Effect of protective coating on marginal integrity of nanohybrid composite during bleaching with carbamide peroxide: A microleakage study.

ABSTRACT

Aim: The aim of the study was to evaluate the microleakage on the marginal integrity of nanohybrid composite during bleaching with carbamide peroxide after applying a protective coating of G‑Coat plus (GC, Japan). Materials and Methods: Class V cavities were prepared and restored with nanohybrid composite restoration in 60 freshly extracted noncarious premolars extracted for orthodontic reasons. Then they were divided into 3 groups. Group 1 ‑ bleaching with carbamide peroxide without G coat plus (n = 20), Group 2 ‑ bleaching with carbamide peroxide with G‑Coat plus (n = 20), Group 3 ‑ without bleaching procedure (n = 20) (control group). In Group 2, G coat plus was applied over the restorative surface and margins. Then all teeth in Groups 1 and 2 were taken and mounted in dental stone. Bleaching trays were custom fabricated over the cast with the help of a heated vacuum‑forming machine. 10% carbamide peroxide (opalescence PF) was applied over the tooth, and the bleaching process was done for about 2 weeks. Then all samples underwent thermocycling and were then immersed in the 2% methylene blue solution for 24 h and observed under a stereomicroscope to evaluate the amount of dye penetration. Data were compared using Kruskal–Wallis test and Mann–Whitney test using SPSS Inc.; Chicago, IL, USA, Version 17.0. Results: Mann–Whitney test shows that the difference in microleakage between Group 1–Group 2 and Group 2–Group 3 is statistically significant (P < 0.05). Conclusion: Significant reduction in microleakage was seen in Group 2 when compared to other groups.