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PubMed1990

Class II composite resin restorations: a three-year clinical study of six different posterior composites.

Class II restorations of five light-cured posterior composite materials (Occlusion, P 30, Fulfil, Profile and Heliomolar) were followed for three years, and restorations of another material (Distalite) were followed for two years. Twenty-four dentists from The Public Dental Health Service in the county of Bohuslän placed 242 Class II restorations in 213 patients. The restorations were evaluated after three years using the USPHS criteria. Stone casts were used to categorize quantitatively the amount of occlusal wear according to the Leinfelder method. No differences could be found between the different materials regarding clinical properties. The failure rate (USPHS ratings Charlie) was low, 6.5 per cent. The average occlusal wear after three years for most of the materials was about 100 micrometers. Heliomolar showed a better resistance to wear compared with the other materials.

Acid Etching, Dental↗

PubMed1989

[Optical and scanning electron microscope study of gingival microleakage in Class II composite restorations].

It has been studied the gingival microleakage and the polymerization contraction gap in composites class II restorations. The influence of two different composites, a microparticle [Heliomolar (Vivadent)] and a high filled one [P-50 (3M)], has been compared with different adhesion systems: a) gingival enamel acid-etch technique. b) Dentinal adhesives [Gluma (Bayer) and Scotchbond 2 (3M)]. c) A adhesive varnish [Dentin Protector (Vivadent)]. The gingival microleakage is only prevented when a microparticle composite [Heliomolar (Vivadent)] and a adhesive varnish [Dentin Protector (Vivadent)] are used together.

Acid Etching, Dental↗

PubMed1987

Thermal degradation products from an ethylene methacrylic acid copolymer-partial metal salt as the cause of industrial bronchitis.

A self-employed physician developed industrial bronchitis due to the inhalation of fumes arising from the heating of a molded ethylene methacrylic acid copolymer-partial metal salt (Surlyn) in the basement of his home. Symptoms resolved following removal from exposure. A number of known irritants are given off as degradation products of Surlyn ionomer resin, including acrolein, aldehydes, and methacrylic acid. This case is unusual because of the nature of exposure and an unexpected fall in forced expiratory volume in 1 second after provocation testing.

Anesthesiology↗

PubMed1998

Adhesion between collagen depleted dentin and dentin adhesives.

PURPOSE: To determine the influence of sodium hypochlorite treatment of dentin on shear bond strength and morphology. MATERIALS AND METHODS: Shear bond strengths of several dentin bonding agents were compared following specific surface treatments that included manufacturer's directions, etching plus sodium hypochlorite, and sodium hypochlorite alone. The treated surfaces and interfaces between bonding materials and treated surfaces were observed using an FE-SEM. RESULTS: Acetone-containing systems yielded equivalent or higher shear bond strengths when sodium hypochlorite was used following etching, as compared with normal procedures. In these cases it is proposed that the adhesive interacts strongly with the treated surface, that contains a high mineral content.

Acetone↗

PubMed2005

Preparation and evaluation of poly(polyethylene glycol methyl ether acrylate-co-polyethylene glycol diacrylate) monolith for protein analysis.

A poly(polyethylene glycol methyl ether acrylate-co-polyethylene glycol diacrylate) monolith was prepared by UV-initiated polymerization. Methanol and ethyl ether were selected as porogens from a variety of organic solvents to achieve the desirable characteristics of the monolith. The preparation of the monolith could be achieved within 10 min. The monolith was macroscopically homogeneous, had low flow resistance, and did not swell or shrink significantly in tetrahydrofuran. Inverse size-exclusion data indicate that the monolith had a total porosity of 75.4% and an internal porosity of 9.1%. The monolith could be used for size-exclusion separation of peptides, although it could not separate proteins with molecular masses between 10 and 100 K due to its unique pore size distribution. It was found to resist adsorption of proteins in capillary liquid chromatography when using 100 mM phosphate buffer (pH 7.0) containing 0.5 M NaCl. Complete recovery of both acidic and basic proteins was achieved. The monolith can be used for applications in which inert materials are required for protein analysis.

