Shear bond strength of a new one-bottle dentin adhesive

PURPOSE

To test the shear bond strength of a new adhesive, 3M Single Bond, to dentin surfaces containing different degrees of moisture. Two commercially available one-bottle adhesives (Prime & Bond, One-Step) and a conventional three-step system (Scotchbond Multi-Purpose Plus) were included for comparison.

MATERIALS AND METHODS

120 bovine teeth were embedded in acrylic and the labial surfaces were polished to 600 grit to create standardized dentin surfaces for testing. Resin composite was bonded to dentin using a gelatin capsule technique. Four adhesive systems were evaluated with three different degrees of surface moisture (moist, wet, and overwet). Shear bond strengths of adhesives to dentin were determined using a universal testing machine and analyzed by ANOVA and Tukey's post hoc tests.

RESULTS

Single Bond had mean shear bond strengths of 19.2, 23.2 and 20.3 MPa to moist, wet, and overwet dentin, respectively. Bond strengths of the three-component system Scotchbond Multi-Purpose Plus ranged from 23.1 to 25.3 MPa, but were not significantly higher than the values for Single Bond. Prime & Bond had bond strengths similar to those of Single Bond, but One-Step had significantly lower bond strengths (P < 0.05) in the wet and overwet conditions.

Dental materials citations: Part A, January to June 1997

OBJECTIVE

A search was conducted in biomedical journals published from January 1997 to June 1997 to identify all dental materials publications and sort them into major categories.

METHODS

Tables of contents for 79 journals for the period of January to June, 1997 were inspected and divided into 17 categories. Citations were analyzed by both frequency in journals and in categories, as well as compared to frequencies for previous years.

RESULTS

A total of 445 citations were detected in 79 journals for the period January 1997 to June 1997. Certain journals (n = 19) demonstrated a higher citation frequency (> or = 10 citations for 6 months) and represented 77.8% of all citations. The greatest number of citations continued to involve bonding (n = 97), resin-based restorative materials (composites; glass ionomers) (n = 95), prosthodontic materials (n = 51), and pulp protection/luting materials (n = 48). Frequencies by category were very similar to those for the last four years.

SIGNIFICANCE

The compiled literature citations provide a supplement for researchers and academicians seeking information in existing electronic databases.

Restorative considerations with vital tooth bleaching

This paper explores the implications of bleaching procedures on restorative dentistry. The effects of tooth whitening systems on the bond strength, marginal integrity, color and other properties of restorative materials are reviewed. Also, clinical considerations in combining bleaching and aesthetic restorative techniques are discussed.

Dental materials citations: Part B, July to December 1996

OBJECTIVE

A search was conducted in biomedical journals from July 1996 to December 1996 to identify dental materials publications and sort them into major categories. They were compared by frequency in different journals and in different categories during recent years.

METHODS

Tables of contents for 16 primary and 51 secondary journals were inspected from July to December of 1996 and were divided into 17 categories. The frequencies of citations for primary journals and for different citation categories were examined over a four-year period from 1993 to 1996.

RESULTS

There were 334 total citations from July to December 1996. The greatest number of citations continued to involve bonding (n = 159) and resin-based (composites; glass ionomers) restorative materials (n = 158). The numbers of articles by journal and by category were very similar over the last four years. The average number of articles per year was 531 +/- 15.

SIGNIFICANCE

The literature citations compiled in this list provide a supplement for researchers and academicians to the current electronic databases.

The effect of resin desensitizing agents on crown retention

Many dentists use resin primers and adhesives to prevent post-cementation sensitivity of teeth restored with crowns. However, little information is available regarding the effect of these resins on crown retention. This laboratory study concluded that two popular resins, Gluma Desensitizer (Heraeus Kulzer) and One-Step (Bisco Dental Products), had little or no effect on the retention of crowns luted with zinc phosphate, glass ionomer or resin-modified glass ionomer cements.

