Repair Bond Strength of Aged Composite Using Argon Plasma

Objectives: This study evaluated the effect of atmospheric pressure plasma (PL), sandblasting with aluminum oxide (SA), silanization (SI) and hydrophobic adhesive resin (HR) applications, and their combinations on the bond strength of fresh resin composite to water-aged restorative resin composite.
Methods: Seventy pre-polymerized composite plates (15 mm long x 8 mm wide x 3 mm thick) were fabricated using Filtek Supreme Ultra composite and stored in distilled water for 4 months. The aged plates were polished with 600-grit SiC paper and assigned to the following experimental groups: 1- untreated; 2- SA + SI + HR; 3- HR; 4- PL + HR; 5- SA + HR; 6- SA + PL + HR and 7- PL. After treatments, a silicone mold was used to construct a 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=10) and statistically analyzed by two-way ANOVA and Tukey test (α=0.05).
Results: Mean (SD) bond strengths were (in MPa): 1- 2.1(0.5)a; 2- 27.4 (2.6)b; 3- 23.1(4.0)b; 4- 23.2(3.7)b; 5- 28.8(2.7)b; 6- 23.5(4.9)b and 7- 5.3(1.7)c. The lowest bond strengths of fresh composite to water-aged resin composite were obtained for untreated group and PL application (group 7). Remaining groups showed higher bond strength and no statistical difference among them.
Conclusions: While argon plasma used with other methods did not reduce composite repair strength, it alone was not as beneficial as other methods that included a hydrophobic adhesive resin.