Acrylates↗

PubMed2003

Studies in formulation and pharmacotechnical evaluation of controlled release transdermal delivery system of bupropion.

The objective of the present study was to design and evaluate unilaminate transdermal adhesive matrix systems capable of diffusing bupropion base at a constant rate over an extended period of time as an alternative route of administration. Unilaminate transdermal adhesive matrices have been fabricated with different concentrations of Eudragit E as the adhesive and rate-controlling polymer. The in vitro release and epidermal flux through human cadaver skin were studied. The release of drug from the matrices obeyed zero order release kinetics (r2 = 0.9810 to 0.9960). The delivery rate of bupropion ranged from 10.5 mg to 31.4 mg per day from a 3.14 cm2 area of matrix. The relation between concentration of bupropion base in matrix and epidermal flux, concentration of drug in matrix, and epidermal adsorption of bupropion during diffusion follow hyperbolic fashion. Triethylcitrate (TEC) and dibutylphthalate (DBP) have no influence on the diffusion of bupropion through human cadaver skin when used as plasticizers. Incorporation of succinic acid in the adhesive matrix retarded diffusion due to the formation of rigid cross linking of the polymer, while propylene glycol and myristic acid, alone or in combination, significantly enhanced the flux of bupropion through human cadaver skin.

Adhesives↗

PubMed2001

Improved performance of a chitosan-based adsorbent for the sequestration of some transition metals.

Polyethyleneimine (PEI) was chemically introduced onto chitosan by its reaction with epoxide groups of grafted poly(glycidyl methacrylate) (poly(GMA)) chains for enhanced metal chelating properties and improved physical stability in acidic conditions. Graft polymerization of poly(GMA) onto chitosan was initiated by Ce(IV) ammonium nitrate (CAN). Infrared spectroscopy revealed the presence of significant epoxide groups to confirm the success of both grafting and amination stages. Batch adsorption experiments showed the higher affinity of the modified chitosan resin for Cu2+, Zn2+ and Pb2+. The capacity enhancement was even more pronounced in the case of Zn2+ and Pb2+, which exhibits more complicated three dimensional coordination requirements. Optimum metal adsorption occurs at above pH4. Regeneration of the resin with sulphuric acid-ammonium sulphate was also found to be feasible.

Adsorption↗

PubMed2000

Use of fluoride-containing sealant on proximal surfaces.

A visible light curing sealant was developed for the prevention of caries on the smooth surfaces especially on the proximal surfaces. The sealant is mainly composed of dimethacrylate monomers. It contains a total amount of 2.28 mass% fluoride as poly(methyl methacrylate-co-methacryloyl fluoride) and sodium fluoride. The fluoride-containing sealant could be successfully applied to the proximal surfaces between the first and second primary molars by making access to the interproximal space with an orthodontic separating module. Availability of fluoride was assessed by the concentration of fluoride released into 1 ml of distilled water as a function of time from disks 5 mm in diameter and 0.2 mm in thickness. Ten microg of fluoride was measured on the first day; after 3 days the rate remained fairly constant at about 1 pg/day for a period of 28 days. The fluoride uptake and the improved acid solubility were investigated in vitro using bovine incisors. The fluoride of the control, that is enamel without sealant treatment, was not detectable. The fluoride incorporated into enamel after 37 hours application was 2,100 ppm at 2 pm from the enamel surface. The enamel solubility to acids decreased by the fluoride incorporation.

Animals↗

PubMed1989

Fat intestinal absorption in the catfish--a histochemical study in glycol methacrylate embedded tissue.

The intestinal absorption of lipids was investigated in plastic sections from glycol methacrylate embedded intestine after fat administration. In the catfish, the lipids are absorbed by the enterocytes of the proximal intestinal segment, thus forming fat cytoplasmic inclusions that were demonstrated by Sudan black B staining. The histochemical characterization of lipids by the Nile blue sulphate test revealed the neutral or triglyceride nature of the cytoplasmic droplets, both after the corn oil and oleic acid feeding. There is lipid accumulation in the lamina propria and lymphatic vessels.

