Shear bond strengths of one-bottle adhesives to oil-contaminated enamel

Bonding agent underneath sealant: shear bond strength to oil-contaminated

This study evaluated in vitro the shear bond strength of a resin-based pit-and-fissure sealant (Fluroshield - F) associated with either an ethanol-based (Adper Single Bond 2 - SB) or an acetone-based (Prime & Bond - PB) adhesive system under conditions of oil contamination. Mesial and distal enamel surfaces from 30 sound third molars were randomly assigned to 2 groups (n=30): I - no oil contamination; II - oil contamination. Contamination (0.25 mL during 10 s) was performed after 37% phosphoric acid etching with an air/oil spray. The specimens were randomly assigned to subgroups, according to the bonding protocol adopted: subgroup A - F was applied to enamel without an intermediate bonding agent layer; In subgroups B and C, SB and PB, respectively, were applied, light-cured, and then F was applied and light-cured. Shear bond strength was tested at a crosshead speed of 0.5 mm/min in a universal testing machine. Means (+/- SD) in MPa were: IA-11.28 (+/-1.84); IIA-12.02 (+/-1.15); IB-9.73 (+/-2.38); IIB-9.62 (+/-2.29); IC-28.30 (+/-1.63); and IIC-25.50 (+/-1.91). It may be concluded that the oil contamination affected negatively the sealant bonding to enamel and the acetone-based adhesive system (PB) layer applied underneath the sealant was able to prevent its deleterious effects to adhesion.

Influence of handpiece maintenance sprays on resin bonding to dentin

OBJECTIVE

To investigate the influence of maintenance spray on resin bonding to dentin.

MATERIALS AND METHODS

The crown of extracted, caries-free human molars was transversally sectioned with a model trimmer to prepare the dentin surfaces from mid-coronal sound dentin, and then uniformly abraded with #600 silicon carbide paper. The dentin surfaces were randomly divided into three groups: oil-free spray group where maintenance cleaner for air bearing handpieces was sprayed onto the dentin surface for 1 s and rinsed with water spray for 30 s; oil-containing spray group where maintenance cleaner for micro motor handpieces was sprayed onto the dentin surface for 1 s and rinsed with water spray for 30 s; and control group where the surface was rinsed with water spray for 30 s and then air-dried. These surfaces were then bonded with Clearfil SE Bond (Kuraray Medical), and resin composite (Clearfil AP-X, Kuraray Medical) build-up crowns were incrementally constructed on the bonded surfaces. After storage for 24 h in 37°C water, the bonded teeth were sectioned into hour-glass shaped slices (0.7-mm thick) perpendicular to the bonded surfaces. The specimens were then subjected to microtensile bond strength (μTBS) testing at a crosshead speed of 1.0 mm/min. Data were analyzed with one-way ANOVA and the Tukey-Kramer test.

RESULTS

Maintenance spray-contaminated specimens (oil-free and oil-containing spray groups) showed significantly lower μTBS than control specimens (P < 0.05). However, there was no significant difference between the spray-contaminated groups (P > 0.05).

CONCLUSION

Maintenance spray significantly reduces the bond strength of Clearfil SE Bond to dentin.

The influence of dental unit waterline cleaners on composite-to-dentin bond strengths

BACKGROUND

One approach to controlling dental unit waterline (DUWL) contamination by microorganisms is the addition of chemical cleaners to the treatment water. Yet, there is concern that these cleaners might affect the bonding of resin-based composites to enamel and dentin. The authors evaluated the influence of DUWL cleaners on composite-to-dentin bond strengths.

METHODS

The authors tested the strength of resin-based composite bonded to dentin in specimens treated with distilled water (control) or one of four cleaners. They tested a total-etch adhesive, a self-etching primer/adhesive and an experimental self-etching primer/adhesive. The authors stored the specimens for 24 hours at 37 C and tested them to determine their bond strengths.

RESULTS

The mean shear bond strengths (SBSs) varied according to the cleaner and adhesive used, ranging from 14.7 to 21.9 megapascals. However, the authors found no statistically significant differences and/or interactions between mean SBSs of specimens treated with the various DUWL cleaners and adhesives (P > or = .05).

CONCLUSIONS

The tested DUWL cleaners did not significantly influence composite-to-dentin bond strengths for the total-etch adhesive and self-etching primer/adhesives used in this study.

