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At least 973 records · Page 54Linked to original sources
PubMed2004

Effect of two different restorative techniques using resin-based composites on microleakage.

PURPOSE: To evaluate in vitro the extent of microleakage of Class II cavities restored with two different brands of resin-based composite, one hybrid (Tetric Ceram) and the other "packable" (Surefil) taking into account two variables: the localization of the margins and the insertion technique. METHODS: 100 bovine teeth, recently extracted, had standardized Class II slot cavities prepared on the mesial and distal surfaces with the gingival floor located on enamel or dentin, for a total 200 cavities. The teeth were randomly divided into eight groups of 25 teeth each (25 restorations in each group): (1) margin on dentin, restored with Surefil, bulk insertion; (2) margin on dentin, restored with Tetric Ceram, bulk insertion; (3) Margin on enamel, restored with Surefil, incremental technique; (4) margin on enamel, restored with Tetric Ceram, incremental technique; (5) margin on enamel, restored with Surefil, bulk insertion; (6) margin on enamel, restored with Tetric Ceram, bulk insertion; (7) margin on dentin, restored with Surefil, incremental technique; (8) margin on dentin, restored with Tetric Ceram, incremental technique. After this procedure, the teeth were subjected to 1000 thermocycles, stained with 2% methylene blue solution, and then sectioned in the mesiodistal direction. Dye penetration at tooth/restoration interface was scored based upon the extent of the dye using a light stereoscope x 35. RESULTS: All groups showed considerable levels of microleakage at both dentin and enamel margins (P < 0.05). Restorations with margins in enamel using the hybrid resin-based composite with the incremental technique did not show statistically significant differences when compared to bulk placement. However, restorations with hybrid resin-based composite have significantly less microleakage than either bulk or incremental technique for the "packable" resin-based composite Surefil. As for the margins in dentin, Tetric Ceram in bulk placement did not differ from the incremental technique and Tetric in bulk placement had significantly less microleakage than Surefil either bulk or incremental technique. The hybrid resin-based composite with margins in dentin and incremental technique showed less microleakage than the "packable" resin in bulk placement. CLINICAL SIGNIFICANCE: The two types of resin-based composites, hybrid and "packable" were unable to completely prevent microleakage. The study demonstrated the difficulty in sealing a proximal margin.

Animals↗
PubMed2004

Zirconate coupling agent for bonding resin luting cement to pure zirconium.

PURPOSE: To evaluate the shear bond strengths of two dual-cured resin luting cements to pure zirconium and the effect of zirconate coupling agent on the bond strength. METHODS: The two different-shaped pure zirconium specimens (99.9%) were untreated or treated with one of the four primers including zirconate coupler and then cemented together with one of the two dual-cured resin luting cements. Half of the specimens were stored in water at 37 degrees C for 24 hours and the other half thermocycled 20,000 times before shear bond strength testing. RESULTS: Regardless of the resin luting cement and thermocycling, specimens treated with the mixture of zirconate coupler and resin bonding agent showed the highest shear bond strength among the five treatments. Surface treatment with the mixture of zirconate coupler and resin bonding agent showed significantly greater shear bond strength compared with other treatments at 20,000 thermocycles. The application by the mixture of zirconate coupler and resin bonding agent on the pure zirconium metal surface appears to be effective for bonding between zirconium and dual-cured resin luting cements.

Aluminum Silicates↗
PubMed2004

[Study on purification of total flavonoids from seed residue of Hippophae rhamnoides with macroporous resin].

OBJECTIVE: To study the conditions and parameters of purifying total flavonoids from seed residue of H. rhamnoides. METHOD: Absorption capacity of three resins for total flavonoids was compared. With the yield and purity as indexes, the process of absorbing and purifying total flavonoids from seed residue with D101 macroporous resin absorbent was selected by orthogonal design. RESULT: The D101 resin was the best of the three resins and its absorption capacity was determined to be 63.00 mg x g(-1) wet resin. The optimum process condition was 30% ethanol as eluting solvent, wet resin vs crude herbs: 2:1, diameter vs height: 1:10, eluting solvent vs crude herbs: 10:1, absorbing time for 3 h. The yield of total flavonoids from seeds residue of H. rhamnoides by this process was 2.39%, and the purity reached 64.81%. CONCLUSION: The process is simple and convenient and the regeneration of resin is easy. So this method of purification is advisable.

Ethanol↗
PubMed1992

Evaluation of CNBr, FMP and hydrazide resins for immunoaffinity purification of factor IX.