Animals↗

PubMed1979

Purification of soluble immune complexes from serum using polymethylmetacrylate beads coated with conglutinin or C1q. Application to the analysis of the components of in vitro formed immune complexes and of immune complexes occurring in vivo during leishmaniasis.

A procedure for the isolation of immune complexes from human sera has been developed. Two steps are involved: (1) lipid-free serum is precipitated by polyethylene glycol; (2) the solubilized precipitate is absorbed on a column of polymethylmethacrylate beads coated with conglutinin (K) or C1q; the column is washed, the complexes are then eluted, using 0.02 M EDTA (for K column) or 0.5 M NaCl (for C1q column). This procedure permitted the purification and the characterization of soluble 125I-BSA-anti-BSA, 125 I-tetanus toxoid-anti-tetanus toxoid, and 125-I-HBsAg-anti-HBsAg complexes made in vitro in the presence of fresh human serum. The isolated complexes were shown to contain antigen, antibody, C1q, C1r, C1s and C3. When normal human serum was submitted to such a procedure, no detectable amount of protein was present in the final eluted fraction. Immune complexes formed in vivo were also purified by conglutinin column from the serum of a patient with disseminated leishmaniasis. The isolated material was found to contain IgM, IgG, C1q, C1r, C1s, C3c and C3d. The purified complexes dissociated at acid pH were found to contain anti-IgG and anti-leishmania antibodies.

Adult↗

PubMed2000

Effect of a sodium hypochlorite gel on dentin bonding.

UNLABELLED: It has been suggested that the hybrid layer (HL) does not play any important role in the mechanism of adhesion to dentin. To substantiate this hypothetical insignificance of the HL, sodium hypochlorite (NaOCl) has been used to remove collagen from etched dentin prior to bonding. OBJECTIVES: The present study was conducted to determine the effect of a commercial 10% NaOCl gel on the dentin shear bond strengths and HL ultra-morphology of two simplified dentin adhesives. The null hypothesis tested was that treatment of etched dentin collagen with NaOCl would not compromise dentin bonding. METHODS: The labial surface of eighty bovine incisors was polished to expose middle dentin. The specimens were randomly assigned to two total-etch adhesive systems (N = 40): Prime&Bond NT (Dentsply Caulk); and Single Bond (3M Dental Products Division). After rinsing off the etchant, one drop of 10% NaOCl (AD Gel, Kuraray Ltd.) was applied to the etched dentin surface and left for 0 (control), 15, 30, or 60 s. The gel was rinsed off with water and the dentin surface kept visibly moist prior to the application of the adhesive as per manufacturer's instructions. The respective composite resin was subsequently applied and light-cured. After 24 h in water at 37 degrees C, the specimens were thermocycled for 500 cycles in baths kept at 5 and 55 degrees C and the shear bond strengths measured. The data were analyzed with two-way ANOVA. For TEM, sixteen dentin disks were taken from middle dentin of extracted human third molars, assigned to the eight treatment sequences, and observed. RESULTS: The increase in the NaOCl application time resulted in a progressive decrease in shear bond strengths for both dentin adhesives. For Single Bond, the application of AD Gel for 60 s resulted in a reduction of bond strengths to 38% of that obtained for the control. For Prime&Bond NT, the mean bond strength obtained when AD Gel was applied for 60 s was 31% of that obtained for the control. The application of AD Gel resulted in distinct morphology for each one of the two adhesives tested. For Single Bond, the general morphology of the collagen network was maintained, regardless of the deproteinization time. The interfibrillar space within the collagen network increased with increasing deproteinization times. For Prime&Bond NT, the general appearance of the HL was maintained for deproteinization times of 15 and 30 s. When the NaOCl gel was applied for 60 s, the morphological appearance of the HL lost its fibrillar arrangement. While remnants of the collagen fibers were observed in one of the dentin disks, the other specimen showed an amorphous structure without any discernible HL morphological features. SIGNIFICANCE: The integrity of the collagen fibrils left exposed upon acid-etching plays a major role in the mechanism of adhesion of the specific adhesive systems tested in this study. The intermingling of the adhesive monomers with the filigree of collagen fibers or HL should still be considered the paramount dentin bonding mechanism.