CLINICAL IMPLICATIONS

The conclusions imply that bonding of resin-based composites to dentin is not affected by the cleaners tested when they are used to treat DUWL contamination.

Influence of a 3-step tooth disinfection procedure on dentin bond strength

STATEMENT OF PROBLEM

Clinicians have used disinfection materials to remove surface contaminants during cavity preparation. It has been postulated that disinfection materials may negatively affect shear bond strength of restorative materials. If so, large numbers of restorations may be predestined for early failure with the use of a disinfection protocol.

PURPOSE

The purpose of this study was to determine whether there is a difference in the bond strength between dentin and resin composite with a 3-step disinfection technique compared to a conventional bonding technique without the additional disinfection protocol.

MATERIAL AND METHODS

Sixty human molar teeth were sectioned parallel to the occlusal surface to expose mid-coronal dentin and mounted parallel to a bond shearing device on a universal testing machine and divided into 2 groups. In the 3-step disinfection group (n = 30), specimens were treated with chlorhexidine, Tubulicid red, and sodium hypochlorite before dentin bonding, following the manufacturer's instructions for All Bond 2. In the control group (n = 30), specimens were treated only with the bonding protocol of All Bond 2. To ensure a uniform bond surface area, core paste was syringed into a cylindrical mold (2.38-mm diameter and 2.00-mm height) that was in contact with the dentin bonding surface of each specimen and allowed to polymerize under constant force. All specimens were subjected to fracture by shear loading in a universal testing machine at a uniform crosshead speed of 0.05 mm per minute and expressed as MPa. Statistical analysis was performed using the Student t test (alpha = .05). The mode of failure was noted after a visual examination using a light microscope under x30 magnification. Failures were recorded as adhesive, cohesive or mixed, and statistical analysis was performed using a chi-square of homogeneity (alpha = .05).

RESULTS

A significantly higher shear bond strength was found for the 3-step disinfection group (mean shear bond strength, 25.3 +/- 4.6 MPa) compared to the control group (mean shear bond strength, 20.5 +/- 3.4 MPa) (P < .0001). Most failures were adhesive for the control group, but the fracture modes were evenly divided for the 3-step disinfection protocol group. A chi-square test of homogeneity showed a value of 12.3, df = 2, P = .0012.

CONCLUSIONS

The 3-step disinfection technique group showed a significantly stronger dentin shear bond strength compared to the conventional bonding technique without disinfection.

Effects of saliva contamination on resin-resin bond strength

OBJECTIVE

The purpose of this study is to evaluate the effects of saliva contamination on microtensile bond strength (microTBS) between resin interfaces and to determine which decontamination methods best re-established the original resin-resin bond strength.

MATERIALS AND METHODS

Ninety-six light-cured resin composite cylinders of Z-250, Renew, Clearfil APX, and Pertac II were randomly divided into six groups. For each material, one group of specimens was not contaminated, serving as the control. For the other specimens, the top surface of each block was treated with saliva that was slowly dried (Treatment 1); dried forcefully (Treatment 2); slowly dried, rinsed, and dried (Treatment 3); slowly dried, rinsed, dried, and bonded with Single Bond, One-Step, Clearfil SE Bond, or Prompt L-Pop (Treatment 4); or slowly dried, but not rinsed, and bonded using the same adhesives (Treatment 5). Two 2-mm increments of resin composite were applied and light-cured. After 24 h, the assemblies were trimmed for microtensile bond testing and were loaded to failure at 1 mm/min. Data were analyzed using two-way and one-way ANOVA and Fisher's PLSD (p<0.05).

RESULTS

Control values ranged from 45.1 MPa for Pertac II to 71.5 MPa for APX. Treatment 1 caused significant reduction in resin-resin bond strength for all materials tested but for two of the materials in treatment 2. Pertac II was the only material that did not show a statistical difference from control group for treatment 3. Treatment 4 re-established the control values for Z-250 and Renew and treatment 5 was the only one to show no statistical difference for all materials tested. SEM observation revealed a smooth surface in treatment 1, but treatment 3 showed a few craters. Treatment 4 and 5 showed a mixture of cohesive failure in the composite and adhesive.

SIGNIFICANCE

The most reliable method for decontaminating saliva from resin surfaces involves the application of adhesives.