Microleakage of Class II resin-based composite restorations with flowable composite in the proximal box.

PURPOSE: To compare microleakage of Class II hybrid resin-based composite (RBC) restorations with and without low viscosity (flowable) RBC in the proximal box. MATERIALS AND METHODS: Conservative Class II cavity preparations were made in 50 extracted premolars randomly assigned to five groups (n = 10). OptiBond FL dentin bonding agent, and Prodigy hybrid RBC were used to restore all cavity preparations. Preparations in four of the five groups were restored with flowable RBC as the initial increment in the proximal box. The four flowable RBCs tested were: AEliteFlo, Revolution, UltraSeal XT and Flow-It. In the control group, the entire preparation was restored only with hybrid RBC. Specimens were stored in water at 37 degrees C for 24 hrs after restoration, thermocycled 1,000x, immersed in 2% basic fuchsin, sectioned and evaluated for microleakage. Microleakage was scored on a 0-4 scale. RESULTS: Non-parametric Kruskal-Wallis one-way ANOVA followed by Wilcoxon signed ranks test was used for statistical analysis. The use of any of the four flowable RBCs tested did not influence microleakage significantly (P > 0.05) in Class II RBC restorations.