Effect of nano-filled protective coating on the microleakage resistance of a nanocomposite during bleaching treatment

This in vitro study aimed to examine the effect of a nano-filled protective coating material on microleakage of a nanocomposite resin during bleaching treatment. Standardized class V cavities were prepared in the middle third of the buccal surfaces of ninety human incisors and restored with two-step etch-and-rinse adhesive and nano-hybrid composite for three groups (n = 30). In Group A, the restorations were covered with coating material G-Coat Plus and bleached with 10% carbamide peroxide. In Group B, the teeth were only bleached. In Group C, no bleaching or coating material was applied. In Group A and B, bleaching was performed 8h/day for 14 days. The marginal adaptation of tooth-restoration interfaces was examined by SEM. Microleakage was assessed by dye penetration on sectioned specimens under stereomicroscopy. Marginal gap and microleakage were analyzed respectively by independent-samples t-test and Kruskal-Wallis test (p = 0.05). Application of bleaching treatment increased the percentage of interfacial gaps for Group B and C (P<0.01). When Group B and C were compared, bleaching increased the microleakage (P<0.01). The lowest microleakage was found in Group A (P<0.01). The application of resin coating material on the surface a nanocomposite restoration may effectively reduce micro-leakage and gap formation before bleaching treatment.

Automated summary

This in vitro study found that the application of a resin coating material on the surface of a nanocomposite restoration can effectively reduce microleakage and gap formation before bleaching treatment.