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At least 19 recordsLinked to original sources
PubMed1985

Time-dependent deformation of composite resins--compositional considerations.

The compressive yield strength and creep of 21 dental composite resins were evaluated and correlated with filler volume percent and extent of cure in the resin. In general, yield and creep of composites were more dependent upon filler volume fraction than on extent of cure. However, the types of monomers and fillers used in the composite formulation appeared to play a major role in determining the compressive characteristics of the materials.

Carbon↗
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↗
PubMed1990

[Bond strength of etched enamel to direct composite resins, to indirect composite resins and to etched and silanized porcelain].

The adhesion to enamel of composite resin inlays are not documented as much as porcelain inlays and direct composite resins. This study evaluates the adhesion of a light cured composite resin (P-50) used in an indirect technique and secondarily polymerized by heat. No significant differences were found between adhesion of P-50 used with an indirect technique and adhesion of porcelain (Mirage). P-50 used with the direct technique yield adhesion values significantly lower than the indirect techniques.

Acid Etching, Dental↗
PubMed1989

[Relation of surface texture of fine finishing diamond point for composite resin and polished surface of composite resin].

Distribution of diamond grain size of seven fine finishing diamond points was measured by a digital image analyzer. Also influence of diamond grain size of fine finishing diamond points on finished surface of two types of visible light cured composite resins (semihybrid type and submicron filler type) were investigated. Diamond grain size was almost from 10 to 100 microns 2 in area. Diamond grain size was closely related to the surface roughness of semihybrid type composite resin, although it was not related to that of submicron filler type composite resin. Surface roughness of a submicron filler type composite resin finished at a low speed was less than that at a high speed. Grain size of diamond point and revolution speed may play an important role in surface texture of composite resin.

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↗
PubMed1989

[Study on composite resin cores. Part 2. Effect of pressing composite resin].

In this study, we investigated effects of pressing in building composite resin cores on compressive strength, retention of prefabricated post and sealing ability. 1. Compressive strength increased by pressing in composite resin cores. 2. Prefabricated post to the retentive forces was not influenced by pressing, but increased when bonding agent was used. 3. Pressing was very effective to improve sealing ability of composite resin to tooth structure. 4. Sealing ability of light-cured composite resin was not influenced by pressing but by curing types of bonding agent.

Composite Resins↗