Effect of erosive and abrasive challenges on the bond strength and marginal degradation of composite restorations

Abstract

Purpose: To evaluate the microtensile bond strength (μTBS) and the presence of marginal gaps (MG) on composite restorations submitted to erosive and abrasive challenges. Methods: Seventy bovine incisors were sectioned in two halves; one half was used for the μTBS assay and the other for the MG measurement. For μTBS, the dentin on the incisal edge was exposed, the adhesive system was applied (Single Bond 2), and composite blocks were built (Filtek Z250). For MG, two rounded-shaped cavities were prepared and restored with the same materials. Specimens (n=10/μTBS and n=10/MG) were distributed into 7 groups: G1 – control; G2 – abrasive challenge (2 brushing cycles, for 35 days); G3 – erosive challenge (two 90 s immersions into 20 mL of a citric solution, for 35 days); G4, G5, G6, and G7 – abrasive challenge performed 0, 15, 30 or 60 min before the erosive challenge. Beamshaped specimens were tested for μTBS until failure. MG was measured by means of qualitative scores, recorded in 8 regions from the margin. Results: No significant differences in μTBS means or MG scores were detected among the tested experimental groups. Conclusion: The abrasive and erosive challenges were not able to affect the bond of a conventional two-step adhesive system to tooth substrates.