The American Red Cross has developed an immunoaffinity chromatography method to purify human coagulation Factor IX to high levels of purity for therapeutic treatment of hemophilia B. The resin currently used in this process is Sepharose CL2B, a cross-linked 2% agarose, which is activated with cyanogen bromide to immobilize an anti-Factor IX monoclonal antibody. This study evaluated two alternative resins and coupling chemistries, a synthetic polymer bead activated by 2-fluoro-1-methyl-pyridinium toluene 4-sulfonate (FMP) and a cross-linked 2% agarose bead with free hydrazide groups for site-specific coupling. The cyanogen bromide and FMP chemistries immobilize the monoclonal antibody in a random orientation. In hydrazide coupling, the monoclonal antibody is immobilized by the non-antigen-binding part of the molecule which, theoretically, should increase the amount of immobilized monoclonal antibody able to bind antigen. To examine this, the capacity of the resins to bind Factor IX and the purity and recovery of Factor IX eluted from the resins were measured. The FMP-activated resin exhibited the lowest capacity, binding only 2% of the Factor IX feed. Sepharose CL2B bound 87% of the loaded protein, while the hydrazide resin bound 43%. These results suggest that (a) hydrazide activation may be insufficient to orient monoclonal antibody and (b) other factors such as steric hindrances and diffusional resistances during immobilization may be important. Neither of the other resins tested demonstrated improved performance compared with cyanogen bromide-activated Sepharose CL2B for the immunoaffinity purification of Factor IX.

Antibodies, Monoclonal↗
PubMed1992

[The cytotoxic effects of composite resin adhesive agents on gingival cell culture using the agar coating method].

Because the luting agent interfaces of restorations can approximate the periodontium, it is critical to determine the biocompatibility of luting agents. In this study, the cytotoxic potential of resin luting agents on cultures of gingival fibroblasts was evaluated for direct microscopic cytotoxicity. For light cured composite resin luting agents, the exposure time was found to be significant. To compare the chemically and light cured resins, fully cured microfill resin's cytotoxicity was equal to the chemically cured resin's cytotoxicity. The least cytotoxic effect was occurred with hybrid type composite resin while the profound effect with unpolymerized microfill resin.

Adhesives↗
PubMed2006

[Biocompatibility test of polymethylmethacrylate denture base resin containing silver-supported antimicrobial agent STR-1 at nanometer level].

OBJECTIVE: To evaluate the biocompatibility of polymethylmethacrylate(PMMA) denture base resin containing silver-supported antimicrobial agent STR-1 of nanometer level in vitro. METHODS: According to the national standards for biological evaluation of dental materials, the cytotoxicity of denture base resin containing STR-1 at concentrations of 5 g/L and 10 g/L was examined by molecular filtrating method, and the hemolysis of STR-1, denture base resin containing STR-1 at concentrations of 5 g/L and 10 g/L was also surveyed. RESULTS: The control denture base resin without containing STR-1 and the denture base resins containing STR-1 at concentrations of 5 g/L and 10 g/L were not cytotoxic to L929 cells. Two hours and 24 hours after cell culturing, the filter membranes of the control and experimental groups were stained evenly with blue color. The staining intensity was not decreased and the fading areas were 0 mm2 during the culturing. The cytotoxicity grades were 0. The hemolysis rates of the antimicrobial agent STR-1 and the denture base resins containing STR-1 at concentrations of 5 g/L and 10 g/L were 1.7%, 3.5% and 3.7% respectively. They were less than the national guild standard 5% which represent no hemolysis. CONCLUSION: The PMMA denture base resins containing silver-supported antimicrobial agents STR-1 of nanometer level at concentrations of 5 g/L and 10 g/L exhibit good biocompatibility.

Animals↗
PubMed1990

[Study on visible-light curing soft resins consisting of fluoropolymers. 2. Effect of fluoroalkyl alpha-fluoroacrylate monomers].