Enhancement of resin bonding to heat-cured composite resin

The purpose of this study was to evaluate the effectiveness of various surface treatments used to enhance the bond strength of resin cements to two different laboratory-processed composite resins. Seventy specimens of a microfilled composite resin (Concept) and 70 specimens of a micro-hybrid composite resin (Herculite XRV) were fabricated in metal wells and subjected to heat (250 degrees F) and pressure (85 psi) curing. An additional 70 specimens of each material were fabricated in the shape of disks and also subjected to the same heat/pressure curing. All composite resins were subjected to one of seven treatment regimens. The like-treated specimens were then bonded together using dual-curing resin cement and a uniform seating force (106 gm). After 7 days, bonded specimens were thermocycled 1000 times at 5 and 55 degrees C, and debond shear strengths were determined on a Universal Testing Machine. The use of microabrasion (50 microns aluminum oxide at 60 psi) and ceramic layer deposition (30 microns aluminum oxide with a ceramic additive at 75 psi) consistently improved the shear bond strength of the resin cements to both composite resins. The other treatment combinations provided varying effects. In conclusion, microabrasion or ceramic layer deposition are preferred methods to enhance the bond of resin cements to composite resins.

Effects of viscosity and surface moisture on bond strengths of resin-modified glass ionomers

PURPOSE

To evaluate the effects of surface moisture and material viscosity on the shear bond strength of resin-modified glass ionomers to dentin.

MATERIALS AND METHODS

Sixty human teeth were mounted in phenolic rings and ground to obtain flat facial and lingual dentin surfaces. The specimens were assigned to six treatment groups. Three groups were first conditioned with 10% polyacrylic acid. On one surface of each specimen, dentin was left visibly moist prior to application of the restorative material. On the opposite surface the dentin was dried, but not desiccated, after conditioning. For these three groups, Fuji II LC resin-modified glass ionomer was mixed at powder/liquid (P/L) ratios of 1.4, 3.0 and 3.6 and applied to the conditioned dentin in 2.5 mm diameter molds. The other three groups were treated with Vitremer primer. One surface of each specimen was "dry" and one surface was "moist" before primer application. Vitremer restorative material was mixed at P/L ratios of 2.2, 2.5 and 2.8 and applied to the primed surfaces. Shear bond strengths were measured using a universal testing machine. Data were subjected to three-way ANOVA and Tukey's multiple comparisons test.

RESULTS

Mean shear bond strengths of the two materials ranged from 6.9 to 10.4 MPa and varied little regardless of the viscosity of the materials or the degree of surface moistness. The differences among viscosities and surface moistness were not statistically significant. IN this in vitro study, the shear bond strengths of two resin-modified glass ionomers were unaffected by the viscosity of the materials and the surface moisture of the dentin substrate.

Dental materials citations: Part A, January to June 1996

OBJECTIVE

A search was conducted to identify the dental materials publications that appeared in biomedical journals from January 1996 to June 1996 and to compare the frequency of citations among the different categories.

METHODS

The tables of contents of 16 primary journals and 48 secondary journals were examined to identify dental materials articles that were published from January to June 1996. These citations were divided into 17 categories and the numbers of citations in each category were compared. To assess the usefulness of the citation listing, a survey of Academy of Dental Materials subscribers was conducted (n = 153 of 382 or 40.1% have responded to date).

RESULTS

As in previous years, the greatest number of citations were found in categories of bonding (n = 83) and resin-based restorative materials such as composites and resin-reinforced glass ionomers (n = 80). Results of the reader survey indicated that 84.3% of the respondents have used the citations lists, and 95.4% feel that its publication should be continued.

SIGNIFICANCE

The literature compiled in this list serves to supplement the electronic indexing mechanisms so that academicians and researchers can have ready access to the current literature in the field of dental materials.

Effect of low-viscosity resins on the performance of dental adhesives

PURPOSE

To determine whether the use of low-viscosity intermediate resins (LVR) reduces microleakage of dental adhesive systems.

