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At least 19 recordsLinked to original sources
PubMed1978

The strength of multilayer and repaired composite resin.

Composite resin surfaces that formed against a plastic matrix or that polymerized while exposed to air were excellent substrates for the adhesion of new resin. Samples formed by the addition of composite resin to a cut surface had a tensile strength of one half of the cohesive strength of the resin. Coating the cut surface with a thin layer of unfilled resin enhanced bonding of the second composite resin layer. The use of a thin layer of unfilled catalyst resin as a bonding agent caused the most rapid development of strength and the greatest strength in samples tested after 7 days.

Adhesiveness↗
PubMed1991

Influence of carboxylic anhydrides on selected mechanical properties of heat-cured resin composites.

Resin composites are still in need of improved abrasion resistance for them to be ideal restorative materials for use in large occlusal cavities. The present study proposes a concept for additional cross-linking of dental monomers, by which mechanical properties and possibly the resistance to abrasion of the resin composites are increased. Cyclic acid anhydrides were added as cross-linking agents to different monomer mixtures, which were then loaded with filler. The monomer mixtures were varied with respect to type and ratio of monomer and anhydride. For measurement of diametral tensile strength, flexural strength, modulus of elasticity, and modulus of resilience, specimens were initially cured by light and then post-cured for one h at 150 degrees C. Resin composites based on UEDMA and HEMA were found to be superior to BISGMA- and TEGDMA-based composites. Increases in mechanical properties were highest when unsaturated anhydrides were used. An optimal effect of anhydride addition was found in resin composites also containing methacrylamide. Such materials resulted in a 20% increase in the mechanical properties investigated.

Acrylamides↗
PubMed1977

Working time and strength in relation to consistency of composite resins.

Composite resin pastes can be made more fluid for injection purposes by adding small amounts of enamel bond resin before mixing. The aim of this work was to study the influence of the added resin on the working time and on the early and final strength of the composite. The pastes of two different brands diluted with their respective resins and the working time of the mix was determined by measuring the time during which it was possible to squeeze the material from a Centrix syringe. The results revealed that adding universal resin reduced the working time of both brands. The catalyst resin increased the working time of Adaptic but with Concise the amount of the catalyst paste had also to be increased to gain more working time. Adding catalyst resin did not affect the early strength or the strength after 24 h. Furthermore, it was observed that adding resin reduced the amount of porosities in the composite.

Composite Resins↗
PubMed1992

Adhesion between the resin shell and composite resin.

Adhesiveness between the resin shell and composite resin was examined. As the resin shell, SR-PE-ISOCETTE, made from thermosetting crown and bridge resin, was used. The shear bond strengths between the resin shell and photocurable composite resin bonded by various methods were measured after 1-day of immersion in water at 37 degrees C. Super-bond C & B treatment to the resin shell effectively improved the adhesiveness, giving a bond strength of about 14 MPa. Clearfil new bond, Clearfil porcelain bond, Unifast and MMA/TBBO treatment gave almost the same bond strengths of about 7-9 MPa. Silane coupling agents were not effective for improving the bond strength. It was revealed that 4-META was necessary for obtaining good adhesion between SR-PE-ISOCETTE and composite resin.

Boron Compounds↗
PubMed1991

Effect of a triclosan/copolymer/fluoride dentifrice prophylaxis on the shear bond strength of a composite resin to enamel.

A new fluoride dentifrice formulation containing triclosan and a copolymer has been introduced. The purpose of this study was to evaluate the shear bond strength of a resin composite bonded to enamel previously cleaned with this new dentifrice formulation. A total of 45 human extracted permanent molars were used. A flat enamel surface was obtained with 600 grit SiC paper and the teeth randomly distributed into 3 groups of 15 teeth each: Group 1: Pumice prophylaxis with a rubber cup and slow-speed handpiece; Group 2: Prophylaxis with a conventional fluoridated dentifrice (Colgate); Group 3: Prophylaxis with a triclosan/copolymer/NaF dentifrice (Colgate). After prophylaxis, the teeth were acid-etched with a 37% phosphoric acid gel for 30 seconds, rinsed and dried. An unfilled resin (Coe Bond) was thinly applied with a brush and cured for 30 seconds. A nylon ring was placed over the area and filled with a light-cured resin composite (Occlusin). The teeth were thermocycled for 100 cycles, mounted in plastic cups and plaster, and sheared with a knife-edged blade in an Instron running at a crosshead speed of 1 mm/min. The results in MPa were as follows: Group 1: 11.34 +/- 4.57; Group 2: 13.46 +/- 3.60; Group 3: 13.84 +/- 4.33. An ANOVA showed that there was no statistically significant difference among the groups. Fracture within the enamel occurred in 27% in Group 1, 47% in Group 2, and 67% in Group 3. The results support the use of the fluoride dentifrices tested in this study for prophylaxis prior to bonding procedures.

