Shear bond strength of chemical and light-cured glass ionomer cements bonded to resin composites

A bond between glass ionomer cements (GIC) and resin composites is desirable for the success of the ‘sandwich’ restoration. Chemically cured glass ionomer cements have been the traditional materials used in this technique since its development, but etching the GIC was necessary to obtain a bond to the composite facing. Producing a very smooth GIC surface has aided in better determining the magnitude of the chemical bond between glass ionomers and resin composites. Shear testing of bonded specimens has revealed that chemical bonding is minimal (0.21 MPa) in conventional glass ionomers, but does exist (4.92 MPa) between GIC and resin composite regardless of the filler content (microfilled vs hybrid) of the composite. Thermal stressing affects the bond to resin-modified glass ionomers, but has no significant effect on self-cured cements. Of all combinations tested, Vitremer/Scotchbond/Silux Plus showed the highest mean shear bond strength. Based on the clinical need for an adhesive bond between GIC liner/base and resin composite, the resin-modified glass ionomer would appear to be the material of choice.     

Analysis of strength properties of light-cured resin composites.

OBJECTIVES: To determine and correlate the compressive and tensile strengths of resin composites, to scale their failure probability and to analyze their failure mode under combined state of stresses. METHODS: Ten brands of composites were tested for compressive and diametral tensile strengths. A recently introduced device for testing of pure shear stresses was modified to adapt to smaller specimens. Uniformity of pure shear stress distribution in the significant section was verified by a photoelastic model. Loading specimens in pure shear up to failure determined their mode of fracture under combined state of stresses. RESULTS: Diametral tensile strength yielded values that were 20% of their respective compressive strength. Multiple comparison test indicated that strength properties of the tensile strength test were much more sensitive in predicting differences between resin composites when compared to a compressive strength test. Pertac (Espe) had the highest compressive strength, Graft LC (GC) and Z-100 (3M) had the highest diametral tensile strength. No correlation was found between tensile and compressive strengths. The Weibull modulus disclosed differences in the liability of the materials to fracture. When combined state of stresses were applied through the pure shear test, failure of each specimen occurred at the principal tensile planes. SIGNIFICANCE: Compressive strength cannot predict the ability of the resin composite to withstand tensile stresses. The importance of compressive strength is limited as failure of a brittle material occurs in tension.     

Shear bond strength of resin teeth to heat-cured and light-cured denture base resin

The failure of the bond between acrylic resin teeth and denture base material remains a considerable problem. Previous research has indicated that the introduction of a bonding agent to the tooth-resin interface significantly increased the tensile bond strength. To further investigate this finding, and to complement the earlier study, a shear strength assessment was carried out. Both a commercial and an experimental bonding agent were evaluated for tooth retention when applied to heat-cured and visible light-cured (VLC) resin. A significant increase in shear bond strength was obtained when bonding agents were applied. The experimental cement gave the greatest increase in strength, although the VLC resin failed to achieve the same degree of tooth attachment as the heat-cured resin.     

Build-up and repair of light-cured composites: bond strength

Interfacial bond strengths of light-activated composites were measured as a function of age using a transverse strength test. Bond strength between layers decreased with the age of the initial layer and reflected the setting curves of the composites. The highly-filled composites exhibited the greatest bond strengths. Uncut surfaces provided a better substrate for bonding than did ground surfaces. Use of a bonding agent on both uncut and ground surfaces improved bond strengths. Mean repair strengths of light-activated composites were similar to those of self-curing composites. Composites with ground surfaces aged for one wk had mean repair strengths 27% of the cohesive strength without bonding agent and 48% with bonding agent.     

Effect of irradiation time to light-cured resin composite on dentin bond strength.

This study examined the relationship between the irradiation time of three light-cured resin composites and their bond strength to dentin using two adherend surfaces. The light-cured resin composite systems selected were: Scotchbond/Silux, Scotchbond 2/Silux, and Clearfil Photo Bond/Photo Clearfil A. The adherend surfaces selected were a flat dentin surface and a box-shaped cavity. The greatest bond strength for all resin systems was recorded using the longest irradiation time. The bond strengths increased with an elevated irradiation time. When comparing the flat surface and a box-shaped cavity, the bond strength of the box cavity was greater than the flat surface with similar conditions except for 20 and 30 seconds of Scotchbond and 30 seconds of Clearfil. The correlation between bond strength and irradiation was greater for the flat surface than for the box-shaped cavity. This implied that the bond strength of the box-shaped cavity may be more susceptible to polymerization shrinkage.     