New experimental visible-light cured soft resins were prepared by combining a vinylidene fluoride/hexafluoropropylene copolymer (2-6 F), or a vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer (2-4-6 F) with 2,2,3,3-tetrafluoropropyl alpha-fluoroacrylate (4 FFA), 2,2,3,3,3-pentafluoropropyl alpha-fluoroacrylate (5 FFA), 2,2,3,3,4,4,5,5-octafluoropentyl alpha-fluoroacrylate (8 FFA), or 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl alpha-fluoracrylate (12 FFA). Some properties of the resins prepared were measured to determine whether they would be candidate materials for the soft denture liner. Water contact angles increased with the increase in the number of fluorine atoms contained in the monomers: 85-90 degrees in 4 FFA, 90-93 degrees in 8 FFA, and 92-93 degrees in 12 FFA. Softer resins were obtained with 2-4-6 F, especially by the combination with 8 FFA giving the softest resin with a hardness of 43-46 (JIS A). Water sorption after 10 weeks was considerably low: 0.4-2%: 0.4-0.9% in 4 FFA/2-6 F and about 2% in 8 FFA/2-4-6 F. Solubility was 0.2-0.4% in the resins with 4 FFA and 1.0-1.4% with 8 FFA or 12 FFA. Amount of residual monomer was low, and the maximum was 0.4% in the resin with 12 FFA. Thus hardness and water sorption of the resins prepared were superior to those of the commercial soft materials.

Denture Liners↗
PubMed1990

[Relationship between length of resin tag and bond strength of bonding adhesive].

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)

Acid Etching, Dental↗
PubMed1990

Studies on posterior composite resins with special reference to class II restorations.

Longevity, clinical performance and some related factors of posterior composite resin restorations were investigated through clinical follow-up and laboratory studies in vivo and in vitro. Class I and Class II restorations using two experimental posterior composite resin materials were followed clinically for a four-year period. USPHS evaluation criteria were used. Assessments of wear were also made indirectly using the Leinfelder method. Marginal leakage of bacteria (in vivo) and of dye (in vitro) were studied on modified loaded Class II composite resin restorations lined with GlumaR and LifeR. The grade of conversion (cure) of the posterior composite resin material and the colonization of bacteria at proximal tooth surfaces restored with posterior composite resins were evaluated. Seven per cent of the restorations were evaluated as failures and had to be replaced during a 4-year period. The failures were mainly due to fractures and postoperative sensitivity. The calculated occlusal wear rate was 34-40 microns/year. Occlusal loading of Class II restorations in vitro resulted in a higher frequency of restorations with marginal leakage. The marginal leakage for occlusally-loaded Class II restorations in vivo and in vitro could be reduced if dentine bonding was utilized. The grade of conversion (cure) was increased in the in vivo situation compared to the in vitro. Bacterial colonization of strepococcus mutans on the proximal surfaces of posterior composite restorations showed higher frequencies compared to that on sound tooth surfaces. From the results of these studies, it may be concluded that the tested posterior composite resin materials can be used in Class I and II restorations with a good prognosis for at least 4 years. When posterior composite resins are used as restorative for posterior teeth, the following conditions should be considered: The occlusal loading should be minimal, dentin bonding should be used, the increased risk of colonization of streptococcus mutans should be acted on and regular clinical and radiographical follow-up should be performed.

Bacteria↗
PubMed1989

[Influence of thermal cycling on the adhesive strength of adhesive resin cement].

The purpose of this study was to examine the influences of thermal cycling on the adhesive strength of the adhesive resin cements. Four kinds of adhesive resin cements, which belonged to the commercial composite resin inlay products, were used for the study. They were CR Inlay Cement, Duo Cement, Dual Cement and P-30 diluted with Enamel Bond. The shear adhesive strengths to tooth substance and composite resin inlay were measured. Adhesive strength to etched enamel : CR Inlay Cement showed the highest values of 274 kg/cm2 after immersion in water at 37 degrees C for 24 hours and 230 kg/cm2 after 300 thermal cycles at 4 degrees C for 3 min and at 60 degrees C for 3 min. Adhesive strength to etched dentin : P-30 diluted with Enamel Bond showed the highest values of 64 kg/cm2 after 24-hour immersion in water, and 63 kg/cm2 after 300 thermal cycles. Adhesive strength to composite resin inlay : CR Inlay Cement showed the highest values of 310 kg/cm2 after 24-hour immersion in water, 306 kg/cm2 after 300 thermal cycles, and 297 kg/cm2 after 1000 thermal cycles. Adhesive resin cements other than CR Inlay Cement, showed a decrease in adhesive strengths to tooth substance and composite resin inlay after thermal cycling. Especially, Dual Cement and Duo Cement showed considerable decreases.

Adhesiveness↗
PubMed1989

[A comparative analysis of the characteristics of META-DENT denture resin system].