MATERIALS AND METHODS

Wedge-shaped Class V cavities were prepared in sound extracted molars. Occlusal margins were in enamel and gingival margins were in dentin/cementum. Five adhesive systems (All-Bond 2, Clearfil Liner Bond 2, OptiBond, Prime & Bond and Scotchbond Multi-Purpose) were applied to the preparations strictly according to manufacturers' directions on one side of the tooth and with the addition of LVR (OptiBond FL Adhesive or Protect Liner F) on the other. All cavities were restored with Z100 resin composite. Specimens were then stored in water at 37 degrees C for 24 hours, thermocycled 800x, stained with silver nitrate, sectioned, and evaluated for leakage. Marginal penetration of silver nitrate was scored on 0-3 scale.

RESULTS

Statistical analysis (Kruskal-Wallis non-parametric ANOVA) revealed a significant difference (P < 0.0001) in leakage at dentin margins. Multiple pairwise comparisons of control groups revealed considerable overlapping between groups, but with a trend toward less leakage by OptiBond and Clearfil Liner Bond 2. Leakage of Scotchbond Multi-Purpose was significantly reduced when Protect Liner F was used.

Effect of a surface sealant on microleakage of Class V restorations

PURPOSE

To evaluate the effect of a low-viscosity surface-penetrating sealant on microleakage around Class V restorations.

MATERIALS AND METHODS

Box-shaped Class V preparations were made in the facial and lingual surfaces of 50 extracted human teeth. Occlusal margins were in enamel and gingival margins were in dentin/cementum. Preparations were restored with the following systems (n = 20): Dentin Conditioner + Fuji II LC; ProBond primer + VariGlass VLC; OptiBond + XRV Herculite; Scotchbond Multi-Purpose + Silux Plus; and Scotchbond Multi-Purpose + Restorative Z100. Half of the restorations in each group were randomly selected and sealed with Fortify resin immediately after finishing and polishing. Specimens were thermocycled 500x between 5 degrees and 55 degrees C and subjected to a silver nitrate microleakage test. Penetration of the silver nitrate tracer was evaluated and recorded using a 0-4 ordinal scale. Data were analyzed using non-parametric statistical tests.

RESULTS

All of the restorative systems had very little leakage at enamel margins, regardless of whether the resin sealant was used. Each of the systems except VariGlass had minimal leakage at unsealed dentin margins also. Application of the resin sealant significantly reduced leakage at the interface between VariGlass and dentin or cementum, but had no effect on the other restorative systems.

Review of dental materials citations: Part B, July to December 1995

OBJECTIVE

A lag of many months occurs between journal issue publication and updates to electronic databases. The objective of this literature analysis was to identify and categorize all of the dental materials citations in biomedical journals that were published from July 1995 through December 1995.

METHODS

Seventeen primary and 51 secondary journals were searched using their tables of contents to detect and record dental materials publications from July to December of 1995. Those journals that were typically rich in dental materials articles were classified as primary ones. Citations were categorized into 17 topics and divided into subsections. The review excluded case reports, most literature related primarily to dental implants, and most articles on biomedical materials used outside of the field of general dentistry.

RESULTS

The greatest number of citations was related to topics of dentin bonding and resin-based restorative filling materials (composites and glass ionomers). There was no major change in the number of dental materials publications per year reported from 1993 (n = 786) to 1995 (n = 751).

SIGNIFICANCE

This citation list provides a comprehensive resource for use by academicians and researchers to bridge the gap between initial publication and access to electronic searching methods for major databases.

Restoration of primary molars using a new "compomer" material

The primary advantages of glass ionomer restorative materials are adhesion to tooth structure and release of fluoride. A new material has been recently introduced for the restoration of cervical lesions and Class I defects in primary teeth. The material combines the properties of glass ionomers with the advantages of a single-component, light-activated composite resin and is known as a "compomer". This new material contains two resins, instead of the acidic polymers found in conventional glass ionomers. The restorative material releases fluoride and can be infected directly into the cavity. With its own bonding agent, the compomer offers a simple and relatively rapid technique. The learning objective of this paper is to describe the utilization of the new restorative material in conjunction with a bonding agent to restore conservative cavity preparations in primary molars. Two clinical cases are used to illustrate the presentation.