Analysis of Variance↗
PubMed1991

An in vitro study of the tensile strength of composite resins repaired with the same or another composite resin.

Interfacial tensile bond strengths of self-cured and light-activated composite resins, repaired with the same or another composite resin were measured. The bond strengths were measured as a function of age of the substrate or as a function of the adhered surface treatment. One control group of solid resin samples was tested for tensile strength. Other groups of specimens, matured for 48 hours, 7 days, and 1 year, were cut in half and ground flat before a fresh mass of composite resin was added. Six groups were coated with a thin layer of intermediate resin or bonding agent before the fresh composite resin was added. In general, the repaired composite resins revealed lower strength than did the cohesive samples, with bond strengths ranging from 19% to 52% of the strengths of the unrepaired resins. The intermediate resin increased the bond strength in all cases.

Composite Resins↗
PubMed1991

Connective tissue reactions to glass ionomer cements and resin composites.

This study evaluated the histopathologic reactions of rat connective tissue to two glass-ionomer cements (Fuji Cap II, Fuji Ionomer Type III) and two microfilled light-cured composite resins (Helio-molar Radiopaque and Helioprogress). IRM (zinc oxide-eugenol cement) was used as a control. Discs of the materials, 5 mm in diameter and 2 mm thick, that had set for 15 minutes were implanted under the dorsal skin of 75 Sprague-Dawley rats. There were 15 rats in each group and each animal received two identical implants. Five rats from each group were terminated at 7, 28 and 85 days after implantation. Histologic sections of the implant sites were stained with hematoxylin and eosin. Findings at all study periods indicated that Fuji Ionomer Type III elicited more intense reactions than the other materials. Reactions to Fuji Cap II, Heliomolar Radiopaque and Helioprogress, at all study periods, were comparable to each other and to IRM.

Acrylic Resins↗
PubMed1990

Repair of defective Class I composite resin restorations.

Composite resin restorations undergo dimensional changes that can eventually result in marginal defects. Unlike silver amalgam restorations, which usually should be completely removed before the tooth is restored again, bonded composite resin restorations can often be repaired. This report demonstrates a step-by-step technique for repairing a defective Class I composite resin restoration with a new application of resin after elimination of the defect. The method has proved successful over the last 8 years.

Composite Resins↗
PubMedDate not supplied

Class I composite resin restoration.

Composite resin materials and methods for their use have improved to the extent that long lasting Class I carious lesions on stress-bearing surfaces can be restored with predictable results. This article demonstrates a step-by-step clinical technique for placement of a Class I composite resin restoration lined with a light-hardened glass-ionomer dentin replacement foundation. Emphasis is placed on tooth isolation, thoughtful handling of the respective materials, and the importance of final sealing of the resin/enamel margins.

Composite Resins↗
PubMed1978

Experimental osteotomy fixed with a composite resin.

Some composite resins used in dentistry are claimed to have qualities superior to those of the commercial bone cements. A bis-GMA composite resin was used for the fixation of experimental tibial osteotomies in rats. The osteotomies were fixed with bis-GMA in 84 rats, while intramedullary nailing was used in 28 rats. In 28 rats used as controls the osteotomy was left unfixed. Radiologic, histologic, microradiographic and oxytetracycline (OTC) fluorescence studies were performed after 1,2,3,6, 12, 18 and 24 weeks. The most favorable results as regards the healing of osteotomy were obtained in the intramedullary nailing group, but the results with bis-GMA fixation were more favorable than those obtained in the untreated group. It is concluded that the material employed is suited for the fixation of osteotomies and that the bone tolerated the tested material well.

Animals↗
PubMed1992

Effects of 'resin-compatible' cavity varnishes on composite resin microhardness.

Although the use of cavity varnishes with composite resins has traditionally been discouraged, several "resin-compatible" varnishes are currently available. This in vitro study evaluated the effects of resin-compatible cavity varnishes on a hybrid composite resin. The results of the study indicate that these varnishes soften the composite resin in contact with varnished dentin.

Composite Resins↗
PubMed1977

A temporary space maintainer using acrylic resin teeth and a composite resin.

A one-session technique for preparing a temporary space maintainer has been described. The technique consists of attaching an acrylic resin pontic to etched surfaces of natural adjacent teeth by means of a composite resin. The main advantages of this technique are elimination of premature tooth preparation, good esthetics, fair strength, low cost, and rapid completion of the restoration without the need of a dental laboratory.

Acid Etching, Dental↗