A newly developed denture resin based on a 4-META containing monomer became recently commercially available. It has been claimed that this resin system has the unique ability of creating bond to Cr-Co alloys without any mechanical retention. The objective of this study was to determine the chemical composition of the new resin, to study the bonding mechanism with a Cr-Co alloy and to compare its physical and mechanical properties to a commonly used acrylic denture resin. The analysis revealed that the new system contains 5% by weight 4-META in MMA liquid and 28% poly (ethyl methacrylate) in PMMA. No practical differences were noted in the stress-strain characteristics and hardness values between the resin systems. The META-DENT resin was more abrasion resistant. The bond of META-DENT to the Cr-Co alloy was greatly superior than that of the conventional resin. The bonding mechanism may be related to enhanced physical wetting due to reduced META-DENT viscosity and probably complexation of the anhydride groups with either Cr or Co.

Acrylic Resins↗
PubMed1988

Tensile bond strength of orthodontic resins on the human tooth surface.

Composite resin has been used in the field of orthodontics for more than twenty years. Although there have been many studies and discussions regarding the bond strength of orthodontic brackets to the human tooth surface, a definitive conclusion has not yet been established. In this study, sixty bicuspids extracted from teenagers were employed for testing, in conjunction with 6 different brands of orthodontic resins: Concise, Unitek, Ormco, American, Mono-lok and Right-on. On the buccal surface of the crown, the tensile bond strength for the various resins were tested and recorded. The bond strength was 0.69 kg/mm2 for Concise, 0.64 kg/mm2 for Unitek, 0.58 Kg/mm2 for Ormco, 0.55 kg/mm2 for American, 0.54 kg/mm2 for Mono-log and 0.45 kg/mm2 for Right-on, respectively. The broken surfaces were examined by scanning electron microscopy, as well as energy dispersive x-ray spectrometry. The broken surfaces were either at interface between the resin and bracket base, at the resin itself, interface between tooth surface and resin or in a combination of them. On the broken surface of the bracket base, components of broken tooth fragments were also detected. The percentage for the frequency of samples of each type of orthodontic resin of broken tooth fragments found was 30% for Concise, 10% for Unitek, 50% for Ormco, 40% for American, 50% for Mono-lok and 80% for Right-on.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Intra-oral bonding of 4-META/MMA-TBB resin to vital human dentin.

PURPOSE: To investigate and compare the in vivo and in vitro tensile bond strengths of a 4-META/MMA-TBB adhesive resin (Superbond C&B, C&B-Metabond) to human dentin. MATERIALS AND METHODS: Caries-free teeth present on patients and scheduled for extraction for orthodontic reasons were used. Flat dentin surfaces were prepared and a 4-META/MMA-TBB resin applied. After 10 minutes, the teeth were extracted. Extracted caries-free teeth were also used and treated similarly. Tensile bond strength was evaluated and all specimens were sectioned immediately after bond testing, after polishing the debonded area or after treating the surfaces with HCl acid. RESULTS: Data were analyzed statistically, and no significant differences could be determined between third molars and first premolars, and in vivo and in vitro specimens. Further, tensile stress fractured specimens were examined under scanning and transmission electron microscopy. Widths (+/- 5 microns) of hybrid layers and impregnation of adhesive monomers into 10-3 solution demineralized vital human dentin substrates were essentially similar to those observed in extracted samples. The adhesive resin penetrated tubules to form resin tags, unimpeded by intra-tubular fluid under physiologic pressure in intra-orally prepared specimens. A hybrid layer formed on resin tags to seal against microleakage and pulpal attack by bacteria and their by-products. An acid-resistant hybrid layer was also observed in enamel. Finally, hydroxyapatite crystals that were encapsulated by polymerized 4-META/MMA-TBB resin was observed at the bases of resin-reinforced hybrid layers in the human dentin substrates. This observation is consistent with earlier findings and appears to be essential in maintaining durable dentin bonds.

Acrylic Resins↗
PubMedDate not supplied

Composite resin bond strength after enamel bleaching.

This study evaluated the effect of enamel bleaching with a commercial product on the sheer bond strength of a composite resin. A total of 45 human extracted permanent molars were used. A flat enamel surface was obtained with 600-grit SiC paper. The teeth were then randomly distributed into three groups of 15 teeth each: Group 1: Enamel etching with 37% phosphoric acid gel (Coe) for 60 seconds, placement of an unfilled resin (Coe) thinly applied with a brush and a composite resin (Occlusin); Group 2: Enamel bleaching (Rembrandt Lighten Bleaching Gel, Den-Mat) for one hour, etching for 60 seconds and placement of unfilled and composite resins. Group 3: Enamel bleaching for 24 hours, etching for 60 seconds, and placement of unfilled and composite resins. A nylon ring over the etched enamel retained the composite resin. The teeth were thermocycled (X100) and sheared with a knife-edged blade in an Instron machine running at a cross-head speed of 1 mm/min. The results in MPa were: Group 1: 12.86 +/- 4.83, Group 2: 12.33 +/- 2.95, and Group 3: 7.67 +/- 1.98. An ANOVA revealed that Groups 1 and 2 were significantly different from Group 3 (P < 0.001). Fracture within the enamel occurred in 53% in Group 1, 33% in Group 2, and 0% in Group 3. The study reveals that the shear bond strength of composite resins is significantly reduced after enamel bleaching for 24 hours.