Viscoelastic stress analysis of thermally compatible and incompatible metal-ceramic systems.

OBJECTIVE: The purpose of this study was to analyze transient and residual midpoint deflections and stresses in metal-opaque porcelain-body porcelain systems with matched and mismatched thermal contraction coefficients. METHODS: Calculations and measurements were made for seven trimaterial strips that covered a wide range of thermal contraction mismatches among constituent materials. Midpoint deflections were measured in a beam-bending viscometer during slow cooling from an initial temperature of 700 degrees C. Linear regression analysis with a correlation coefficient of 0.950 was used to compare measured and calculated residual midpoint deflections. Stress relaxation data were fit to a three-term exponential series by nonlinear regression analyses with correlation ratios ranging from 0.9972 to 0.9999. RESULTS: While finite element analyses correctly predicted the general shape of the deflection behavior as a function of temperature for all combinations, the best agreement between measured mean residual midpoint deflections and calculated values (+250 microns vs. +268 microns) was obtained for strips composed of a Au-Pd alloy (alpha m = 13.5 ppm/ degree C) with a medium expansion opaque porcelain (alpha o = 13.3 ppm/degree C) and a high expansion body porcelain (alpha B = 14.4 ppm/degree C). The highest calculated residual tensile stress of +26 MPa at the surface of body porcelain was associated with the 0.5-mm-thick Ni-Cr-Be alloy strip (alpha m = 15.1 ppm/degree C) with medium expansion porcelains (alpha o = 13.5 ppm/degree C and alpha B = 13.9 ppm/degree C). The smallest measured residual deflection (+10 microns) was also associated with this combination. The results of this study indicated that metal-ceramic strips are sensitive indicators of stress development caused by a thermal contraction mismatch; however, the magnitudes of the residual deflections do not necessarily correlate with the stress magnitudes in the ceramic. SIGNIFICANCE: Currently there are no U.S. or international standards that define the maximum difference in thermal contraction coefficients that can exist between a metal and its ceramic veneer without causing transient failures of ceramic during cooling or delayed failures in ceramic because of high residual tensile stresses. The present research represents a major step in understanding the various factors that influence the development of transient and residual stresses. A knowledge of the effects of process variables on stress development is necessary for selection of potentially successful metal-ceramic systems and for optimizing the design of dental prostheses.     

Effect of filler content of light-cured composites on bond strength to bovine dentine.

The bonding of light-cured composites to tooth tissues is known to be disturbed by polymerization shrinkage, and polymerization shrinkage is affected by the filler content of composites. This in vitro research examined the relationship between the filler content and bond strength to dentine of light-cured composites. Experimental light-cured composite systems with filler contents of 45, 55, 65 and 75 per cent by volume were used in both bond strength to dentine and shrinkage tests. The surfaces selected as substrates were a flat surface and a box-shaped cavity prepared in bovine dentine. The lowest bond strength was obtained with the 45 per cent filler content composite in the box-shaped cavity. Bond strength increased with increasing filler content. Volumetric polymerization shrinkage decreased with increasing filler content. The polymerization shrinkage at 120 s after light curing was 5.24 per cent for the 45 per cent filler content system, 4.77 per cent for the 55 per cent, 2.14 per cent for the 65 per cent and 1.68 per cent for the 75 per cent. The correlation between bond strength and shrinkage was greater for the cavity than it was for the flat surface. This implies that bond strength in the box-shaped cavity may have been affected more by polymerization shrinkage than with the flat surface. The findings lend support to the view that filler content is one of the important factors influencing the physical properties of composites.     

Microshear bond strength of resin bonding systems to machinable ceramic with different surface treatments