Acid Etching, Dental↗

PubMed2002

Effect of surface conditioning and restorative material on the shear bond strength and resin-dentin interface of a new one-bottle nanofilled adhesive.

OBJECTIVES: To determine the effect of different combinations of surface conditioning (DeTrey Conditioner 36, NRC, no etching) and restorative materials (Dyract AP, Spectrum TPH) on the shear bond strength of Prime and Bond NT to enamel and dentin, and to characterize the resin-dentin interface produced by these combinations. METHODS: Shear bond strength was tested on 30 enamel and 30 dentin flat labial surfaces of extracted bovine teeth. The enamel and dentin specimens were randomly assigned to six groups of five teeth each and treated using different combinations of surface conditioners and restorative materials with Prime and Bond NT. Scanning electron microscope (SEM) observation of argon-ion-etched specimens was done to evaluate the resin-dentin interface. RESULTS: The type of surface conditioning and restorative material had significant effects on dentin bond strengths. Etching the dentin prior to application of Prime and Bond NT significantly increased bond strength and caused formation of a hybrid layer for Spectrum TPH. For Dyract AP, dentin etching generally did not improve bond strength despite the formation of a hybrid layer. On enamel, Prime and Bond NT had consistently high bond strengths on etched specimens. SIGNIFICANCE: The results showed that Dyract AP and Spectrum TPH, when used with Prime and Bond NT have different bonding mechanisms and the effect of surface conditioning on their shear bond strength differs. Clinicians should be aware of these effects in order to optimize bonding.

Acid Etching, Dental↗

PubMed2000

The nanoleakage phenomenon: influence of different dentin bonding agents, thermocycling and etching time.

"Nanoleakage" takes place within the hybrid layer zone of the dentin-composite interface in spaces not occupied by polymerized resin. The purpose of this study was to quantify the amount of nanoleakage in specimens treated with one of six different bonding agents. For one agent, different etching times were used, and for two agents results after thermocycling were obtained. Standardized class V cavities were prepared in 165 extracted human molars with cervical margins located in dentin. After placement of the composite using bonding agents, the teeth were stored in a 1% rhodamin-B-isothiocyanate solution for 24 h at 20 degrees C, embedded in methacrylate, and sectioned parallel to the long axis of the tooth. A confocal laser scanning microscope was used to visualize a layer 10 microm below the prepared surface of the section. The lengths of the penetrated pathways were measured, representing the amount of nanoleakage. In all materials tested, penetration pathways appeared within the hybrid layer in absence of gap formation. Penetration lengths of the tested materials were in a range from 69 +/- 24 microm to 469 +/- 333 microm. Thermocycling had no statistically significant influence, and etching for 15 s resulted in statistically significantly shorter penetration compared to longer etching.

Acid Etching, Dental↗

PubMed1984

The initial gap around large composite restorations in vitro: the effect of etching enamel walls.

Composite resin restorations in cavities are generally associated with the development of a contraction gap during the first minutes after insertion. Enamel-Bond-Concise composite restoration were placed on both approximal sides of extracted pre-molars. The cervical walls of all cavities extended beyond the enamel-cement junction. The enamel walls of one of the cavities in each tooth were acid-etched. The contraction gap was kept air-filled and open at the margin through the use of a special technique. Enamel Bond resin with a fluorescent additive was applied to occlusal and cervical margins of the restorations. The fluorescent resin was "passively" drawn into the gap. In unetched cavities, resin penetrated both cervical and occlusal gaps and some areas of the gap at the axial wall. In cavities with etched enamel, the penetration occurred only at the cervical wall. The distance of penetration from the cervical margin varied from 1 to 6.5 mm, and the width of the contraction gap filled with the fluorescent resin varied from 3.5 to 16 micron. Comparison of the width of the gap at the cervical wall in etched and unetched cavities suggested larger gaps for etched cavities. The method used offers a new technique for the measurement of the contraction gaps around composite resin restorations.

