBII sigma and AP-X. The bond strengths of nine other combinations were not statistically different (p > 0.05). There were many cohesive failures in dentin or resin composite, using all combinations. From the results, it was concluded that the interchangeability of the resin composites and bonding systems should be clinically acceptable.
 ...
PMID:[Interchangeability of resin composites and bonding agents based on bis-GMA or UDMA]. 1092 Dec 44

In dentistry, adhesion promotion with 3-methacryloyloxypropyltrimethoxysilane is usually sufficient, but its hydrolytic stability is a continuous concern. The hydrolytic stability of an alternative, 3-isocyanatopropyltriethoxysilane, was compared with that of conventional 3-methacryloyloxypropyltrimethoxysilane. Two silanes, both in 0.1 and 1.0 vol-% in ethanol-water, were evaluated in the attachment of an experimental bis-phenol-A-diglycidyldimethacrylate (Bis-GMA) resin to grit-blasted (with two different systems) titanium. Silane hydrolysis was monitored by FTIR spectrometry. Bis-GMA resin was applied and photo-polymerized on titanium. The specimens were thermocycled (6000 cycles, 5-55 degrees C). Surface analysis was carried out with scanning electron microscopy. Statistical analysis (ANOVA) showed that the highest shear bond was achieved with 0.1% 3-isocyanatopropyltriethoxysilane (12.5 MPa) with silica-coating, and the lowest with 1.0% 3-methacryloyloxypropyltrimethoxysilane (3.4 MPa) with alumina-coating. The silane, its concentration, and the grit-blasting method significantly affected the shear bond strength (p < 0.05). SEM images indicated cohesive failure of bonding, and, in conclusion, 3-isocyanatopropyltriethoxysilane is a potential coupling agent.
 ...
PMID:Isocyanato- and methacryloxysilanes promote Bis-GMA adhesion to titanium. 1579 Jul 44

Cibacron Blue F3GA was covalently attached onto monosize poly(glycidyl methacrylate) [poly(GMA)] beads for purification of lysozyme from chicken egg white. Monosize poly(GMA) beads, 1.6 microm in diameter, were produced by a dispersion polymerization technique. The content of epoxy groups on the surface of the poly(GMA) sample determined by the HCl-pyridine method (3.8 mmol/g). Cibacron Blue F3GA loading was 1.73 mmol/g. The monosize beads were characterized by elemental analysis, FTIR and SEM. Adsorption studies were performed under different conditions in a batch system (i.e., medium pH, protein concentration, temperature and ionic strength). Maximum lysozyme adsorption amount of poly(GMA) and poly(GMA)-Cibacron Blue F3GA beads were 1.6 and 591.7 mg/g, respectively. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium adsorption capacity and correlation coefficients. Results suggest that chemisorption processes could be the rate-limiting step in the adsorption process. It was observed that after 10 adsorption-elution cycle, poly(GMA)-Cibacron Blue F3GA beads can be used without significant loss in lysozyme adsorption capacity. Purification of lysozyme from egg-white was also investigated. Purification of lysozyme was monitored by determining the lysozyme activity using Micrococcus lysodeikticus as substrate. The purity of the eluted lysozyme was analyzed by SDS-PAGE and found to be 88% with recovery about 79%. The specific activity of the eluted lysozyme was high as 43,600 U/mg.
 ...
PMID:Monosize poly(glycidyl methacrylate) beads for dye-affinity purification of lysozyme. 1651 58


1 2 3 4 Next >>