PURPOSE: The bond strength and bond durability of two high-viscosity dual-curing resin luting agents with different surface treatments of ceramic were investigated. MATERIALS AND METHODS: GN-I machinable ceramic surfaces were treated with 37% phosphoric acid for 30 s (PA), 5% hydrofluoric acid for 5 s (HF-5), 10 s (HF-10), or 30 s (HF-30), or blasting with 50-microm Al2O3 for 10 s (AB). The roughness of the ceramic surface was measured. Treated ceramic surfaces were bonded with three resin bonding systems (RBS): Ceramic Primer/LinkmaxHV (CP/LMHV), Monobond S/VariolinkIIHV (MBS/VLIIHV), or MBS/Heliobond/VLIIHV (MBS/HB/VLIIHV). A microshear test was used to measure the bond strength after 24 h (TC 0) and subsequent thermocycling (TC 10,000 at 4 degrees C and 60 degrees C). ANOVA was performed for statistical analysis, with significance set at p < 0.05. RESULTS: For three RBSs, bond strength at TC O was not affected, regardless of ceramic surface treatment (p > 0.05). All combined groups of ceramic surface treatment and resin bonding system decreased after 10,000 thermal cycles, especially groups treated with alumina blasting and bonded with each of three RBSs (p < 0.05). MBS/HB/VLIIHV with each surface treatment did not improve the bond strength and durability compared with MBS/VLIIHV. CONCLUSION: CP/LMHV and MBS/VLIIHV obtained sufficient bond strength and bond durability to GN-I machinable ceramic by only cleaning with PA; the application of HB may not be necessary.     

Monomer composition and bond strength of light-cured 4-META opaque resin

A light-cured opaque resin was prepared with 4-(2-methacryloxyethoxycarbonyl) phthalic anhydride (4-META), bifunctional methacrylates, and titanium dioxide (TiO2). The relation between monomer composition and bond strength was examined with seven methacrylate monomers. Methyl methacrylate (MMA) was useful as a solvent of 4-META. However, it was not sufficiently cured by photo-initiator. The bond strength of a triethyleneglycol dimethacrylate (TEGDMA)-based composition was superior to other monomer-based compositions after repeated thermocycles. 1,6-bis(methacryloxy-2-ethoxycarbonyl-amino)-2,4,4-trimethylhex ane (UDMA) effectively provided viscosity to the composition. The prepared opaque resin consisted of 4-META/MMA-TEGDMA primer, TEGDMA-UDMA-based monomer, and titanium dioxide. This opaque resin bonded strongly to alumina-blasted cobalt-chromium alloy. The light-cured 4-META opaque resin may be useful for bonding prosthodontic composite to metal frameworks.     

The bond strength of a visible light-cured reline resin to acrylic resin denture base material

The introduction of Triad visible light-cured denture resin has led to several applications. Among them is direct intraoral relining of complete and partial dentures. This study investigated the bonding characteristics of Triad reline resin to four commonly used heat-cured denture base resins. The shear and tensile bond strengths of Triad resin and four denture base resins were determined and compared with intact tensile strengths. The findings of this study indicate that the bond strength of Triad resin to denture base resin is sufficiently high to suggest its clinical applicability.     

Shear bond strength of dual-cured and self-cured resin composites to dentin using different bonding agents and techniques

This study determined the effects of bonding agents on the shear bond strength of dual- and self-cured resin composites to dentin. Two light-cured dentin bonding agents (Excite and One-Step) and a dual-cured bonding agent (Excite DSC) were compared. Light activation of the bonding agents prior to placement of the resin composites was also evaluated. This in vitro study was performed on 120 extracted non-carious human third molars. The occlusal part of the crowns was removed to expose a flat dentin surface. The teeth were then randomly divided into three major groups for Excite, One-Step and Excite DSC as bonding agents. The specimens in each adhesive group were divided into four subgroups: with and without light activation of the bonding agent and with dual-cured (Luxacore Dualcure, DMG, Hamburg, Germany) or light-cured resin (Luxacore, DMG, Hamburg, Germany) composites. After placing the restorations, the specimens were kept in water at 37 degrees C for 24 hours before being tested for shear bond strength on an Instron universal testing machine at a crosshead speed of 0.5 mm/minute. The results showed that the shear bond strength of dual-cured resin composite to dentin was significantly higher than that of self-cured resin composite (p = 0.017). Light activation of the bonding agents prior to applying the resin composites led to a significantly higher shear bond strength of the resin composites to dentin, compared to no light activation (p < 0.05).     

An in vitro study of the bond strength of two light-cured composites used in the direct bonding of orthodontic brackets to molars.

This study examines methods of improving the bond strengths of the light-activated composites, Heliosit-orthodontic, and Transbond. Begg brackets were bonded onto each of the four surfaces of 50 molar teeth that had been previously extracted. The bonding systems used were Right-on (R), Heliosit-orthodontic (H), Heliosit with a precured composite resin on the mesh (HPC), Heliosit with a precured intermediate bonding resin on the mesh (HPR), Transbond (T), and Transbond with a precured layer of resin on the mesh (TPC). The shear bond strengths were tested on a M5K tensile tester, crosshead speed 0.5 mm/min. After bracket removal, the enamel surface of the bonding site was examined and assessed with the adhesive remnant index (ARI). The shear bond strength in mean mPa +/- 1 SD was found to be significantly greater for HPC, HPR, and TPC than for H (P < 0.001). The ARI scores suggest that bond failure is associated more with the micromechanical bond with enamel for HPC and HPR. The results indicate that the chemical properties of the two light-activated adhesives were improved by precuring on the mesh base of the bracket before bonding.     