Bond strengths of glass ionomers using a dentin adhesive

PURPOSE

To determine the effect of All-Bond 2 adhesive on the shear bond strengths to dentin of Fuji II LC, Photac-Fil, and Vitremer.

MATERIALS AND METHODS

The occlusal surfaces of 60 extracted human third molars were ground flat to expose dentin and were polished to 600 grit. The teeth were randomly assigned to six groups (n = 10). In three groups, dentin was treated using the conditioner or primer recommended by the manufacturer. In the remaining groups, dentin was treated with All-Bond 2 etchant, primer, and adhesive. Restorative materials were applied to the treated surfaces in gelatin capsule matrices and were light-cured. Specimens were thermocycled, and shear bond strengths were determined using a materials testing machine.

RESULTS

The use of All-Bond 2 improved the mean bond strength of Photac-Fil from 1.7 to 8.7 MPa, but decreased the bond strength of Vitremer from 7.3 to 5.5 MPa. The bond strengths of Fuji II LC were 7.5 and 7.9 MPa, with and without the use of All-Bond 2, respectively. ANOVA and Duncan's multiple range test showed that only the difference for Photac-Fil was statistically significant.

Bonding of resin composites to resin-modified glass ionomers

PURPOSE

To evaluate the bonding between resin composites and resin-modified glass ionomer restorative materials.

MATERIALS AND METHODS

Bar-shaped specimens of Fuji II LC, Photac-Fil, and Vitremer were fabricated in a mold. After application of unfilled resin, resin composite (either Silux Plus or Restorative Z100) was condensed into the mold against the glass ionomer substrate and was light-cured. These bonded specimens, as well as intact specimens of each material, were placed on a three-point bending apparatus and were loaded until failure using a Zwick testing machine. The transverse strength of each specimen was calculated.

RESULTS

Mean transverse strengths of bonded specimens ranged from 50% to 78% of the transverse strength of the intact glass ionomer materials. The lowest transverse strength was 18.1 MPa, for Photac-Fil/Z100, and the highest was 29.6 MPa, for Fuji II LC/Silux. Statistical analysis indicated that the type of composite used had no significant effect on transverse strength. However, the type of resin-modified glass ionomer used was significant. Although there was much overlap between materials, bonded specimens made with Fuji II LC had the highest absolute strength, and those made with Photac-Fil had the lowest absolute strength. Bonded Vitremer specimens had the highest transverse strength relative to the cohesive strength of the material.

Shear bond strengths of resin-modified glass-ionomer restorative materials

The purpose of this study was to evaluate the shear bond strength of resin-modified glass-ionomer restorative materials to dentin. The materials tested were Fuji II LC, Geristore, Photac-Fil, VariGlass VLC, and Vitremer. Ketac-Fil, a conventional glass ionomer, was used as the control. The occlusal surfaces of 60 extracted molars were ground flat in dentin using 600-grit silicon carbide abrasive paper. Dentin surfaces were treated according to manufacturers' instructions, and restorative materials were applied using gelatin capsule matrices. Shear bond strengths were determined after the specimens were thermocycled 500 times. Mean bond strengths of the resin-modified glass ionomers ranged from 1.4 MPa (Photac-Fil) to 12.3 MPa (Fuji II LC). Except for Photac-Fil, all values were significantly higher than the control. Pairwise comparisons between the means for Fuji II LC and Vitremer, Vitremer and Geristore, and Geristore and VariGlass were not significantly different.

Review of dental materials citations: Part A, January to June 1995

OBJECTIVE

Electronic databases are an excellent resource for identifying relevant references for research and education projects. However, these databases are not yet a substitute for direct inspection of the literature because: (a) there still is a lag of many months between journal issue publication and updates of the database, and (b) most databases selectively report a portion of the entire literature. The objective was to identify and categorize all the dental materials citations in biomedical journals that were published from January 1995 through June 1995.

