Role of bonding agents in the repair of composite resin restorations.
ABSTRACT Six commonly used composite resin materials and recommended bonding systems were tested to assess shear bond strength at the interface between aged and new composites with and without bonding. Test specimens were aged in water for 60 d before new composite was placed. Shear bond strength was assessed after 22 ± 2 h (Test 1) and after additional ageing by thermocycling (5-55°C/5,000 cycles) (Test 2). After an additional 180 d in water, the aged specimens were randomly divided into three groups to blind the test with respect to the aged composite. New composites were placed on aged specimens (two groups with and one without bonding agent) and thermocycled (Test 3). After 24 h (Test 1), the mean shear bond strength of the test specimens was 21-26 MPa when bonding agents were used, as opposed to 10-15 MPa without bonding agents. After thermocycling (Test 2), the mean shear bond strength was 16-23 MPa with a bonding agent and 17 MPa without a bonding agent. After 180 d in water and subsequent thermocycling (Test 3), the mean shear bond strength was 9-13 MPa with bonding agent and 2-3 MPa when no bonding agent was used. The results of this study therefore indicate that the use of bonding agents significantly improves the quality of composite repair.
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ABSTRACT: Contamination between incremental layers of a composite resin restoration can occur during surgical procedures. The present study sought to evaluate how two decontamination treatments affected the shear bond strength between layers of a saliva-contaminated composite resin surface. Forty disks of a nanohybrid composite resin were prepared and divided into four groups (n = 10). The surfaces of all specimens (except for samples in Group 1, the positive control) were contaminated with human saliva. For the negative control samples (Group 2), no decontamination was performed. For Group 3 samples, acid etching was performed and adhesive was applied. For Group 4, surfaces were roughened with a diamond bur prior to acid etching and adhesive application. The specimens were submitted to a shear bond strength test, and the data were analyzed using one-way ANOVA and Tukey tests (α = 0.05). No significant differences were detected between the mean shear bond strengths of samples in Groups 1, 3, and 4 (p < 0.05). Shear bond strength was significantly reduced in Group 2 samples (p < 0.05). Acid etching and the application of adhesive improved shear bond strength, producing values similar to those in the positive control group.General dentistry 09/2012; 60(5):e312-4.