Argon Plasma Effect on Bond Strength of Bulk-fill Composite Repair

Objectives: This study evaluated the effect of atmospheric pressure plasma (PL), sandblasting with aluminum oxide (SA), and their combination on the bond strength of fresh bulk-fill resin composite to water-aged restorative bulk-fill resin composite.
Methods: Forty pre-polymerized composite plates (13 mm long x 6,5 mm wide x 3 mm thick) were fabricated using Filtek Bulk Fill Posterior Restorative (3M ESPE) and stored in distilled water for 4 months. The aged plates were polished with 600-grit SiC paper and assigned to the following groups: 1- SA (50 μm) for 10 s; 2- PL (for 30 s); 3- SA + PL and 4- SA + silane + hydrophobic adhesive resin (control). After treatments, a silicon mold was used to construct a bulk-fill composite resin cylinder (1.5 mm high, 1.5 mm diameter) on each aged composite plate. Following water storage for 24 hours, samples were submitted to shear bond testing. Data were expressed in MPa (n = 6) and statistically analyzed by one-way ANOVA and Tukey test (α=0.05).
Results: Mean (SD) bond strengths were (in MPa): 1- 7.0(2.3)b; 2- 4.6 (1.8)c; 3- 5.6(1.2)bc and 4- 18.1(2.2)a. The highest bond strength of fresh bulk-fill composite to water-aged bulk-fill resin composite was obtained for control group, followed by SA, SA + PL and PL application.
Conclusions: The conventional method to repair composites that included SA, silane and hydrophobic adhesive resin yielded the highest bond strength of fresh bulk-fill composite to water-aged bulk-fill resin composite. PL alone and its combination with SA were not beneficial as control.