The effect of various surface treatments and bonding agents on the repaired strength of heat-treated composites

Statement of problem. Some clinical situations may require the repair of a secondary polymerized or aged composite. The higher indirect resin conversion rate may prove to be a disadvantage if a repair procedure based on covalent bonding from unreacted methacrylate groups is attempted. Purpose. This study evaluated the effectiveness of different combinations of surface treatments and 2 bonding agents used to enhance heat-polymerized and aged composite repairs. Material and methods. Ninety Herculite XRV and 90 Heliomolar Radiopaque specimens were prepared and then postpolymerized and stored for 4 weeks. All composites were subjected to 1 of 9 treatment regimens that involved adding fresh composite onto a corresponding postpolymerized composite (Herculite/Herculite or Heliomolar/Heliomolar). The surfaces were treated with different combinations of air abrasion, phosphoric acid, hydrofluoric acid, acetone, Special Bond II, Heliobond, and Prime & Bond 2.0. Results. Surface treatment with air abrasion resulted in the strongest repairs; surface treatment vith phosphoric acid resulted in the weakest repairs. Conclusion. The use of air abrasion and Prime & Bond 2.0 adhesive consistently improved the shear bond strength for both composites tested.