Shear bond strength of one-bottle dentine bonding systems.

The purpose of this in vitro study was to determine the shear bond strength (SBS) of composite resin to human, buccal dentine, using four one-bottle dentine bonding systems. Eighty recently extracted human molar teeth were embedded in metal rings by means of self-curing acrylic resin. The projecting buccal surfaces were ground wet on 600 grit silicone carbide paper in order to expose superficial dentine. The teeth were randomly divided into four groups (N=20): 1=Prime&tBond 2.1 (PB, Dentsply); 2=Scotchbond 1 (SB, 3M); 3=Optibond Solo (OS, Kerr) and 4=Syntac Single Component (SY, Vivadent). The dentine surfaces were etched, treated with one of the four dentine bonding systems, and cylinders of matching composites were then bonded to the surfaces by means of a silicone rubber split mould. All specimens were stored for 24 hours under water at 37 degrees C. The bonds were then stressed to failure with an Instron testing machine, operating at a crosshead speed of 0.5 mm/min. The data were statistically analysed (Kruskall-Wallis). The mean SBS (MPa) were: PB = 12.5 +/- 2.0; SB = 16.2 +/- 1.9; OS = 17.4 +/- 3.1 and SY= 8.1 +/- 1.9. There was a statistically significant difference (P = 0.0001) between the mean of SY and the other 3 groups, and also between PB and the other groups. There was no statistically significant difference (P = 0.244) between the SBS of OS and SB. SY demonstrated the lowest SBS.     

Shear bond strength and microleakage of dentin bonding systems.

This study evaluated the shear bond strength and microleakage of class V non-retentive restorations with 10 different dentin bonding systems. Some were tested with different composite resins. For the shear bond test, eight specimens were prepared for each product and tested in a universal testing machine. For the microleakage test, 158 V-shaped class V cavities extending to the cementoenamel junction were prepared, coated with a dentin bonding system, and restored with a composite resin. After 250 thermocycles, the teeth were immersed in a dye solution for 48 hours, longitudinally sectioned, and evaluated for microleakage. Both test procedures resulted in significant differences between the various materials. The bond strength failed to completely prevent microleakage at the dentinal wall. The new generation of dentin bonding systems offer a significant improvement over previous materials.     

Shear bond strength of composite resin to amalgam: an experiment in vitro using different bonding systems.

The shear bond strength between amalgam and composite resin with and without the use of adhesive systems was evaluated. It was found that the application of Cover-Up II or Prisma Universal Bond prior to placement of composite resin enhanced the shear bond strength between amalgam and composite resin more than five times; and a shear strength of 4.34 and 4.30 MPa was measured respectively. Acid-etching of the roughened amalgam surface prior to application of Prisma Universal Bond decreased the bond strength by nearly 45%.     

Antibacterial properties of resin composites and dentin bonding systems.

This paper reviews the research conducted on the evaluation of antibacterial properties of commercial composites and adhesive systems, in addition to the discussion on many attempts to achieve antibacterial composites or adhesives. With regard to composites, commercially available products including fluoride-releasing materials have no antibacterial effect after being cured, which may explain why composites accumulate more plaque than other filling materials. The attempts to provide composites with antibacterial properties involve alterations to the resin components and filler components, and the trials can be subsequently classified into two groups based on the release profile of antibacterial components; agent-releasing or non-agent-releasing materials. Each type of antibacterial composite has advantages and disadvantages, and further modifications are needed to achieve clinically useful materials. Among proprietary dentin bonding systems (DBS), the products which contain glutaraldehyde or have an acidic property exhibit some antibacterial effects. However, the antibacterial properties shown by these products are only side-effects which are derived from the constituents included to produce superior bonding characteristics, and appear to be unreliable. Inclusion of antibacterial components into DBS has also been attempted using several methods, and the results of in vitro tests indicate that some of the trials seem promising. It is worthy of continuing the attempts to develop DBS which can inhibit invading bacteria after the placement of restoration as well as residual bacteria in the cavity. Achievement of bio-functional composites or DBS with therapeutic effects would contribute to prevent secondary caries.