METHODS

Seventeen primary and 56 secondary dental journals were manually searched via their tables of contents to detect dental materials publications from January to June of 1995. Dental materials citations were categorized into 17 major sections and further divided into several subsections. The review excluded case reports and literature primarily related to dental implants or biomedical materials outside of dentistry.

RESULTS

Three hundred-sixty-nine citations were identified. The greatest number of citations were associated with dentin bonding, composites, and glass ionomers. There was no significant increase in dental materials publications vs. the number reported for 1994.

SIGNIFICANCE

This list provides a comprehensive source for review by academicians and researchers to bridge the gap between initial publication and electronic citation.

Topical fluoride and glass ionomer microhardness

PURPOSE

To evaluate the effect of topical fluoride gels on the microhardness of three glass ionomer cements.

MATERIALS AND METHODS

Cylinders of Ketac-Silver, Photac-Fil, and Fuji II LC were fabricated, stored in distilled water at 37 degrees C for 48 hours, and exposed to a neutral sodium fluoride gel (Karigel-N), and acidulated orthophosphoric acid gel (Karigel), and a stannous fluoride gel (Omni) at 37 degrees C for 36 hours. Knoop hardness was then recorded.

RESULTS

Statistical analysis showed significant differences (P<0.01) between groups related to material and treatment Ketac-Silver did not demonstrate significant differences in hardness, whereas exposure to APF decreased the Knoop hardness of Fuji II LC and Photac-Fil.

Depth of cure of resin-modified glass ionomers

OBJECTIVES

The cure of all resin-modified glass ionomer materials depends to some degree on light activation. However, the materials have chemical-cure mechanisms that could increase depth of cure. Thus, this study was conducted to evaluate the depth of cure of five resin-modified glass ionomer restorative materials.

METHODS

Five specimens of Fuji II LC (GC America), Geristore (Den-Mat), Photac-Fil (ESPE America), VariGlass (Caulk/Dentsply), and Vitremer (3M Dental Products) were fabricated in Teflon molds. Each material was visible light-activated for 40 s. Specimens were 5 mm x 5 mm x 9 mm (depth), but material at depths greater than 5 mm was too soft to measure. Microhardness (KHN) at the surface and at 1 mm increments below the surface of each specimen was measured at 10 min, 1 d, and 7 d after light-curing.

RESULTS

At 10 min post-irradiation, the top layers (0-1 mm) of each material were significantly harder than the deeper layers (4-5 mm). However, at 1 d, Geristore, Photac-Fil, Vitremer and Fuji II LC had uniform hardness, regardless of depth. In contrast, VariGlass hardness decreased significantly with depth, from 43.3 at the surface to 11.7 at 5 mm. At 7 d, Photac-Fil, Vitremer and Fuji II LC had more uniform hardness regardless of depth than either Geristore or VariGlass. Data were analyzed using ANOVA and Duncan's multiple range tests.

SIGNIFICANCE

Immediately following light activation, the upper layers of each material were harder than the deeper layers, but the degree of cure in the deeper layers improved over time. VariGlass was the only material in which bottom hardness (5mm) and top hardness remained significantly different at 1 d, suggesting that VariGlass has less effective chemical-cure mechanisms than the other materials tested.

