The Repair of Resin-Modified Glass Ionomers with Bulk-Fill Flowable and Packable Composites using the Eight-Generation and Universal Dentin Bonding Agents

Background: To investigate shear bond strength regarding the repair of resin-modified glass ionomers (RMGIs) with bulk-fill flowable and packable composites using eighth-generation and universal dentin bonding agents. Materials and Methods: One-hundred-fifty specimens were prepared using polymethylmethacrylate-resin injected into preformed cylinders. Inverted recessed holes with convergent walls 4 mm deep and 4 mm wide were created using Operative Friction Grip 330L and inverted diamond burs. These holes were used as reservoirs for RMGI II LC. The resulting RMGI specimens were roughened with medium coarse diamond burs and placed in distilled water for 24 hours at 37o C to remove debris. RMGI surfaces were etched with 37% phosphoric acid for 20 seconds, rinsed with copious water, and air-dried without desiccation. Each RMGI specimen was placed in an Ultradent bonding clamp in preparation for adding the tested material. Specimens were divided into 6 groups: (1) Bulk-fill flowable composite (BFF) no adhesive (control), (2) Packable composite (PC) no adhesive (control), (3) BFF + iBond, (4) BFF + Futurabond-DC, (5) PC + iBond, and (6) PC + Futurabond-DC. Shear bond Strength was determined using an Ultra Tester Machine. Results: The SBS among and between groups were statistically assessed with repeated measures multivariate analysis of variance (MANOVA). The Tukey honestly significant difference test with an alpha level of 0.05 was used for post-hoc testing. Repeated measures MANOVA indicated that there were important differences between groups (Wilk's lambda, P < 0.0001), with BFF + Futurabond-DC resulting in the highest SBS. Conclusion: The study indicates that BFF combined with eighth-generation dentin bonding adhesive is a reliable method for the repair of RMGIs.