Repair Bond Strength and Leakage of Non-Aged and Aged Bulk-fill Composite

Purpose: This study evaluated repair protocols of a non-aged and aged bulk-fill composite in terms of bond strength and leakage. Materials and Methods: Ninety-six bulk-fill resin specimens were constructed; half were submitted to thermocycling. Specimens were divided into six groups (n = 16) according to the repair treatments: CG: no repair (control group); Ad: adhesive; DbAd: abrasion with diamond bur + adhesive; SbAd: sandblasting + adhesive; DbSiAd: abrasion with diamond bur + silane + adhesive; and SbSiAd: sandblasting + silane + adhesive. Resin blocks were bonded to the treated surfaces to simulate repair, and the specimens were submitted to microtensile bond strength testing. The failure area was evaluated under a stereomicroscope (40X magnification), and leakage after specimen immersion in silver nitrate solution for 24 h was evaluated under a microscope (200X magnification). Three-way ANOVA (surface treatment, chemical agent, aging) and Tukey's test were performed. Results: Ad and DbAd groups showed the lowest bond strengths, while Ad was the only group negatively influenced by aging. The other groups were statistically similar to the CG in both conditions. All groups exhibited leakage, but groups without silane presented a greater percentage of leakage, mainly when diamond burs were used. Thermocycling did not influence leakage, nor did surface treatment in groups with silane. Conclusion: For composite repair, the use of silane is recommended, mainly when diamond burs are used as a mechanical surface treatment. Keywords: aging, composite resins, repair, sandblasting, silane