Shear bond strengths of composite to dentin using six dental adhesive systems

The development of adhesive agents for bonding composite to dentin has rapidly evolved in recent years. It is postulated that dentin bond strengths in the range of 17 MPa are sufficient to resist the polymerization shrinkage of composite resins. The purpose of this study was to evaluate the shear bond strengths of the following dentin adhesive systems: All-Bond 2 (Bisco), Imperva Bond (Shofu), Optibond (Kerr), Permagen (Ultradent), ProBond (Caulk/Dentsply), and Scotchbond Multi-Purpose (3M). Sixty human molars (10 per group) were mounted in phenolic rings, and the occlusal surfaces were flat ground in dentin to 600 grit. The prepared dentin bonding sites were treated according to the directions for each of the systems evaluated. A gelatin capsule technique was used to bond Bis-Fil composite cylinders to the teeth. The specimens were stored in water at 37 degrees C for 24 hours. Mean shear bond strengths were as follows: Scotchbond Multi-Purpose: 23.1 +/- 2.6 MPa, All-Bond 2: 21.4 +/- 7.8 MPa, Imperva Bond: 19.8 +/- 6.1 MPa, Optibond: 19.7 +/- 3.6 MPa, ProBond: 16.3 +/- 4.5 MPa, and Permagen: 16.2 +/- 3.0 MPa. There was not a significant difference (P<0.05) in the bond strengths of Scotchbond Multi-Purpose, All-Bond 2, Imperva Bond, and Optibond. The bond strengths of Scotchbond Multi-Purpose and All-Bond 2 were significantly greater (P<0.05) than ProBond and Permagen. Current-generation dentin adhesive systems have approached or exceeded the theoretical threshold value to resist contraction stresses during polymerization of resin materials.

Short-term fluoride release/uptake of glass ionomer restoratives

OBJECTIVES

The short-term fluoride release/uptake of four glass ionomer restoratives was measured and compared to the fluoride release after exposure to three commercial fluoride gels.

METHODS

Materials tested were: 1) Ketac-Fil (ESPE GmbH); 2) Ketac-Silver (ESPE GmbH); 3) Photac-Fil (ESPE GmbH); and 4) Fuji II LC (GC Corp.). Twenty discs of each material were fabricated and stored in deionized water at 37 degrees C. Initial fluoride release was measured at 24 h intervals for 7 d, and 24 h intervals at the end of each week for 5 wk. After 6 wk, samples were divided into groups and each group was treated for 6 min with one of the following commercial fluoride gels: acidulated phosphate fluoride (APF), neutral sodium fluoride (NaF), and stannous fluoride (SnF2). Control specimens were placed in deionized water. After exposure, fluoride measurements were carried out at 24 h intervals for 7 d, and 24 h intervals at the end of 2 wk. Fluoride exposure was repeated, and measurements were again recorded over 3 wk.

RESULTS

Initial fluoride release by all materials was highest during the first 24 h and decreased sharply over the first week. After exposure to APF, fluoride release increased significantly for all materials. Exposure to NaF also resulted in increased fluoride release for all materials although it was not as high as the increase recorded after exposure to APF. Exposure to SnF2 did not result in significant fluoride release by any material.

SIGNIFICANCE

The results of this study suggest that certain fluoride gels may replenish fluoride within some glass ionomers and thus prolong their cariostatic potential.

Bonding to enamel and dentin: a brief history and state of the art, 1995

The acid-etch technique for bonding composite resins to enamel has revolutionized the practice of restorative dentistry. The ability of clinicians to bond restorative materials to enamel has fundamentally changed such diverse areas as cavity preparation, caries prevention, and esthetic treatment options. Although bonding of resin to dentin has proved to be a difficult challenge, ongoing advances are improving the reliability and predictability of dentinal adhesion. The purpose of this article is to provide a brief history of enamel and dentinal bonding, as well as an overview of the current state of the art.

Review of the 1994 dental materials literature

OBJECTIVES

Electronic databases provide strong support for research and education literature searches. However, there is still some lag in time between publication and updates of the database. The objective of this summary was to identify and categorize the 1994 dental materials scientific literature that dealt with restorative dentistry.

METHODS

Seventeen primary journals were manually searched via the Tables of Contents and 88 secondary journals were manually or electronically searched. Dental materials citations were categorized into 15 major sections and several subsections, excluding case reports and literature primarily related to dental implants or biomedical materials outside of dentistry.

RESULTS

Nearly twelve hundred citations were identified, the largest number being associated with composites and glass ionomers.

SIGNIFICANCE

This list provides a comprehensive source for review by academicians and researchers to bridge the gap between initial publication and electronic citation.