Analysis of Variance↗
PubMed1994

Properties of acrylic resins incorporating 4META for bonding to cobalt-chromium alloys.

Polymer substitution into proprietary 4-methacryloxyethyltrimellitate anhydride (4META) resins creates tooth coloured veneers for cobalt-chromium overlay dentures. The elastic moduli and shear-bond strengths of proprietary resins (matched) and resins polymerised from 4META monomers and substituted polymers (unmatched) were determined. Bond strengths were similar for matched and unmatched heat curing resins (mean 14.1 (SD 1.6 MPa)) but differed for matched (6.9 (SD 1.3) MPa) and unmatched self-curing resins (5.7 (SD 0.9) MPa). Preparation of the alloy surface immediately before packing with resin dough provided significantly higher bond strengths. Structural examination in a scanning electron microscope suggested that bonds developed by unmatched resins may provide less satisfactory clinical performance.

Acrylic Resins↗
PubMedDate not supplied

Improvement in the tensile bond strength between resin cement and dentin surfaces after temporary cement application.

PURPOSE: The aim of this study was to evaluate the efficacy of three tooth conditioners in restoring the reduced bond strength between resin cement and teeth resulting from remaining temporary cement. MATERIALS AND METHODS: Ethyl dihydrogen phosphate, methacryloxyethyl dihydrogen phosphate, and 2-methacryloxyethyl hydrogen maleate were evaluated as conditioners. After eliminating the temporary cement with a curette from the bovine dentin surface, the conditioners were applied onto the surface of the specimen and a resin cement was adhered. Stepwise scanning electron microscopic observation and tensile bond strength measurement were carried out. RESULTS: Granular substances were present on the dentin surface even when the temporary cement was carefully eliminated with a curette. When primer and resin cement were applied on this surface without conditioner application, no resin tag or hybrid layer was observed and the mean bonding strength between tooth and adhesive resin cement was 1.8 MPa. In contrast, resin tag and hybrid layer were observed after primer and resin cement application when the dentinal surface was treated with conditioner. Mean tensile bone strength values increased to 6.2 MPa for specimens treated with 20% methacryloxyethyl dihydrogen phosphate for 60 seconds. CONCLUSION: The authors recommend methacryloxyethyl dihydrogen phosphate as it provides high tensile bond strength values and requires no additional rinse step.

Analysis of Variance↗
PubMed2003

Modelling the adsorption kinetics of erythromycin onto neutral and anionic resins.

In this study the selective adsorption method was chosen to enable the recovery of erythromycin. The following sorbents were tested: neutral resins (XAD-4, XAD-7 and XAD-16) and an anionic resin (IRA-410). A mathematical kinetic model for the adsorption of erythromycin against time, on XAD-4, XAD-7 and XAD-16 resins, is proposed. Both Freundlich and Langmuir models showed a good fit for the sorbents XAD-7 and IRA-410 resins. The highest adsorption efficiency was observed when synthetic neutral resin, XAD-7 and XAD-16, were used. The estimated affinity and concentration factors show that the neutral resins tested are adequate for the selective adsorption of erythromycin. The estimated values of enthalpy and free energy of adsorption, lower than 12 kJ mol(-1) and -2 kJ mol(-1), respectively, indicate that a physiosorption process occurred.

Acrylic Resins↗
PubMed1991

Microleakage and shear bond strength of resin and porcelain veneers bonded to cast alloys.

Four resin veneering materials and four methods of retaining the veneer on metal castings were compared with metal ceramic restoration. Variations in microleakage were noted between the four resin materials retained by mechanical retention beads. When mechanical and chemical modes of a resin and porcelain veneer retention were compared, there was no microleakage with one mechanically and two chemically retained resin groups including one metal ceramic group. The resin materials tested understandably produced substantially lower shear bond strengths than the metal ceramic specimens. Higher shear bond strengths were recorded for the retentive beads than for the resins retained by three chemical bonding techniques. There was no direct correlation between microleakage and shear bond strength.

Acrylic Resins↗