Acid Etching, Dental↗

PubMed2005

Microtensile bond strength of total-etch and self-etch adhesives to the enamel walls of Class V cavities.

PURPOSE: To determine the difference in microtensile bond strengths (MTBS) of resin-based composite bonded to the enamel of cavity preparations using a conventional or a self-etching adhesive. METHODS: Buccal and lingual Class V cavities were prepared in each of 12 caries-free human molars. Six teeth were randomly selected to be restored with Spectrum TPH resin-based composite and Prime & Bond NT adhesive. The remaining six teeth were restored with the same composite and Prompt L-Pop self-etching adhesive. Enamel/composite sticks were cut from each specimen and subjected to microtensile bond testing. Each debonded specimen was evaluated by SEM to determine the mode of failure. RESULTS: The mean MTBS for Prime & Bond NT specimens was 15.2+/-13.1 MPa. The mean MTBS for Prompt L-Pop self-etching adhesive samples was 18.2+/-14.3 MPa. ANOVA demonstrated no statistically significant difference between the mean MTBS associated with the two adhesives (P> 0.05). The results of SEM analysis revealed that the bonding failures occurred primarily at the interface between the adhesive and the enamel, suggesting a primarily adhesive failure.

Acid Etching, Dental↗

PubMed1988

Experimental implantation of hydrogel into the bone.

The present study deals with the application and possibilities of insoluble hydrophilic gels (poly(2-hydroxyethyl methacrylate] as substitutes of bone tissue experimentally. Their biocompatibility is examined with regard to the porous qualities of the implant and to its chemical structure, and their behavior in the cancellous and compact bone is evaluated. It was found that the modifications of hydrogels used in the experiment are biocompatible, with the compatibility increasing in proportion to increasing porosity. The nonporous and microporous hydrogels are not compatible and are demarcated. The sintered macroporous gel is surrounded by a thin fibrin membrane. By adding methacrylic acid to the hydrogel surface, adhesion increases markedly. Marked destruction also appears in the polymer especially in the cancellous bone. By an active destruction of the polymer, no direct phagocytosis can be proved. Upon breakdown of the implant in the compact bone the activity of the macrophages is delayed. When the gel without methacrylic acid is used alone, destruction does not occur even after 193 days. When methacrylic acid is added to the polymer surface, destruction does occur and the implant is filled only by bone trabeculae.

Animals↗

PubMed1990

Histo-pathological study of pulp response to a composite resin restoration with two lining materials.

This histopathological study investigated the pulp reaction to a restoration system employing a posterior composite resin with or without the pulp protection of visible light curing calcium hydroxide composition and alpha-TCP cement lining to dentin. Black's class V cavities were prepared in 120 adult dog teeth. They were then extracted for histological examination. As a result of this study, their lining materials were found to be effective in pulp protection. To understand the pathological finding, the pH values of "Fulfil", "Universal bond", "VLC Dycal" and "Vitacemen Type II" were measured. The pH levels of "Fulfil" and "Universal Bond" were mildly acidic (4.79-5.18) before polymerization, with no subsequent changes. "VLC Dycal" was initially a strongly alkaline (11.75) and remained this condition. "Vitacemen Type II" was initially acidic (3.78), but eventually reached the milder acidity of 5.12 after 24 hours.

Adhesives↗

PubMed1977

Surface-modified acrylic polymers in artificial heart pumps.

Blood chambers of counterpulsation heart pumps were subjected to a special hydrophilization process in order to reduce the coagulation activity of the surface of poly(methyl methacrylate) (PMMA). The chemical treatment of the surface was carried out in three variants, namely A (ethylenglycol), B (diethylenglycol), C (glycerine) by using concentrated sulphuric acid with subsequent neutralization [12]. Controls were performed with the same pumps made of PMMA but without surface treatment. 30 dogs were used in the experiments.

Acrylic Resins↗